EM1 Micro Focus Adjustment - Why and How to Perform

Brenji49

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Don't want to clutter the thread, but do want to echo thanks for the time and energy to create this thread and keep it going. It's inspired me to find a 50 f2 and Ed 50-200 to start. Just ordered the alignment tool!
 

Baenwort

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So a post in this thread has me wondering if I should do AF Cal with filters on if I often shoot that way?

I'm getting a LensAlign kit as a combo father's day/ birthday gift (hardware for father's day and software for birthday) as I shoot C-AF nearly all the time and it was the only thing I could think of when asked by my family for gift ideas. I only have m43 lenses so I'm curious how much adjustment they will need as Phocal never got back with his testing data.

Would it be useful to others to share the results here?
 

barry13

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Would it be useful to others to share the results here?
I'm interested.

I had a really hard time with AF on the ZD 12-60mm with a CPL a few months ago when in the shade... so much so that I decided against taking it on a vacation (as I expected I'd use the CPL a lot) and took the 12-40mm instead. Ended up being overcast so I didn't use a CPL, but I did miss the extra reach.
 

Mack

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I'll add getting the FocusTune software along with the LensAlign MkII ruler helps to understand your fingering of the shutter release.

On my E-M1 Mark II, the FocusTune software was giving me some odd results when I would set the AF Tune to -20 to run a test. Sometimes it would report "Zero" in the software and not -20 or whatever I placed there. Sometimes the software's "Focus Point" would say CF-L2 or some other nonsense too.

What happens with the E-M1 Mark II is that it has a very slow shutter button. If you stab it too quick, it does not accept your -20 number and stays at zero so you get a soft image. The release has to be pressed consistently, slowly, and fully or else it will not send the AF Tuning correction to the lens. Stabbing at the E-M1 Mark II shutter button is BAD!

Oddly, the E-M1X seems to be less prone to stabbing the shutter and registers the correct AF Tuning value as it is faster in operation than the E-M1 Mark II. I had little issue with the E-M1X and AF tuning verses the E-M1 Mark II which gave me fits going back to it. When I went back to re-check some lenses on the E-M1 Mark II, it gave me some bad tuning results and for several tests the AF Tuning point was not changing from zero. The E-M1X spoiled me as I could trigger the button faster. The E-M1 Mark II does not like my same triggering action used on the E-M1X and it will result in a soft image if I punch or stab it too quick. Sometimes the little green focus square on playback on the LCD would be missing as well (Olympus really needs to add that green focus square to their Workspace software, imho.).


Fwiw, the cam.dat file's text in the FocusTune software needs to be altered for the E-M1X too so the software will read it. It's sort of long and don't know if I should post it here. You might be able to figure it out looking at the file in a text reader and change it yourself.
 

Phocal

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Fwiw, the cam.dat file's text in the FocusTune software needs to be altered for the E-M1X too so the software will read it. It's sort of long and don't know if I should post it here. You might be able to figure it out looking at the file in a text reader and change it yourself.
If you contact them they will update it for the fix. He probably hasn’t had anyone report a problem with the EM1x yet.
 

Mack

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Somehow the firmware updates deleted my 300mm and 420mm lens tuning data when I updated the 300mm lens. Not having it written down I needed to recheck the 25 AF spots Olympus uses so this time I used the FocusTune software on each of the 25 AF tuning spots.

I only checked the -2, -1, 0, +1, and +2 tuning numbers in the body knowing they would be close (Unlike my Nikon which needed a -19, but it had severe back-focus issues even new.). I did three shots of each of the five locations so it would average in the software. Seems easy enough.

However, the 300mm and the 420mm (300mm with the MC-14 1.4x tele-converter.) would need to be done on both the E-M1 mark II and the E-M1X. Count that as 4 tests.

Bad part was it took me 5.5 hours to do each one of the four! I used a 12 second self-timer for each trigger, and then did each AF square of shots in the software before moving onto the next AF square. Bloody timing consuming as it took about 22 hours to finish the testing on the two bodies with the 300mm and the 420mm tele-converted lens too.

