# Bokeh comparison 24-70 f/2.8 vs 24-105 f/4



## zerotiu (May 30, 2011)

I want to buy a semi all around zoom lens for travelling which has good image quality. I've planned this for a long time but I still stick to the prime lens mostly  because I'm not sure whether 24-105 is good one or not.

I've searched this on google. I find that some people say that the bokeh quality of 24-105 is good enough but others say that it has 'spikey' bokeh. I know 24-70 f/2.8 definitely has better quality from 24-105 but the weighs will kill me slowly (950 grams?). I like to shoot from low angle, so I'll think this very carefully. I've tried the 24-70 on 60d / 550d but I never try 24-105. 

Also I find this one very confusing : 'small aperture (f/2.8) will help us to take children photos. IS is useless'. 
I know IS doesn't do anything to capture moving objects, but can we just increase the ISO to get faster shutter speed? I mean when it's still in a good acceptable range (ISO 200-1600 maybe).

Please share your blurry images to me. I tend to pick 24-105 because the weighs,IS,and more range but if the bokeh quality and image quality of 24-70 is very very very very very far more superior than 24-105, than I'll think about this again.

Thanks

* I will place one that I pick on 5ds (5d3 : )


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## Flake (May 30, 2011)

Both of these lenses are designed for FF cameras, the short end on a crop camera is not wide angle, but there's another drawback. On FF f/2.8 is just about fast enough to begin developing a bokeh on crop it's never going to develop like a fast prime will, obviously the F/4 is worse.

Photozone shows examples of the Bokeh of each lens it tests so it's worth a visit, unfortunately they didn't start including it on the crop tests so you'll have to view the FF ones.

Not saying where in the world you are going to, and at what time of year makes a reccomend impossible! There's a big difference between Stockholm in January & Jeddah in June!

The 24 - 70mm f/2.8 L is a fantastic lens - if you can get a good copy and there are many out there which aren't, for me though the lack of IS and an extra 35mm makes it a no brainer. It's quite a bit cheaper too, so there's enough change to buy a 50mm f/1.8 which will develop a bokeh properly on a crop frame. Image quality of the 24 - 70mm is better, but not massively so I'd be more concerned about losing the wide angle though and the 17 - 55mm EF-s IS f/2.8 is worth considering, Sigma do a very good competitor which would save you some money, do consider those.


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## zerotiu (May 30, 2011)

I will put 24-70 or 24-105 on FF body, please ignore the crop body things.

I know that we can't compare the bokeh quality on crops sensor vs FF. FF body has shallower DOF, bigger sensor, and more vivid. That's why I want to change to FF body.

and yes, I've had 50mm and 85mm ( f/1.8 ) and I'm sure I'll change to prime lens when I want to take portrait shoot


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## Cornershot (May 30, 2011)

Bokeh is going to be better on the 24-70 but a more important thing to consider is how you want to use the lens. Are you shooting a lot of night, indoor, low light shots? Or are you mainly shooting in the bright day? The 24-70 is going to give you better all around, all condition performance but the 24-105 is going to give you that added zoom. You can just get the former and also carry a long prime like a 100 f2, which is pretty light and relatively cheap.


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## zerotiu (May 30, 2011)

Cornershot said:


> Bokeh is going to be better on the 24-70 but a more important thing to consider is how you want to use the lens. Are you shooting a lot of night, indoor, low light shots? Or are you mainly shooting in the bright day? The 24-70 is going to give you better all around, all condition performance but the 24-105 is going to give you that added zoom. You can just get the former and also carry a long prime like a 100 f2, which is pretty light and relatively cheap.



I want to say that if I need the best image quality, I'll switch to prime lens (even 24-70 can't beat the sharpness of prime lens, can it? :-* )

I will use the lens (24-70 or 24-105) for travelling, shooting group indoor (if it is portrait, again I'll switch to 85 or 50).

The main idea is : Is 24-105 has the worst bokeh quality if it is compared with other zoom lens? Is the bokeh quality unacceptable?

that's why I like to see example images of 24-105 f/4 vs 24-70 f/2.8 (the other forum show this comparison on a crop body, so it's different, I can't use it as a standard)

I appreciate all images which are shared


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## Flake (May 30, 2011)

You haven't looked at Photozone have you?

The Canon EF 24-105mm L is capable of producing a pleasing bokeh for a zoom lens. The circular out-of-focus highlights show a slight halo effect at 105mm f/4. Stopping down to f/5.6 reduces the effect but it's not overly worrisome anyway. The out-of-focus blur is very smooth and nothing to worry about (at 105mm). However, regarding its rather moderate max. aperture the 24-105mm L isn't really suitable for shallow depth-of-field applications. 

