Manual Focus Micro Adjustment

Al Chemist

Be kind to a stranger, it is contagious!
Nov 23, 2014
84
1
i have been using Zeiss lenses on the 5DSR and was frustrated by trying to use the green focus confirm light in the lower right corner...too hard to watch and not very sensitive. I then discovered that when you are using "auto focus point expansion", that the outer 4 (or 8) focus pts will blink out when in focus. The long focus throw of Zeiss lenses helps because that blinking out is very sensitive. When in focus these points go out but either direction past focus they reappear.

I noticed that on the 100 MP that focus was not perfect and then went to the afma settings to see if I could do that. You can actually record an adjustment for these lenses and also record their serial number. I almost always use my camera hand-held so this really has made a difference. I did what I guess is a "manual focus micro adjustment" for all 4 of my Zeiss lenses.

I think this should work for any manual focus lens if the camera reads exif data.
 

Zeidora

EOS 7D MK II
Feb 15, 2015
668
10
Interesting. Do you use the stock screen or a focusingscreen.com matt version? I use the latter and never bother with the green focus confirm. I mainly shoot tripod, but was positively surprised when I shoot with the Otus 55 at 1.4 handheld and nailed focus in off-center area (eye of moving person). My main go-to lens is also the 100 MP.
 

Al Chemist

Be kind to a stranger, it is contagious!
Nov 23, 2014
84
1
Hi Zeidora,
I'm using the standard screen. This method works best with the 100MP and the 135APO due to a narrower depth of field. I also find it works pretty well on the 50MP. I was actually pretty surprised at the difference I saw in my series of test images using different settings. All required a positive adjustment not that that means anything.

By the way, thank you very much for your knowledgeable posts!
Richard
 

Dholai

EOS T7i
Feb 5, 2014
53
4
I have the exact same issue that Al described. The latest 135 mm Milvus gave me this headache recently! While it is a phenomenal lens with unbelievable image quality, to me, it seemed like it is front focusing! My eyesight is not great and I was depending on the focus confirmation beep with the AF point lighting up briefly while looking through the OVF.

Al, could you please explain what you did in a little more details ( MFMA- I guess) ?

thanks

Dholai

P.S. I use it on 5DMK IV and 5DsR
 

Al Chemist

Be kind to a stranger, it is contagious!
Nov 23, 2014
84
1
Hi Dholai,
I set up the camera on a tripod and just used the 2 sec shutter delay. I set the lens at f2 and focused on my target which I placed at 3.4 meters. The target consisted of a metal ruler set at 45 degrees and a vertical focus target. In the camera under the auto focus settings there is one for "AF microadjustment"...furthest AF menu to the right. I took a series of images at -15/-10/-5/0/+5/+10/+15. If you press info you can make the changes for the lens. If you press info while in the adjustment slider window, it allows you to input the lens serial number. I then processed the images identically and converted the RAW format to jpg. I then looked at each image at a large enlargement and I then picked the setting which gave the best focus of the target with out of focus points equal front to back on the ruler. The whole process is tedious. You do want to select "Adjust by Lens" and not "All by the same amount". Hope this helps. I know this will work on my 5D3 but I don't have a 5D4.
 

Jack Douglas

CR for the Humour
Apr 10, 2013
5,983
808
Alberta, Canada
It seems, from the wisdom of others, that the distance front and rear is not generally equal when you are in focus on an object. How much difference it makes in this case I am not qualified to speculate but in my own AFMA activities it was leading me astray.

Jack
 

Zeidora

EOS 7D MK II
Feb 15, 2015
668
10
Jack Douglas said:
It seems, from the wisdom of others, that the distance front and rear is not generally equal when you are in focus on an object. How much difference it makes in this case I am not qualified to speculate but in my own AFMA activities it was leading me astray.

Jack
Are you referring to extent of DOF in front and to rear of focal plane? That is generally 1/3 towards camera, 2/3 away from camera. In macro it gets closer to 50/50 front/back. That is true for any lens.
 

