I'm Astonished!

[Coastliner]

Have a look at this:

And the original (after a bit of Pshop Levels etc.).

I took this with a Canon 60D and a Canon 70-300 lens @300, and am amazed that this is possible without a telescope.  It took a fair bit of learning and processing, but I got there. The original 12 lights and 6 darks were stacked in DSS then the massive amount of vignetting was removed using PixIsight, then the image was messed about with (technical phrase) in Pshop. Part of the lower edge is missing due to encroachment of the vignetting, but overall I'm pleased and encouraged. 12 x 30s on a Star Adventurer.

The challenge now is to do it better! Any ideas on how I can  avoid the speckled background noise?

Cheers,

Neil.

[Bobby1970]

thats a great image. Got my own star adventurer coming shortly. Hope to try something similar. :-)

[michael.h.f.wilkinson]

Nice one. Taking flats would help with the vignetting. "More data" is the usual mantra from DSO imagers to combat noise

[laudropb]

Nice image. Thanks for posting.

[ollypenrice]

300mm is a respectable focal length for large targets. A focally reduced Takahashi FSQ85, for instance, has a FL of 328mm.

In a DSLR background sky noise and colour mottle is always a problem. The best way to attack it is by dithering between sub exposures. That is, moving the camera slightly so different parts of the sky are caught on different pixels each time. Tony Hallas recommends a dither of at least 12 pixels (which is still not a lot with small DSLR pixels.) CCD imagers dither but by a smaller amount.

And then, yes,  more exposures and flats are the way forward.

At shorter focal lengths, where tracking accuracy does not need to be so accurate, you could try longer subs, too.

Olly

[Davey-T]

Good start Neil, I can manage 90secs on the SW Adventurer with Canon 300mm f/4 lens, if you mount the camera on the L dovetail and file out the slot you can leave the polar illuminator in place and check and tweak the PA while imaging, looks like you may have jogged the tripod or caught a gust of wind, I use an intervalometer and mirror lock as the 300 is a bit inclined to wobble given an excuse.

Dave

[Alien 13]

Good start you didnt say what ISO you are using but 800 or 1600 should be a fine, you need to aim for exposures of 1-2 mins but keep an eye on the exposure histogram and if it gets too far to the right drop the ISO down to 400.

As said flats are a must with this target theres too much going on for software tools although they do work ok on flat star fields.

Alan

P.S. There are quite a lot of people on here using camera lenses for AP its fast and fun.

[des anderson]

GREAT IMAGE....for a 300mm lens,thanks for sharing.Des

[Coastliner]

Thanks for all the replies, I will take the time to assimilate the info tomorrow now, and I'll find out what ISO I used. I think I understand what flats are for now given the vignetting problem. Dithering bothers me slightly, is it possible to shift the camera by the right amount between subs?

[Knight of Clear Skies]

It's surprising how many large targets are up there that don't necessarily require a lot of focal length. Andromeda is neither the largest nor the brightest, the North America nebula is an easier target.

I've never bothered with dithering myself, a nice thing about unguided imaging is the slightly inaccurate tracking does some dithering for you. Possibly not optimal but combined with kappa-sigma stacking mode it does a good job of reducing noise. If you do give it a go just a small tweak of the camera position in any direction will be fine. The thing to avoid is moving too far - DSS can have trouble stacking frames when the FOV shifts too much, especially when using a zoom lens which tends to produce more distortion. For example, I haven't been able to get kit lens subs on the Milky Way from different nights to stack successfully.

Hope you enjoy the Star Adventurer and lens combo.

[Coastliner]

It's surprising how many large targets are up there that don't necessarily require a lot of focal length. Andromeda is neither the largest nor the brightest, the North America nebula is an easier target.

I've never bothered with dithering myself, a nice thing about unguided imaging is the slightly inaccurate tracking does some dithering for you. Possibly not optimal but combined with kappa-sigma stacking mode it does a good job of reducing noise. If you do give it a go just a small tweak of the camera position in any direction will be fine. The thing to avoid is moving too far - DSS can have trouble stacking frames when the FOV shifts too much, especially when using a zoom lens which tends to produce more distortion. For example, I haven't been able to get kit lens subs on the Milky Way from different nights to stack successfully.

Hope you enjoy the Star Adventurer and lens combo.

Oh dear me - more stuff to learn - "kappa sigma stacking mode" . Does it ever stop!

[Knight of Clear Skies]

Oh dear me - more stuff to learn - "kappa sigma stacking mode" . Does it ever stop!

It's a learning curve, certainly, but fortunately kappa-sigma is just a radio button in the DSS stacking options.

[Coastliner]

Thanks for all this guys, great stuff. Woke up to a clear blue sky, loaded the camera into my bag, with the same lens as I used to take the lights, with the intention of taking a few flats using the sky. And, you've guessed it, one hour later and we have solid cloud cover.  I'll take the flats sometime and apply them to the original data that the images above were constructed from and post the results.

BTW, originals taken at f/5.6, iso 1600, 30 secs. 16 lights, 8 darks, no bias, flats, etc.

Neil.

[Coastliner]

Good start Neil, I can manage 90secs on the SW Adventurer with Canon 300mm f/4 lens, if you mount the camera on the L dovetail and file out the slot you can leave the polar illuminator in place and check and tweak the PA while imaging, looks like you may have jogged the tripod or caught a gust of wind, I use an intervalometer and mirror lock as the 300 is a bit inclined to wobble given an excuse.

Dave

Thanks Dave. A couple of questions: would you be able to post a pic of the mod you did to the star adventurer? Looking at the illuminator it seems I would have to file away a significant amount of the bracket to fit it. And, how can you tell if the tripod has moved by the image?

[StuartJPP]

I was in the same boat as you a few years ago...didn't realise that you could do all of this with a camera lens...roll on a few years and I am still amazed...

But a lens is nothing more than a refracting "telescope"...

My advice is to gather as many subs as you can...don't be tempted to go for many different targets in a night...stick to one target and if you think you have got enough subs...keep getting some more.

[Coastliner]

Thanks Stuart, knowing that I can get that image with only 12 short subs has given me the incentive to take more next time.