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Archive 2015 · Canon 35mm f/2 IS weirdness

  
 
yelloguy2
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p.1 #1 · p.1 #1 · Canon 35mm f/2 IS weirdness


I just bought this lens a months or so back. I have shot with it 2-3 times and every time I do, at f/2 9 out of 10 shots (roughly) are OOF. Doesn't matter if I use the center focus point (Canon 6D body) or the peripheral points. The problem is that if it consistently misses focus I could contact Canon or something. But I do get in-focus shots every once in a while. But since it misses focus almost always, I don't even want to shoot at f/2 so I am afraid of experimenting.

I just don't know what to do with this lens. I have a 85 1.8 and a 50 1.8 II and both find focus wide open 9 times out of 10 so it is not my technique.

Any suggestions?



Sep 06, 2015 at 12:21 PM
EB-1
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p.1 #2 · p.1 #2 · Canon 35mm f/2 IS weirdness


How far from zero was the was lens calibration you did before the AF issues appeared?

EBH



Sep 06, 2015 at 12:29 PM
Dave McGaughey
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p.1 #3 · p.1 #3 · Canon 35mm f/2 IS weirdness


Micro adjust the lens AF and report back. 9/10 wrong sounds close enough to always wrong.


Sep 06, 2015 at 01:16 PM
Gochugogi
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p.1 #4 · p.1 #4 · Canon 35mm f/2 IS weirdness


I have that same combo and it is rare to get an OOF, and I shoot a lot at F2.0. I experienced something similar to what you described with the EF-s 40 2.8 STM on my SL1: about 30% of images were OOF. Didn't matter if I shot at F8 or 2.8, was blazing sunlight or twilight or placed the center point precisely on the target (in single point mode of course). Very consistently 1/3 of the images were OOF. Oddly, it was okay on my 6D and the EF 35 3.0 IS USM was fine on my SL1 as well. I never solved the mystery but got rid of the 40 2.8 STM. It also suffered pronounced coma and focused slow so I was happy to see it go.

Neither lens needed MA on my 6D.



Sep 06, 2015 at 01:16 PM
Ian.Dobinson
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p.1 #5 · p.1 #5 · Canon 35mm f/2 IS weirdness


Dave McGaughey wrote:
Micro adjust the lens AF and report back. 9/10 wrong sounds close enough to always wrong.


yeah . the 1 out of 10 is probably wrong as far as the lens/body combo is concerned and you've just lucked it being wrong in the right direction if you get the drift



Sep 06, 2015 at 01:25 PM
Gunzorro
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p.1 #6 · p.1 #6 · Canon 35mm f/2 IS weirdness


Have you done a thorough AFMA on it? You don't mention if you did.

I am very satisfied with mine. I'd hate to say it focuses 100%, but seems to be right on the mark if I pick the right target.



Sep 07, 2015 at 12:13 AM
RobertLynn
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p.1 #7 · p.1 #7 · Canon 35mm f/2 IS weirdness


Try the dot tune method for AF calibration. It's very fast and easy.

50X the focal length in mm, so 1750mm. 1750mm=68.89 inches. So set up a high contrast AF target in line with the focal plane approx. 68 inches from the camera. Doesn't need to be 68.89, could be 65, or 70. Just get it close to that.

Take the camera and place it in live view mode. Use the 10X magnifying setting and auto focus on the target. Verify that it is a sharp capture. Turn off the live view and then turn the focus mode to MANUAL, while not bumping the focus ring. Now you're ready to begin narrowing down the AF tune range. You're going to pick a number, either + or -, doesn't matter. All you're doing is looking for the range of numbers that give you a verifiable focus confirmation. Hold the AF button on and look in the view finder for the green light to light up. Keep doing this, both plus and minus, until you find the number where you do NOT get an AF confirmation. So say you get one at +16 and not one at +17, then +16 is the end of the tune range on the positive side. Continue this for the negative side as well.

Then you calculate the midpoint of those two numbers. So if your camera tells you -8 and +17 are the two ends of the spectrum, you select an AF tune value in the middle of that, so +4.5. Since there's no +4.5, you pick either +4 or +5.

There's a video on youtube, as well as a well laid out thread on this forum. This is the method I use to AF tune my lenses.

Another way to check the AF of that lens is to focus it in LV at 10X magnification and check the results against regular AF through the VF.



Sep 07, 2015 at 08:44 AM
DLP
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p.1 #8 · p.1 #8 · Canon 35mm f/2 IS weirdness


Not sure what to suggest other than sending it in to be checked assuming it is still under warranty. Like others here I get excellent results from my copy. I don't think I've ever had an oof image I could fault the lens for and most of my shots with this one are wide open.


Sep 07, 2015 at 09:31 AM
yelloguy2
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p.1 #9 · p.1 #9 · Canon 35mm f/2 IS weirdness


I am going nuts here. I don;t think mfa is doing anything for me. But first, thank you all for taking the time to reply. Thank you Robert for typing up the instructions. I got the whole thing all set up but then I realized I don't understand what you mean by "keep doing this, both plus and minus." What am I doing here? I turned the focus ring but there are no numbers and the focus indicator light goes out pretty quick at very slight movement of the focus ring.
So I decided to use the old fashioned trial and error mfa. I took shots at -20, -15 all the way up to +20. And the extremes get blurry for sure. Other than that, I think -10 looks ok as well as 0. I am comparing this to the one photo I took in live view. I am linking 100% zoom captures from my mac.

