# IS substitute for faster glass in low light? Not convinced.



## 00Q (Feb 17, 2012)

Many people say that having IS gives you 3 stops of compensation. Which means that you can have a faster shutter speed of 3 stops. 

Im not totally convinced by this. take a 24-70 f/2.8 and the 24-105 f/4 IS. This means, (if we skip out the details regarding DOF, bokeh etc and just focus on getting a shot,) that in low light, say shooting at 70mm:

1)if your 24-70 is giving you a shutter speed of 1/4 second which assume you can't hand hold..

2)then according to 24-105 without the IS at f/4, your shutter speed will be 1/2 second due to smaller aperature

3)but IS means that you gain 3 stops when means your effective shutter speed is 1/16 second, much better than the 24-70mm f/2.8 and so you could get a crisp shot. 

Im not totally convinced that it really translates to 3 stops in low light. I have shot with both lenses before. Could someone confirm this? 

i.e. what Im trying to say is that if we have the option to purely getting a crisp shot in low light and have the option to either get a faster lens or a slower lens with IS, it is not equivalent. Because this means it is much cheaper getting IS than faster glass (given IS claims to be 3-4 stops)

thanks,


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## marekjoz (Feb 17, 2012)

The image is not as sharp or simply blurry? Comparing this way different lenses could lead to misinterpration. Maybe it's better to check the same on 24-105 with IS on and off. This would be better probably. Comapring images from different lenses and interpreting them this way may be confusing, ie because 24-70 is a better lens than 24-105. What comes from the comparison between 24-70 and 24-105 (wth IS off) set on same apperture and focal?


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## ghosh9691 (Feb 17, 2012)

IS does not change the shutter speed. It just allows you to hand hold at lower shutter speeds easily. In your example, your 24-105 would still use 1/2 second shutter speed, but because of IS your chances of getting a sharper image would be higher. But if your subject has any kind of motion, even IS will not help and it will be blurred.


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## 00Q (Feb 17, 2012)

ghosh9691 said:


> IS does not change the shutter speed. It just allows you to hand hold at lower shutter speeds easily. In your example, your 24-105 would still use 1/2 second shutter speed, but because of IS your chances of getting a sharper image would be higher. But if your subject has any kind of motion, even IS will not help and it will be blurred.



yes exactly. now the questions is if the 24-105 requires 1/4 of a second (compared to 1/2 on the f/2.8), the IS allows you to hand hold it more steady, so what is the "effective" shutter speed? People claim that IS compensates 3-4 stops. does this translates to directly an effective shutter speed?


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## Hillsilly (Feb 17, 2012)

If taking a photo of a stationary object, then you'd have a greater chance of a sharp photo with the f/4 IS. But you're still stuck with a 1/2 second shutter speed. If you're taking photos of people or anything involving action, the faster shutter speed of a f/2.8 lens might work better.


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## Jim K (Feb 17, 2012)

00Q said:


> yes exactly. now the questions is if the 24-105 requires 1/4 of a second (compared to 1/2 on the f/2.8), the IS allows you to hand hold it more steady, so what is the "effective" shutter speed? People claim that IS compensates 3-4 stops. does this translates to directly an effective shutter speed?


Are you thinking that IS changes the shutter speed or ISO setting? It doesn't.

If the f/2.8 requires 1/2 sec at 2.8 then the 24-105 f/4 will require 1 sec at f/4. If the IS compensates 3 stops it would *be like * trying to hold the camera at 1/8 sec. both lenses require the same amount of light to make the shot.

At a higher shutter speed you may move out of the "shake" zone and into an area where you can handhold better. If the scene requires 1/15 at f/2.8 at the ISO you picked it will require 1/8 at f/4 with either lens but holding a lens with 3 stop IS at 1/8 sec *is like * holding a no IS lens at 1/60 sec because the lens reduces the vibration/movement AS IF the camera was shooting with a shutter speed 3 stops faster. 3 stops.


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## neuroanatomist (Feb 17, 2012)

IMO, IS is a substitute for faster glass, if you're shooting static subjects (or want motion blur, but not shake blur, in your shot). IS is not a substitute for fast glass with moving subjects - in those cases, you need more light to allow a faster shutter speed to freeze motion, and the fact that IS allows shooting at even slower shutter speeds than normally possible is not helpful. 