With all the software settings installed, I went to check them on the scrub jay bird at the feeder. Seems even though they were all set per the software, adding one more point to all of the software's AF tuning numbers shifted the focus back a bit so more of the bird appeared in focus and sharper. I think a round bird needs a bit of back-focus added so that's what appeared to work better by adding on one extra point to what the software said. One added point may be only about 2/10 inch back-focus at ~25 feet, i.e. not much.

Below are the settings for the 300mm and the 420mm in the E-M1 Mark II and the E-M1X. I did add one point to the 300mm data for both, but yet to do that with the 420mm and it is the software's unaltered numbers.

What a fookin' job, but it's done! :yahoo:

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Phocal

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Somehow the firmware updates deleted my 300mm and 420mm lens tuning data when I updated the 300mm lens. Not having it written down I needed to recheck the 25 AF spots Olympus uses so this time I used the FocusTune software on each of the 25 AF tuning spots.

I only checked the -2, -1, 0, +1, and +2 tuning numbers in the body knowing they would be close (Unlike my Nikon which needed a -19, but it had severe back-focus issues even new.). I did three shots of each of the five locations so it would average in the software. Seems easy enough.

However, the 300mm and the 420mm (300mm with the MC-14 1.4x tele-converter.) would need to be done on both the E-M1 mark II and the E-M1X. Count that as 4 tests.

Bad part was it took me 5.5 hours to do each one of the four! I used a 12 second self-timer for each trigger, and then did each AF square of shots in the software before moving onto the next AF square. Bloody timing consuming as it took about 22 hours to finish the testing on the two bodies with the 300mm and the 420mm tele-converted lens too.

With all the software settings installed, I went to check them on the scrub jay bird at the feeder. Seems even though they were all set per the software, adding one more point to all of the software's AF tuning numbers shifted the focus back a bit so more of the bird appeared in focus and sharper. I think a round bird needs a bit of back-focus added so that's what appeared to work better by adding on one extra point to what the software said. One added point may be only about 2/10 inch back-focus at ~25 feet, i.e. not much.

Below are the settings for the 300mm and the 420mm in the E-M1 Mark II and the E-M1X. I did add one point to the 300mm data for both, but yet to do that with the 420mm and it is the software's unaltered numbers.

What a fookin' job, but it's done! :yahoo:

View attachment 755490
View attachment 755492
I am guessing you either didn't read what I wrote or just had to test it for yourself. Here is what I wrote...……………..

"When I first did this on my EM1 my OCD forced me to test every single focus point. I took an entire weekend doing this and determined that it’s a huge waste of time. I came up with a few differences of +/-1, but the time involved was just not worth it and I am not positive my small differences were not due to my error. I spent the next few times randomly testing different points (because my OCD forced me to at least check a few) each time I did this and now……..I just use the all points as I said above. What the all points does is use the center point for the testing and applies the setting you use to all the focus points. Just a faster way of setting them all the same. But the option is there to test each point and make a different setting for each. I have just not found a need for this. Maybe on a DSLR where the sensors (remember they use different sensors for image and focus) are not perfectly parallel this would be needed. But with all on one sensor in the EM1, I have decided it is not needed and have not seen any evidence to change my mind. I should note here that I use all my focus points. I shoot for composition and hate the focus and recompose method, so I do move the focus point around when shooting. Even doing this I have not seen evidence that one focus point is worse off than another."

From everything I have tested I don't believe you need to do all the one points, only the center one. In theory the only way for there to be a difference between them is when in a DSLR and using two sensors (one for image, one for autofocus) and they are not perfectly parallel to each other. With the PDAF on the sensor there is really no way for this to happen.

It only takes me about 30 minutes to do a lens, an hour for a prime since I have to do each end.
 

Mack

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I just like getting it close to my satisfaction. Olympus is much closer than my Nikons or Canons ever were.

