# Faster (f/2.8) Lenses on 5DII or Slower (f/4) lenses on 5DIII?



## chas1113 (Sep 18, 2013)

I wonder if Canon (or some enterprising measurebator) has actually quantified the autofocus speed/accuracy benefit on the 5D Mark III with f/4 lenses compared to the 5D Mark II with f/2.8 lenses? Anyone know?

Practically everyone has attested to the vast improvements of the 61-point AF system versus the 9 points of the 5D II with the same f/2.8 lenses. But for many of us (non-pros, hobbyists, or just people who don't like the weight/expense of the 2.8 lenses) have built lens kits comprised of slower f/4 zooms and the like. I currently have a 5DII that I like very much, but (like most) yearn for the AF accuracy of the 5DIII. My quandary is, would you benefit more by upgrading to f/2.8 lenses and keeping the 5DII or keeping your f/4 lenses and upgrading to the 5DIII. Which combinations would yield better AF results?


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## neuroanatomist (Sep 18, 2013)

That sort of thing is pretty difficult to quantify but I'd bet that, in general, an f/4 lens on the 5DIII would deliver better AF performance than an f/2.8 lens on a 5DII.


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## chas1113 (Sep 18, 2013)

Thanks, Neuro. I figured you'd have a definitive answer....


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## neuroanatomist (Sep 18, 2013)

Well, thanks....but I'd hardly call my answer definitive.  An educated guess, at best. But I do know that my 24-105/4L nailed focus more frequently and consistently on my 1D X than my 70-200/2.8L IS II on my 5DII.


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## chas1113 (Sep 18, 2013)

That's good to know. Thanks. And consistent with what I would hope/expect.


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## agierke (Sep 18, 2013)

It also would depend greatly on what area of the auto focus system was being used and under what conditions. It's not such a cut and dry situation.

Use of center point only and recompose on the 5d2 using F4 and above would most likely yield acceptable results in most circumstances. Try that at F2.8 and wider and your results will plummet.

I wanted more creative freedom out of my auto focus system plus added reliability at wide open apertures. Couple that with my transition to the use of fast primes and the 5D2 just didn't cut it. The 5D3 was a necessity for me and something I had been pining for since I purchased the 5Dc upon its release. 

As a pro I needed predictable and dependable results in some of the toughest conditions. I got by with the 5D2 for a while only because I couldn't afford a 1D series camera, but there were far too many times the gear couldn't perform reliably for the way I wanted to shoot. The 5D3 changed that and I can now shoot with much more confidence.

As a non pro, you may or may not find a benefit to the 5D3s focusing system. You may see a more immediate benefit to a 2.8 zoom. Heck, I work with some pros who still won't consider shooting wider than F5.6 and have no interest in the 5D3s AF system. In the end it's to each his own.

For my own experience though, the AF system on the 5D3 brought added functionality to ALL my lenses to the point that it was like having a whole new set of lenses. It was that much better than my 5D2.


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## Mt Spokane Photography (Sep 18, 2013)

As long as you just use the center point, the 5D MK II focuses quickly even in low light. The f/4 lenses in general are not quite as good as the newer f/2.8 lenses, but they are still very good lenses. 

I'd say that the 5D MK II is still a worthy camera, and I'd go for the top of the line lenses. However, if you want to use other than the center point, or need to track subjects as they move, then a 5D MK III is the one.

I bought the MK III, and like it, but I have not used the advanced tracking features as much as I should. I did use them in low light, and found tracking was possible most of the time.


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## scottkinfw (Sep 18, 2013)

A 5DIII is a lot less expensive than upgrading your current lenses.

You can always sell your old lenses and update one at a time as $ is available.

Of course, it is a matter of your preference, and there are tradeoffs either way.

sek


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## chas1113 (Sep 18, 2013)

agierke said:


> It also would depend greatly on what area of the auto focus system was being used and under what conditions. It's not such a cut and dry situation.
> 
> Use of center point only and recompose on the 5d2 using F4 and above would most likely yield acceptable results in most circumstances. Try that at F2.8 and wider and your results will plummet.
> 
> ...



Agierke: This is particularly helpful as I am mainly a focus/recompose type. I wonder if the f/4 cross points of the 5D Mark III would really help me as they are arranged away from the center point....hmmmm.