The EF 24-70mm is a comparatively "fast" lens thanks to its max. aperture of f/2.8. It's surely not as capable as tele prime lenses but you can achieve a quite shallow depth-of-field specifically at 70mm so let's have a look at the bokeh (out-of-focus) quality now. 
The background blur is very smooth and buttery resulting in a very pleasing bokeh in many "mainstream" scenes. However, the foreground blur isn't quite as harmonious. Out-of-focus highlights show a near circular shape at large aperture settings but the inner zone of these "discs" is quite busy/nervous (see also the "meadow" in the sample image section). All-in-all the bokeh may not be flawless but it's still decent for a standard zoom lens (such lenses are rarely perfect here). 

It used to be the case that prime lenses were better than primes, however now this is just an outdated myth, lenses like the 70 - 200mm f/2.8 IS L MkII will outperform most of the primes in its focal length and equal the others. Computer design has led to huge improvements in the quality of zoom lenses, the problem in Canons range is that most of the primes are rather elderly designs, and one of the issues they really don't perform well is the corners & borders on FF. A certain native sharpness is sufficient, it really doesn't matter is one lens is sharper than another you have the unsharp mask to equalise this. If you really do want sharpness don't buy a 5D MkII ! buy a Lecia M8.

It might be said that there is a line in the sand as to what level of quality is acceptable, any more than this is vanity for pixel peepers. No one else in reality is going to say Oh look at the quality of that lens! You will be remembered for quality of the photographs you produce and not the quality of the equipment you use!


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## zerotiu (May 30, 2011)

my bad, I didn't see the next page button.

You guys help me a lot, maybe I will stick to 24-105 1st. 4/3 cameras have better image quality after I've read, but DSLR is more fast and versatile with the continous shoot


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## YoukY63 (May 30, 2011)

Here is a sample of 24-105 f/4L bokeh (on 5DmII).

In my opinion this zoom lens produces a very nice bokeh (for a zoom  ).




IMG_5248 par YoukY63, sur Flickr


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## Flake (May 30, 2011)

Sorry Youky but that image doesn't show any Bokeh, it's mildly out of focus. Unfortunately the image doesn't include any Exif data, but I suspect you shot this around f/5.6 - 6.3 ?


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## neuroanatomist (May 30, 2011)

I find the 24-105mm to be a very versatile lens on FF as a general purpose zoom. It does manage to produce a decent bokeh, too. Here are a couple of additional examples:




EOS 5D Mark II, EF 24-105mm f/4L IS USM @ 105mm, 1/60 s, f/4, ISO 400




EOS 5D Mark II, EF 24-105mm f/4L IS USM @ 105mm, 1/125 s, f/4, ISO 400


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## Admin US West (May 30, 2011)

neuroanatomist said:


> I find the 24-105mm to be a very versatile lens on FF as a general purpose zoom. It does manage to produce a decent bokeh, too. Here are a couple of additional examples:



Beautiful children. They'd look great with any camera!!


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## zerotiu (May 30, 2011)

wow...lovely 

@neuro , I do believe that you have 24-70 as well, can you share the image results ?


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## Cornershot (May 30, 2011)

Here's an example from a 24-70. f2.8 at 2000/sec.


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## Mencho(22) (May 31, 2011)

Here are some examples of the 24-70mm


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## neuroanatomist (May 31, 2011)

zerotiu said:


> wow...lovely
> 
> @neuro , I do believe that you have 24-70 as well, can you share the image results ?



Thanks! 

Sorry, but I don't have the 24-70/2.8. I do have the 16-35/2.8 II and the 70-200/2.8 IS II. Since I have the very capable 24-105, and excellent primes for portraits (85/1.2 II, 135/2) and low-light situational shooting (35/1.4), I've been holding out for an IS version of the 24-70 (i.e. I don't really _need_ it - still might end up with the current one if no refresh occurs...).


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## awinphoto (May 31, 2011)

I think this conversation has ventured a bit off topic from the original question at hand... is the 24-105 a good compromise to the 24-70... A few years ago I had the same question and so i borrowed 2 lenses for a wedding (a night time wedding) and they were the 24-70 and 24-105. I put the 2 lenses from CPS in a series of tests (on how I shoot) and I went in knowing I was using flash as the wedding so low light wasn't a huge dealbreaker for me. While I wasn't thrilled that either lens extended while zooming (the 70 hid the zoom inside the hood while the 105 was visible) at the end of the day, I packed the 24-105 with me to the wedding and to go alongside my 17-40 for wides. Images quality, to me, came out to be a wash. I know the photozone people says it has some pincushioning, however in my tests, it really wasn't anything to lose sleep over. I didn't end up buying either because budget wise I couldn't justify it, however I do plan on being first in line with the 5D mark III comes out and that will also force me to buy the 24-105 as a standard lens, oh shucks... The 24-70 is a great lens, but at the end of the days its all on how you shoot. Go to your camera store and test them out. PS... bokeh is affected by so many factors including image capture size, proximity of lens to subject to background, aperture, magnification and MM of the focal length, etc... If bokeh is your main concern, there's so many other ways in pulling it off than just pure aperture