Roger Cicala of Lensrental is happy with 3 points of AF tuning (That's his estimate of company tolerance.) so the average of my 420mm being at a -2 somewhere in the 25 spots with the fast focus toggle of the E-M1X just gets me closer in average. On the 420 mm, there is a spot on the E-M1X (4th row) where it can go 3 points fast on the E-M1X toggle which is maybe enough to make a difference on a small bird by shifting it about 1/2-3/4 inch at 25 feet. Since Olympus allows to calibrate them all, I did them all if for nothing else to confirm they weren't whacked somewhere.

Aside, did you find anything worthwhile as regards to intentionally back-focusing? I wasn't happy with the AF tuning software putting me at say "0" on birds where a +1 seemed to help since the further tail or body may be worthwhile and within the DOF by the additional back-focus and not using any front-focus or the software's optimum point.

Bird below is cropped from smaller frame, but I can see the black whiskers on backside of its beak with the added +1 to what the software said. With it set per software, I wasn't getting any behind the bird whiskers or feathers in focus in a larger majority of shots. Never thought adding back-focus would be beneficial.
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Phocal

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Since Olympus allows to calibrate them all, I did them all if for nothing else to confirm they weren't whacked somewhere.
They do and I understand checking it but honestly there is no need to do it every time (which this should be done on a regular basis because gears and wires to wear/stretch). For a DSLR where you can have alignment issues between the two sensor this is needed. What I did with my Canons was check the edges and if they were fine I wouldn't do all the points, but if off I would do all of them because it meant my sensors where not perfectly parallel.

side, did you find anything worthwhile as regards to intentionally back-focusing? I wasn't happy with the AF tuning software putting me at say "0" on birds where a +1 seemed to help since the further tail or body may be worthwhile and within the DOF by the additional back-focus and not using any front-focus or the software's optimum point.
This is one of those that only you can decide since this is really a DoF issue and not a focusing issue. Personally I want my camera to focus as close to perfect as possible. If I want those back feathers in focus I will stop down. I do way to much close shooting where the DoF is so small that any back focus would ruin the shot because the eye wouldn't be all in focus. There is also really only one spot that is in 100% focus, the rest of the DoF is actually not 100% in focus. I want to ensure the eye of my subject is as sharp as it can possibly be.

In this photo I am shooting from 10.5 feet away, which gives a DoF of about 1/2 inch, this basically covers the depth of the eye. Any back focusing would have put the forward eye ridge out of focus.

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Baby Gator 003 by Phocal Art, on Flickr

Once again a shot from 7.2 feet away with a DoF of 1/2 inch, any back focusing and the eye would not be perfectly in focus.

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No Fear by Phocal Art, on Flickr

This one shot from 5.2 feet has a DoF of .2 inches, which just barely covers the depth of the eye.

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Unsure by Phocal Art, on Flickr

So it is basically up to you. I personally want my lenses to focus as close to perfect as possible so I know that what I want is 100% in focus.
 

Mack

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Some of this may be subject dependent too.

Just in shooting perched bird head-on and got its chest in the smallest green AF square on the "newly calibrated" E-M1X thinking "Great test!" But the thing's beak is sharper than its chest where the AF square was even with the 12 shots set in Pro Capture Low (I wish Olympus would add that green AF square in their software, but I suppose it might raise other concerns.). So guess I will add +2 to what the calibration software said and try it again. The E-M1 Mark II was closer too. Ugh!
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Fwiw, here is what the E-M1 Mark II looked like with the 12-100mm f/4 post test. The bottom center +5/-1 was the odd one from the better center, but some of the Imagetest results sort of point to it around the 70mm mark. Haven't done that lens on the E-M1X yet (and don't want to do all 50 of them!) so I set it globally based on the center only. Good 'nuff for now.

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zzffnn

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Question for those who have done this the right way (single point is good enough for me) with a m4/3 telephoto lens (> 100mm), how far did you have to adjust? +/- 3? +/-2? +/-5?