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## chas1113 (Sep 18, 2013)

Mt Spokane Photography said:


> As long as you just use the center point, the 5D MK II focuses quickly even in low light. The f/4 lenses in general are not quite as good as the newer f/2.8 lenses, but they are still very good lenses.
> 
> I'd say that the 5D MK II is still a worthy camera, and I'd go for the top of the line lenses. However, if you want to use other than the center point, or need to track subjects as they move, then a 5D MK III is the one.
> 
> I bought the MK III, and like it, but I have not used the advanced tracking features as much as I should. I did use them in low light, and found tracking was possible most of the time.



Mt Spokane Photography: You nailed it. For _*most*_ of my shooting, the 5D center point with assist points is adequate _*most*_ of the time. There are occasions when shooting my dog (who's fast!) that the keeper rate is abysmal even in AI Servo. It would be for the focus tracking ability of the 5DIII that I would consider upgrading.


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## chas1113 (Sep 18, 2013)

scottkinfw: That's what makes this a quandary, I guess. If I were a pro sports shooter or BIF exclusively, it'd be easy: bite the bullet and ante up for a 1DX and all 2.8 lenses. There is _*something*_ to the center point focusing capabilities of the 5DII, however, as my 100 L nails focus at 2.8 much more reliably than my f/4 zooms. Decisions, decisions! I think I may follow your lead and upgrade to 2.8s in the near term with an eye on body upgrade as prices drop. Thanks all.


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## chas1113 (Sep 18, 2013)

From Agierke: "For my own experience though, the AF system on the 5D3 brought added functionality to ALL my lenses to the point that it was like having a whole new set of lenses. It was that much better than my 5D2."

This is REALLY the way I want to go. It's taken me a while to build my lens stable and I like it pretty much the way it is. If the body swap would breathe new life into them, that would be my preference.


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## agierke (Sep 18, 2013)

> From Agierke: "For my own experience though, the AF system on the 5D3 brought added functionality to ALL my lenses to the point that it was like having a whole new set of lenses. It was that much better than my 5D2."
> 
> This is REALLY the way I want to go. It's taken me a while to build my lens stable and I like it pretty much the way it is. If the body swap would breathe new life into them, that would be my preference.



i think you will find that it will. its a change in approach but once you get the hang of it its well worth it. moving forward after that you can be confident that you will be getting the most out of any new lens purchases whether they be 2.8 zooms or fast primes.

if you feel strongly that focus point freedom and reliability is what you personally need for growth then the 5D3 is for you. staying with the 5D2 and going with 2.8 zooms will likely exacerbate any focus issues you may already be experiencing with the focus and recompose technique.


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## Dylan777 (Sep 18, 2013)

The dual cross points on 5D III make huge diff.


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## chas1113 (Sep 18, 2013)

Great responses guys....you've all hit on the main sensor design differences through anecdotal experience....appreciate it. Great brain trust here. Looks like it's a body upgrade for me.


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## sanj (Sep 18, 2013)

I find these auto focus speed measurements and discussions bit unnecessary as the cameras and lenses are fast enough in most rarely ever to miss a shot.


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## mrsfotografie (Sep 18, 2013)

Heheheh don't discount the 5DMkII, it's still one hell of a camera. AF is overrated just like full auto or 'Program' exposure. 8)

Why? Servo tracking and AF speed are never as fast as good anticipation. If you know where your subject will be, and you focus accordingly, you will nail your subject where even the best AF misses! I'm more and more convinced of this as my technique improves and I become less and less reliant on AF. 

AF is slower than pre-focusing because the AF system measures and refocuses. This is always slower than pre-focusing. 

Still I must admit I usually prefer my 7D for animal and sports photography, because (besides reach/crop) well sometimes I'm a little lazy and then I prefer technology to sort things out for me.  :


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## neuroanatomist (Sep 18, 2013)

paul13walnut5 said:


> agierke said:
> 
> 
> > Use of center point only and recompose on the 5d2 using F4 and above would most likely yield acceptable results in most circumstances. Try that at F2.8 and wider and your results will plummet.
> ...



You apparently don't understand, or are ignoring, the reasons Why Focus-Recompose Sucks, to which agierke was alluding.


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## agierke (Sep 18, 2013)

> Quote from: paul13walnut5 on Today at 09:28:46 AM
> Quote from: agierke on September 17, 2013, 10:10:54 PM
> Use of center point only and recompose on the 5d2 using F4 and above would most likely yield acceptable results in most circumstances. Try that at F2.8 and wider and your results will plummet.
> 
> ...



