Alright, so how can you tell when the camera body itself needs repair and microadjustment isn't going to help?
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.
Ehrm... the target pattern should be at 45 degree angle with the lens... at least with the testing system that I used. You then focus on a black/white target after which you can see your actual focus point on scales that are printed at both sides of the target. These scales must come closer to, and further away from the lens as the target, hence the 45 degree angle.
ciao!
Nick.
my equipment: Canon 5D2, 7D, full list here
my Smugmug site: here
I was hopeful about the attachment plate, but it seems really tight on the body.
Depending on the focus test method and pattern we're talking about, the 45 degree angle is or is not required. I've used both types of test (even the tree method).
According to the Canon recommendations posted earlier in the thread, they want you to test squarely against a flat surface.
Currently, I'm using the copy of the ISO Test Pattern (which won't work at an angle). But it has really fine lines, so I thought it might be easier to figure out what's "in focus" or not.
However, I have tried the ruler-looking angle kind as well. And the results there are also inconsistent - sometimes it shows a little front focus, and sometimes a little back focus.
Now... here's something interesting.
I have AF Point Expansion turned on, but I'm using One Shot mode almost all the time.
That doesn't matter, right? Well... maybe...
The symptoms in Post #11 appear to replicate my problem with the 45 degree angle test pattern.
So I am going to test more.
But this might explain it... it's like the fact that "High Speed Sync" kicks in AT the Sync Speed, not ABOVE the Sync Speed. So leaving it on all the time isn't safe.
One shot mode only for micro adjust. Reserve AI Servo for moving targets like BiFs or motorcycles. AF point expansion does help in AI servo.
I'm using One Shot mode for almost all my shooting. Including this test.
What I'm saying is that I have left the AF Point Expansion on "just in case" and it might be affecting my focus. Even though Canon says it shouldn't.
If the expanded focus points are still in effect in One Shot mode, they may "lock on" to objects that are subtly in front of or behind the focus plane.
High Speed Sync has a similar issue. It should not be invoked at the Sync Speed, but it is.
It should only be invoked above the sync speed.
After 2 rounds of testing involving the following factors:
On a tripod
With a focus chart on an angle
Winding the lens to infinity prior to focus / exposure
Using a remote trigger
On One Shot mode
With IS turned off
f/2.8, 1/500s, ISO 200 (70-200mm lens)
Trying -5, 0, +5
Taking 3 shots at each AF adjustment
Waiting 2 seconds between adjusting the lens / settings before taking the shot (so there's no vibration)
What I notice between turning on and off AF Point Expansion is that:
When AF Point Expansion is ON, each of the 3 shots at each AF Microadjustment is focused slightly differently. But, it is inconsistent. I would not consider some shots "in focus".
When AF Point Expansion is OFF, each of the 3 shots at each AF Microadjustment are focused much more consistently. I can see the effect of the AF Microadjustment a bit more. Now I feel I could start to calibrate lenses (if needed).
I mean, there are some slight variations, but I would look at the second set of shots with the AF Point Expansion OFF and consider them within "tolerances".
I don't think this is nearly scientific, so if someone else could post some observations, that would be great. I'm on the latest Firmware 2.1.1.
I have to do some more testing now, but I think this may be my issue... I'm trying to remember when I turned this feature on or if it coincided with a Firmware update.
Comments
Ehrm... the target pattern should be at 45 degree angle with the lens... at least with the testing system that I used. You then focus on a black/white target after which you can see your actual focus point on scales that are printed at both sides of the target. These scales must come closer to, and further away from the lens as the target, hence the 45 degree angle.
Nick.
my equipment: Canon 5D2, 7D, full list here
my Smugmug site: here
Yup, I am on a tripod... I should have said that.
I was hopeful about the attachment plate, but it seems really tight on the body.
Depending on the focus test method and pattern we're talking about, the 45 degree angle is or is not required. I've used both types of test (even the tree method).
According to the Canon recommendations posted earlier in the thread, they want you to test squarely against a flat surface.
Currently, I'm using the copy of the ISO Test Pattern (which won't work at an angle). But it has really fine lines, so I thought it might be easier to figure out what's "in focus" or not.
However, I have tried the ruler-looking angle kind as well. And the results there are also inconsistent - sometimes it shows a little front focus, and sometimes a little back focus.
Now... here's something interesting.
I have AF Point Expansion turned on, but I'm using One Shot mode almost all the time.
That doesn't matter, right? Well... maybe...
I just found this:
http://photography-on-the.net/forum/showthread.php?t=624340
And check out this guy's test shots in the thread...
http://photography-on-the.net/forum/showthread.php?t=652220
The symptoms in Post #11 appear to replicate my problem with the 45 degree angle test pattern.
So I am going to test more.
But this might explain it... it's like the fact that "High Speed Sync" kicks in AT the Sync Speed, not ABOVE the Sync Speed. So leaving it on all the time isn't safe.
Moderator of the Technique Forum and Finishing School on Dgrin
I'm using One Shot mode for almost all my shooting. Including this test.
What I'm saying is that I have left the AF Point Expansion on "just in case" and it might be affecting my focus. Even though Canon says it shouldn't.
If the expanded focus points are still in effect in One Shot mode, they may "lock on" to objects that are subtly in front of or behind the focus plane.
High Speed Sync has a similar issue. It should not be invoked at the Sync Speed, but it is.
It should only be invoked above the sync speed.
What I notice between turning on and off AF Point Expansion is that:
When AF Point Expansion is ON, each of the 3 shots at each AF Microadjustment is focused slightly differently. But, it is inconsistent. I would not consider some shots "in focus".
When AF Point Expansion is OFF, each of the 3 shots at each AF Microadjustment are focused much more consistently. I can see the effect of the AF Microadjustment a bit more. Now I feel I could start to calibrate lenses (if needed).
I mean, there are some slight variations, but I would look at the second set of shots with the AF Point Expansion OFF and consider them within "tolerances".
I don't think this is nearly scientific, so if someone else could post some observations, that would be great. I'm on the latest Firmware 2.1.1.
I have to do some more testing now, but I think this may be my issue... I'm trying to remember when I turned this feature on or if it coincided with a Firmware update.