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## zerotiu (May 31, 2011)

awinphoto said:


> I think this conversation has ventured a bit off topic from the original question at hand... is the 24-105 a good compromise to the 24-70... A few years ago I had the same question and so i borrowed 2 lenses for a wedding (a night time wedding) and they were the 24-70 and 24-105. I put the 2 lenses from CPS in a series of tests (on how I shoot) and I went in knowing I was using flash as the wedding so low light wasn't a huge dealbreaker for me. While I wasn't thrilled that either lens extended while zooming (the 70 hid the zoom inside the hood while the 105 was visible) at the end of the day, I packed the 24-105 with me to the wedding and to go alongside my 17-40 for wides. Images quality, to me, came out to be a wash. I know the photozone people says it has some pincushioning, however in my tests, it really wasn't anything to lose sleep over. I didn't end up buying either because budget wise I couldn't justify it, however I do plan on being first in line with the 5D mark III comes out and that will also force me to buy the 24-105 as a standard lens, oh shucks... The 24-70 is a great lens, but at the end of the days its all on how you shoot. Go to your camera store and test them out. PS... bokeh is affected by so many factors including image capture size, proximity of lens to subject to background, aperture, magnification and MM of the focal length, etc... If bokeh is your main concern, there's so many other ways in pulling it off than just pure aperture



I will explain my question more detail. Actually my main concern is 'how good is the background can be blurred when I shoot my object /subject'. So it can be distinguished without making the background ugly. 

After reading your and other comments here, I've made a conclusion that 24-105 is a good lens with L series quality. 24-70 on the other hand has smaller aperture , slightly better image, and L series quality too.


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## dstppy (May 31, 2011)

Okay, I figure I'm going to get slapped for bringing this up, but on a crop body, why aren't more people recommending the 15-85 over the 24-105? 

I have both, and keep gravitating back to the 15-85 . . . sort of regretting the 24-105 purchase. It has occurred to me that the 15-85 was designed to be the 'crop version' of the 24-105, no?

Granted, I've taken only a few hundred photos with the L lens vs over 2000 with the 15-85.

"I will explain my question more detail. Actually my main concern is 'how good is the background can be blurred when I shoot my object /subject'. So it can be distinguished without making the background ugly. "

I think any f4 is capable of doing this (make it still distinguishable); the "ugly" you're talking about is what you get when you have a faster lens  You can still change the stop to get this effect on a faster lens as well.


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## Flake (May 31, 2011)

dstppy If you read one of my previous posts you'd see I reccomended the 17 - 55mm f/2.8 because background blur is an issue, and because it falls into roughly the same price bracket. the 15 - 85mm doesn't fit into either of these catagories. While on it's own it might be a good enough lens it just doesn't fit the OPs requirements.


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## awinphoto (May 31, 2011)

The 24-105 is more than capable of producing very nice images with nice bokeh. Some of the main complaints of the 24-105 are slight distortion at the 24 and pincussion at 150, however as I said, for most everyone, unless you shoot architecture and doing a lot of "photo stitching" then, that really isn't that big of a deal for 99% of everyday shots. The 24-70 is/was a very nice lens, but image quality, doing side by side shots in my studio for commercial work, when I tested them, I didn't see any appreciative difference between the 2 lenses to justify the extra weight and strain I would have to go through to use it and hand hold it (with my 2 camrea system). Dont fret about purchasing either lens. 

Regarding the 15-85 suggestion... There are a few reasons to choose the L over this lens and a few visa versa... first of all, in favor of the L (either one) is fully weather sealed and construction. The L's are built like a tank. Secondly, while I dont care one way or the other, but the constant F2.8/4 aperture throughout the range. On the 15-85 it's 5.6 at the 85 range vs on the 24-105, at the 85 range it's still F4. At the 105 range the L lens is a hair sharper all around. Lastly, it can work on any canon EF camera (crop or non-crop). If at any time you upgrade/borrow/whatever another camera you can be 100% sure you can still use your gear. 

Now with that said, the cheaper lens is still less weight, easier to hold, not as high profile, sharper in the corners at wide angle and compared to the two, should your 15-85 break you wouldn't be as much out of pocket as the 24-105 or the 24-70 for that matter. Keep in mind, Canon has and is using a 3 tier system on lenses... a cheap consumer lens, 15-55, a mid-range semipro lens, 15-85, and then pro series 24-105 or even the 17-55. They have this symmetry throughout the lens line up from the 50mm's, to 70-300's etc... They even do that for the cameras... rebels, xxd, xd. There's no knock on however uses the inexpensive versions however they are seen to be more of a jumping off tool or a reason to upgrade tool to get your feet wet and then start longing to upgrade.