Say I have a shot at ~100mm on FF, that means I'd nominally need 1/100 s to effectively handhold the shot. Say I have a lens with a 4-stop IS system, that means I can, in theory, handhold that shot at 1/6 s and still get a reasonably crisp shot. 

So...below an example using a 4-stop IS lens at 95mm, completely handheld (no bracing, no leaning against a wall, just free standing on a narrow bridge)...exposure time is *0.5 s* - a full stop more than the rated IS benefit. I used f/5.6 to get an even longer exposure for more blur of the falling water. Now, at 100% you can see some shake-induced blur in the shot, but even at 1600 pixels (click the image, then view all sizes > original), it not really evident.




EOS 5D Mark II, EF 70-200mm f/2.8L IS II USM @ 95mm, 1/2 s, f/5.6, ISO 100


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## triggermike (Feb 17, 2012)

I have shot many photos handheld with the 24-105 at 1/8 of a second with perfect results. As previously mentioned before, IS does nothing for _moving objects._ In situations where the subjects are moving (does not have to be fast-moving), low f-stops are king to obtain fastest "real" speed.

BTW, who says the 24-70 is a much better lens than the 24-105?


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## marekjoz (Feb 17, 2012)

triggermike said:


> BTW, who says the 24-70 is a much better lens than the 24-105?



No, not me (I don't have 24-70), though I think you refered to my post. I meant that comparing images from 24-70 to 24-105 (with IS on) should not lead to statement, that IS doesn't work as it should (allowing longer exposures with same lighting conditions) but rather that some other cicrumstances could occur (like *in example*, that someting which interpreted as blurred was just not sharp or even that lens has better IQ than the other with current apperture and focal). I pointed that better comparison would be to compare images on same lens with IS on and off with different exposure times. On the other hand *excluding* other factors than IS could be made by comparing images from 24-70 to 24-105 (with IS off) and shoot with the same apperture.
English is not my native language so sorry for misunderstaning if that's the case.


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## 00Q (Feb 17, 2012)

Hillsilly said:


> If taking a photo of a stationary object, then you'd have a greater chance of a sharp photo with the f/4 IS. But you're still stuck with a 1/2 second shutter speed. If you're taking photos of people or anything involving action, the faster shutter speed of a f/2.8 lens might work better.



+1 thanks so much. This clears up everything.


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## skitron (Feb 17, 2012)

neuroanatomist said:


> (or want motion blur, but not shake blur, in your shot



To me, this is one of the coolest things about IS, you can get a clean background and good subject motion blur without much fuss. Plus 'IS pan mode' where you can get essentially the opposite, a clean subject and plenty of background 'motion' blur. Of course it's also nice for stationary subjects too. All in all a very nice feature to have (especially since it has an off switch) as long as it's fully understood and expectations are set accordingly.


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## awinphoto (Feb 17, 2012)

it will be adequate for reducing/eliminating camera shake in some situations, but wont reduce motion blur. If given a chance between F4 and IS and F2.8 and no IS, the IS may give you an additional stop or two compensation that the 2.8 wont, but try to always shoot at the fastest shutter or tripod when in doubt


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## keithfullermusic (Feb 17, 2012)

IS allows me to use my 100-400mm at 400mm with no shake blur - and thats the old IS. Clearly it won't help if my subject is moving, but it is still incredibly useful at times.


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## Mt Spokane Photography (Feb 17, 2012)

00Q said:


> Many people say that having IS gives you 3 stops of compensation. Which means that you can have a faster shutter speed of 3 stops.



It does not mean you can use a faster  shutter speed. IS lets you use a slower shutter speed and reviewers often test it, and it works. BUT- only for static subjects.

You are always free to use faster shutter speeds as long as there is enough light.

Here is a image on my 100-400mmL handheld thru my back window at 1/25 sec 400mm. I grabbed my camera and snapped the image with whatever settings were on it. I was amazed that a 1/25 sec image came out at all. Seconds later, he slowly started to roll the baby goat off, and motion blur took over. He loves the goats, but it hurts when they play on his back. A few months ago, we watched a new set of babies, and one was on the roof of his goat house and jumped on the horses back as he walked by. As soon as the horse took one step, the goat left. It can be a real circus.







