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DPChallenge Forums >> Photography Discussion >> Moire Method for Micro Adjustment of Lenses
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01/02/2013 08:30:42 PM · #1
I just did the Moire method of micro adjustment for lens focus. According to this method, my 50mm 1.4 and new Sigma 35mm 1.4 do not need any adjustment. My 85mm 1.8 needed a backward focus adjustment of +12. This was a very easy method to follow and very quick compared to Canon's suggested method. So far, seems very accurate. I need to take some test shots with the 85mm 1.8 to make sure it works well with this adjustment, but it makes sense as my brain was telling me the 85 looked soft at 1.8 (compared to a previous copy I had on an old 30D which I remembered to be tack sharp at 1.8).

Anyone else tried this method?

Message edited by author 2013-01-02 20:30:56.
01/02/2013 08:42:02 PM · #2
Not yet but looks interesting, so thx for the link...... I worked thru the paper target thing and am a believer but it was such a PITA, so open to new methods.
01/02/2013 08:52:47 PM · #3
i tried a similar approach over the weekend to see what the all the MA hoopla was about. i had a hard time getting the camera to focus on the lcd screen from the min working distance of 50 x focal length,which for my 50mm was about 8 ft, maybe i needed a bigger lcd.

01/02/2013 09:32:57 PM · #4
This sounds like a really ingenious method... too bad I can't use it for my 5D, LOL.
01/03/2013 02:25:22 AM · #5
Ooh going to try this tonight then, what distance is a good starting point then only read the first page as I'm on my phone
01/03/2013 09:54:22 AM · #6
Originally posted by Giles_uk:

Ooh going to try this tonight then, what distance is a good starting point then only read the first page as I'm on my phone


I positioned each lens so that the entire computer screen was inside the frame (27" imac). Then I used liveview to zoom to the center target area. If you're calibrating a zoom, don't forget to calibrate at the longest length. This may make it difficult for people with crop sensors and longer lenses. Also make sure your computer screen is 90 degrees. Tilting forward or back will make the effect less noticeable and harder to adjust accurately.

Also, because the moire amount is somewhat subjective, do the test a second time once you have dialed in any adjustments to confirm the change as accurate.

Message edited by author 2013-01-03 09:57:04.
01/03/2013 10:19:56 AM · #7
Originally posted by kgeary:

Originally posted by Giles_uk:

Ooh going to try this tonight then, what distance is a good starting point then only read the first page as I'm on my phone


I positioned each lens so that the entire computer screen was inside the frame (27" imac). Then I used liveview to zoom to the center target area. If you're calibrating a zoom, don't forget to calibrate at the longest length. This may make it difficult for people with crop sensors and longer lenses. Also make sure your computer screen is 90 degrees. Tilting forward or back will make the effect less noticeable and harder to adjust accurately.

Also, because the moire amount is somewhat subjective, do the test a second time once you have dialed in any adjustments to confirm the change as accurate.


see now thats what i was talking about i though you needed to be a certain distance form the screen when focusing when you MA a lens? the number i heard was 50x the focal length, or 2.5m (8') for a 50mm, 4.25m (13') for a 85mm, etc.

using this method you dont need to do that?

Message edited by author 2013-01-03 10:20:27.
01/05/2013 08:44:50 PM · #8
Originally posted by mike_311:



see now thats what i was talking about i though you needed to be a certain distance form the screen when focusing when you MA a lens? the number i heard was 50x the focal length, or 2.5m (8') for a 50mm, 4.25m (13') for a 85mm, etc.

using this method you dont need to do that?


I've read 40x focal length at different times, but I've never really understood why 40x is the magic number. What I've found that works for me is to test the lens at the distance I'm most likely to use it at. For most of the mid range lenses, 40x is probably not far off where I'd use it anyway, but I test my macro lenses closer than that, and my for my long lenses, I use a utility box on a hillside across the street from my house as the focus target, and use the sloped sidewalk next to the utility box as the "ruler". The utility box and sidewalk method worked wonders for my 300 f4.

I just tried the moire method on my most troublesome lens (Tamron 28-75). Ingenious. Once I understood what I was doing, it was much faster and easier than trying to use the focus target and yardstick method, and I got results that are fairly consistent with other tests I've run. And the camera only overheated and shut down once while I was figuring it all out.
01/14/2013 10:46:31 PM · #9
I tried this today and I don't quite get it. I placed myself at the required distance and couldn't pick up any patterns at all, except for my 70-300mm, which was far closer than it should have been.

I went through the process anyway with all my lenses just based on sharpness of what I was seeing, and sadly I cannot blame my crap photos on focus issues. Except for the 12-24mm, which did need an adjustment... but I focus that manually anyway so it was a tease of hope.
01/15/2013 03:50:19 PM · #10
Originally posted by bohemka:

I placed myself at the required distance and couldn't pick up any patterns at all...

Was zooming in too much in Live View.
01/15/2013 04:27:08 PM · #11
When I saw the test pattern was a GIF, I was half expecting a scary face to pop up after 30 seconds.
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