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Re: [OM] E-M1 focus testing

Subject: Re: [OM] E-M1 focus testing
From: Don Holbrook <donholbrook@xxxxxxxxxxx>
Date: Sat, 30 Jul 2016 12:07:34 +0000 (UTC)
Thanks for the comments, Moose.  It was on a small tripod w/slight breeze.  9 
shots w/differential of 1.  Perhaps camera angle to a deep flower has some 
effect.  Just a first test.......I'll try different settings.  Happy to have 
figured out the menu....99 shots is a bit much.

----- Original Message -----From: Moose <olymoose@xxxxxxxxx>To: Olympus Camera 
Discussion <olympus@xxxxxxxxxxxxxxxxx>Sent: Sat, 30 Jul 2016 03:54:59 -0000 
(UTC)Subject: Re: [OM] E-M1 focus testing

On 7/29/2016 7:48 PM, Don Holbrook wrote:> After using the TG-4 for stacking, I 
decided to try the EM-1 for comparison. Only certain lenses will focus stack, 
and others will only bracket. I made three shots: 60 macro stack, 60 macro 
bracket w/CS6 stack, and 14-150 bracket w/CS6 stack to see any differences. All 
three are unedited jpegs. Comments can only help!>> 
http://zone-10.com/tope2/main.php?g2_itemId=20466>> 
http://zone-10.com/tope2/main.php?g2_itemId=20468>> 
http://zone-10.com/tope2/main.php?g2_itemId=20470

No big, obvious differences. But you need to use a tripod for careful 
comparison; changes in subject size and/or orientation make it hard to see 
subtle differences.

What settings did you use? It looks like the stacks weren't deep enough to 
catch the back part of the cluster (which may or may not be what you want.)

Aperture and the Focus Differential setting interact in a way I didn't expect. 
Some of my early shots had an odd quality where the sharpness got greater, 
lesser, greater, and so on, with focal distance. I did some searching and 
reading.

It seems that the way it works is that Focus Differential setting tells the 
camera how much sharpness variation you are willing to accept with depth. The 
camera knows the DoF for the lens and aperture setting, and spaces the stack 
accordingly.

If I set for 10 shots and aperture @ f2, those shots will be very closely 
spaced and the total focal depth of the stack will be relatively shallow. If I 
change the aperture to f11, the stack will be much deeper. Or, if I need the 
lens speed, I can leave it open and increase the number of shots in the stack.

My current default settings are:

1. Number of shots = 12 This is simple. The shot buffer fills up at about 
12-13. The first 12 in a stack are always taken very quickly. Any more, and 
those over 12 come very much slower. Fine on a tripod, a pain handheld. (If I 
don't wait for the buffer to clear, the first shots in the next stack also go 
slow.)

2. Aperture = f5.6 or f8 Again, simple; these are generally the best IQ 
apertures for &micro;4/3 lenses, at least in my experience. As I am stacking 
for DoF, there's no point in using smaller apertures that balance lens 
sharpness against diffraction. Anything larger makes the stack shallower and 
may have less than the best IQ of which the lens is capable.

3. Focus Differential = 1. I definitely saw focal differences that annoyed me 
with depth at three. One, with the above other settings, has been giving me 
results I like. Two might be OK.

Another caveat. The stack starts at the current focus distance and works its 
way farther away until it has taken the set number of shots. With subjects like 
flowers, insects, etc., its really easy to miss a bit or two that are closer to 
the camera than where the lens is focused, resulting in a wonderful image, but 
for a couple of prominent bits that are softer - right up front. So I've taken 
to focusing, then moving the camera back just a little before pushing the 
release the rest of the way. This has been working well for me.

This is true for the E-M5 II, and I imagine the E-M1. The TG-4 works 
differently, at least for in-camera stacks, apparently evaluating the whole 
frame to determine closest part of the subject.

{Moose}

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