Bloke Loc: Waynesboro, Pennsylvania

I tried my hand at some star shots last night, having missed the scheduled appearance of the ISS. Don't know if I got the time wrong, or the direction, but I was all ready for it and it didn't come. It would be difficult for them to 'reschedule' or 'reroute' it, so I guess I screwed up somewhere...

Anyway, I took multiple exposures of each set, planning to stack the images. Turns out the program I have doesn't align the star images, so you get a line of dots. I am posting my first test shot, of Orion coming up over a roof. The bright object to the lower left is Jupiter, and above that are the twins of Gemini. You will probably need to download it to see most of the stars.

Obviously, this isn't the look I was going for... Can anyone suggest a decent (cheap!) program which will align the star images? I know the roof in this particular shot will be an issue, but I have some better ones.

Orion in (most) of his glory...

adamroutley Loc: Wolverhampton, UK

What software are you using?

Deep Sky Stacker aligns and is free. Also, shoot in RAW but you probably already know that. What settings are you using to shoot?

Bloke Loc: Waynesboro, Pennsylvania

Thanks, I'll try that out. I tried Registax, but it is somewhat less than intuitive. I tried using it to stack the 3 frames which I used above, but it only aligned 2 of them. There doesn't seem to be any documentation, and I can't find anything relevant on youtube either.

I am shooting ir RAW, although in this case I am wondering about that. For an image with a plain black background and a few white dots, what is really gained by using RAW? I am focused manually on infinity, and using 10 or 15-second exposures (which is the max the SX50 can do). The reason I question the RAW is, it takes the camera almost as long to save the image between shots as it does to take the exposure. I think there would probably be less of a gap if I were just shooting jpeg.

I realised at some point during the session that I hadn't even thought about ISO, which was set to AUTO. For some reason unbeknown to me, it had set it to 80 - and wouldn't let me change it. It said that the ISO was limited by the slow shutter speed... I would have thought that *that* is exactly the time that you want a faster ISO than 80, but that's just my logic...

I shot a bunch of exposures for each of several views, basically pressing the shutter as soon as the camera was ready. Some of them, I can't see anything on there at all. If I play with them in LR, I get a load of blue 'stars' all over the image, randomly. I don't know if these are fainter stars being brought out by the long exposure, or (more likely) some kind of digital noise.

Some of the shots look like they will be ok, if I can stack them together. So far, that has been my stumbling block... It is amazing how far these suckers can move in about 10 seconds!

adamroutley Loc: Wolverhampton, UK

Shooting in RAW will hold a LOT more data hence the long save times. It will pick up things that you wont be able to see but when you start post-processing those artefacts will come through. When you save to jpeg it will just ignore blank spaces and compress the file.

To shoot at night I generally use the following settings:

15 seconds MAX exposure unless using a tracking mount
focus to infinity
use either a remote control or a 2 second timer on your shots.

Then using deep sky stacker, you will need to read up but you need a combination of a few different shots, stars/lights/darks etc..

Hope that's a good start anyways.

I'm looking to get a 300mm lens to help get more detail.

Bloke Loc: Waynesboro, Pennsylvania

I have all the lens length I could possibly need - using an SX50 - but I am going more for constellations than high-zoom shots. I am using my lens pretty much wide as it goes. I would like to be able to frame the constellations I am going for, but none of the stars is visible in the viewfinder or screen. I have to aim and guess...

I didn't shoot any dark frames, and I don't know what the others are yet! I only tried image frames so far. I need to go read up, I guess!

adamroutley Loc: Wolverhampton, UK

A 300mm is perfect to get the Pleiades and with a bit of post processing you will pick out the reds of the gases etc!

I really should invest in a t-ring adapter and get hooked up to my celestron, that could be interesting!

mrova Loc: Chesterfield, VA

Bloke, I'm using StarStaX, which is easy to use and free. I use it cause it was free and runs on my Mac. I believe it has several settings where it can fill in some of those gaps.
A question, what are your settings? I recently did a star trails over several hours, 284 images all together, that came out pretty good, at least for me. I set my ISO at 3200, with long exposure (can't remember how long).
Good luck and keep at it.