I read this entire thread twice and found about 6 published data points from 3 members, including 4/3 and m4/3 lenses. All final adjustment fell within +/-5, most (except one) of which fell within +/-3, about two m4/3 (300/4 and 45)l did not need adjustment. Teleconventer addition seems to require some fine focus tuning.
 
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Phocal

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Some of this may be subject dependent too.

Just in shooting perched bird head-on and got its chest in the smallest green AF square on the "newly calibrated" E-M1X thinking "Great test!" But the thing's beak is sharper than its chest where the AF square was even with the 12 shots set in Pro Capture Low (I wish Olympus would add that green AF square in their software, but I suppose it might raise other concerns.). So guess I will add +2 to what the calibration software said and try it again. The E-M1 Mark II was closer too. Ugh!
View attachment 755646


Fwiw, here is what the E-M1 Mark II looked like with the 12-100mm f/4 post test. The bottom center +5/-1 was the odd one from the better center, but some of the Imagetest results sort of point to it around the 70mm mark. Haven't done that lens on the E-M1X yet (and don't want to do all 50 of them!) so I set it globally based on the center only. Good 'nuff for now.

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several things...………………………….

First, where you using SAF or CAF?

Second, how much of a crop is this? It honestly seems like a pretty good crop given the lack of detail I am seeing in the feathers.

Third, why did you mention Pro Capture? Not sure what it has to do with focus accuracy.

Forth, I would never put the focus point anywhere but the eye. I know it is easier to put it on the body but you are not focusing on what you really want in focus, they eye. Setting up your calibration to solve the problem of focusing on the chest but getting the eye sharp is not really a good idea in my opinion. You have no control over the distance the eye is in front/back of the eye and the eye will always be a little soft compared to the chest. I shoot a lot of cycling and learned that you have to put the focus point on the head, no matter how hard it can be because using the body puts the focus point to far behind the face. Because that distance can change depending on the person or their riding position, so you can really setup a focus system to correct for that.

Fifth, I have some questions about how you are doing the calibration. Can you explain the procedure you are using? As in...…………..are you shooting from the calibration menu? If not, how are you taking the photos at the different settings for the software? Are you defocusing between each shot? How are you defocusing? When you defocus do you move the lens the same direction, as in to do force it to focus closer or farther way each time or both? What distance are you running the test at? For the zoom do you use the same distance for each end?
 

Phocal

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You edited your post...……………..I thought you had mentioned some stuff about using a ruler at an angle. Here is what I said in the original post about that method and I stand my assessment of using just a ruler.

"The focus tune system has a method for setting it up (not going into all that because they have videos that explain it all). But I do want to mention a few things. The first is that their method ensures the camera is perfectly parallel to the target and ruler. If you are not perfectly parallel you are introducing problems into the testing and will not get accurate results. The system also has you shooting a flat target, not a slanted ruler like most doing a homemade setup use. The advantage here is that if you shoot a slanted ruler you have no control over where the camera actually focuses. By that I mean it could use the top part of the focus point or the bottom or the dead center and that will change how the image looks as to where it focused. By using a flat target that is perfectly centered with the zero point of the slanted ruler you avoid any issue of where the focus point actually focused. One other thing about shooting a ruler, getting the center of the focus point at exactly the zero point is going to be next to impossible.

I am sorry, I just can’t see how a homemade setup or shooting a brick wall is going to be more accurate than this system. Sure it can be done but that is hoping for good luck and that you got everything perfectly aligned. Plus, $200 really is stupid cheap if you care about having your gear perform at its optimal ability."

Question for those who have done this the right way (single point is good enough for me) with a m4/3 telephoto lens (> 100mm), how far did you have to adjust? +/- 3? +/-2? +/-5?
I am sure we could come up with an average but it really has little to no bearing. Better lenses (as in the pro lenses) will have tighter tolerances and in theory should need less adjustment. I say in theory because it is possible (odds are pretty large) for a pro lens to get just the right parts to be at the right ends of a tolerance to make for a large adjustment. Just like it is possible for a cheap lens to be nearly perfect. I also wouldn't put much stock into any numbers generated not using some type of system like Focus Tune. The chance for error any other way is just to great for it to be a valid data point.
 

