AF Microadjustment, Lensalign Pro and Repeatability

[HDNitehawk]

I sent of and got the Lensalign Pro last week. I set it up this weekend and began testing my back up camera (which I use as a walk around camera for work) and the 35mm F1.4L. I am using a 5D Mark II on this test.


I set it up at the minimum distance, ran a series of pictures and checked them on the computer. Very accurate results in the set. Then I tried the camera at various other distances. I found only slight variations in results in these three test which could be contributed to distance.


Then later I decided to check again, because I am somewhat of a perfectionist. Every time I have reset up in a different location I get slightly different results. Some may be contributed to lighting, maybe not because I have tried to eliminate this possibility.


My results have varied from Plus 3 with Plus 3 leaning toward the forward focus side and Plus 6 leaning toward the back focus side.


How I am taking the pictures is sets of 8 at each point, from 0 to 10. Renaming the files out of EXIF data and then reviewing full screen. Either at 100 or 200% depending. Each set has been very consistent and accurate in that you can easily establish the DOF that is being generated at each setting and see the gradual change from one point to the next.


The variation in results is from one set to the next.


I understand that the wider angle lens will not adjust as well as the telephoto's.


So I guess what I am trying to figure out is this normal for the 35mm lens? Is this just from the subtle change in lighting from one test set up to the next?


Or does the camera AF system float a little bit and this is the norm?


Or is the simple answer, I am to picky, set it at plus 5 it will back focus more than front focus and go test the next lens.

[andnowimbroke]

I did have trouble at first because of weak light, but even then, I had a lens that varied from distance to distance and actually used the afma enable/disable button to change between working distances ( enable +5 for distant shots and disable for closer work or whatever it was).I can't really speak for your lens though. I also cheated later on when checking after a couple months. I did the 10x live view thing ( zoomed to the scale side) with flapping mirror only I just focused. The ones that didn't focus right the first time, I just refocused again without manually unfocusing and it would usually sneak up and hit it the next time. I guess that meant it was in the margin of error. I wouldn't set up a camera like that, but just from a re-test point of view, I guess it didn't waste too much time, and I got to get out my ruler for only the second time since I bought it

set it at plus 5 it will back focus more than front focus

Which way would be best? Doesn't blur in front of yourfocus point"work faster" for a lack of a better word and the blur behind gives you more room play? Hope that made sense. And just to put things into perspective, with the system, your getting rid of all variables, but once it's in your hands and your swaying backward and foreword or they are..well, afma isn't meaningless, but it's not the end-all-be-all either.

[HDNitehawk]

Which way would be best? Doesn't blur in front of yourfocus point"work faster" for a lack of a better word and the blur behind gives you more room play? Hope that made sense. And just to put things into perspective, with the system, your getting rid of all variables, but once it's in your hands and your swaying backward and foreword or they are..well, afma isn't meaningless, but it's not the end-all-be-all either.

Thanks andnowimbroke


I suppose which way would work best would be the back focus. At 12' the DOF for this lens at 1.4 is 3'. I think its real close that the autofocus is really going to be important, between 3 and 8 feet in a room of people taking pictures. I suppose aim for the nose and you should catch there face very well if your back focused just a little?





Rick

[neuroanatomist]

Hmmm...I haven't done immediate test-retest of my adjustments, but when I went through the AFMA on my 5DII, I also retested 4 lenses (or so I was thinking at the time) that I had previously AFMA'd on my 7D, with 4-6 months between tests. Two of the four (85L, 100L Macro) were the same, one was different by one unit (70-200mm II went from +1 to +2). The fourth lens was the 24-105mm, and that one had a substantial change - then I smacked my head as I realized that it wasn't the same specific lens - I initially bought a used copy, which I sold when I bought the 5DII to get a new lens at the kit price. So, of three lenses retested two had no difference and one changed by one unit.

[HDNitehawk]

Last night I restested again the 35mm. I set up directly under the overhead lighting in the living room so to get good pictures. I left the tripod set up and did several tests. I ended up at plus 5 and they were consistent. I am thinking it is just the subtle variations inlighting.