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## zerotiu (May 31, 2011)

I will definitely take 24-105 before considering buying 24-70.. or maybe not , saving for more primes 
Thanks guys!


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## Act444 (May 31, 2011)

> Okay, I figure I'm going to get slapped for bringing this up, but on a crop body, why aren't more people recommending the 15-85 over the 24-105?



Well, I suppose it depends on the shooter, but the variable aperture is what kills it for me. I read a review on it and I think it said by the time you get to 50mm you're already at f5.6. No thanks...I'm willing to give up the wide end for more reach, a constant 4.0 aperture and IS which I think is a decent compromise that makes it a good travel/walkaround lens. 

Also nice to have better image quality, a sturdier product and higher resale value. But by all means, the 15-85 sounds like a fine lens- for those that demand it.


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## Cornershot (May 31, 2011)

For me the choice is simple. It isn't so much about which has better bokeh, though that's a nice thing to have. It's about light gathering and low light performance. The 24-70 will have much better low light focusing and better capability in darker scenarios. The focus on the 24-105 will hunt more in low light and require higher ISO, hence noise. 

In bright daylight, I'd go for the 24-105 because it probably is as good and offers more flexibility. The 24-70 isn't the end all. My 16-35 and 70-200 will out shoot the 24-70. Oh, how I love those two former lenses. But the 24-70 is the only viable all condition choice in that zoom range and with that aperture.


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## neuroanatomist (May 31, 2011)

zerotiu said:


> I will explain my question more detail. Actually my main concern is 'how good is the background can be blurred when I shoot my object /subject'. So it can be distinguished without making the background ugly.



So, are you talking about bokeh or not? Technically, there are two aspects to the out of focus blur you're talking about. One is quantity - how much OOF blur. That's a function of depth of field, which is determined by:

[list type=decimal]
[*]aperture
[*]focal length
[*]subject distance
[*]circle of confusion (i.e. sensor size)
[/list]

In practice, aperture is the primary determinant, since everything else gets normalized for by shot framing (e.g., if you want to take a tightly-framed head shot, you can frame it with a 135mm lens at 5' or an 85mm lens at 3' on FF, or an 85mm lens at 5' on APS-C, etc., but in all cases you're changing focal length, subject distance, and/or sensor size to compensate for the necessary framing, leaving aperture as the only independent variable). 

Depth of field determines the quantity of the OOF blur - thinner DoF (wider aperture) means more OOF blur. So, if that's what you mean by 'how good is the background can be blurred when I shoot my object /subject', the 24-70/2.8 will deliver _more_ OOF blur than the 24-105/4, for the same subject.

The other aspect is the quality of that OOF blur, and that's what 'bokeh' means. Is the OOF blur 'smooth' or 'jittery'? Are specular highlights round, and if so, are they uniform discs, or dimmer at the edges? Is the bokeh 'pleasing' or 'nervous'? Lots of subjective terms there, because in essence, bokeh is subjective. 

One easy way to evaluate bokeh is if there are specular highlights in the OOF area (there's more to bokeh than how the highlights are affected, but they're an easy way to judge). That's probably the reason Flake previously responses that the image posted by YoukY63 had no bokeh (it does, but there aren't any specular highlights in the OOF-blurred area).

So, the bottom line is that the 24-70 will produce more OOF blur than the 24-105, and both lenses have similarly good (but not great) bokeh. 



zerotiu said:


> After reading your and other comments here, I've made a conclusion that 24-105 is a good lens with L series quality. 24-70 on the other hand has smaller aperture , slightly better image, and L series quality too.



Getting the 24-105 means with f/4, you may have to work a little harder to ensure adequate physical separation between your subject and the background. At the other end of the spectrum, my 85mm f/1.2L II can blur out a background that's literally just behind the subject (e.g. a head resting on a pillow, the pillow is OOF) - but the trade off is you have to work to get both eyes in focus...


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## awinphoto (May 31, 2011)

As always I agree with Neuro's analysis however yes, the 24-70 will give MORE, no much, but more OOF than the 24-105. In a typical portrait, in practice an F4 will typically get most of the face if not all in focus... 2.8 you may get the nearest eye in focus with the second eye slightly OOF. Wider you go the more OOF you get. I think the original poster realizes if he wants and fully cares about bokeh, he wants and will need to get into fast primes... Also rememeber F4 to F2.8 is 1 stop, but on the same hand, it's only 1 stop. Will the 24-105 give you pleasing OOF WHEN you shoot in a situation to get good OOF? yes. I would even go as far as saying when applicable, the OOF area is as pleasing as the 24-70 when shot in situations where the OOF areas are similar. This once again falls into the situation of knowing what equipment you are using and being comfortable with your equipment when you need to. I would still recommend going to a camera store and testing the lenses out there... As long as the store is under the impression they're going to make a sale, i'm sure they will allow you as much time with the equipment as possible until you make your mind up. Then go home and buy online for cheaper, haha.


