Did you physically draw the target or do it on PS and print? Could you give us a high res copy?
I have wanted to do this for a while, and this might be the motivation to do so!
Thanks,
Z
It is the purpose of life that each of us strives to become actually what he is potentially. We should be obsessed with stretching towards that goal through the world we inhabit.
Good questions, Jim. I don't actually know, but that won't stop me from expressing my opinions on the matter. :giggle
I don't think the distance from the focus target matters much. My guess is that a lens that front focuses does so regardless of the distance to the subject. Let's say for the sake of argument that the amount of the error changes with distance. As long as you dial in the lens at a particular distance, it should still be dialed in at other distances as well. The amount of error might change, but the zero-point of perfect focus should be the same regardless. I haven't heard of lenses that are sharper at one distance than at another, have you?
No I haven't heard of lenses that are sharper at one focal distance than another, but I can see how that could occur, I think. Maybe it is a non-issue. I suspect focusing issues are larger with longer lenses than shorter focal length ones, but that may not always be true.
Now a larger question is for zoom lenses, what focal length do you calibrate at? You do hear of lenses that are sharper at some focal lengths than others. The Canon 16-35 MKII is one such lens. It's sharpest at the wider end. Evidently the MKI version of this lens was sharper on the longer end. So you could turn your MKII into a MKI by calibrating it for the long end. Doesn't sound like a good tradeoff. So choose wisely.
Cheers,
-joel
When calibrating my Sigma 150-500 I calibrated it at the long end of the zoom, and used a distance of about 40-50 feet, as that is far enough out to be at infinity for practical purposes. I am not sure these are the correct anwsers, but it seems to have sharpened my images with the lens at 500mm.
Did you physically draw the target or do it on PS and print? Could you give us a high res copy?
I have wanted to do this for a while, and this might be the motivation to do so!
Thanks,
Z
Seriously, I did this in about 10 minutes on my computer at work using the best tool available on that machine - MSPaint :lol
I'll see if I still have it and if so, I'll figure a way to make it available. But, really, there's nothing magical about it. Just create something that has lots of vertical and horizontal high-contrast boundaries and you're set.
Great thread. Thanks a ton for making all this info available to the rest of us.clap
Since no good deed goes unpunished, I have a quick question for you. My new 50D does not recognize the Tammy 28-75 f/2.8 in the calibration mode. Does that mean it's a waste of time to attempt calibrating or will it remember this lens anyway? I have no idea of whether it reports distance info.
Here's the target I used. You can click on the image to get the "original" size for download. Enjoy!
Thank you! Now I have a project for tonight.
Z
It is the purpose of life that each of us strives to become actually what he is potentially. We should be obsessed with stretching towards that goal through the world we inhabit.
Yup - seen it and I'm a victim of myth #2. I can't get consistent results with that thing. It's like the camera refuses to focus on the same post twice. YMMV
Great post Scott!
As for the questions about how far to shoot from target, there is a good post by Chuck Westfall (Canon Spokesman) that states the distance should be at least 50x the focal length of the lens. His example is a 50mm should be shot from 2.5meters (8 feet).
Scott and others: Any thoughts on what to do with the zooms? I'm waiting on the arrival of my 17-55 and 70-200 and expect to run through the microadjustment routine soon. I'm guessing I'll do each at their short and long ends but am open to other thoughts. I've also heard arguments that you should not try to adjust lenses under about 30mm focal length.
Actually, here is the entire post and it answers my question (test at longest focal length of zoom and/or most used focal length)
What is the best way to use the Micro Focus Adjustment on the Mark III?