Phocal

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I know people may read thru here and think I am super anal about this and how it is done. But this is one of those things that you need to be very anal about to do correctly. I feel like my results speak to how much being anal retentive to this process can help in photo taking. It also allows me to get the shot and get out quickly while knowing my camera focused as accurately as possible because when I am laying on the ground a few feet from a gator I don't have time to be messing around with trying to fool my camera into focusing where I need the focus to be.
 

Mack

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several things...………………………….

First, where you using SAF or CAF?

Second, how much of a crop is this? It honestly seems like a pretty good crop given the lack of detail I am seeing in the feathers.

Third, why did you mention Pro Capture? Not sure what it has to do with focus accuracy.

Forth, I would never put the focus point anywhere but the eye. I know it is easier to put it on the body but you are not focusing on what you really want in focus, they eye. Setting up your calibration to solve the problem of focusing on the chest but getting the eye sharp is not really a good idea in my opinion. You have no control over the distance the eye is in front/back of the eye and the eye will always be a little soft compared to the chest. I shoot a lot of cycling and learned that you have to put the focus point on the head, no matter how hard it can be because using the body puts the focus point to far behind the face. Because that distance can change depending on the person or their riding position, so you can really setup a focus system to correct for that.

Fifth, I have some questions about how you are doing the calibration. Can you explain the procedure you are using? As in...…………..are you shooting from the calibration menu? If not, how are you taking the photos at the different settings for the software? Are you defocusing between each shot? How are you defocusing? When you defocus do you move the lens the same direction, as in to do force it to focus closer or farther way each time or both? What distance are you running the test at? For the zoom do you use the same distance for each end?
1. C-AF. I've been playing with the C-AF+TR part but gave up as I think it slows it down. The scrub jays are too skittish and maybe 1-2 seconds to get it before they fly off.

2. Crop is maybe 2x. Luckily it holds up the primary wing feather detail so focus is good. The online JPG maybe not so good.

3. Bird is skittish and doesn't stay in the open long. Maybe 1-2 seconds. In Pro Capture Low set to 15 FPS and 12 shots, they are usually gone by the time the PCL sequence finishes and my triggering the shot. They do bob their heads up and down a lot too which makes it hard to get an eye AF lock-on. PC Low is supposed to AF between each shot and appears it does.

4. I've placed it on the eye when lucky, but still seems wherever it is going to reminds me of the issues the Sony A7iii owners have with eye-focus where their cameras focus on the bridge or tip of the nose instead. Sony may have corrected in by adding in some BF by now. I think Nikon also had issues with eye-focus and maybe adding BF as well - but my Nikons always BF'd anyway even new.

On my E-M1 MK II I have had times where the green square and confirmation AF beep is clearly on the bird's body, but focus is on a small twig (Like below shot.) maybe 2 small green AF squares off to the side. Weird, and why I wish Olympus would add the green AF square to their software for confirmation, but they don't.

5. Followed the online M. Tapes "Distance Calculator" of 25' for the 300mm, and 35' for the 420mm. I shot three for each tuning point along with 12 second self-timer on 15# weighted tripod so software would average Only first shot was manually defocused near to me as I moved to next AF tuning number. Taking several shots at same number seemed to help the final curve.

___________

I took the E-M1X out on the bird and set the software's recommendation of zero to +2 to move it back more on the bird. Head of bird was far sharper given 25 foot distance with the 300mm at f/5.6. Tape's online "Distance Calculator" says DOF is 4 inches at the 25x test setting with that lens setting which seems far too generous to me. My +1 added as with the E-M1 MK II was satisfactory, but the E-M1X seems to produce better with a +2 for me. If I was shooting flat subjects on a copy stand the software's numbers may be better, but the roundness of the bird and size seem to need some BF to get the DOF bubble moved back for better coverage. Don't know the AF square's coverage of a small bird's eye at distance either so it might be reading more of the body and the need to shift it back a bit (i.e. The Sony A7iii eye-focus miss, or mess.).

