?? Canon AF microadjustment

CynthiaM

I'm a new owner of a 7d and getting my feet wet with the microadjustment of lenses. Would very much appreciate your taking a look at these images and give me some feed back as to whether or not I'm on the right track with the microadjustment.

These images are from the Canon 100-400mm lens.

The first image is at iso 400, 400mm focal length, f/6.3, 1/1600. It was shot handheld, using AI Servo, with AF point expansion. It was shot raw, minimally processed in Lightroom 3 for exposure and tonality with sharpening of about 40, clarity about 45. No other adjustments were made:


This shows the AF point:


And here is a 100% crop:



This image was also shot at 400iso, focal length of 250mm, f/6.3, 1/2000. Also shot handheld, using AI Servo, with AF point expansion. Same processing as above; minimal with sharpening at 57, clarity at about 50:


This shows the AF point:


And the 100% crop:


This camera has a definite learning curve but I think I'm getting the hang of it. Look forward to your comments.

Thanks
Cynthia

ziggy53

Very nice images. I would reserve AI-Servo AF for subjects moving at a more rapid rate and in a more or less predictable motion. AI-Servo is "predictive" AF meaning that it samples an object's motion and then tries to predict the proper focus for a future point in time, as in when the shutter actually fires or during a short image burst sequence. AI-Servo used on slow moving or static subjects can yield unpredictable results.

For slow motion and static objects, and when you are also shooting from a static position, the better choice is usually One-Shot AF mode.

CynthiaM

ziggy53 wrote: »

Very nice images. I would reserve AI-Servo AF for subjects moving at a more rapid rate and in a more or less predictable motion. AI-Servo is "predictive" AF meaning that it samples an object's motion and then tries to predict the proper focus for a future point in time, as in when the shutter actually fires or during a short image burst sequence. AI-Servo used on slow moving or static subjects can yield unpredictable results.

For slow motion and static objects, and when you are also shooting from a static position, the better choice is usually One-Shot AF mode.

Thanks, Ziggy, for such a fast response!

They were moving. In the first one, I was hoping to catch them in flight, but as they started scurrying through the water, I started shooting. Tried to predict where the birds would go and had the camera waiting for them to walk into the frame and when they did, started shooting. In the second one, the bird had its beak in the water and kept moving back and forth and around, foraging for food. I understand what you mean about not using Servo for stationary subjects. I made that mistake the first time out when birds really were not moving about figuring if they did move or start to fly, I would catch it. But all the shots were of birds that were relatively motionless and Servo was not the best choice. But with these two shots there was definite movement; I was waiting for the movement before I started shooting. I was moving the camera around following the birds, especially in the second one, almost panning.

Allen

When shooting birds microadjustment really is not something that can help.
There is no way to fool the camera in finding the eye, preferable, instead of
focusing on a high contrast area, 500L+1.4x has a very small DOF. Although it
is needed if the general high contrast area is off or if the bird is very close
where the center spot can pick out the eye/head. I AF the bird then almost
always manually fine tune focus on an eye glint, best, or anything I can
find around the eye/head. If I don't have time to do that I'm shootin' craps,
less keepers.

CynthiaM

Allen wrote: »

When shooting birds microadjustment really is not something that can help.
There is no way to fool the camera in finding the eye, preferable, instead of
focusing on a high contrast area, 500L+1.4x has a very small DOF. Although it
is needed if the general high contrast area is off or if the bird is very close
where the center spot can pick out the eye/head. I AF the bird then almost
always manually fine tune focus on an eye glint, best, or anything I can
find around the eye/head. If I don't have time to do that I'm shootin' craps,
less keepers.

When shooting birds, which AF focus mode are you using? One shot? Servo? I would think Servo would not work with your method of manually fine tuning the focus.

I wish you could fool the camera to find the eye and hone in on the focus. Wouldn't that be nice. My question has more to do with the micro focus adjustment on the later model Canon cameras and if it looks as though I have this lens calibrated so that the sharpest part of the image is actually in the AF zone rather than the lens being mis-calibrated. I see from some of your galleries that you are now using a 7d. Have you tried the microfocus adjustment built into the camera? Assuming you do it correctly, it's got to be a plus. While it will not assure that you are focusing on the eye of a bird, it will assure that the camera is focusing on the selected AF point and not somewhere else.

Allen

CynthiaM wrote: »

When shooting birds, which AF focus mode are you using? One shot? Servo? I would think Servo would not work with your method of manually fine tuning the focus.