The question is simple enough, but the answer really depends on the lenses you're using and the way you use them. To begin with, it should be clarified that there are two types of in-camera AF microadjustment for the EOS-1Ds Mark III and EOS-1D Mark III cameras: the first adjusts the point of focus equally for all Canon EF lenses, whereas the second adjusts the point of focus for up to 20 individual lens types, at one adjustment per lens. In both cases, the point of focus can be adjusted up to +/- 20 steps in 1-step increments. Also in both cases, any adjustments you make apply only to the specific camera body in question; lenses themselves are never modified by the camera's AF microadjustment settings. The amount of focus adjustment per step is proportional to the maximum aperture of the lens, with the goal being to increase the precision of the adjustment with large aperture lenses since they have a smaller depth of focus. With all that as a preamble, here is an unofficial procedure for selecting and using an AF microadjustment setting:
Mount the camera to a sturdy tripod.
Position a reference target for the camera to focus on. The reference target should have sufficient contrast for the AF system to read, should be flat and parallel to the camera's focal plane, and should be centered with respect to the picture area.
Lighting should be bright and even.
Camera-to-subject distance should be no less than 50 times the focal length of the lens. For a 50mm lens, that would be at least 2.5 meters, or approximately 8.2 feet.
Set the lens for AF and the camera for One-Shot AF, and manually select the center focusing point.
Shoot at the maximum aperture of the lens via manual mode or aperture-priority AE, and adjust the exposure level if necessary to achieve an accurate exposure of the reference target. Use a low ISO setting to reduce noise.
If the lens has an image stabilizer, shut it off.
Use a remote switch and/or the camera's self-timer to release the shutter. Use mirror lock as well.
Take three sets of images at microadjustment settings of -5, 0 and +5, i.e, three consecutive images at -5, three consecutive images at 0, and three consecutive images at +5.
Examine the resulting images on your computer monitor at 100% pixel magnification.
Take additional sets of test images at different microadjustment settings if necessary until the sharpest image is achieved.
Register the corresponding microadjustment settings in the camera.
Here are a few additional precautions to observe:
• Do not attempt to autofocus on an angled chart, because doing so will degrade the consistency of the camera's focusing measurement. Keep in mind that the camera's AF sensor is comprised of multiple pairs of linear pixel arrays. If you attempt to autofocus on a single line in an angled focusing chart, only a few pixels from each active pixel array will "see" the target. Ideally, the contrast in the reference target should cover the entire area of the camera's center focusing point, and the reference target should be perfectly parallel to the camera's focal plane.
• For best results, manually set the focus on the lens to infinity for every exposure before allowing the camera to autofocus the reference target.
• Expect some minor variations in focusing accuracy within each set of three test images, even though they were all taken at the same microadjustment setting. This is completely normal, and is due to the tolerances of the camera's AF system.
• Expect smaller microadjustment settings to have a greater effect with telephoto lenses, and vice versa for wide-angle lenses.
• If you are attempting to set microadjustments for a zoom lens, it is important to realize that the camera's setting may only be accurate for the focal length setting you test. The instruction book suggests testing at the longest focal length of the lens, but you may find it more efficient to choose the focal length you use most often.
• Some EOS cameras and some EF zoom lenses may require more sophisticated calibration than the in-camera AF microadjustment settings can provide. In such cases, it may be necessary to have calibrations performed at a Canon Factory Service Center.
• Last but not least, there is no "official" Canon method for setting AF microadjustments, so this procedure is unofficial. If you think you can do better, then by all means, go for it. Towards that end, be advised that some independently made tools are designed to help you set AF microadjustments accurately. One of these is the LensAlign kit, due out soon from RawWorkflow.com
Thought I would post my version of the microAF target. This one is loosely based on the lensalign system only my version is made with....wait for it....LEGOS!
Setup
Viewfinder view
Details
The black legos in the middle are the ones with a hole in the middle. These are used in the second column and then there is a white column behind that. This way I am able to ensure that the camera is exactly parallel to the target. You can see this in the viewfinder view where there is a small white dot in the middle of the center black lego. The ruler is at an approximately 45 degree angle from the target.
I enjoy seeing the DIY solutions to focus evaluation. For those that are so inclined and capable of building a precision test setup (many that are at least in part inspired by LensAlign), I applaud your work.
