thewayne: (Default)
[personal profile] thewayne
This is actually a combination of two photos.

I was shooting at the observatory last year in June, using an interval timer to do some experiments with star streaks. Lots of fun, very tedious compositing the photos! But worth it. What I did not know was that I caught a transit of the International Space Station!

But there was a problem: the dome was facing north. The photo was a great shot of the streak of the ISS, plus the blank back wall of the dome, the butt of the telescope, so to speak.

So yesterday evening I did a little Photoshop work, very little work, actually, and produced this.



I'll explain just how easy it was and show you the original under the cut.


Here's the original. You'll notice the shadows are very different, that's because the photos above and below are 30+ minutes later! If you look in the top left and top right corners, you can also see that the stars have moved and that the sky is darker in the top photo.



This is the photo with the dome opening facing the camera. It was actually very easy to do, and the first time that I've used this technique which I learned probably about a decade ago. In Photoshop, you can bring in photos in layers. So you open the photo with the ISS streak, then you bring in the photo with the dome facing you in a layer just above the star streak photo. You note where the streak begins. There's a tool called an Eraser, and what it does is it literally tears a hole in the layer that you're working on, removing the bits that make up the image, letting whatever is in the layer below show through. Thus, you end up with a 'hole' in the image - thusly!



Thus the deed is done.

The question is: is this altered photo still a photograph? I would say no, for the most part, I would call it a photographic illustration. If I were to sell the rights to it, I would make sure that the buyer understood that it was a composite, and I would show them exactly how I did it.

I tried doing it in the other direction by erasing the back-facing dome, which would mean the star field would be true to the time of when the ISS transited, but the sky's exposure around the dome was different as it was 40 minutes later. It just didn't work.

Even though this video isn't from that shoot, it shows what I was trying to accomplish.

Here endeth the lesson.

THIS was the end result of the shooting of that night:



This last photo represents a composite of 298 photos shot from 10:16pm to 12:51am! During that time the telescope observed many different objects, thus accounting for its spinning back and forth like a dervish.

Date: 2018-12-05 10:11 pm (UTC)
kellan_the_tabby: My face, reflected in a round mirror I'm holding up; the rest of the image is the side of my head, hair shorn short. (Default)
From: [personal profile] kellan_the_tabby
Nice!

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