Scanning an Ektar Night exposure

Greetings,

I posted this on Flickr, so apologies if you have seen this elsewhere.

OK, so for my first set of scans I went straight to the 'hard' basket. I decided to scan a 120 minute night exposure I did using Ektar. I tried using auto settings. I tried using vuescan and setting the base colour and base exposure. In the end, I did a raw scan, inverted it in photo shop (just using the standard invert). and then went to town with levels and colour balance.

While I think the final output was OK (see below), I am wondering whether there is more of a structured way to deal with this. The other thing is I know there is detail in the rocks that are totally black (I could see it in the scan)....without going all out in PS, I really couldn't get a good balance between the sky (I wanted to show SOME darkness - that is what I saw after all) and the rocks.

Would it be worth while using something like ColorPerfect to help invert?

Cheers

Star Trail @ Pt Willunga by Ashley The Hoff, on Flickr

For this kind of picture colour is not important. Actually your picture already shows very nicely the different colours of the stars (white, blue, yellow, orange), you might want to boost saturation to give that "false colour NASA look" but your colours would be right nonetheless.

Regarding the shadow detail, I don't know if I get what you say right. If you see the details in the negative and not in the scan, the problem is in the exposure of the scan. This is normally a problem arising with slide scans. Negative scans should have a dynamic range which is easily entirely captured by a scanner.

If you see the details in the scan and want to raise brightness of the rocks without influencing the sky, the faster mode I would use is to simply use Curves. Raise the line very near the black point, while keeping the rest of the line where it is.

Or, the problem might be in your black point, basically in converting the image from raw scan to TIFF, you have blocked the shadows. Don't block the shadows. When using Levels, don't discard the flat portion of the histogram by dragging the left triangle to the right (or do it but within the appearance you want to reach).

Re, the shadow detail. I can see it in the TIFF. I can see it in the invert. I suppose, I lost it while trying to bring the overall exposure down, which I did in PS. Like I said, it was very much a click and see, click and see exercise, with many stops and restarts and in the end I kind of stopped when I got a reasonable output with the stars.

I'll try again tonight.

Cheers

In that case perhaps you should be scanning & processing for the shadows. A TIF file can contain more info then a JPEG so make sure the detail you are trying to keep stays intact.

More to the point, you'll need 16-bit TIFF's. While 8-bit TIFF's done use the lossy data compression schemes that JPG does, I recently ran into some banding and blocked shadows when scanning as 8-bit TIFF's. This was on Ektar, Portra and Astia, so it's not just exclusively due to the higher density of Astia shadows compared to Ektar highlights.

--Greg