Starting to roll






Over he goes, and the goats leave quickly. IS does not let you freeze moving subjects!


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## AprilForever (Feb 17, 2012)

Mt Spokane Photography said:


> 00Q said:
> 
> 
> > Many people say that having IS gives you 3 stops of compensation. Which means that you can have a faster shutter speed of 3 stops.
> ...



Indeed. Although, a supertele lens without IS is extremely hard to use hand-held...


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## 7enderbender (Feb 17, 2012)

neuroanatomist said:


> IMO, IS is a substitute for faster glass, if you're shooting static subjects (or want motion blur, but not shake blur, in your shot). IS is not a substitute for fast glass with moving subjects - in those cases, you need more light to allow a faster shutter speed to freeze motion, and the fact that IS allows shooting at even slower shutter speeds than normally possible is not helpful.
> 
> Say I have a shot at ~100mm on FF, that means I'd nominally need 1/100 s to effectively handhold the shot. Say I have a lens with a 4-stop IS system, that means I can, in theory, handhold that shot at 1/6 s and still get a reasonably crisp shot.
> 
> ...




What he said. Only I would argue that it does NOT make IS a substitute for fast glass. It's really for different applications which is one of the reasons why any comparison between the 24-70 and the 24-105 to me always results in, yeah, there are reasons to own both...

It is my experience that IS on the 24-105 works surprisingly well given the limitations outlined by Neuro above. I recently used it for a live music shoot and the results were better than I had expected. No, it obviously doesn't help with motion blur but if things are relatively static you can increase DOF by stopping down a little as opposed to the look of a fast prime for example. All depends. Not sure how this would compare to having a monopod in such a scenario. That may actually be better overall. Plus I personally fully expect the IS to go bust within a few years or at least go out of whack. It's a loosely moving lens element. That can't be good in the long run. So I usually have it turned off and really just bought the 24-105 because it was scuh a good deal with the 5DII. It's good for what it is but I don't rally love it. Still hoping to trade it for a 24-70 (original) at some point.


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## JFeldhaus (Feb 17, 2012)

I have a question that somehow belongs to this topic:

Is there any benefit of turning IS off if you don't need it? esp. if it's a cheap lense ..?


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## keithfullermusic (Feb 17, 2012)

You can turn it off if you're on a tripod. You can also turn it off if you don't need it (shorter focal length and really bright) because it uses more battery.


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## briansquibb (Feb 17, 2012)

Sometimes you just need a greater DOF than using fast glass wide open can buy you

higher ISO might be a substitute for faster glass


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## JFeldhaus (Feb 17, 2012)

keithfullermusic said:


> You can turn it off if you're on a tripod. You can also turn it off if you don't need it (shorter focal length and really bright) because it uses more battery.



So the only benefit from switching off IS is less battery usage? Does it it affect the image in any way?


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## marekjoz (Feb 18, 2012)

JFeldhaus said:


> keithfullermusic said:
> 
> 
> > You can turn it off if you're on a tripod. You can also turn it off if you don't need it (shorter focal length and really bright) because it uses more battery.
> ...



On a tripod you should switch it off. I'vre probably read somewhere, that newest IS detects if is on tripod and doesn't go crazy. Usually when lens with IS is on tripod it tries anyway to stabilize something that in fact is not moving. It causes unintentional movement so makes IQ worse. So the rule - always turn off when on tripod.


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## rocketdesigner (Feb 18, 2012)

7enderbender said:


> *Plus I personally fully expect the IS to go bust within a few years or at least go out of whack. It's a loosely moving lens element. That can't be good in the long run. So I usually have it turned off *



Is this a valid concern? 
Does IS add to maintenance problems ... or worse, especially in this lens (pls say no, I just got one)?