Al Chemist

Be kind to a stranger, it is contagious!
Nov 23, 2014
84
1
Thank you, I guess I knew about the difference in front to back out of focus but it totally didn't enter my mind while looking at the test images. I mainly looked at the focus target since that was sharpest...the out of focus points on the ruler were harder to decipher so I just roughly used those. I will go back and look and I'll bet that I see a difference.
 

Al Chemist

Be kind to a stranger, it is contagious!
Nov 23, 2014
84
1
I have an app for my smartphone that shows depth of field for specific cameras and different focal lengths at various f-stops that it shows these front to back differences. I cannot say how accurate this app is but for a 135 lens at f2 at 11 feet, the depth of field in front is 1.38 inches and in back it is 1.41 inches. At close distances that difference is negligible but as the distance from the camera increases, the difference would be more apparent.
 

midluk

EOS RP
Aug 27, 2015
321
0
I find the moiré method much easier to use than the ruler method.
Use a monitor to display an image filled with a checkerboard pattern (1x1 or 2x2, depending on the pixel density of the monitor and camera sensor) and a high contrast area in the center to focus on.
If you choose the right distance between monitor and camera (depending on focal length) you will get a very pronounced green/magenta moiré pattern (mostly stripes) when the image is properly focused. After achieving auto focus (or manual focus with AF confirm), don't take an image but switch to live view (zoom in 10x) and check if you have reached the point of maximum moiré (increasing saturation in picture style might help). You can slightly adjust focus to check in which direction the focus is off and repeat the procedure with different correction settings until focus is either spot on, or about 50%/50% front and back focus.
 

Viggo

EOS 5D SR
Dec 13, 2010
3,891
442
With my Zeiss 100 mp and the 21 mm it makes a huge difference if you rely on the green dot whether you pull focus from mfd or infinity. If I used from infinity and pressed the shutter exactly when it beeped it never missed at any distance.
 

rfdesigner

EOS 6D MK II
Sep 12, 2014
876
0
New Forest, UK
sites.google.com
Zeidora said:
Jack Douglas said:
It seems, from the wisdom of others, that the distance front and rear is not generally equal when you are in focus on an object. How much difference it makes in this case I am not qualified to speculate but in my own AFMA activities it was leading me astray.

Jack
Are you referring to extent of DOF in front and to rear of focal plane? That is generally 1/3 towards camera, 2/3 away from camera. In macro it gets closer to 50/50 front/back. That is true for any lens.
+1

it's physics rather than lens design.

I always find thinking about the extreme cases useful.

As you stop any lens down you might expect the DoF to reach to infinity if it isn't focused too close, but you can't reasonably expect the other end of the DoF to reach zero (so the DoF reaches further behind than in front). As you get nearer to minimum focus distance, the aperture required to reach infinity gets increasingly small, at macro distances it's simply impossible, the DoF becomes less unevenly distributed.
 

Jack Douglas

CR for the Humour
Apr 10, 2013
5,983
808
Alberta, Canada
"As you stop any lens down you might expect the DoF to reach to infinity if it isn't focused too close, but you can't reasonably expect the other end of the DoF to reach zero (so the DoF reaches further behind than in front)."

It's helpful to be able to use a bit of reasoning such as presented here! :) Another thing that occurred to me is that a vertical target and a 45 degree plane with ruler etc. will have half the target further away and as such the objects will be smaller in appearance, which tends to influence how the brain perceives them relative to focus, or not?

Jack
 

Zeidora

EOS 7D MK II
Feb 15, 2015
668
10
chrysoberyl said:
How difficult is the screen replacement?
You need a small cross/philips screw driver, some decent light, and a reasonably clean (household clean) surface. Takes about 30 minutes if you take it nice an slow. Once you've done it once, it could be done in 5 minutes. There are instructions with the screen, and there is also at least one youtube video.

