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Author Topic: Faster (f/2.8) Lenses on 5DII or Slower (f/4) lenses on 5DIII?  (Read 7198 times)

chas1113

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Re: Faster (f/2.8) Lenses on 5DII or Slower (f/4) lenses on 5DIII?
« Reply #30 on: September 18, 2013, 05:50:52 PM »
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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Re: Faster (f/2.8) Lenses on 5DII or Slower (f/4) lenses on 5DIII?
« Reply #30 on: September 18, 2013, 05:50:52 PM »

neuroanatomist

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Re: Faster (f/2.8) Lenses on 5DII or Slower (f/4) lenses on 5DIII?
« Reply #31 on: September 18, 2013, 06:28:12 PM »
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?

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

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Re: Faster (f/2.8) Lenses on 5DII or Slower (f/4) lenses on 5DIII?
« Reply #32 on: September 18, 2013, 06:48:42 PM »
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?

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

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Re: Faster (f/2.8) Lenses on 5DII or Slower (f/4) lenses on 5DIII?
« Reply #33 on: September 18, 2013, 09:00:30 PM »
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?

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.

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.

Drizzt321

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Re: Faster (f/2.8) Lenses on 5DII or Slower (f/4) lenses on 5DIII?
« Reply #34 on: September 18, 2013, 10:27:05 PM »
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?

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.

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.

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.
5D mark 2, 5D mark 3, EF 17-40mm f/4L,  EF 24-105mm f/4L IS USM, EF 135mm f/2L, EF 85mm f/1.8
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Rienzphotoz

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Re: Faster (f/2.8) Lenses on 5DII or Slower (f/4) lenses on 5DIII?
« Reply #35 on: September 19, 2013, 12:45:04 AM »
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

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Re: Faster (f/2.8) Lenses on 5DII or Slower (f/4) lenses on 5DIII?
« Reply #36 on: September 19, 2013, 06:49:26 AM »
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.  :P
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Re: Faster (f/2.8) Lenses on 5DII or Slower (f/4) lenses on 5DIII?
« Reply #36 on: September 19, 2013, 06:49:26 AM »