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## wickidwombat (Feb 18, 2012)

i still work on the theory i would rather have it and not need it than need it and not have it
but i'm find with all my non IS lenses so not too worried really just certain shooting contditions i REALLY need IS and my 24-105 is my workhorse for those occassions.

its interesting that canon is addidng IS to all these primes, it will be very interesting to see if a revised 135mm f2 gets IS


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## marekjoz (Feb 18, 2012)

wickidwombat said:


> its interesting that canon is addidng IS to all these primes, it will be very interesting to see if a revised 135mm f2 gets IS



And what I'm afraid of that adding IS to 135 would make the price much higher. As it was also here mentioned, Canon loses on dolar devaluation comparing to yen. Customers don't like see higher prices, so the best way for them is to put a new product on a shelf with a higher price, even if it's somehow improved old version. What good is, that the new product would be probably better, the bad, that the price s higher, what we see with 24-70 mk2. If this theory works, we should see many new lenses quite soon.


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## 7enderbender (Feb 18, 2012)

rocketdesigner said:


> 7enderbender said:
> 
> 
> > *Plus I personally fully expect the IS to go bust within a few years or at least go out of whack. It's a loosely moving lens element. That can't be good in the long run. So I usually have it turned off *
> ...



I have no proof for that hence my calling it an expectation on my part. The thing is that I'm still trying to get over my disappointment that I now have to use EF lenses and that all my FD glass won't work with digital. I had always resented the idea of moving to the EOS system because I don't like the feel and build quality of the EF lenses (or any other lenses from "modern" AF systems). I have lenses that are almost 30 years old and look and work pristine. I'm pretty sure that this won't be the case with any of my new lenses, L or non-L, IS or non-IS. Just saying.


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## Mt Spokane Photography (Feb 18, 2012)

AprilForever said:


> Indeed. Although, a supertele lens without IS is extremely hard to use hand-held...



Thats for sure. I sold my 600mm f/4 (Non-IS) and got a nice easy to hold 100-400mm L. I did take a few handheld shots with my 600mm, just to see if it was possible. It is, but for me, a minute or less was all I could hold it up and be reasonably still. I probably still have the images, but I did not identify them specifically as handheld, and I used a really high shutter speed as well.

I would not use my 100-400mm at 400mm without IS unless really carefully secured on a tripod with no wind.


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## wickidwombat (Feb 18, 2012)

7enderbender said:


> The thing is that I'm still trying to get over my disappointment that I now have to use EF lenses and that all my FD glass won't work with digital. I had always resented the idea of moving to the EOS system because I don't like the feel and build quality of the EF lenses (or any other lenses from "modern" AF systems). I have lenses that are almost 30 years old and look and work pristine. I'm pretty sure that this won't be the case with any of my new lenses, L or non-L, IS or non-IS. Just saying.


you really need to talk to edmika I got a 600f4.5 FD lens in mint condition and his adaptor it works great on both my 5Dmk2 and my 1Dmk3


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## Caps18 (Feb 18, 2012)

Hillsilly said:


> If taking a photo of a stationary object, then you'd have a greater chance of a sharp photo with the f/4 IS. But you're still stuck with a 1/2 second shutter speed. If you're taking photos of people or anything involving action, the faster shutter speed of a f/2.8 lens might work better.


This is correct.

When you shoot in low light, the faster glass always will win out to IS because you can boost ISO and shutter speed and stop motion blur of the subjects.

It is something I run into all the time. The 50mm f/1.2 was kind of nice since I was able to get most shots at a faster shutter speed than my other lenses.


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## neuroanatomist (Feb 18, 2012)

Caps18 said:


> The 50mm f/1.2 was kind of nice since I was able to get most shots at a faster shutter speed than my other lenses.



Sure, as long as you're willing to trade a very thin DoF for that fast shutter speed. As a side note, if shooting wide open, you weren't getting the full benefit of f/1.2, either, assuming you're using a dSLR - you were getting the light of f/1.5 or so, and your camera was surreptitiously bumping up the ISO.


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## Caps18 (Feb 18, 2012)

Even shooting at f/2.8, the 50mm f/1.2 will be able to produce an image exposed the same as one taken with a 24-70mm f/2.8 @ 50mm at f/2.8 with a faster shutter speed.

And then there is the 24-105 f/4 IS that will require a slow shutter speed to gather enough light at f/4, where the 50mm f/1.2 set at f/4 will still be able to use a quicker shutter speed to stop the subject motion. If there is no subject motion, then it doesn't matter much if you can hold the camera steady or have a tripod.


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## rocketdesigner (Feb 18, 2012)

Neuro, Mt Spokane et. al. where do you typically have sharpness set? Or do you sharpen in post?