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## Flake (May 31, 2011)

Sorry Neuro but focal length does not affect DoF it's yet another myth which has been perpetuated, nor does subject distance.

http://www.luminous-landscape.com/tutorials/dof2.shtml

Magnification affects DoF which is why Macro has such a thin DoF & aperture, circles of confusion are not really anything to do with the sensor size, again that comes down to magnification, you need more to fill the frame on a FF camera.

In optics, a circle of confusion is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as disk of confusion, circle of indistinctness, blur circle, or blur spot.


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## awinphoto (May 31, 2011)

Flake said:


> Sorry Neuro but focal length does not affect DoF it's yet another myth which has been perpetuated, nor does subject distance.
> 
> http://www.luminous-landscape.com/tutorials/dof2.shtml
> 
> ...



While to a degree I agree with you and the link regarding focal length to the extent that yes, you take the 400mm and take the wide angle and zoom in tight to the same crop and perspective of the 400mm, all things being equal, if the lenses are good, the OOF should be the same, however as you can see with the full image, it is easier for the layman to physically see the OOF on the 400mm and it's harder for most people to conceptualize that if they get very close and crop to the same size, it will be the same. 

I do have to disagree about the subject to background not making a difference... macro you have a razor thin focal plane because you are focusing inches away from the lens. I shoot daily studio small product photography for a local company and at f8, at a distance of 12-18 inches, I only get a focal plane of about an inch, inch and a half. I dont dare go to F11-16 on the 50D because of the lens sweet spot and wider apertures will give me less than an inch focal plane. Distance of subject to foreground/background has EVERYTHING to do with bokeh. Why do you think the iphone has like 4-5 depth of field calculators... just so people can get focal plane info in a pinch while out in the field shooting.


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## neuroanatomist (May 31, 2011)

Flake said:


> Sorry Neuro but focal length does not affect DoF it's yet another myth which has been perpetuated, nor does subject distance.
> 
> http://www.luminous-landscape.com/tutorials/dof2.shtml



Sorry, Flake, but it's not a myth - it's fact. In the article you link, the author is changing the both focal length *AND* subject distance simultaneously (decreasing both focal length and subject distance), in order to keep subject size equivalent. This was, in fact, the point of my statement that aperture is the primary determinant, _in practice_, as in the example of the head shot. 

Pick the DoF calculator of your choice, e.g. DOFMaster, change only the focal length, and DoF changes. So yes, focal length affects DoF - but only if you keep other factors constant. To reiterate, in practice we _care_ about those other factors. If you just go by the numbers, you can get more OOF blur with the 24-105/4 than the 24-70/2.8. For example, I can frame a head shot with my 70-200/2.8 IS II at 70mm f/2.8, and then zoom in to 105mm and stop down to f/4 - and I'll get more OOF blur at 105mm f/4. But I won't have a head shot anymore, I'll have an eyes-and-nose shot, and I don't want that. So I'll have to walk backwards to frame the whole face at 105mm, and have less OOF blur (but if I stop down to f/2.8, I'll have the same OOF blur as at 70mm f/2.8, with increasing focal length and increasing distance effectively canceling each other out, again reducing it to a matter of aperture).



Flake said:


> Magnification affects DoF which is why Macro has such a thin DoF & aperture, circles of confusion are not really anything to do with the sensor size, again that comes down to magnification, you need more to fill the frame on a FF camera.
> 
> In optics, a circle of confusion is an optical spot caused by a cone of light rays from a lens not coming to a perfect focus when imaging a point source. It is also known as disk of confusion, circle of indistinctness, blur circle, or blur spot.



Yes, I can read wikipedia, too, and even copy and paste from it. Understanding what you read or copy/paste is not the same thing. If you go one line up from where you copy/pasted on wikipedia, you'll see: "For the closely related topic in microscopy, see Point spread function," - PSFs are something I work with routinely in an experimental setting. Circles of confusion are, arguably, the most important determinant of the DoF, in the strictest sense. By definition, 'depth of field' is that part of an image which is acceptably sharp, as opposed to that which is blurred. CoC is what determines what is sharp and what is not, and thereby determines what is within the DoF and what is not. What makes CoC confusing (pun intended) is that real CoC depends not only on the way in which the image is captured, but also the way in which the image is viewed. For example, an image that appears acceptably sharp when viewed at 600 pixels wide on an LCD display may be a blurry mess when printed at 20x30", even if the resolution supports a large print. 

However, when discussing CoC in terms of cameras, we have no control over viewing/printing - therefore, 'standardized' values are used based on an assumed print size (A5, if memory serves). Those standard values are applied to different sensor sizes, and APS-C has a smaller CoC than FF. The take home is that the standard values for sensor formats mean smaller sensors will have deeper DoF for the same subject framing (and MF/view cameras have larger CoCs, meaning they have shallower DoF for the same framing compared to FF/35mm. So yes, CoC values are relevant for both sensor (or film) sizes and for determining DoF.

