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Archive 2012 · 50L and 5D3 outer focusing points..
  
 
BryantFC
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p.1 #1 · 50L and 5D3 outer focusing points..


Am I going crazy or just being OCD? I'm using a Canon 5D mark III and a 50L f1.2. After getting it calibrated correctly in correct conditions
using Reikan Focal, i'm getting inconsistant results from using outer focus points. Mine required a +5MA adjustment which imo, isn't too extreme.
From f1.2 and on up using the center cluster area, subject area i'm focusing on is always sharp and on point. This is using Single AF one shot and
Single Spot AF one shot.

But the biggest issue is when I start using outer focusing points. Both single point and spot AF, AF areas are slightly heavily softer than center point.
It slightly improves once i start shooting at f2.8 and up. I also own a 35L which required +8MA and an 85mm f1.8 that requires -4 MA. Every single focus point
is just as sharp as center point with these two lenses. I don't understand why it's a constant issue with the 50L. My question is that is there something wrong with my lens
or is it just a particular characteristic of this lens?


Here's a small test I did using a tripod and available morning light.

5+MA center point by BryantFC, on Flickr


5+MA outer left point by BryantFC, on Flickr
slightly softer and i'm focusing on the "hydro" this is the furthest outer left point at +5 on my 5d3.

now this is the weird part. if i dial in a +15MA and shoot the same shot, it's sharper in the same area.


15+MA outer left point by BryantFC, on Flickr

this also applies to the furtest outer right point on the 5d3. +5 for the first and then +15 on the second.


5+MA outer right point by BryantFC, on Flickr


15+MA outer right point by BryantFC, on Flickr


I also found that if i switched to just using 15 AF points, it's slightly better. For instance, here's a shot I did yesterday using one of the outer focus points with the 15 AF
points, and although it's not as sharp as usual, something doesn't look right to me..

This is f1.2 focus on eye and outer focus point using 15 AF point.

50L f1.2 by BryantFC, on Flickr




Is the issue my own issue due to user error? Am I expecting too much out of extreme shallow depth of field at wide apertures? I can't say I can blame my 5D3 due to the fact that
I don't have this problem on my other two lenses..

I'd like some strong advice on this since this is my go to portrait lens. It is a pain because I bought the 5d3 for the AF system and to get rid of focus recompose.
If it is a lens issue and it's out of warranty, any idea how much Canon will charge to calibrate it to my 5d3?
Sounds like a good reason for me to sign up for CPS Silver soon..





Aug 13, 2012 at 03:56 PM
Wahoowa
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p.1 #2 · 50L and 5D3 outer focusing points..


Let's assume that it's user error and there is no fault to the copy of your lens or the lens design.

And it looks to me like you got everything figured out. You have the camera & lens calibrated. You put this on a tripod. That said, the only scenario that might cause the focus to be off is that you didn't defocus the lens first before taking those shots.

I've never used Reikan Focal. But if you do the micro adjustment the way I do it, it will require a lot of focusing and defocusing works. If you don't defocus, some lenses will likely struggle to find the same sharp spot.

Also, I do the micro adjustment in bright enough light.

Hope this helps.

Edited on Aug 13, 2012 at 05:56 PM · View previous versions



Aug 13, 2012 at 04:30 PM
Binh Ly
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p.1 #3 · 50L and 5D3 outer focusing points..


I have found that the 50L is the most difficult lens to test on a tripod. It will behave very inconsistently that you will just get more confused. Why don't you take it out for a spin, shooting real world portraits at distances that you would normally use it and then decide from there. I stopped testing that lens on a tripod because the results are so inconclusive. I bring it out to a real-world job and it behaves perfectly. I use it on a 5D III also without any issues regardless of which AF point I use (but I only turn on the cross points on my 5D III).


Aug 13, 2012 at 04:39 PM
BryantFC
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p.1 #4 · 50L and 5D3 outer focusing points..


@Wahoowa, yes. I never knew that about the whole defocus thing. Usually when I AF, i press it once, take the shot and press it again about another three or two times just to ensure i'm getting it right. Then I take a few frames of the same pose just in case if one is out of focus. I guess that could help in the future.

@Binh Ly

here are a few real world shots. the first one is at f1.2 and on the eye to the right from your viewing


these two are at f2.0



Different focusing distances and they're on point using outer focus points. It's like the lens works when it wants to and that's where i'm getting a huge headache.



Aug 13, 2012 at 04:50 PM
 

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Binh Ly
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p.1 #5 · 50L and 5D3 outer focusing points..


Your real world shots look excellent. So I wouldn't worry too much about it.


Aug 13, 2012 at 10:25 PM
mttran
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p.1 #6 · 50L and 5D3 outer focusing points..


Binh Ly wrote:
Your real world shots look excellent. So I wouldn't worry too much about it.


+1, like Binh said - your set is doing fine.



Aug 13, 2012 at 11:33 PM
Wahoowa
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p.1 #7 · 50L and 5D3 outer focusing points..


I agree to the above that your real world examples look fine.

In the real world situations, you don't need to defocus because the lens is most likely at the out-of-focus position anyway, even if you try to take a photo on a tripod. However, keep pressing the shutter release button might not be a good idea. It's similar to why it's not a good idea to have IS system on when the camera is set up on a tripod. (New lenses detect automatically if it's on a tripod, but I'm talking about some old lenses.) Having an element moving when the camera is steady does not help, but makes it worse. Similarly, forcing the lens to refocus when it's already at the sharpest spot will make it on par at best.

Nice photos, BTW.



Aug 14, 2012 at 12:30 AM





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