First Astro photos

[JohnC]

I went 9 miles to one of my favourite spots hoping to see some NLC's for the first time. .I had a grand view to the WNW but then saw the sky was very light in the NNE  and assumed they would show there  so I had to drive a mile or two to get that view. ..first photo. I didn't see any and stayed until 0130 so I had a go at Ursa Major and then the SW sky. Still trying to get the exposure time right. The first one was taken at 2353.   13 seconds f2.8 28mm lens ISO 250




Looking SW. 6 secs. ISO 200 28mm f2.8


Looking SW again but 13 seconds.

[jgs001]

Nice start John, that 28mm looks like it's a cracking lens. I think you can probably get 20-25 seconds (of course with bright skies like that first one ....) without trailing at 28mm, probably worth a try pushing it a bit... Also, well worth looking at stacking images, as this increases the SNR... Don't worry about field rotation, as long as the stars don't trail in each sub and you don't get too many subs you'll be fine. Have a look at this tutorial I wrote for a photography forum... http://johnsastroblog.blogspot.com/2009/01/basic-widefield-astrophotography.html there's far more to it than covered here, but I kept being asked how I produced my astro images and how it could be done without an investment in expensive mounts.

[JohnC]

Cheers, John. Well, at last a start. I'll read up on your link later, thanks.

 I was told that the Canon f2.8 28mm was a very  good lens and just the job for this so I got it.    - how can you tell that from the photos ?. I wasn't going to post them ,more of a test run really to see if I could get anything half decent. I was surprised how they turned out but the thing that really, really surprised me was that I took them into Develop wondering how to sharpen or whatever and whether it made any difference and took the exposure up and a whole load more stars appeared - I was  absolutely amazed, I still am.

I see people quite often stack but I'm not good with software  but I really should give it a try, maybe with  the moon,in a better phase than now, would be a better starting point than these small stars.

[jgs001]

I'm comparing to my nifty fifty, which with an aperture of f1.8 is amazingly fast and the light gather is quite astonishing... but.... I get coma all around the edges of the image (the stars look like little elongated comets). It's not a problem as such with Iridium flares as the stars are trailed anyway with 30s exposure to capture the lead in and lead out, but it's very obvious if you're trying to get pin point stars. That always surprises me, just how much the camera captures... It's quite amazing to see, after taking a series of shots, like the 6 hours worth I captured on M81/M82 and then stack it, the image looks almost blank... a few quick curves to stretch it and bang... it's all there.

DSS using it as I describe is very much plug and play... Just dump the images in, click once, make a cuppa and if it's a fast enough machine by the time you come back they should all be stacked.

[rjgjr]

I've enjoyed reading this little thread so far. I'm a big fan of widefield photography and John's blog on the subject was very interesting. I've always used my 400D cheapo 18-55 kit lens and have had very good success with it as long as I can get it focused properly, not having live view. Luckily having very dark skies where I live, I've never really tried taking multiple images and stacking in DSS, something I'll have to try, and I've never shot any darks, again, something I'll have to try. With my 18-55, I usually just back the f/stop off to about 4 and as John mentions, shoot a 30 second exposure, leaving no noticeable trailing unless you zoom or enlarge. I've been trying out my nifty 50 and find that 8 seconds, backed off to about f/2.2 works well without trailing, although I can go about 10-13 seconds around the polar regions with no trailing. I generally shoot at 1600 ISO, just a very bad habit, but I can get away with it for the most part because of my dark skies. As John mentions, the wider the aperature the better, I can only image what a good piece of glass will produce. I've got a couple of examples here with regards to differnt lenes.

This first image, a single image,  shot with 18-55mm kit lens @ 18mm, 30 seconds, f/4, ISO 1600 and has not been retouched



The second image I think I posted a couple of weeks ago. It's a single image, shot with my nifty 50, 13 seconds, f/2, ISO 1600, not retouched



There's just so many aspects that can be achieved with differnt lenes, aperatures, and exposure speeds. The best thing is, they're all free for the taking with digital.

I'd really like to see other examples in this thread from other members of the forum about widefield astrophotograhy from a static tripod. I think it would be very interesting to view each others works and techniques.

[jgs001]

Richard, Here's the two examples I posted in my blog using the techniques detailed there. The groups were taken whilst on holiday last year. I'm hoping to get some more this year, although with any luck, where we're holidaying will be much a better dark site. These were done with the kit lens, focused using liveview, mounted on a lightweight Manfrotto portapod, mirror lockup and self timer to minimise shake.

10 x f3.5, 30s @ISO800, with 5 darks apiece. From experiments recently with my Astro images, next time around, I'll probably not bother with the darks.

[rjgjr]

Beautiful images John, I took some shots last night under marginal viewing conditions, didn't quite get my focus on so it wasn't real sharp. Added some darks and loaded them into DSS and didn't get very good results. I'm going to have to break down and read through the help pages and instructions a little more so I know what I'm trying to accomplish. The shame in not having live view is that I use my distant neighbors security light for focus and usually get pretty good results, but about 10% of the time it just doesn't cut it. Technology marches on!!