But. I set up to do the 24mm F1.4L using my main 5d mark II and ran the range from minus 10 to plus 10. I ended up with a very good 9


Then I brought the lens back, same tripod same set up but this time I turned off the microadjustment and did 10 pics on default. Then turned it back on and ran a test betweeen plus 5 and plus 15. The second set, was totaly off.....it was hitting on about plus 6.


So a third test, this time it hit plus 8 to plus 9 like the first.


I am wondering if just doing the test where your continualy changing the settings over and over if the camera might read the setting a little diffrent each time. What I am going to try to do now is do the test, find the setting, and come back later to see if it duplicates by just using only the one setting.


These two lens I really don't need percission and accuracy after about 12 feet. But real good accruacy up close will make some interesting pics at f1.4

[neuroanatomist]

I set up directly under the overhead lighting in the living room so to get good pictures.

Is the overhead light your only light source? If so, is the LensAlign positioned far enough back so the focus target is well-lit? Here's the setup I use for longer focal lengths, where I need the target near a wall so I can set up the camera up to 32' from the target. There's a light shining down onto to the ruler so that's illuminated (the side light on a Tiffany torchire lamp, in this case), but also notice the gooseneck light pointing at the LensAlign from the front for a bright, even illumination of the focus target plate.


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[HDNitehawk]

I set up directly under the overhead lighting in the living room so to get good pictures.

Is the overhead light your only light source? If so, is the LensAlign positioned far enough back so the focus target is well-lit? Here's the setup I use for longer focal lengths, where I need the target near a wall so I can set up the camera up to 32' from the target. There's a light shining down onto to the ruler so that's illuminated (the side light on a Tiffany torchire lamp, in this case), but also notice the gooseneck light pointing at the LensAlign from the front for a bright, even illumination of the focus target plate.
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I set it up several diffrent ways. One of the locations I noticed later I was getting uneven lighting on the ruler portion. So I discarded those results. One way I had good lighting from the windows. Two others I set up directly underneath overhead lights. The last place I used was in my living room, setting up directly underneath the overhad ceiling fan fixture. Of course the fan was turned off so there was no vibration. Then I turned on selected lights in the halls, other rooms and tried to keep the same lights on continualy. I reset WB to K at 3200 so that it was about right for ambient.


I thought about buying some cheap tungsten lights to brighten the rooom, but for the 35mm and 24mm the lighting I am using right now is probably going to be very similar to the situations I want the AF to be accurate in. Outside shooting and landscapes the AF usally isn't going to matter as much.


I think some of the problem was lighting and it was causing slight variations. This is good info to know, even though it doesn't affect it much it seems toaffect some.From now on I will just be consistent from one test to the next and do each the exact same way.


I am thinking that possibly just the act of just changing the AF adjustment over and over can create a little diviation. So what I am going to do from here on out, is establish the actual value I want by running through the scale once or twice and then retest just that single point value several times over the course of the next few days just to verify it is consistent. If it seems like it is off I can just go up or down 1 and recheck again later. I did this last night with both lenses. I took a series of 20 pictures with both lens, which are mounted on seperate cameras. Rather than trying to determine a exact centernumber on the scale(which is kind of hard with these wide lenses) I just logged Front Focus, Dead On and Back Focus. The 35mm F1.4L tested exactly the way it had been the night before, it came up with 3 FF, 4 DO, and 14 Slight BF which is what I wanted (I may adjust this by one if I feel the bf is to much). The 24MM came back 7FF, 4 DO, 10 BF and its test was consistent with the day before. So far from one day to the next the results at just that AF adjustment location appear to be consistent. I am going to recheck this over the next few days to see how it fairs.


(Side Note: I really haven't comared the two as I had no need because they are diffrent focal lengths. But the 35mm F1.4L and the 24mm F1.4L II are sister lens with the same similar body (which I already knew). But side by side the last few days I the II version of the 24mm F1.4L puts out better looking pictures than the 35mm. The color and contrast arenoticablybetter on the 24mm. Not that the 35mm isn't an awesome lens, it is, I would like to see the updated 35mm F1.4L IIvesrion some time in the future)


Thanks for the help


Rick

[neuroanatomist]

Thanks for sharing your results, Rick!