Thank you neuro, that was exactly what I was talking about. 

And Paul13Walnut5, I've come to expect better from you than to rush judgement and toss out degradations like that. I do understand very well what you detailed in your post. But that doesn't circumvent the simple physics of shallow depths of field and the problems one encounters with the focus and recompose technique. You can get away with focus and recompose at F4 on most focal lengths but wider apertures than that it becomes a tremendous problem.


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## paul13walnut5 (Sep 18, 2013)

neuroanatomist said:


> You apparently don't understand, or are ignoring, the reasons Why Focus-Recompose Sucks, to which agierke was alluding.





agierke said:


> You apparently don't understand, or are ignoring, the reasons Why Focus-Recompose Sucks, to which agierke was alluding.




Neither of *you* _apparantly understand_ that the shooting aperture has nothing to do with the focus accuracy.

f4 might get everything reasonably sharp at 17mm on 135mm / leica / minature format DSLR's, but won't get you far anywhere else unless eveything in your scene is on the same focus plane.

The advice is useless, tosh. My biggest gripe is that somebody would actually read it and try it and miss out on important shots. Might as well have said get a lens with hyperfocal scales and shooting everything at f11. It's got about as much to do with how AF works. Jaysus.

Unless of course you meant that we should all buy lenses no faster than f4 so we can give our AF systems a chance for point and recompose. Or try just not using it

I stand by it lads.


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## neuroanatomist (Sep 18, 2013)

paul13walnut5 said:


> neuroanatomist said:
> 
> 
> > You apparently don't understand, or are ignoring, the reasons Why Focus-Recompose Sucks, to which agierke was alluding.
> ...



Utter tosh, and standing by it only makes you appear foolish. 

To be clear, the issue isn't the accuracy of the focus system itself, but the accuracy of focus in the resulting *image*. Most people care about the latter, usually only CR geeks like me care about the former. Yes, we get that moving the camera after focus is achieved isn't, strictly speaking, a problem with focus _system_ accuracy. We also understand that a deeper DoF with a narrower aperture is really just masking the problem. People who could easily understand that locking focus then walking two paces forward before taking the shot would lead to a misfocused image if the DoF is thin, sometimes have trouble understanding that shifting the camera in an angular motion can cause the same problem. 

Are you saying that with a wide aperture and a relatively close subject (i.e., conditions resulting in thin DoF), focus-recompose _doesn't_ lead to back-focused shots? Or are you merely quibbling over terminology?


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## agierke (Sep 18, 2013)

> Neither of you apparantly understand that the shooting aperture has nothing to do with the focus accuracy.
> 
> f4 might get everything reasonably sharp at 17mm on 135mm / leica / minature format DSLR's, but won't get you far anywhere else unless eveything in your scene is on the same focus plane.
> 
> ...



i dont disagree with your technical assessment of either of your posts....but none of that has anything to do with what Neuro and I are suggesting to the OP.

to be clear, if AF accuracy is the desired result coupled with the focus and recompose technique then what i am advising to the OP is buying the 5D3 would be a better option for him using his existing lens lineup and using the improved responsiveness of the 5D3's outer points when composing RATHER than buying 2.8 zooms and continuing to do focus and recompose. 

yes, buying 2.8 zooms offers better AF on the 5D2...but any accuracy gained is wasted on the focus and recompose technique as the very simple physics of the technique circumvent the accuracy of the original focus acquisition...unless of course your are shooting at F4 and above with the extra depth of field that would compensate for the discrepancies introduced with the recomposition. at this point....a wiser recommendation would to be just buy the 5D3 to take advantage of better, more accurate focus points outside of the center point and ditch focus and recompose.

this is sound advice...which does not ignore your completely valid points about how AF systems work coupled with different lenses capable of different maximum apertures. your posts do ignore however the very real problems the focus and recompose technique introduces to focus accuracy....especially at apertures greater than F4. the OP should be made aware of this to help inform him of his decision.

i appreciate your enthusiastic points...but you are arguing something that 1. i dont disagree with and 2. doesnt have anything to do with the actual point that i am discussing.


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## chas1113 (Sep 18, 2013)

In addition to the points above, my technique could very well change based upon the technological improvements and ergonomics of the 5DIII AF. Having been a focus/recompose shooter since my Nikon F days in the '60s, the 5DII outer points never engendered the confidence to change my shooting style. Maybe the tech in the 5DIII can teach this old dog new tricks.