Bloke Loc: Waynesboro, Pennsylvania

I have StarStax, but it doesn't do what I am looking for. I don't want the trails, I need a program which will adjust and register the star images on top of each other.

I have tried several programs, but haven't gotten very far in testing some of them. When I shot the photos I am working with, I had no idea about dark frames or any of that stuff. From what I read, you need to take the dark frames in the same conditions that the image frames were taken, so it renders that shoot useless. I think. There is so much info out there on this stuff, that I find myself drowning at times...

This also seems to be one thing that the SX50 is not the best choice for. Some of its limitations tend to get in the way. When we get a decent clear night with temperatures not too far into the deep freeze, I am going to try again, and see what I can come up with.

adamroutley Loc: Wolverhampton, UK

Dark frame = leave your camera on, but just put the lens cap on and take the same number of frames.

Flat frames = take a few pictures of a white sheet of paper. (I think)

Thing is, the darks and flats can be reused over and over to an extent

Bloke Loc: Waynesboro, Pennsylvania

That's what I would have thought. One source I read, however, stressed that the dark frames should be shot using the same exposures and in the same conditions as the image shots. I am a bit vague as to *why*, though. Also, why you would need to shoot more than one? It seems a bit strange, the concept of standing out there in the bitter cold, shooting a whole bunch of 15-second exposures, with the lens cap on!

Algol Loc: Georgia

Dark frames usually reveal the bad pixels that is inherent to any digital camera, usually these pixels show up as red, green or blue dots. When you take multiple fames and stack them you get the red, green and blue pixels, then you subtract the resulting stack from the images you are stacking.
Try using an ISO of at least 800 or better yet higher still. As you approach the 3200 mark you will notice a lot of noise which looks like red, green and blue speckles all over the place. This is what needs to be subtracted out of the image frames by using the dark frames.
You can also go back and look at some of my posted images. Most were taken at ISO 3200 using a Canon 60Da camera at various focal lengths including some at the telescope itself. Shorter focal lengths means you can use longer (15 second exposures) and non-guided.
Hope this helps.

skylane5sp Loc: Puyallup, WA

A little late to this dance, but you mentioned that it took a long time for your images to transfer to storage and you suspected that RAW was the culprit. Are you sure that you camera isn't automatically taking a "dark" frame? My FZ200 does that with any exposure over a second or two so it can do it's own "stacking" to eliminate noise or hot pixels in it's final processed image. Can't turn it off either so that makes it impossible to take multiple exposures to get unbroken star trails. One exposure, one dark frame of the same length, one exposure, one dark frame, etc. In all my post purchase reading, I discovered that this is common with most bridge cameras.

Bloke Loc: Waynesboro, Pennsylvania

I don't think it was doing that... If it *was* then it wasn't storing them. The issue is a bit moot, since I have acquired a used T4i, and will be trying that out for astro stuff, as soon as we get out of the current deep-freeze!
Isn't it a shame that the 'seeing' is so much better on winter nights, when the sensible among us are not out engaged on such silly pursuits?

I will still have to look into the whole dark frame issue, but this camera should alleviate some of the other issues I was having with the SX50 - focus, shooting speed, stuff like that.

skylane5sp Loc: Puyallup, WA

It won't store the "dark frame" as a separate image. It just uses it internally to process the previous long exposure.

Algol Loc: Georgia

I have the new Canon 60Da (the a is for astronomical). It has the infrared filter replaced and does an outstanding job on nebulae etc. It also takes a dark frame just after the light frame of the same exposure time and subtracts it automatically which results in a nice image even at ISO 6400. I can however turn this off but have found that even though exposure times are doubled, it seems to do a better job that I can manually.