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Author Topic: 'Scheimpflug' with Helicon on Alpa  (Read 2862 times)
rljones
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« on: September 13, 2006, 10:42:26 AM »
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One limitation of Alpa is no Scheimpflug via tilts. Helicon's Focus permits an enhanced DOF by effectively stitching serial images through the planes of the subject from near to far. Since this is what Scheimpflug attempts to do (but only through one longitudinal plane), Focus might be a useful tool with the Alpa/Horseman cameras for tabletop, landscape or architectural photography.

Have any of you with an Alpa/Horseman and a digital back tried this software?

-Robert


Helicon's site - http://www.helicon.com.ua/pages/index.php?focus_overview
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Graham Mitchell
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« Reply #1 on: September 13, 2006, 04:22:31 PM »
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I tried this software a few months ago. It sometimes worked very well, and other times became confused and produced garbled images. A new version was recently released which I haven't tried yet. Even when it did work, serious image degradation was apparent at 100%.

So, could be useful when you plan to downsample anyway, otherwise this product has some maturing to do.

Just my opinon.

Sample of a normal image:



Output from Helicon Focus:


That worked well (other than IQ degradation)

Here is another trial which didn;t work:


Look at HF output (see garbled background):



There are several tuning parameters to learn and optimise to avoid these things happening. Also take as many images as possible with minute differences in focus. That should help.
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BernardLanguillier
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« Reply #2 on: September 13, 2006, 04:51:17 PM »
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These problems result from the fact that focussing a lens at various distances tupically results in a change of its actual focal lenght.

Because of this, the program not only has to merge several images, but also to rescale them.

I haven't use this soft, but my guess is that the parameters are meant at defining the variation of focal lenght occuring when the focus is modified.

There are other offerings for DoF stacking that appear to give good results. I typically do it manually in PS.

Regards,
Bernard
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Graham Mitchell
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« Reply #3 on: September 13, 2006, 04:56:36 PM »
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Quote
I typically do it manually in PS.

Regards,
Bernard
[a href=\"index.php?act=findpost&pid=76261\"][{POST_SNAPBACK}][/a]

Yes, you are right in a way. You can specify the limits of rotation and scaling per increment, for example.

Doing it manually in PS is very slow but you have full control.

HF is MUCH faster when it works, and could still be recommended for certain image types where you don't need full resolution image quality.
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