Pixel Shift with the Z8 - real world applications?

[Ellis Vener]

You have my blessing.

 

[Ryan Mack]

I've been playing with these images using my Merge Raw LR Plugin and found some interesting results. If you want to learn more about Merge Raw please see this post: https://www.dpreview.com/forums/post/67539396 I have just updated it to version 0.3.0 which includes the below mentioned improvements for light painting/star trails/light streaks.


NX Studio has a bug causing this sort of artifact. I think they are accidentally applying an erroneous resize or fractional pixel offset to one color channel.


My app (Merge Raw) does not have this bug, and it does some exposure matching, so it does a much better job in the sky but there is still subtle pixel shift artifacts.


In my new light painting mode Merge Raw can eliminate most of pixel shift artifacts but loses some sharpness.


NX Studio is affected by movement artifacts in the pixelshift.

[ATTACH alt="My app in "normal" pixel shift mode with deghosting disabled gets the same artifacts."]3461479[/ATTACH]
My app in "normal" pixel shift mode with deghosting disabled gets the same artifacts.


With deghosting enabled my app removes the artifacts (along with the light trails).


In my new brightest pixel mode it does the best it can, but it's still not awesome. Would probably look better without using pixel shift.

 

[Thom Hogan]

My take away from this is that for the longer exposures "hot pixels" are a bigger issue than read or shot noise and that pixel shift does a much better job of managing them.

You're starting to discover why I wrote that you should take the discussion away from long exposures. Not only is their hot pixel noise present, but amp noise, and the FPN starts to raise its head, as well.

Certainly this would have some impact on astrophotography, but I don't know how you do pixel shift with astro. For more normal uses of pixel shift (with shorter shutter speeds), the discussion of what happens in noise also shifts ;~).

 

[Thom Hogan]

Edit: Actually if all your shots were slow your sky issue may be caused by the sky darkening as the sun set.

What I was going to write. To get the full benefits of pixel shift you have to have ruthless "sameness" going on.

Thom,

By “ruthless sameness” am I correct in thinking that in practical terms that means

-no camera movement

-no subject movement

- no variation in lighting between frames

-no variation in exposure caused by even slight differences in shutter speed and aperture size

?

Yes. Everything you can control to be the exact same between the exposures.

 

[Ernie Misner]

Hi Clint -

I just posted a first impressions review of pixel shift:

https://www.dpreview.com/forums/thread/4747192

My wife is an artist known for the incredible detail in her images. Especially for her larger work, having a lot of pixels helps when we print giclee prints. Even at 45MP I struggled to get the resolution she demands.

With pixel shift I can now get that. As the sample image of a portion of a map shows, the sharpening effect is dramatic.

So for reproduction work, pixel shift is very useful.

Thank you for the very useful comment. How did you process your images, and what are our options for processing them? Do you know if NX Studio has an option for that yet?

Hi Ernie-

NX Studio is the only app I know of for combining the different frames into a single image.

Once combined, a few apps can open the NEXF file that results.

Thanks a bunch. Did you mean NEF or NEXF? So apparently just stacking the frames in PS does not work.

Edit - I see that NEXF is indeed a real file type. Is that still a raw file? I wonder what that stands for.

Yes, I meant NEXF, and (my bad) actually the correct extension is NEFX. That's the RAW file type for a merged pixel-shift set that is saved as a single file by NX Studio.

Here is part of a directory listing showing a 32-shot pixel shift set with its NEFX file below, then a 4-shot set, then an 8-shot set. It looks pretty small in my preview - hopefully you can see it larger in Gallery view.

Thank you, and very interesting to see this. You must have wound up with a very large file!

--
Ernie Misner

Ernie Misner

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