I would, however, like to make the point that if done wrong, or casually, or in a flawed test environment, the results of setting AF Adjustments can be destructive rather than constructive. My goal with LensAlign was to provide a solution that was easy and fast to set up, accurate and repeatable over time. Checking the AF system is not a one time deal. The performance of AF systems can and do change over time and of course vary based on body/lens combinations as well as many other factors.
Michael, good to see you here, and I do have a question. What do you think of Chuck Westfall (Canon Inc) recommended testing distance of no less than 50x the focal length? I can't discern enough detail in the LensAlign scale at those distances. An example is the 50mm lens at 8'. I have to be more like half that distance in order to get an accurate read. This is with a 5DMII at 100%. Any words of wisdom here?
Michael, good to see you here, and I do have a question. What do you think of Chuck Westfall (Canon Inc) recommended testing distance of no less than 50x the focal length? I can't discern enough detail in the LensAlign scale at those distances. An example is the 50mm lens at 8'. I have to be more like half that distance in order to get an accurate read. This is with a 5DMII at 100%. Any words of wisdom here?
Thanks and regards,
-joel
I used the ISO 12233 Test Chart taped to a wall and the 50x focal length distance. Viewed at 100% magnification (and sometimes more when I was in doubt) you could tell fairly easily when the discrete lines started to merge. I did it all in ACR with no sharpening applied. It was a little disconcerting that nothing ever looked really sharp, but you could discern the differences and I think I am seeing a fair improvement in real world shots since I went through the process.
Note: the real chart costs about $100, but the freebie version in the link above is close enough for rock 'n' roll if you have a decent printer. It may not suffice for habitual pixel peepers.
Well, isn't that cool, Richard. I can see exactly how that would work. That's clever the way they have the converging line patterns in all four corners as well as in the center so that you can readily see if the alignment is off.
I'm definitely going to print it out at full size, and compare the results with my LensAlign.
Ok so I have a 50d, did the first steps that you listed here with a tree in my yard, went inside, processed them like you said..... the only problem? I cannot see any difference between any of the photos......any tips? (also, trying to do the AF adjustment with sigma lenses, could this be my issue?)
Ok so I have a 50d, did the first steps that you listed here with a tree in my yard, went inside, processed them like you said..... the only problem? I cannot see any difference between any of the photos......any tips? (also, trying to do the AF adjustment with sigma lenses, could this be my issue?)
In order to use the AF Micro-adjust capability the lens has to be recognized by the host camera. If the lens does does not annunciate to the camera then micro-adjustments may not be retained by the camera. (At least that is my understanding.) Not all lenses annunciate to the camera and fewer non-manufacturer lenses are recognized. If the lens is not recognized that could very well be part of the problem.
If you have any Canon lenses be sure to test them as they probably are recognized and you can use that experience to verify proper operation.
My own recommendation is to start the micro-adjustment procedure using a textured flat wall at a typical shooting distance for the particular lens being tested. Using a tree can introduce additional error in that you cannot be certain to eliminate AF distractions from surrounding objects and the fact that tree limbs and branches are not very flat objects, leading to possible focus error.
Brick walls work nicely for the first part of checking AF. Once you gain consistent results from the wall test you can progress to more complicated and difficult scenes to determine AF accuracy during those circumstances. IOW, if you cannot get consistent results from a brick wall, most other scenes will be off as well.
Make sure to do any critical focus tests with at least twice the MFD for the particular lens, and testing at typical distances is better yet. The exception to the twice-MFD suggestion might be true "macro" lenses which do a very good job with close focus subjects.
Ziggy is, of course, correct and it's probably time to update some of the information I've posted in this thread. I no longer use the "tree method" as I've found it to have a couple of problems. Instead, I use a DIY knockoff of the LensAlign Tool.
At the distances I use my tool (and doing the math) it quickly becomes appearant that getting the focal plane of the camera close to parallel with that of my tool is good enough. Here are a couple of pictures of the tool I use:
1. When using it indoors, it helps to have a good, constant light source shining on the target - helps the AF find it's spot.
