70D - Back to MFA

Started Jan 31, 2014 | Discussions thread
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Myer Senior Member • Posts: 2,784
70D - Back to MFA

I have a 70-300L lens. I don't have a tripod sleeve for the lens and it won't sit still on my tripod without moving.

So I decided to do some real life tests and hopefully come to some conclusions before my eyes go buggy. And they do.

At this point my concern is the tele end so I didn't bother with the wide end.

I decided I would shoot at ISO 200 if I could. That was fine.

I wanted my lens at full tele and wide open (f5.6).

I used Av mode to set the aperture.

After each shot I checked shutter speed and it was 1/2000. IS was on as this was hand-held.

I shot 4 pictures of a stop sign with a street sign just above it. They were about 75-100 yards from me. The 4 pictures were all AF. 1 & 4 were MFA 0.      2 and 3 were -2 and +2.

I couldn't tell one from the other.

So I redid the test and took 6 shots.

1 & 6 were with MFA 0.

2 -10,     3 -5,     4 +5,     5 +10

The sharpest appeared to be #3 (MFA -5) with #1 & #6 a very close second.

I redid the test at a slightly closer distance. Around 75 yards.

The results were the same. A little bit minus (-) appeared to be best.

Given the tripod restraints can anybody suggest something better?

Unless there's a better approach my next step would be to try 6 more shots.

MFA 0,  -2,  -4,  -6,  -8,  0

I don't want to do too many at a time as it becomes difficult to look at.

If say -6 appeared to be best I would redo the test using

-4,  -5,  -6,  -7,  -8

I would repeat the last test to confirm.

And last I would go one number on each side of whichever appears best. And again to confirm.

Finally, I would do several shots at 0 and several at the winner of the test. If the winner is best I'll assume that's what it should be.

Any real life comments?

Canon EOS 70D
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