Does Macro have a thin aperture? That's a new on on me. I didn't even know apertures had measurable thickness. But yes, DoF is thinner with macro distances. In fact, most of the approximations that underlie typical optical formulae do not hold at near 1:1 magnification or greater (and when you get significantly higher magnifications, i.e. microscopy - there's a whole new set of formulae).


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## WarStreet (May 31, 2011)

Flake said:


> Sorry Neuro but focal length does not affect DoF it's yet another myth which has been perpetuated, nor does subject distance.
> 
> http://www.luminous-landscape.com/tutorials/dof2.shtml
> 
> ...



Flake, thanks for the link. As you know, on another post I calculated the background blur of the 400mm 5.6 to see if it is good enough for my intended framing. I have the impression that DOF is different from background blurring. 

example: 

Using a FF camera (24mm sensor height) shot in landscape orientation framing a 2m height subject and 100m between the camera and background

(1) 400mm @ 5.6: subject distance : 33.73m, subject to background distance 66.27m 
gives 2.39m DOF, and 0.56mm spot diameter on background

(2) 300mm @ 5.6: subject distance : 25.30m, subject to background distance 74.70m
gives 2.39m DOF, and 0.47mm spot diameter on background

(3) 300mm @ 4.0: subject distance : 25.30m, subject to background distance 74.70m
gives 1.71m DOF, and 0.66mm spot diameter on background

From what I did, the magnification and aperture seems to determine the DOF, and background blurring is a different measure than DOF. The 400mm 5.6 has same DOF of 300mm 5.6 but it blurs the background more. I am new to all this, so would like to verify this with all of you, since I am using this math to determine which lens to purchase.


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## dstppy (Jun 1, 2011)

Act444 said:


> > Okay, I figure I'm going to get slapped for bringing this up, but on a crop body, why aren't more people recommending the 15-85 over the 24-105?
> 
> 
> 
> ...



Well, I'm asking because I e-mailed CR before I got any lenses and that was his starting recommendation . . . I soon after regretted not getting the L and lusted after it.

Weatherproofing omitted, the 15-85's build quality rivals the 24-105. I understand if one feels the need for a constant aperture, but it's f/5 at 50mm, so, barbaric as that seems, I've missed more not being able to drop below 24mm on a crop vs. what 2/3 of a stop can buy me at 50mm.

Don't get me wrong, I swear by EF (because I know I'll upgrade) and hate the concept of a crop sensor . . . it just seems as if a lot of people are shooting on the 24-105 because it's a good FF (and decent crop) lens and the pros swear by it . . . I just haven't seen anyone who's taken a lot of shots with it and chosen the latter over it.

Then again, what do I know, I think the 50mm f/1.4 is a great lens, and I'll argue that 50mm is more usable than 85mm on a crop body . . . call me a redneck with a camera


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## zerotiu (Jun 1, 2011)

okay, now I understand, this is what I get :

24-105 with :

[105mm * f/4 * 3 meters ]


from subject will give the same OOF as :

24-70 with :

[60mm * f/2.8 * 2 meters] 

* So if I want the DOF more shallow , get closer to the subject but like neuro had said I won't get the whole image, maybe just nose or something else.

I've said it on my comment before that I know that f/4 can't beat f/2.8 in making OOF background. I want to know can f/4 make okay OOF background too so the subject can still be distinguished.

FYI, previously I compare the OOF with my old 18-55 f/3.5-5.6. With f/4 I still get decent OOF background (it is on my t2i. I believe I'll get shallower DOF on FF body). Then I found someone said that 24-105 produce spikey bokeh but all your images shared is good for me. So 24-105 isn't always produce it.

wow, thx again for the OOF background information


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## NormanBates (Jun 1, 2011)

WarStreet said:


> Using a FF camera (24mm sensor height) shot in landscape orientation framing a 2m height subject and 100m between the camera and background
> 
> (1) 400mm @ 5.6: subject distance : 33.73m, subject to background distance 66.27m
> gives 2.39m DOF, and 0.56mm spot diameter on background
> ...



as you see, bokeh is a complex issue, it depends on depth of field but also on perspective

you could have also included a 28mm lens, and you'd see that moving your subject closer (to see as much from it as with the longer lenses) and keeping the aperture at f/5.6, DoF is unchanged; but the look of the background changes big time: with a 28mm, you'll see a whole building behind your subject, and it will be out of focus but you'll still know it's a building, and recognize its features; with a 400mm lens, with the background at the same distance, all you see behind your subject is a small patch of wall, so it will not be just out of focus, it will be blurred beyond recognition. So depth of field is the same, but the background will be a lot softer on longer lenses.