I wish you could fool the camera to find the eye and hone in on the focus. Wouldn't that be nice. My question has more to do with the micro focus adjustment on the later model Canon cameras and if it looks as though I have this lens calibrated so that the sharpest part of the image is actually in the AF zone rather than the lens being mis-calibrated. I see from some of your galleries that you are now using a 7d. Have you tried the microfocus adjustment built into the camera? Assuming you do it correctly, it's got to be a plus. While it will not assure that you are focusing on the eye of a bird, it will assure that the camera is focusing on the selected AF point and not somewhere else.

I very rarely switch out of One Shot and am using the 7D now. Although it
focuses very good I can't rely on apparent focus within the DOF when
doing huge crops of small birds.

paddler4

If you want to see whether your lenses need microadjustment, you will need to shoot something that is static and has a clear focus point that the AF can detect to see whether the AF is accurate. If you search on google, you will find several methods for testing this. I have a 50D, which also has microadjustment, and I tested 4 lenses with the expectation that at least one needed adjustment. All of them were pretty much spot on. the problem with the images that led me to test were all my doing. Your luck may be different.

Dan7312

Another test chart for micro adjustments.

http://regex.info/blog/photo-tech/focus-chart

Ric Grupe

Good info here from Ziggy and Allen.

I would suggest trying Spot AF.

From this page:

Spot AF mode:
The first totally new option with the EOS 7D. You can manually choose any single AF point (as outlined immediately above), but now actually reduce the size of that AF point. This allows you to read an even smaller area of the subject, and focus even more precisely on one particular element in a scene — such as the nearest eye in a portrait, or a precise part of a flower in a macro photograph.
Spot AF allows you to manually select a single AF point, and reduce its size for even more precise placement of your sharpest plane of focus. A smaller box within a single AF point indicates Spot AF is active.

When Spot AF is active, a small secondary box appears inside of the manually-chosen AF point, so you see a “box within a box” in the viewfinder. Like with Manual AF point selection, you can freely choose any of the 19 AF points for Spot AF, whether in the center or off-center. With Spot AF, like Manual AF point selection, you’re only using ONE AF point at a time.
A couple of important notes about Spot AF: While the AF point size is definitely reduced compared to ordinary Manual AF point selection, it’s not the tiny square you see in the finder. The actual area being sampled by the AF sensor is larger than that inner box, so allow for that when composing and shooting. Also, dual-axis, cross-type sensitivity remains at all AF points if you select Spot AF mode, so there’s no loss of effectiveness there.
The benefit of Spot AF — its ability to let you pin-point focus upon a tiny area of a scene — has obvious potential benefits and applications, and we’re sure advanced users and pros will come to appreciate this new feature. But this can have a possible downside, too. By forcing AF upon only a tiny area of your subject, if that happens to fall upon a part of your subject that’s relatively plain, solid and lacking detail, the AF system may have trouble focusing upon it. This can be a real problem with fast moving subjects, especially if they’re moving erratically. At times like these, actually having a larger area can be a more effective way to shoot.

Here is a video.

CynthiaM

Thanks to all of you for your responses. I did my own setup for the calibration; I set up a bunch of old books with the titles in the landscape orientation on the spine. I'm more comfortable checking text for sharpness; must be a result of going to the optometrist all these years and comparing which view is sharper. Then opened the series in DPP, went into 100 % view and had it show the AF point. I was able to go from one image to the next, looking at nuances of crispness within the AF point. DPP also indicates what the AF adjustment was. Then I went out and shot the images in the original post.

So going back to my original question which is not questioning how to microadjust, but whether or not status-post microadjustment it looks as though what is in the AF point is the sharpest point of the image or does it look like something else is the sharpest point?

Thanks for your help,
Cynthia

pathfinder

I found that the 7D does a pretty good job on airplanes in flight by using AI Servo with the center pattern of 9 AF points used shooting in High Frame Rate. For stationary subjects single AF point precisely placed in Single Shot mode is best as Ziggy said.

Previously with a 40D or 50D I always used single AF points in One Shot mode, but the the 7D worked pretty good for aircraft in flight as described above, and I suspect it will for BIFs as well.

I rarely shoot BIFs at apertures smaller than f5.6 if I have a choice as I want a bid of DOF safetly ( most really long glass rarely is much wider anyway - maybe f4 )

I have done micro adjustment on several lenses, it can be a lot of work if you have several lenses to do. I only do it if I am unhappy with the sharpness of my images after I am certain it is focus and not technique that is limiting my images.

catspaw

Another way to do micro adjustments was done by someone I know, outlined in her blog here:

http://nicolesyblog.com/2010/06/21/lens-af-micro-adjustment/

tethering and two people helps, but you can probably do it alone (with a bit more work).

(and yes, as a Nikon owner I REALLY want this feature!!!! )