Shooting Orion

[primeshooter]

I wanted some advice regarding stacking. I have a D850 and planning on using a 50mm 1.4 lens to shoot this well known constellation to really bring out all the nebulae etc in processing. I want to gather as much detail as possible (do not have a tracker) but have decided to stack many images.

I tend to use this website: http://www.clarkvision.com/articles/image-stacking-methods/

as I do like his true colour, non blue night sky images and there is a lot of information here which I am digesting. That said I cannot wrap my head around the stacking part. Many sources recommend a minumum of 32 exposures, but the more the better.

If I use a 50mm lens, and the rotation of the earth is considered, at ISO 1600, f/1.4 and 5-6 seconds max, there is going to be a lot of star movement, if I shot enough frames and used an even longer lens, after all these multiple exposures have been taken and all that time passed, the constellation might not even be in the frame anymore? How does this work (using a dramatic example here to illustrate, e.g. if I used a 135mm f2 lens which is much more magnified and the earth's rotation will show up faster).

I was going to use deepskytracker to align automatically or I could trial Photoshop. I was also going to follow his processing guide after the stack.
Any advice? (no plans for tracker at moment, just want to maximise what I have right now and see how good I can get orion to come out).

I am going to try this with clear skies this evening, thanks in advance.

 

[Rudy Pohl]

Hi Primeshooter,

You have outlined a good beginning, the best thing now is get out there and start shooting. I suggest you bring and try both lenses as Orion will be so small with a 50mm on your full frame D850 that you'll be hard pressed to even see the nebulosity.

Take a bunch of shots with each lens, stack your images in both DSS and photoshop, plus another free stacking program called Sequator, and post your results here, we'd love to see them

Good luck,
Rudy

Rudy Pohl

Explore Rudy Pohl’s 992 photos on Flickr!

www.flickr.com

 

[Cbernhardt]

70 mm on a FF, would frame the entire Orion constellation. 200 mm would frame both Orion’s Belt and the Orion nebula below it. To get closer would require more telephoto power.

 

[primeshooter]

70 mm on a FF, would frame the entire Orion constellation. 200 mm would frame both Orion’s Belt and the Orion nebula below it. To get closer would require more telephoto power.

What about 64 shots at 200mm. How is that possible without orion moving off axis. Lots of sites say you can stack but how can you stack without a mount? The earth is rotating after all so even at 85mm exposed for 64 frames will move the object off the frame by the last exposure. Thus what would the point of the stack be?

 

[Lyle Aldridge]

70 mm on a FF, would frame the entire Orion constellation. 200 mm would frame both Orion’s Belt and the Orion nebula below it. To get closer would require more telephoto power.

What about 64 shots at 200mm. How is that possible without orion moving off axis. Lots of sites say you can stack but how can you stack without a mount? The earth is rotating after all so even at 85mm exposed for 64 frames will move the object off the frame by the last exposure. Thus what would the point of the stack be?

If you're going to shoot more than a handful of sub-exposures, even assuming your original short-FL example, you need to track manually between shots. With camera and lens on a tripod, you'll want to realign every few shots, so that what's in the field of view remains as constant as possible from shot to shot. There are various ways of doing this with varying accuracy, and if the session takes a while, you'll need to start rotating the camera as part of the adjustment to account for "field rotation." But if you use dedicated stacking software, like the DeepSkyStacker or Sequator programs Rudy suggested, the software will automatically make adjustments to keep the stars aligned in the stack. The resulting stacked image will thus have somewhat different pixel dimensions that your individual images.

Your OP mentioned using Photoshop, which I believe would be absurdly laborious. Bringing out large amounts of nebulosity in the constellation will require several dozens, possibly hundreds, of sub-exposures to produce a worthwhile result. In the versions I have, at least, Photoshop doesn't do the job of keeping stars aligned. I have to do it manually, by adjusting the opacity of each layer. IMO, trying to do that with more than a half-dozen exposures is way more effort than it's worth, especially since good stacking software can be downloaded as freeware.

 

[primeshooter]

70 mm on a FF, would frame the entire Orion constellation. 200 mm would frame both Orion’s Belt and the Orion nebula below it. To get closer would require more telephoto power.

What about 64 shots at 200mm. How is that possible without orion moving off axis. Lots of sites say you can stack but how can you stack without a mount? The earth is rotating after all so even at 85mm exposed for 64 frames will move the object off the frame by the last exposure. Thus what would the point of the stack be?

If you're going to shoot more than a handful of sub-exposures, even assuming your original short-FL example, you need to track manually between shots. With camera and lens on a tripod, you'll want to realign every few shots, so that what's in the field of view remains as constant as possible from shot to shot. There are various ways of doing this with varying accuracy, and if the session takes a while, you'll need to start rotating the camera as part of the adjustment to account for "field rotation." But if you use dedicated stacking software, like the DeepSkyStacker or Sequator programs Rudy suggested, the software will automatically make adjustments to keep the stars aligned in the stack. The resulting stacked image will thus have somewhat different pixel dimensions that your individual images.

Your OP mentioned using Photoshop, which I believe would be absurdly laborious. Bringing out large amounts of nebulosity in the constellation will require several dozens, possibly hundreds, of sub-exposures to produce a worthwhile result. In the versions I have, at least, Photoshop doesn't do the job of keeping stars aligned. I have to do it manually, by adjusting the opacity of each layer. IMO, trying to do that with more than a half-dozen exposures is way more effort than it's worth, especially since good stacking software can be downloaded as freeware.

Hi. So you'd recommend deepskystacker? How many shots without moving the camera on a tripod with a 50mm lens?

 

[Lyle Aldridge]

Hi. So you'd recommend deepskystacker? How many shots without moving the camera on a tripod with a 50mm lens?

I use both DSS and Sequator with Windows, and Siril with Linux, and recommend any of those over Photoshop for stacking, if that's the question.

In my experience, however, DSS seems slightly more capable than Sequator when it comes to aligning stars shifted within the FOV. That result assumes that you get the settings right, and unfortunately, DSS has more of them to get wrong.

Sequator, on the other hand, has fewer settings, is a bit easier to use, and completes the task much more quickly. You might try both of them and decide which you prefer. They're both free.

As for how many exposures between camera shifts at 50mm, your guess is probably as good as mine. Others here have undoubtedly used such a short focal length many more times than I, and can perhaps jump in here with more precise guidance on that point. Obviously, however, the more often the better, within reason. You're trying, after all, to replicate the effect of a tracking mount on which each and every shot is shifted from the one before it.

 

[mermaidkiller]

30x10seconds, steady camera

It is indeed simple. I used my 6d with a 50mm f/2.5 macro and took 30 frames of 10 seconds each. I used a UHC footer because of moderate light pollution and stacked with DSS and postprocessed with Photoshop. The patches are due to some cirrus clouds.

Edit: Photoshop can be used for stacking which works fine as long as there is no foreground in the image, so for this picture I did not stack with Photoshop, but I used it for narrow field images taken with telephoto or telescope.

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