2. A different view of the tool
And, for those who would like it, here's a link to the target (I printed mine using the simple tool, MSPaint )
It is the printed target one should focus the camera on. Doing so helps to take a bunch of the AF error potentials out of the equation. In addition, using something like the printed targe I've included here helps provide a very high-contrast target for the camera to focus on - the idea is to make it as easy as possible for the camera to find the "correct" focus as this will help make the process repeatable. Anyway, take the sequece of shots, making sure the ruler is visible in the shot. Now, import them to your computer and use the ruler to help decide which shot is closest to being in focus and go from there.
What I like about this method is that the target has rulers on both sides. So you can be sure the target is laterally square to the camera's sensor if the results from both sides agree. Otherwise you may well be doing more damage than good when you make adjustments.
What I like about this method is that the target has rulers on both sides. So you can be sure the target is laterally square to the camera's sensor if the results from both sides agree. Otherwise you may well be doing more damage than good when you make adjustments.
The down side is that there's no assurance that the camera is focusing where you think it is - a problem with all tools that present a focus target that is at an angle to the plane of the sensor/film.
Regardless of the angle, you have a solid black bar against a gray background. I don't see how it can miss.
Of course, if you don't like the gray background, you could use a chart like this one which has the black bar against a white background. http://focustestchart.com/focus21.pdf
Actually Jeffery specifically mentions the issue of assuring that camera focuses on the card properly. That's why the measurements down the middle of the card card are grayed out except for a full black bar with white lettering on it to focus on.
The down side is that there's no assurance that the camera is focusing where you think it is - a problem with all tools that present a focus target that is at an angle to the plane of the sensor/film.
I just finished the procedures described here: http://focustestchart.com/focus21.pdf using the target of that PDF. It worked pretty well; I had no trouble to focus on this target and could repeat it just as often as I wanted.
I used EOS utility to shoot tethered.
My kit:
- Canon 7D body with v1.23 firmware
- EF-S 17-55mm 2.8
- EF 100mm 2.8L macro
- EF 70-200 2.8L
- Tokina 12-24 4.0 (DX2)
The camera recognizes the Tokina lens as "12-24" and allows you to register it. However, I didn't notice any difference with micro-adjustments. This might be due to it being a Tokina lens or because it's a very wide lens. I wasn't very happy with it's sharpness at 100% at all compared to the Canon lenses I have.
If you're in doubt if your lens is recognized, you can see that when the camera allows you to register the lens or when you change micro-adjustment (it shows the name/type of the lens again).
My 70-200 2.8L was spot on, the rest needed +/- 5 tweaks.
ciao!
Nick.
ciao!
Nick.
my equipment: Canon 5D2, 7D, full list here
my Smugmug site: here
I just finished the procedures described here: http://focustestchart.com/focus21.pdf using the target of that PDF. It worked pretty well; I had no trouble to focus on this target and could repeat it just as often as I wanted.
I used EOS utility to shoot tethered.
My kit:
- Canon 7D body with v1.23 firmware
- EF-S 17-55mm 2.8
- EF 100mm 2.8L macro
- EF 70-200 2.8L
- Tokina 12-24 4.0 (DX2)
The camera recognizes the Tokina lens as "12-24" and allows you to register it. However, I didn't notice any difference with micro-adjustments. This might be due to it being a Tokina lens or because it's a very wide lens. I wasn't very happy with it's sharpness at 100% at all compared to the Canon lenses I have.
If you're in doubt if your lens is recognized, you can see that when the camera allows you to register the lens or when you change micro-adjustment (it shows the name/type of the lens again).
My 70-200 2.8L was spot on, the rest needed +/- 5 tweaks.
ciao!
Nick.
Yeah, I'm thinking that it's because of the wide angle of the lens... more DoF.
Many thanks for your tutorial on AF Microadjustment. The first results of my readjustment of my Canon 7D are Promising... finally I should get the sharp pictures I always wanted and so rarely got.
