Who says dobs are no good for astrophotography

Well, the dob gives super views through the eyepeices, and the resolution cant be beat.
I did a few test shots of the moon a week or so ago, I was happy how they came out, a single frame had a higher resolution of a stacked set in the 12". So now all I have to do is train the drives to null out a slight drift that's present, and I'll be ready to give this a real go.
I never trained the drives when I installed the goto system cos the slight drift is not an issue for visual work.

As for ladders, well, to be honest, most of the times I'm only one or 2 steps up it, its not like I'm up that high, and never ever came close to falling off it as the ladder I use is very good for the job, anyone who lives in a 2 story house can use this ladder, but if you use the wrong type of ladder then youre gonna end up in hospital.

These are fantastic images, no doubt about that. So, how much would a 22" f3.6 cost? I've seen at least one for £7995 UK. (Over 9keur) Make no mistake you will need a scope not much slower than that f/3.6 to do this and as you can see they don't come cheap. You also need pristine dark skies too. As DaveMc mentioned, its horses for courses. If Ap is your thing then you spend your dosh on a decent mount/camera/optics. If you are into visual then a scope like this can't be beat.

If you have any doubt ask yourself this. What would you rather do? Stand in the cold resetting the position of a dob maybe 30 times, taking a short exposure or click 'autoguide' and relax with a cuppa and enjoy the meteors?

If you have bought a big dob its about visual observing. But its nice to know you can still take some nice pickies if you want. Nice to have the choice.

johnomahony wrote: If you have bought a big dob its about visual observing. But its nice to know you can still take some nice pickies if you want. Nice to have the choice.

well, that's it in a nutshell, you dont buy a big dob for imaging solely.
A bid dob is for viewing with a dabble in photography.
A serious eq-mount + Rc scope is for imageing with a dabble in viewing.

as it happens, you can autoguide a servocat driven dob, if you bothered to do so.

Dave_Lillis wrote: as it happens, you can autoguide a servocat driven dob, if you bothered to do so.

Thats the bit I think could be very interesting. Lets face it, there is no way you're going to acheive the results that John linked to with anything slower than f/4ish. However even a fairly rudimentary drive might be enough to give enough tracking ability for short unguided exposures ...and without the hassle of constantly re-framing the image.

Also if anyone has an SBIG camera, you use a 'driftscan' technique with these cameras which allows the stars to trail across a fixed scope and the camera reads off the columns at just the right rate so that the stars are perfectly round. I played around with this before and it works good. However the effective exposure is limited to the length of time it takes a star to drift across the FOV at the sidereal rate. Of course you could then stack lots of them.

I often thought of investing in a *really* fig fast metre class mirror and using it for drift scan surveying.

wow, that would be a very serious piece of gear Dave.
but you got to keep in mind aswell that a dob is gonna give you field rotation, so you'd have to use a derotator or mount the dob on a platform, I suppoose thats a minor cost if you were to get a 36 inch mirror.