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## briansquibb (Feb 18, 2012)

Caps18 said:


> And then there is the 24-105 f/4 IS that will require a slow shutter speed to gather enough light at f/4, where the 50mm f/1.2 set at f/4 will still be able to use a quicker shutter speed to stop the subject motion. If there is no subject motion, then it doesn't matter much if you can hold the camera steady or have a tripod.



Have you mis typed this - you seem to be saying that 2 lens at f/4 will have different shutter speeds


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## marekjoz (Feb 18, 2012)

briansquibb said:


> Caps18 said:
> 
> 
> > And then there is the 24-105 f/4 IS that will require a slow shutter speed to gather enough light at f/4, where the 50mm f/1.2 set at f/4 will still be able to use a quicker shutter speed to stop the subject motion. If there is no subject motion, then it doesn't matter much if you can hold the camera steady or have a tripod.
> ...



It might be true if they would differ enough in their "T" values...


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## Radiating (Feb 18, 2012)

IS vs faster glass has many variables.

First off with high megapixel cameras it helps them acheive a sharper image by default, to the equivalent of shooting at 1/focal length x 2. Second most manufacturers exagerate when they say it's 4 stops of light, maybe in some situations, but really it's really more like 3-3.5.

So at 70mm without IS your minimum shutter speed will be 1/140th to get a tack sharp image, but your minimum shutter speed is only 1/17 at 70mm with IS for tack sharp images. As you can see this tends to lend itself more to subjects that aren't moving much.


Hope that helps.


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## briansquibb (Feb 18, 2012)

Radiating said:


> IS vs faster glass has many variables.
> 
> First off with high megapixel cameras it helps them acheive a sharper image by default, to the equivalent of shooting at 1/focal length x 2. Second most manufacturers exagerate when they say it's 4 stops of light, maybe in some situations, but really it's really more like 3-3.5.
> 
> ...



Once you get to 1/17? shutter speed you will start to incur handshake induced motion blur - even if the subject is stationary.


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## neuroanatomist (Feb 18, 2012)

rocketdesigner said:


> Neuro, Mt Spokane et. al. where do you typically have sharpness set? Or do you sharpen in post?



I shoot RAW, and I usually use the default setting for sharpness in DxO Optics Pro, unless the shot needs more or less sharpening.


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## neuroanatomist (Feb 18, 2012)

briansquibb said:


> Caps18 said:
> 
> 
> > And then there is the 24-105 f/4 IS that will require a slow shutter speed to gather enough light at f/4, where the 50mm f/1.2 set at f/4 will still be able to use a quicker shutter speed to stop the subject motion. If there is no subject motion, then it doesn't matter much if you can hold the camera steady or have a tripod.
> ...



They'll probably have the same shutter speed as metered (at least, that's the case for my 85/1.2L II vs. 24-105mm), but the image from the f/1.2 lens will actually be a little brighter. The difference is about 1/3 stop, nothing I'd consider a significant benefit in terms of stopping subject motion.


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## Mt Spokane Photography (Feb 18, 2012)

rocketdesigner said:


> Neuro, Mt Spokane et. al. where do you typically have sharpness set? Or do you sharpen in post?



I use Raw, setting sharpening in Camera is only for jpegs.

I have a different default sharpening and NR set for each ISO in Lightroom, so its set automatically on import. Most raw images benefit from a little sharpening, LR 4 lets you sharpen selectively only the areas that need it, like hair. That must be done manually with the brush function.


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## Caps18 (Feb 18, 2012)

briansquibb said:


> Have you mis typed this - you seem to be saying that 2 lens at f/4 will have different shutter speeds



I tested it out, and my assumption was incorrect. 

At least in daylight photos, both my 16-35mm (@17mm) and 17mm TS-E at f/4 and ISO100 needed a 1/125sec shutter speed to get the exposure meter to come out the same. In very low light, I still thought I saw a difference between different lenses when using the same ISO and f-stops.

I did do one test in December that I should upload the pictures that showed the sharpness difference that you get by stepping down a 50mm f/1.2 lens in low light compared to 50mm lens with a slower f-stop rating.

And with the faster glass, you still have the option to drop the aperture in order to raise the shutter speed at the cost of depth of field.


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