Alright, so how can you tell when the camera body itself needs repair and microadjustment isn't going to help?
The problem I think I have is that my 5D Mk II doesn't appear to produce consistent sharp focus on a model's eye or nose as much as it used to.
Thinking I would out-smart the camera (and just because I like this feature), I have separated my AF-On button for focus, and I re-focus between shots (often focusing away, and back on) to try and defeat the symptom.
Anyhow, I have tried most of the methods in this post for many many hours now with my three main lenses (24-70L, 135L, 70-200L) and I just don't get consistent results.
I look at some pictures I take at 1/200th, f/2.8 at 100 ISO of a test pattern or test chart and think "oh, +5 looks right". And, if I repeat the test, it seems like +5 looks like crap or no different than, say 0. Increments of +/-1 don't appear to do much at all. But sometimes they do.
I'm 50x from 70mm away (on the 70-200mm lens, or 24-70mm lens both set to 70mm). The target is square to the lens / sensor.
And, I take 3 pictures, use a wireless remote, I have put the shutter / meter / focus function back together, I manually set the focus near Infinity prior to taking each picture, and pause to let the camera come to rest prior to taking the picture. Also, I turned the AF beep back on. So I hear that the camera believes it is in focus.
So, sometimes the pictures are just not sharp. That's infrequent. But what I usually find is that it is very hard to discern a difference between 0, +3, +5 and sometimes between +5 and +7 or +10.
That's at 100% or 200%.
I'm looking at the files directly using www.FastPictureViewer.com so I don't have to do any conversion.
But I've also reviewed them with no sharpening in Capture One.
It's like the adjustments just have no effect. Or random effect.
Any opinions based on your experience?
Thanks...
TTFN
Gregg
Gregger: double-check that the attachment plate isn't a little loose. I had this happen on a 10D. A little locktite and a jeweller's scewdriver solved the issue.
Newspaper photogs specialize in drive-by shootings.
Forum for Canadian shooters: www.canphoto.net
Comments
I have wanted to do this for a while, and this might be the motivation to do so!
Thanks,
Z
No I haven't heard of lenses that are sharper at one focal distance than another, but I can see how that could occur, I think. Maybe it is a non-issue. I suspect focusing issues are larger with longer lenses than shorter focal length ones, but that may not always be true.
When calibrating my Sigma 150-500 I calibrated it at the long end of the zoom, and used a distance of about 40-50 feet, as that is far enough out to be at infinity for practical purposes. I am not sure these are the correct anwsers, but it seems to have sharpened my images with the lens at 500mm.
Moderator of the Technique Forum and Finishing School on Dgrin
I'll see if I still have it and if so, I'll figure a way to make it available. But, really, there's nothing magical about it. Just create something that has lots of vertical and horizontal high-contrast boundaries and you're set.
My Photos
Thoughts on photographing a wedding, How to post a picture, AF Microadjustments?, Light Scoop
Equipment List - Check my profile
Here's the target I used. You can click on the image to get the "original" size for download. Enjoy!
My Photos
Thoughts on photographing a wedding, How to post a picture, AF Microadjustments?, Light Scoop
Equipment List - Check my profile
Great thread. Thanks a ton for making all this info available to the rest of us.
Since no good deed goes unpunished, I have a quick question for you. My new 50D does not recognize the Tammy 28-75 f/2.8 in the calibration mode. Does that mean it's a waste of time to attempt calibrating or will it remember this lens anyway? I have no idea of whether it reports distance info.
Thank you! Now I have a project for tonight.
Z
http://focustestchart.com/focus21.pdf
My Photos
Thoughts on photographing a wedding, How to post a picture, AF Microadjustments?, Light Scoop
Equipment List - Check my profile
As for the questions about how far to shoot from target, there is a good post by Chuck Westfall (Canon Spokesman) that states the distance should be at least 50x the focal length of the lens. His example is a 50mm should be shot from 2.5meters (8 feet).