For the record, I fully understood agierke's point about focus/recompose technique and its ramifications regarding faster, shallower depth-of-field lenses. And agree.

To mrsfotografie: regarding pre-focusing (f/8 and be there) techniques, distance scales have all but disappeared on newer lenses making my tired eyes all the more dependent on sensor tech. I do manual focus all the time with 30-year-old Contax lenses — on things that don't move. My interest is improved AF on things that DO move.

I appreciate all the viewpoints and spirited debate. Is that popcorn I smell?


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## paul13walnut5 (Sep 18, 2013)

Agierke: you had made you focus recompise point before the op had even mentioned that style of shooting.

Neuro: i'm saying there are better ways to solve the particular problem, one of them is a camera with more af points, more accurate af points, for whatever reason, say low light, f4 may not be desirable.

I'm really saddened that i look foolish to you Dr. Brain, breaks my heart that does. I guess that puts me in with just about everybody else who doesn't agree with you. What can I do to cheer myself up? i know i'll have a perusal of your smashing pics of all your flash stands lined up, or all your camera bags. That always lifts me and reminds me what photography is really all about.


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## chas1113 (Sep 18, 2013)

C'mon Paul, lighten up a little. 

You points are just as valid and appreciated. Having shot for for decades myself, I understand stop-down metering and depth of field issues that your posts have addressed. Nobody's rightest here which infers that nobody's wrongest either.

Cheers.


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## agierke (Sep 18, 2013)

excellent position to take Chas, i really wasn't trying to let this thread digress into questioning the validity of other members photography. i really only wanted to offer my opinion from my direct experience.

i hope it proves helpful and whatever you decide, you will certainly have an exciting purchase upcoming!


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## celltech (Sep 18, 2013)

If you are in continuous, high speed servo AF shooting, does the lens/body have time to open the aperture/grab focus/close the aperture to proper setting between every shot?


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## chas1113 (Sep 18, 2013)

I'm not sure that was an issue in my case. I normally shoot in One-shot mode and back button focus. Seems from all I have heard and read that this is the most effective setup for non-predictive action... Assuming that you have basically pre-focused in advance, which I try to do.


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## neuroanatomist (Sep 18, 2013)

paul13walnut5 said:


> Agierke: you had made you focus recompise point before the op had even mentioned that style of shooting.
> 
> Neuro: *i'm saying there are better ways to solve the particular problem*, one of them is a camera with more af points, more accurate af points, for whatever reason, say low light, f4 may not be desirable.
> 
> I'm really saddened that i look foolish to you Dr. Brain, breaks my heart that does. I guess that puts me in with just about everybody else who doesn't agree with you. What can I do to cheer myself up? i know i'll have a perusal of your smashing pics of all your flash stands lined up, or all your camera bags. That always lifts me and reminds me what photography is really all about.



I'm sorry, Paul, but I don't see where I (or agierke, from what I can see) suggested shooting at f/4 or narrower as a _solution_ to the problem of backfocus resulting from focus-recompose. Feel free to point out where I suggested that, ideally with a direct quotation. The point was that switching from an f/4 lens to an f/2.8 lens might reveal this problem, and that turned out to be a relevant observation to the OP. 

You apparently jumped to the erroneous conclusion that those statements constituted advice of some sort (beyond the simple description of the problem), proceeded to call that description 'tosh', accuse me (and agierke) of not understanding the very concept being accurately described, and then descended into sarcastic insults. If you want to be saddened by something, you need look no further than your own immature behavior.


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## frumrk (Sep 18, 2013)

Not that this matters... but I have been thinking of upgrading my 70-200 F4 to a 2.8. I also thought about upgrading from a MK II to a MK III instead. So I took 3 of my lenses... 

50 F1.8
24-70 F2.8
70-200 F4

I was able to find a spot in a dark area that was difficult to focus and then attempted to focus on that area with all three lenses.

I used both the 24-70 and 70-200 at 70mm and I moved up slightly for the 50 1.8.

Now I am not talking about focus accuracy... simply focus lock. In my results... which I didn't expect... here is the order in which the lens performed the focus lock the quickest.

70-200
24-70
50

I thought it would be exactly the opposite.... can anyone explain?