I am thinking that possibly just the act of just changing the AF adjustment over and over can create a little diviation.

Could be. Also, I wonder if some variation is introduced when you mount/unmount a lens (although maybe you didn't change lenses on a given body during your tests).

But the 35mm F1.4L and the 24mm F1.4L II are sister lens with the same similar body (which I already knew). But side by side the last few days I the II version of the 24mm F1.4L puts out better looking pictures than the 35mm. The color and contrast arenoticablybetter on the 24mm. Not that the 35mm isn't an awesome lens, it is, I would like to see the updated 35mm F1.4L IIvesrion some time in the future

Thanks for this info! I've been debating the two lenses for indoor, ambient light shots where the 16-35mm f/2.8L II will likely not be fast enough. I haven't yet done the 'set the zoom to one focal length for the day' test of 24mm vs. 35mm, but knowing my shooting style I'm preliminarily leaning toward 35mm for FF use. But I'm disappointed that there hasn't been an update of the 35L - I know I've said this before, but in the past 4 years every other L-series prime at 100mm and less is either an updated version (14/2.8 II, 24/1.4 II, TS-E 24 II, 85/1.2 II) or newly-released (TS-E 17, 50/1.2, 100/2.8 Macro IS). That leaves the 12-year old 35/1.4 as an aging lens. It could be argued that it's fine as it is, but your observations, the lack of weather-sealing, etc., suggest it's high time for a 35L II.

[HDNitehawk]

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Thanks for sharing your results, Rick!

I am thinking that possibly just the act of just changing the AF adjustment over and over can create a little diviation.

Could be. Also, I wonder if some variation is introduced when you mount/unmount a lens (although maybe you didn't change lenses on a given body during your tests).

But the 35mm F1.4L and the 24mm F1.4L II are sister lens with the same similar body (which I already knew). But side by side the last few days I the II version of the 24mm F1.4L puts out better looking pictures than the 35mm. The color and contrast arenoticablybetter on the 24mm. Not that the 35mm isn't an awesome lens, it is, I would like to see the updated 35mm F1.4L IIvesrion some time in the future

Thanks for this info! I've been debating the two lenses for indoor, ambient light shots where the 16-35mm f/2.8L II will likely not be fast enough. I haven't yet done the 'set the zoom to one focal length for the day' test of 24mm vs. 35mm, but knowing my shooting style I'm preliminarily leaning toward 35mm for FF use. But I'm disappointed that there hasn't been an update of the 35L - I know I've said this before, but in the past 4 years every other L-series prime at 100mm and less is either an updated version (14/2.8 II, 24/1.4 II, TS-E 24 II, 85/1.2 II) or newly-released (TS-E 17, 50/1.2, 100/2.8 Macro IS). That leaves the 12-year old 35/1.4 as an aging lens. It could be argued that it's fine as it is, but your observations, the lack of weather-sealing, etc., suggest it's high time for a 35L II.
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I never switched the lens, as they were on seperate bodies. So probably not an issue, but from all my years playing with diffrent rifle and scope combinations and relating it to camera focus systems, anytime you introduce another variable your results might change slightly.


I have the 16-35mm 2.8L as well. My observation of the lens is that at 35mmthe 16-35mmperformed very well. As nearly well as the 35mm F1.4L, but you know very well the real advantage of the 35mm F1.4L over the 16-35mm is the F1.4L and the awesome thin DOF and blurred surroundings you can produce in a crowded room. I noticed the most diffrence in IQ with the 24mm over the 16-35mm, but I find 24mm a bit to wide in crowded rooms. Plus the F1.4L thin DOF effect is really magnified on the 35mm, at 3' the DOF is .18 feet compared to the 24mm being .4' so its harder to get that effect on the 24mm.


I am sure if there is ever a 35mm F1.4L II lens I will have mine pre ordered as soon as its announced.


Thanks again





Rick