Link: http://www.digitaljournalist.org/issue0812/tech-tips.html
Scott and others: Any thoughts on what to do with the zooms? I'm waiting on the arrival of my 17-55 and 70-200 and expect to run through the microadjustment routine soon. I'm guessing I'll do each at their short and long ends but am open to other thoughts. I've also heard arguments that you should not try to adjust lenses under about 30mm focal length.
E
My site | Non-MHD Landscapes |Google+ | Twitter | Facebook | Smugmug photos
What is the best way to use the Micro Focus Adjustment on the Mark III?
The question is simple enough, but the answer really depends on the lenses you're using and the way you use them. To begin with, it should be clarified that there are two types of in-camera AF microadjustment for the EOS-1Ds Mark III and EOS-1D Mark III cameras: the first adjusts the point of focus equally for all Canon EF lenses, whereas the second adjusts the point of focus for up to 20 individual lens types, at one adjustment per lens. In both cases, the point of focus can be adjusted up to +/- 20 steps in 1-step increments. Also in both cases, any adjustments you make apply only to the specific camera body in question; lenses themselves are never modified by the camera's AF microadjustment settings. The amount of focus adjustment per step is proportional to the maximum aperture of the lens, with the goal being to increase the precision of the adjustment with large aperture lenses since they have a smaller depth of focus. With all that as a preamble, here is an unofficial procedure for selecting and using an AF microadjustment setting:
- Mount the camera to a sturdy tripod.
- Position a reference target for the camera to focus on. The reference target should have sufficient contrast for the AF system to read, should be flat and parallel to the camera's focal plane, and should be centered with respect to the picture area.
- Lighting should be bright and even.
- Camera-to-subject distance should be no less than 50 times the focal length of the lens. For a 50mm lens, that would be at least 2.5 meters, or approximately 8.2 feet.
- Set the lens for AF and the camera for One-Shot AF, and manually select the center focusing point.
- Shoot at the maximum aperture of the lens via manual mode or aperture-priority AE, and adjust the exposure level if necessary to achieve an accurate exposure of the reference target. Use a low ISO setting to reduce noise.
- If the lens has an image stabilizer, shut it off.
- Use a remote switch and/or the camera's self-timer to release the shutter. Use mirror lock as well.
- Take three sets of images at microadjustment settings of -5, 0 and +5, i.e, three consecutive images at -5, three consecutive images at 0, and three consecutive images at +5.
- Examine the resulting images on your computer monitor at 100% pixel magnification.
- Take additional sets of test images at different microadjustment settings if necessary until the sharpest image is achieved.
- Register the corresponding microadjustment settings in the camera.
Here are a few additional precautions to observe:• Do not attempt to autofocus on an angled chart, because doing so will degrade the consistency of the camera's focusing measurement. Keep in mind that the camera's AF sensor is comprised of multiple pairs of linear pixel arrays. If you attempt to autofocus on a single line in an angled focusing chart, only a few pixels from each active pixel array will "see" the target. Ideally, the contrast in the reference target should cover the entire area of the camera's center focusing point, and the reference target should be perfectly parallel to the camera's focal plane.
• For best results, manually set the focus on the lens to infinity for every exposure before allowing the camera to autofocus the reference target.
• Expect some minor variations in focusing accuracy within each set of three test images, even though they were all taken at the same microadjustment setting. This is completely normal, and is due to the tolerances of the camera's AF system.
• Expect smaller microadjustment settings to have a greater effect with telephoto lenses, and vice versa for wide-angle lenses.
• If you are attempting to set microadjustments for a zoom lens, it is important to realize that the camera's setting may only be accurate for the focal length setting you test. The instruction book suggests testing at the longest focal length of the lens, but you may find it more efficient to choose the focal length you use most often.
• Some EOS cameras and some EF zoom lenses may require more sophisticated calibration than the in-camera AF microadjustment settings can provide. In such cases, it may be necessary to have calibrations performed at a Canon Factory Service Center.