Fwiw, I also tried some moon shots and it seemed the sharpest were a +3 on the E-M1 Mark II.

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If one works through the LensAlign and its software, lets say it says "Zero" is perfect and you set that into your camera. Plus, you can verify it is correct on the "Sharpest image" using the software's viewer where it shows maybe an inch ahead and behind the Zero on the ruler to be equal in sharpness. All is well in auto-focus land.

However, in the real world on a small and round bird, that one inch ahead of the ruler's zero is wasted and could be better utilized by moving from that ruler's zero point back onto the bird's body a bit - or a bit of back-focus applied in the AF tuning. Moving the DOF bubble back should make more of the bird within subjective sharpness, imho.

On a larger and flatter object like copying slides or copy-stand work, then zero would be the better choice than applying any BF.

All imho, of course.
 
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Mack

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Question for those who have done this the right way (single point is good enough for me) with a m4/3 telephoto lens (> 100mm), how far did you have to adjust? +/- 3? +/-2? +/-5?

I read this entire thread twice and found about 6 published data points from 3 members, including 4/3 and m4/3 lenses. All final adjustment fell within +/-5, most (except one) of which fell within +/-3, about two m4/3 (300/4 and 45)l did not need adjustment. Teleconventer addition seems to require some fine focus tuning.
There is also the free "MFT Mapper" software, but you'll need to print out the charts it uses. I had issues with wide-angle lenses using it though, but longer ones were okay. Had issues with the ruler on the FocusAlign as well with the wide angles as it covers some of the red dots needed for the software to read being so close to the AF chart.

The tele-converter does seem to need some TLC. Polarizers were the worse for me though as mine needs about a +7 correction on the 300mm.
 
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zzffnn

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@Phocal ,

I realized that was a flaw.That was the exact reason why I edited my previous post. I will do my DIY test again with a flat subject. I fully agree that any serious photographer with the budget should get the proper test rig.

I think knowing an error range may help some people save time or money. If half of the m4/3 lenses do not need fine focus adjustment, then the data may help people decide to postpone doing the proper test (and use the money to get a needed lens first, and fine tune using DIY test, for example). If most m4/3 lenses by themselves need no more than +/- 3, then a faster test sequence would be firstly +6, +3, 0, -3, -6 (instead of starting from +20, +10, 0, -10, -20); then let the results guide us where to go next:
+9, -9; or
+2, +1; or
-2, -1; or
+5, +4; or
-5, -4.
 
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zzffnn

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Would polarizer addition be the worst case scenario for calibrating phase-detection autofocus in mirroless cameras?

I don't know the details, but am guessing that may be the case, since polarizers cause phase shift?
 

zzffnn

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Please ignore this if you are a very serious photographer. If you are a casual hobbyist on a tight budget, try this.

I did an unscientific test in a quick and dirty, DIY way, shooting with E-M1 mk1 and Panasonic 100-300 mk2 on tripod, focus adj. mode, at 300mm f/5.6, remote control, onto a dollar bill flattened onto a flat wall with double-sided tape, then pixel peep into front eye of George Washington (looking at those two dots on the lower left hand corner of the eye).

I shot 5 shots per adjustment point and de-focus by placing a thick subject in front of the dollar bill and let camera focus onto that subject, without moving either camera or dollar bill. I don't think I can move camera or dollar bill to de-focus, without changing the system significantly. I repeated the entire test again for a second time.

I found the following for my lens + camera combo at 300mm end:

1) adjustment point 0, +1 and -1 worked significantly better (and consistently by 1-2 frames sharper) than other adjustments, with -1 or +1 being very slightly better than 0, but that difference is so tiny, that I think deviation in de-focusing itself can cause that difference. They are consitently better than the rest of adjustment points, but you have to pixel peep at pixel level at least 5 times per adjustment point.