I learnt about this when playing with my FoV and DoF calculator:
http://www.similaar.com/foto/dof/dof.php
and it lead me to write these notes:
http://www.similaar.com/foto/dof/dof_notes.html
anc reate this simplified DoF and FoV calculator, which I find much more useful than the usual ones:
http://www.similaar.com/foto/dof/dof2.php

I'm currently running bokeh tests on all my lenses (vintage leitz and carl zeiss jena), making them as scientific as I can; I expect them to be online next week

as with the sharpness tests I run some months ago, I'm learning a lot about my lenses in the process; everybody should run sharpness and bokeh tests on their lenses
(for example, I have two lenses whose bokeh is ugly as hell at maximum aperture, but gets much better slightly stopped down; but that's from tests that neutralize both aperture and perspective issues, so I still don't know if "quantity of bokeh" is enough to counteract this "quality of bokeh" effect)


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## awinphoto (Jun 1, 2011)

zerotiu said:


> okay, now I understand, this is what I get :
> 
> 24-105 with :
> 
> ...



That's what I figured your question was regarding... the answer is yes, you can get decent OOF background if you need it. The "Spikey" bokeh is purely subjective and if you like what you have seen photo wise, then you wont be disappointed. Good luck with your purchase and feel free to let us know if and when you make your purchase and start shooting pictures with your new lens(es)


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## WarStreet (Jun 1, 2011)

NormanBates said:


> as you see, bokeh is a complex issue, it depends on depth of field but also on perspective
> 
> you could have also included a 28mm lens, and you'd see that moving your subject closer (to see as much from it as with the longer lenses) and keeping the aperture at f/5.6, DoF is unchanged; but the look of the background changes big time: with a 28mm, you'll see a whole building behind your subject, and it will be out of focus but you'll still know it's a building, and recognize its features; with a 400mm lens, with the background at the same distance, all you see behind your subject is a small patch of wall, so it will not be just out of focus, it will be blurred beyond recognition. So depth of field is the same, but the background will be a lot softer on longer lenses.



NormanBates, seems we came to the same conclusion. But now I am getting contrasting results. I added the 28mm @5.6 example, and the result of DOF is not similar to the other 5.6 lenses. I compared these results with the DOF master and are similar to mine. I might have a small error in my subject distance estimation, but the real reason for this unexpected result can be found from an article by DOF master. 

from DOF master article : http://www.dofmaster.com/dof_imagesize.html

*Depth of field is the same for all lenses when the image size is constant and the same f-stop is used.
This rule of thumb is approximately true when the focus distance for the shortest lens is less than about 1/4 of the hyperfocal distance for that lens.*

For me, the calculation of the spot diameter on the background is more important. I am currently checking photos from flickr to map these values with the background visual results from the photos. It is a big guess to determine the subject and background distance, but my main aim is to get an idea. Maybe I will try to do some tests with my own photos in a rugby pitch, to get better estimates. It's quit an interesting subject. I wish to find some time reading about it and hoping to understand it better.


Using a FF camera (24mm sensor height) shot in landscape orientation framing a 2m height subject and 100m between the camera and background

(1) 400mm @ 5.6: subject distance : 33.73m, subject to background distance 66.27m 
gives 2.39m DOF, and 0.56mm spot diameter on background
hyperfocal distance = 952.38m

(2) 300mm @ 5.6: subject distance : 25.30m, subject to background distance 74.70m
gives 2.39m DOF, and 0.47mm spot diameter on background
hyperfocal distance = 535.71m

(3) 28mm @ 5.6: subject distance : *2.361m*, subject to background distance 97.639m
gives 3.21m DOF, and 0.06mm spot diameter on background
hyperfocal distance = *4.57m*

(4) 300mm @ 4.0: subject distance : 25.30m, subject to background distance 74.70m
gives 1.71m DOF, and 0.66mm spot diameter on background
hyperfocal distance = 750m


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## NormanBates (Jun 2, 2011)

ok, maybe I went too far, 28mm is already wide angle and things start to change a bit there

with a 50mm, it's basically the same

with my DoF calculator (which seems to use a different CoC value):
400mm f/5.6 @ 33.76m --> DoF=2.00m
300mm f/5.6 @ 25.30m --> DoF=2.00m
200mm f/5.6 @ 16.88m --> DoF=2.00m
100mm f/5.6 @ 8.44m --> DoF=2.03m
50mm f/5.6 @ 4.22m --> DoF=2.12m
35mm f/5.6 @ 2.95m --> DoF=2.25m
28mm f/5.6 @ 2.36m --> DoF=2.43m
24mm f/5.6 @ 2.02m --> DoF=2.62m

http://www.similaar.com/foto/dof/dof.php?f_x=1&f_r=1.5&f_mm=400&f_f=5.6&f_d=33.76


edit:
plus: I think you'll like this:
http://prolost.com/blog/2011/1/9/the-shot-you-can-make.html
http://prolost.com/sycm
http://gallery.me.com/prolost


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## WarStreet (Jun 2, 2011)

NormanBates said:


> ok, maybe I went too far, 28mm is already wide angle and things start to change a bit there
> 
> with a 50mm, it's basically the same
> 
> ...



thanks for the examples and the interesting links.