• Last but not least, there is no "official" Canon method for setting AF microadjustments, so this procedure is unofficial. If you think you can do better, then by all means, go for it. Towards that end, be advised that some independently made tools are designed to help you set AF microadjustments accurately. One of these is the LensAlign kit, due out soon from RawWorkflow.com
My site | Non-MHD Landscapes |Google+ | Twitter | Facebook | Smugmug photos
Link to my Smugmug site
Setup
Viewfinder view
Details
The black legos in the middle are the ones with a hole in the middle. These are used in the second column and then there is a white column behind that. This way I am able to ensure that the camera is exactly parallel to the target. You can see this in the viewfinder view where there is a small white dot in the middle of the center black lego. The ruler is at an approximately 45 degree angle from the target.
E
My site | Non-MHD Landscapes |Google+ | Twitter | Facebook | Smugmug photos
I would, however, like to make the point that if done wrong, or casually, or in a flawed test environment, the results of setting AF Adjustments can be destructive rather than constructive. My goal with LensAlign was to provide a solution that was easy and fast to set up, accurate and repeatable over time. Checking the AF system is not a one time deal. The performance of AF systems can and do change over time and of course vary based on body/lens combinations as well as many other factors.
Carry on
Michael Tapes, Designer
www.LensAlign.com
Thanks and regards,
-joel
Link to my Smugmug site
Note: the real chart costs about $100, but the freebie version in the link above is close enough for rock 'n' roll if you have a decent printer. It may not suffice for habitual pixel peepers.
I'm definitely going to print it out at full size, and compare the results with my LensAlign.
Thanks for the great find!
-joel
Link to my Smugmug site
In order to use the AF Micro-adjust capability the lens has to be recognized by the host camera. If the lens does does not annunciate to the camera then micro-adjustments may not be retained by the camera. (At least that is my understanding.) Not all lenses annunciate to the camera and fewer non-manufacturer lenses are recognized. If the lens is not recognized that could very well be part of the problem.
If you have any Canon lenses be sure to test them as they probably are recognized and you can use that experience to verify proper operation.
My own recommendation is to start the micro-adjustment procedure using a textured flat wall at a typical shooting distance for the particular lens being tested. Using a tree can introduce additional error in that you cannot be certain to eliminate AF distractions from surrounding objects and the fact that tree limbs and branches are not very flat objects, leading to possible focus error.
Brick walls work nicely for the first part of checking AF. Once you gain consistent results from the wall test you can progress to more complicated and difficult scenes to determine AF accuracy during those circumstances. IOW, if you cannot get consistent results from a brick wall, most other scenes will be off as well.
Make sure to do any critical focus tests with at least twice the MFD for the particular lens, and testing at typical distances is better yet. The exception to the twice-MFD suggestion might be true "macro" lenses which do a very good job with close focus subjects.
Moderator of the Cameras and Accessories forums
At the distances I use my tool (and doing the math) it quickly becomes appearant that getting the focal plane of the camera close to parallel with that of my tool is good enough. Here are a couple of pictures of the tool I use:
1. When using it indoors, it helps to have a good, constant light source shining on the target - helps the AF find it's spot.
2. A different view of the tool
And, for those who would like it, here's a link to the target (I printed mine using the simple tool, MSPaint
http://lovenlaughter.smugmug.com/photos/629791946_szJHK-O.jpg
It is the printed target one should focus the camera on. Doing so helps to take a bunch of the AF error potentials out of the equation. In addition, using something like the printed targe I've included here helps provide a very high-contrast target for the camera to focus on - the idea is to make it as easy as possible for the camera to find the "correct" focus as this will help make the process repeatable. Anyway, take the sequece of shots, making sure the ruler is visible in the shot. Now, import them to your computer and use the ruler to help decide which shot is closest to being in focus and go from there.
