Focusing Tips?

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Deanimator
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Joined: Tue Oct 23, 2012 7:01 pm
Location: North Olmsted, Ohio, U.S.A.

Focusing Tips?

Post by Deanimator »

Now that I've got my:
  • CombineZP - Bizarre, one off CombineZP and Windows compatibility settings.
  • camera mounting - Home made mount fixed to shooting table.
  • CFL lighting - 85w CFLs on articulated arm lamps with flower pot reflectors.
  • flash lighting - DSLR Controller set to five second exposure interval.
issues resolved, I can concentrate on technique.

I find that I have a lot of trouble picking an initial focus point for stacking. It seems that I frequently get the initial point wrong, while later images are in good focus. This results in stacked images with both blurry and wonderfully sharp sections.

No doubt some of this is due to the nature of the tiny (1/8") gnats I've been experimenting with. I'm learning that proper modeling lights are really important to getting good focus.

At some point, I plan to get a couple of the Ikea Jansjo work lamps, at least for modeling, but that's a pure luxury that will have to wait until I have suitable employment again.

In the meantime, the 85w CFLs put out a ton of [now focused] light.

Does anyone have any advice on picking proper initial focus points, so that when DSLR Controller works it's way back to the initial point, everything is in focus?

rjlittlefield
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Re: Focusing Tips?

Post by rjlittlefield »

It's nice when tools and a workflow finally come together, isn't it?
Deanimator wrote:Does anyone have any advice on picking proper initial focus points, so that when DSLR Controller works it's way back to the initial point, everything is in focus?
Problems like you've described occur with all sorts of focusing mechanisms.

The usual solution is to move the endpoints farther out, so that even with backlash and focusing errors you get everything you need, plus some more on the ends that you don't. Often those are automatically ignored by the focus stacking algorithm. If they aren't, you can manually exclude them from processing.

Any reason that strategy won't work in your case?

--Rik

Deanimator
Posts: 870
Joined: Tue Oct 23, 2012 7:01 pm
Location: North Olmsted, Ohio, U.S.A.

Re: Focusing Tips?

Post by Deanimator »

rjlittlefield wrote:The usual solution is to move the endpoints farther out, so that even with backlash and focusing errors you get everything you need, plus some more on the ends that you don't. Often those are automatically ignored by the focus stacking algorithm. If they aren't, you can manually exclude them from processing.

Any reason that strategy won't work in your case?
None at face value.

To clarify:

I'm shooting at a gnat resting on an 3" x 5" index card (The lines are a great focusing aid.).

You're recommending that I focus on an area of the card ahead of the subject for the initial point, and an area on the card beyond the subject.

It certainly sounds simpler. I've been trying to focus on specific points on the subject.

I'll give this a shot in the next day or two.

Thanks for your assistance.

Deanimator
Posts: 870
Joined: Tue Oct 23, 2012 7:01 pm
Location: North Olmsted, Ohio, U.S.A.

Post by Deanimator »

I followed your advice and got MUCH better results.

I'm not going to post the picture because, although the stack was good, the image was bad. It was an old specimen and it had deteriorated badly.

I'm going to get a fresh specimen. On the previous failed stack, some of the colors were marvelous, almost resembling an ocelot in places.

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