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## NormanBates (Jun 4, 2011)

My bokeh tests are online, here:
http://www.similaar.com/foto/lenstests/bokehtests.html


I ran several scenarios:
* neutralizing both aperture and perspective:
http://www.similaar.com/foto/lenstests/bokehtests1.html
* neutralizing perspective:
http://www.similaar.com/foto/lenstests/bokehtests2.html
* keeping subject-to-background distance constant:
http://www.similaar.com/foto/lenstests/bokehtests3.html
* keeping camera-to-background distance constant:
http://www.similaar.com/foto/lenstests/bokehtests4.html


I learned a lot doing this

for example:

* I always thought my Carl Zeiss Jena Pancolar 50mm f/1.8 and my Carl Zeiss Jena Sonnar 180mm f/2.8 had great bokeh; it turns out, they both have pretty bad bokeh, but they make up for quality with quantity: the 50mm is relatively fast at f/1.8, and the Sonnar, at 180mm f/2.8, is both long and fast

* vintage glass is a lottery with regards to bokeh too: that Sonnar that came out so bad in my tests is considered one of the mythical "best bokeh ever" lenses:
http://www.rickdenney.com/bokeh_test.htm
(the other possibility is that other people also got fooled by the focal length and speed of this lens, but the fact that my other two sonnars, the 135 and the 300, have much better bokeh, seems to point to my 180 being sub-par)

* another thing that points to vintage glass being a lottery: I expected to come out of this with a conclusion to the tune of "how I learned to stop worrying and just buy Leitz glass"; but the 135mm is actually not stellar: at f/2.8 it's not great, and at f/4 the much cheaper sonnar 135 is actually better

* aperture affects both bokeh quantity and bokeh quality: I hardly ever use the pancolar wide open, because it becomes relatively soft in the corners; stopped down to f/2.8, it is both sharp and pretty nice in terms of bokeh

this bokeh thing is a very complex issue...

next step is to test my father's modern glass and see how it does


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## epsiloneri (Jun 4, 2011)

Great work! Look forward to your "modern" sample.


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## WarStreet (Jun 5, 2011)

NormanBates said:


> My bokeh tests are online, here:
> 
> * keeping camera-to-background distance constant:
> http://www.similaar.com/foto/lenstests/bokehtests4.html



Great work. It's really useful for me, who don't have the energy and time to do such detailed tests. I can't thank you enough for this. 

Due to the vast information of your setup, the spot diameter on the background can be calculated and compared with the related visually result. The camera-to-background test is the one I am interested in as this simulates most sport scenarios. 

At first I was surprised with the contrasting results of the 90mm @2.8 and 135mm @2.8 
I wrongly assumed that you used an FF camera, which would have given the following results :

90mm @2.8 : spot diameter 1.96mm , spot diameter with an infinite background distance : 2.92mm
135mm @2.8 : spot diameter 2.21mm , spot diameter with an infinite background distance : 4.38mm

With an FF camera, in your scenario, the 135mm would blur the background more than the 90mm


Using a Canon APS-C camera, which I think it is what you have used in the test ( at least I hope so ! ) :

90mm @2.8 : spot diameter 0.91mm , spot diameter with an infinite background distance : 1.88mm
135mm @2.8 : spot diameter 0.65mm , spot diameter with an infinite background distance : 2.82mm

With APS-C, it's the 90mm which blurs the background more, and match with your visual results. 
At enough background distance, the 135mm will always give more blurring.

Visually the spot diameter of 0.91mm produce a much better result than the 0.65mm. From my previous test (very rough estimates), I concluded that a 0.60mm - 0.70mm should give an acceptable blur, but one would still recognise what's in the background. The 0.91mm results in an unrecognised backgound (at least for me) 

This shows why the big lenses in sports are so important. The 400 5.6 would produce some acceptable results, but won't achieve the unrecognised background blurring even when used on FF for a 2m hight subject. On the other hand, with a portrait orientation, or with a tight crop, this could be achieved. 

Thanks again for sharing your work.


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## NormanBates (Jun 5, 2011)

yes, it's an APS-C camera (a 550D; I think it's said in the main page, but not in the pages with results)


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## WarStreet (Jun 5, 2011)

NormanBates said:


> yes, it's an APS-C camera (a 550D; I think it's said in the main page, but not in the pages with results)



went through your 4 result pages, but I skipped the main page. Still there was a hint in the result page too, since you are using the ef-s lens, and said that it is the 550D kit lens. Don't know why I assumed an FF camera :


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