2) Adjustment points +3, +2, -2 and -3 are significantly and consistently worse. With -2 being better than -3, which is in turn better than +2 or +3, consistently.

So I left the micro adjustment at point 0, more for convenience.

Yes, I understand professional software and test target will work much better by analyzing average and trend, but I don't have the toy fund for pro test software and target right now.
 

Mack

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Please ignore this if you are a very serious photographer. If you are a casual hobbyist on a tight budget, try this.

I did an unscientific test in a quick and dirty, DIY way, shooting with E-M1 mk1 and Panasonic 100-300 mk2 on tripod, focus adj. mode, at 300mm f/5.6, remote control, onto a dollar bill flattened onto a flat wall with double-sided tape, then pixel peep into front eye of George Washington (looking at those two dots on the lower left hand corner of the eye).

I shot 5 shots per adjustment point and de-focus by placing a thick subject in front of the dollar bill and let camera focus onto that subject, without moving either camera or dollar bill. I don't think I can move camera or dollar bill to de-focus, without changing the system significantly. I repeated the entire test again for a second time.

I found the following for my lens + camera combo at 300mm end:

1) adjustment point 0, +1 and -1 worked significantly better (and consistently by 1-2 frames sharper) than other adjustments, with -1 or +1 being very slightly better than 0, but that difference is so tiny, that I think deviation in de-focusing itself can cause that difference. They are consitently better than the rest of adjustment points, but you have to pixel peep at pixel level at least 5 times per adjustment point.

2) Adjustment points +3, +2, -2 and -3 are significantly and consistently worse. With -2 being better than -3, which is in turn better than +2 or +3, consistently.

So I left the micro adjustment at point 0, more for convenience.

Yes, I understand professional software and test target will work much better by analyzing average and trend, but I don't have the toy fund for pro test software and target right now.
Lots of ways to do it. Slant ruler, FocusTune, SpyderLENSCAL, Dot Tune, Reikan FoCal (Not for Olympus yet.), MTF Mapper, Etc. Just need to take a look at the subsequent images and see how they are coming out, and if another tuning number would help given the circumstances.

I have one I made long ago for my Nikon in the field after I tired of shooting the vehicle's license plate at an angle. I used to arrive long ahead of the models on the sets to set up and would take some test shots of it with whatever lenses I planned to use that day. I discovered back then in the desert heat the Nikons would go for a walk-about with any AF tuning by maybe 7-8 points due to heat. Even the LCD would turn inky looking when it got to around 110 degrees ambient (Black camera was hotter as was the tripod's legs!), but the camera would still fire (I had to use a Sekonic light meter sometimes when the camera's display went black.).

The thing below is one I made from some old plastic rafter square from Harbor Frieght Tools, some Velcro to move the ruler up and down on it for alignment, a hinge for the checkerboard glued to a plastic sheet. Folds flat with the hinge. It's pretty durable and cheap too!

The checkerboard and ruler were made in Windows Paint and printed at home. Nothing fancy. I would make the checkerboard smaller for the smaller Olympus AF squares though, maybe 1/4" for each square, as the Nikon AF sensor's coverage was larger (Mine is 1" squares.).

The ruler's lines are one pixel wide and all done in Windows Paint app. Once you draw a few, just copy and paste the rest and add the type (Probably 10-12 pixels for font size.).

I took one sample with the E-M1X and 300mm f/4 (Bottom) and was playing with the camera's AF pixel tuning in Manual Focus and watched the yellow outline move up and down the ruler in sunlight at around 20 feet.

Fwiw, the Nikon D800E was so bad new that it was near the back of the ruler. I could set the camera's AF tuning, but it was right against the wall at a -19. Finally got the nerve up to tweak the secondary AF mirror's cam lever to fix the thing to zero.

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