Some reasonably steady hands are advantageous. That is very difficult to predict, as people differ in that aspect. I found it very easy, but I do a lot of very small-scale, fiddly stuff professionally. Like preparing teeth from <1 mm snails for scanning electron microscopy.
 

Al Chemist

Be kind to a stranger, it is contagious!
Nov 23, 2014
84
1
Hi Chrysoberyl,
I noticed that you have a 6D. Changing the screen on the 6D is very straight forward...the replacement screen just drops in. I purchased the alternate screen and have not really noticed that much difference.

The great thing about the 6D is that you can set the focus point to light up in red upon focus. I wish the 5 series did the same! I really like this when using Zeiss lenses on my 6D. I have found that, when it lights up in red, the focus has been very good.

I have yet to try a micro adjustment with the 6D but plan to do this soon. I checked the menu while the Zeiss 100MP was on the camera and it allows the same changes as the 5DSR and 5D3. Go to the orange tab in the Menu, select C. Fn II:Autofocus "9" and you can do a micro adjustment on your Zeiss 100 and even input the serial number.
 
Mar 31, 2014
950
56
68
Center of my universe
Zeidora said:
chrysoberyl said:
How difficult is the screen replacement?
You need a small cross/philips screw driver, some decent light, and a reasonably clean (household clean) surface. Takes about 30 minutes if you take it nice an slow. Once you've done it once, it could be done in 5 minutes. There are instructions with the screen, and there is also at least one youtube video.

Some reasonably steady hands are advantageous. That is very difficult to predict, as people differ in that aspect. I found it very easy, but I do a lot of very small-scale, fiddly stuff professionally. Like preparing teeth from <1 mm snails for scanning electron microscopy.
Thanks, good advice as usual. I'll practice on a few snails (snails have teeth?!) first.
 
Mar 31, 2014
950
56
68
Center of my universe
Al Chemist said:
Hi Chrysoberyl,
I noticed that you have a 6D. Changing the screen on the 6D is very straight forward...the replacement screen just drops in. I purchased the alternate screen and have not really noticed that much difference.

The great thing about the 6D is that you can set the focus point to light up in red upon focus. I wish the 5 series did the same! I really like this when using Zeiss lenses on my 6D. I have found that, when it lights up in red, the focus has been very good.

I have yet to try a micro adjustment with the 6D but plan to do this soon. I checked the menu while the Zeiss 100MP was on the camera and it allows the same changes as the 5DSR and 5D3. Go to the orange tab in the Menu, select C. Fn II:Autofocus "9" and you can do a micro adjustment on your Zeiss 100 and even input the serial number.
Thanks very much! I am generally pretty happy with my focusing without the high contrast screen, but I am one who likes to have much or all of the subject in focus. So I am shooting with substantial DOF. Nevertheless, I want to try this micro adjustment.
 

Attachments

Zeidora

EOS 7D MK II
Feb 15, 2015
668
10
chrysoberyl said:
Zeidora said:
chrysoberyl said:
How difficult is the screen replacement?
You need a small cross/philips screw driver, some decent light, and a reasonably clean (household clean) surface. Takes about 30 minutes if you take it nice an slow. Once you've done it once, it could be done in 5 minutes. There are instructions with the screen, and there is also at least one youtube video.

Some reasonably steady hands are advantageous. That is very difficult to predict, as people differ in that aspect. I found it very easy, but I do a lot of very small-scale, fiddly stuff professionally. Like preparing teeth from <1 mm snails for scanning electron microscopy.
Thanks, good advice as usual. I'll practice on a few snails (snails have teeth?!) first.
Attached an image of the teeth (radula) of a 1 mm snail. Width is around 50 µm, so less than the width of an average human hair. No coffee when you prep. it because the tungsten needles shake too much under the stereomicroscope. So a focusing screen is a walk in the park ;-)
 

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