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## chas1113 (Sep 18, 2013)

Interesting result. Assuming the testing procedure is not in question, I'd like to hear any conjecture as well. My own interpretation is that if your 24-70 is older, even the f/2.8 aperture advantage of that lens might not best the newer 70-200 f/4 IS focusing abilities. The 50mm I have no clue about. One would think the f/1.8 would focus appreciably better than either zoom. But this does reflect on my original query: Does the centerpoint 2.8 sensitivity of most Canon dSLRs (and the accompanying fast glass) really pay off when comparing different generations of sensor technology.


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## neuroanatomist (Sep 18, 2013)

frumrk said:


> In my results... which I didn't expect... here is the order in which the lens performed the focus lock the quickest.
> 
> 70-200
> 24-70
> ...



Actually, I don't find that particularly surprising. Here's the thing - an f/2.8 line is more accurate, but that accuracy isn't free. The price you pay for accuracy is speed. In fact, the predictive algorithms for AI Servo AF use mostly data from the f/5.6 lines vs. the f/2.8 lines, because the former are faster. Lens AF speed also plays a role, and the 50/1.8 is the slowest of the bunch.


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## Drizzt321 (Sep 18, 2013)

frumrk said:


> Not that this matters... but I have been thinking of upgrading my 70-200 F4 to a 2.8. I also thought about upgrading from a MK II to a MK III instead. So I took 3 of my lenses...
> 
> 50 F1.8
> 24-70 F2.8
> ...



So the 70-200 was fastest, 24-70 next, and 50 f/1.8 slowest? That's a 24-70 v1?

I'm not surprise the 50 f/1.8 was the slowest. While it has a faster f-number, it has a slow and old AF motor, and it's actual transmissive qualities may or may not be as good as the rest. Which that can certainly matter, especially in a location with a low amount of light.


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## frumrk (Sep 19, 2013)

Drizzt321 said:


> frumrk said:
> 
> 
> > Not that this matters... but I have been thinking of upgrading my 70-200 F4 to a 2.8. I also thought about upgrading from a MK II to a MK III instead. So I took 3 of my lenses...
> ...



Not only am I saying that it was slower... but actually less successful at locking. The test procedure wasn't really scientific... however I did test 3 times with each lens (swapping lenses each time) and the results were always the same. The 50 rarely was able to achieve focus... and the 70-200 F4 was able to achieve focus most of the time.


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## Drizzt321 (Sep 19, 2013)

frumrk said:


> Drizzt321 said:
> 
> 
> > frumrk said:
> ...



Something to actually know, the newer L lenses (forget if those 2 are included) seem to have a better feedback and higher accuracy than older lenses, of which the 50 1.8 definitely is among.


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## Rienzphotoz (Sep 19, 2013)

Hi chas113, I believe you've already made up your mind to go with the body upgrade ... 5D MK III is a fantastic camera I'm sure you will see a far much snappier performance in the way your f/4 lenses work on 5D MK III over the 5D MK II. 
5D MK III is my first full frame DSLR as I upgraded it from 7D ... but I took a different approach i.e. upgraded my f/4 lenses to f/2.8 lenses before upgrading to 5D MK III ... no "scientific" approach, other than wanting to invest in f/2.8 zooms (16-35, 24-70 & 70-200) before I made the body upgrade, it took several years but I eventually did it.
Good luck with your upgrade ... may it serve you well.


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## chas1113 (Sep 19, 2013)

Rienzphotoz said:


> Hi chas113, I believe you've already made up your mind to go with the body upgrade ... 5D MK III is a fantastic camera I'm sure you will see a far much snappier performance in the way your f/4 lenses work on 5D MK III over the 5D MK II.
> 5D MK III is my first full frame DSLR as I upgraded it from 7D ... but I took a different approach i.e. upgraded my f/4 lenses to f/2.8 lenses before upgrading to 5D MK III ... no "scientific" approach, other than wanting to invest in f/2.8 zooms (16-35, 24-70 & 70-200) before I made the body upgrade, it took several years but I eventually did it.
> Good luck with your upgrade ... may it serve you well.



Good to know, thanks. It's nice to have confirmation from multiple sources. My approach to kit building was "slow zooms/fast primes that are lightweight and sharp enough"...but with the 24-70 II coming down in size and weight....it's very tempting. For me, my 17-40 and 24-105 serve me well enough, but there are times when the AF of the 5DII just is so frustrating. Hence my original post. I don't shoot a lot of thin DOF and everyone here has pretty much confirmed upgrading body would be more worthwhile. If the 16-50 f/4 IS comes to pass — (and is great!) — I could see it replacing both zooms. That and my 70-300L and I'd be set.


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