My Photos
Thoughts on photographing a wedding, How to post a picture, AF Microadjustments?, Light Scoop
Equipment List - Check my profile
http://regex.info/blog/photo-tech/focus-chart
http://www.danalphotos.com
http://www.pluralsight.com
http://twitter.com/d114
What I like about this method is that the target has rulers on both sides. So you can be sure the target is laterally square to the camera's sensor if the results from both sides agree. Otherwise you may well be doing more damage than good when you make adjustments.
Link to my Smugmug site
The down side is that there's no assurance that the camera is focusing where you think it is - a problem with all tools that present a focus target that is at an angle to the plane of the sensor/film.
My Photos
Thoughts on photographing a wedding, How to post a picture, AF Microadjustments?, Light Scoop
Equipment List - Check my profile
Of course, if you don't like the gray background, you could use a chart like this one which has the black bar against a white background. http://focustestchart.com/focus21.pdf
Link to my Smugmug site
http://www.danalphotos.com
http://www.pluralsight.com
http://twitter.com/d114
I used EOS utility to shoot tethered.
My kit:
- Canon 7D body with v1.23 firmware
- EF-S 17-55mm 2.8
- EF 100mm 2.8L macro
- EF 70-200 2.8L
- Tokina 12-24 4.0 (DX2)
The camera recognizes the Tokina lens as "12-24" and allows you to register it. However, I didn't notice any difference with micro-adjustments. This might be due to it being a Tokina lens or because it's a very wide lens. I wasn't very happy with it's sharpness at 100% at all compared to the Canon lenses I have.
If you're in doubt if your lens is recognized, you can see that when the camera allows you to register the lens or when you change micro-adjustment (it shows the name/type of the lens again).
My 70-200 2.8L was spot on, the rest needed +/- 5 tweaks.
ciao!
Nick.
Nick.
my equipment: Canon 5D2, 7D, full list here
my Smugmug site: here
Yeah, I'm thinking that it's because of the wide angle of the lens... more DoF.
Many thanks for your tutorial on AF Microadjustment. The first results of my readjustment of my Canon 7D are Promising... finally I should get the sharp pictures I always wanted and so rarely got.
Thanks again.
Regards
The problem I think I have is that my 5D Mk II doesn't appear to produce consistent sharp focus on a model's eye or nose as much as it used to.
Thinking I would out-smart the camera (and just because I like this feature), I have separated my AF-On button for focus, and I re-focus between shots (often focusing away, and back on) to try and defeat the symptom.
Anyhow, I have tried most of the methods in this post for many many hours now with my three main lenses (24-70L, 135L, 70-200L) and I just don't get consistent results.
I look at some pictures I take at 1/200th, f/2.8 at 100 ISO of a test pattern or test chart and think "oh, +5 looks right". And, if I repeat the test, it seems like +5 looks like crap or no different than, say 0. Increments of +/-1 don't appear to do much at all. But sometimes they do.
I'm 50x from 70mm away (on the 70-200mm lens, or 24-70mm lens both set to 70mm). The target is square to the lens / sensor.
And, I take 3 pictures, use a wireless remote, I have put the shutter / meter / focus function back together, I manually set the focus near Infinity prior to taking each picture, and pause to let the camera come to rest prior to taking the picture. Also, I turned the AF beep back on. So I hear that the camera believes it is in focus.
So, sometimes the pictures are just not sharp. That's infrequent. But what I usually find is that it is very hard to discern a difference between 0, +3, +5 and sometimes between +5 and +7 or +10.
That's at 100% or 200%.
I'm looking at the files directly using www.FastPictureViewer.com so I don't have to do any conversion.
But I've also reviewed them with no sharpening in Capture One.
It's like the adjustments just have no effect. Or random effect.
Any opinions based on your experience?
Thanks...
TTFN
Gregg
Forum for Canadian shooters: www.canphoto.net
I assume your camera is tripod mounted, but I do not see that you stated that specifically.
Moderator of the Technique Forum and Finishing School on Dgrin