This is with mfa 0:

mfa zero

This is with mfa -10:

mfa negative 10



Sep 07, 2015 at 03:23 PM
artsf
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p.1 #10 · p.1 #10 · Canon 35mm f/2 IS weirdness


I am new to 6d and also have 35mm f/2 IS. It seems that I am experiencing front-focusing with all my lenses which only happens when shooting at a distance, typically 10ft. and more. LiveView contrast-detect is always precise, only happens when using PhaseDetect including Quick AF in LiveView. This phenomenon dramatically impacts my landscape pictures where the camera essentially does not focus to infinity. It also makes it unreliable to shoot environmental portraits for which I use 85mm f1.8 and 50mm f1.4 a lot - again LiveView is reliable. Do I need to MA all my lenses? Never done it before. Will MA affect near-distance focusing also which works fine? I've been relying on LiveView because of this but it's not fun!


Sep 08, 2015 at 01:16 AM
Ian.Dobinson
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p.1 #11 · p.1 #11 · Canon 35mm f/2 IS weirdness


yelloguy2 wrote:
I am going nuts here. I don;t think mfa is doing anything for me. But first, thank you all for taking the time to reply. Thank you Robert for typing up the instructions. I got the whole thing all set up but then I realized I don't understand what you mean by "keep doing this, both plus and minus." What am I doing here? I turned the focus ring but there are no numbers and the focus indicator light goes out pretty quick at very slight movement of the focus ring.
So I decided to use the old fashioned trial and
...Show more


I presume the image with the large box is the live view image and the small box is the normal (phase detect) AF ?

if so looking at both the Zero and the NEG 10 the Zero is sharper ., so is the closer one to the correct MA.


if your using the -20 to +20 in 5 steps method you need to narrow things down and the do another more refined set (i.e. in steps of 2)

so if zero is close and neg 10 isn't bad (it does look as though its out though) without being what neg 5 and +5 & +10 are like I would say you want to do

-4 -2 0 + 2 +4


I know many on here use the dot tune method and I agree its a good pretty quick method . very good in the field to use at you normal shooting distances .

if you hat home and are in front of a PC/Mac with a good large screen then using the DPP software to do tethered captures works very well .

the part where you bring up the live view and can control the camera lets you focus (using PDAF) . it also has focus adjust buttons they look like <<< << < > >> >>
if you get the camera to focus you can then click each step using < or > . the single step is the same as moving the MA 1 point .



Sep 08, 2015 at 01:47 AM
yelloguy2
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p.1 #12 · p.1 #12 · Canon 35mm f/2 IS weirdness


Thanks very much, Ian. I will try doing this tethered later. I just showed 0 and -10 as an example, -5 also looked like -10.

artsf, I would think that the MA change will affect focusing at all distances. So it may not be ideal for you. But in 6D there is an option to apply MA universally for all lenses. I don't know how that works. If your camera is in warranty, you should be talking to Canon. There is no reason you should have to live like that because the 6D is a fantastic camera.



Sep 08, 2015 at 06:45 AM
RobertLynn
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p.1 #13 · p.1 #13 · Canon 35mm f/2 IS weirdness


Dpp has a tool for AF adjustment? Get out of here? I may have to start using that piece of cap software (seriously, Dpp work flow isn't intuitive, or rather wasn't when I was using it.)

Ian.Dobinson wrote:
I presume the image with the large box is the live view image and the small box is the normal (phase detect) AF ?

if so looking at both the Zero and the NEG 10 the Zero is sharper ., so is the closer one to the correct MA.

if your using the -20 to +20 in 5 steps method you need to narrow things down and the do another more refined set (i.e. in steps of 2)

so if zero is close and neg 10 isn't bad (it does look as though its out though) without being what neg 5 and
...Show more



Sep 08, 2015 at 06:51 AM
johnctharp
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p.1 #14 · p.1 #14 · Canon 35mm f/2 IS weirdness


RobertLynn wrote:
Dpp has a tool for AF adjustment? Get out of here? I may have to start using that piece of cap software (seriously, Dpp work flow isn't intuitive, or rather wasn't when I was using it.)



'Tethered capture' refers to having the RAW files transferred immediately to your catalog, so that you can review them as they're shot and then make adjustments quickly, I believe.



Sep 08, 2015 at 07:51 AM
Ian.Dobinson
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p.1 #15 · p.1 #15 · Canon 35mm f/2 IS weirdness


RobertLynn wrote:
Dpp has a tool for AF adjustment? Get out of here? I may have to start using that piece of cap software (seriously, Dpp work flow isn't intuitive, or rather wasn't when I was using it.)




yeah horrible SW but it does have its uses

the 'tool' isnt really a tool for MA but you can use it as such to get a reading .

what you need to use is the live view preview . you can then control the camera from the computer .
you need to get it to AF using the PDAF (not live view AF) . and then click the single step button until you have the best focus . each single step is 1 MA point . so if you start the camera at zero in the MA setting and click 12 times on on of the < > buttons you know that your MA will be +/- 12 .
then you set that figure in camera and try again just to check .

ive used that method for my 120-300 and 80-200 and find it faster and more accurate the standard method .

I have use the dot tune method as well as thats probably the best in the field method



Sep 08, 2015 at 08:33 AM





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