Basic Astrophotography

[Nadine2704]

Up until now I've just been taking afocal photos using my phone and compact camera and 8" dob.  I recently bought a Canon 70d and want to get more seriously into astrophotography.  I know I'm pretty limited with my dob and no tracking mount, but will be looking at upgrading my equipment once I've got my head around the basics of photography.  I don't want to rush in and buy a ton of equipment that I don't know how to use! 

I'm really just looking for any advice on getting started.  Any tips?  I'll probably be focusing on the moon/planets for now, but would it be possible to image M42?  Is it possible to manually guide my dob during a long exposure?

I'm also slightly confused in regards to attaching my DSLR to my scope... I've bought a t ring adapter, which I thought was all I needed, but I'm now realising that I'm probably being really stupid and need something else.  I've read about camera to telescope adapters and eyepiece projection adapters etc... do I also need one of these?  There was me thinking I could just magically stick my camera on to the telescope!

Sorry if these questions are silly!  I've taken in so much information recently that my brain has turned to mush!

[Purplehayze104]

hiya

well you should be able to image moon an planets without a problem, for connecting to the focuser if you are using a 1.25" eyepiece section then this http://www.firstlightoptics.com/adapters/flo-125-inch-t-mount-camera-adapter.html  will attach to t-ring then slip into the focuser where the eyepiece will go. you could also if memory serves me correctly take apart the focuser eyepiece holder (2 parts, 1 has a single thumbscrew to lock the eyepiece in place screws into a larger part that goes into focuser an tightened up by the 3 thumbscrews on focuser) take them apart an rotate larger piece 180 deg so screw thread facing camera and screw into t-ring, in theory its 2" t-mount.

hope this helps

regards

john

[almcl]

One plan would be to get the attaching-the-camera-to-the-scope-issue sorted (you may be able to do it with the T-ring you already have - take a close look at all the bits that came with scope, unscrew and screw in &c) then try focussing on the moon. Then point at whatever you fancy and take some images. See what happens, post the results here and ask questions, but beware! Once this astro photography bug bites, it can be a real wallet emptier!

If you care to look in my album, all but one of the images were taken with a Skywatcher 200P and a Canon 700 (admittedly on an equatorial mount) but see what you can do?

[D4N]

I'm not sure what dob you have but if it is the 200P then it should actually have a T thread supplied with it.

However at 1200mm focal length and M42 isn't going to fit on the DSLR chip very well.

When you consider that the sky moves along at 15" a second and you will have a pixel scale of 0.7"/pixel the image will move across 21 pixels every second.

The T-thread on these scopes are intended for planetary use.

I think you would need to mount the OTA on an EQ mount to have a chance of doing DSO imaging.

/Dan

Sent from my iPad using Tapatalk

[ollypenrice]

I'm not sure what dob you have but if it is the 200P then it should actually have a T thread supplied with it.

However at 1200mm focal length and M42 isn't going to fit on the DSLR chip very well.

When you consider that the sky moves along at 15" a second and you will have a pixel scale of 0.7"/pixel the image will move across 21 pixels every second.

The T-thread on these scopes are intended for planetary use.

I think you would need to mount the OTA on an EQ mount to have a chance of doing DSO imaging.

/Dan

Sent from my iPad using Tapatalk

While I agree with the gist of it this calculation it isn't correct. If you centre the Dob on the galactic north pole then the pixel at the galactic north pole won't record any drift at all, though it will (in principle) record rotation.

Firstly I'd want to say that there are, broadly, two different astrophotographic technologies which have little in common. There is fast frame solar system (planetary, lunar, solar) imaging which uses video cameras to take lots of very short exposures. These are too short to be affected by the movement of the earth relative to the target so you don't need a fancy tracking mount, though a basic tracking mount is a big help. It can be an alt-az mount. Any movement and rotation between the individual stills from the video will be re-aligned by free software to give you a nice sharp planetary/lunar final image when these stills are combined. Take careful advice before going anywhere near the sun. It is very dangerous withut the right kit.

The larger, fainter, deep sky objects cannot be properly photographed with this technology. You need a mount which tracks the sky while not letting the camera change its orientation towards the target during multi minute exposures. It isn't possible in a few sentences to go into all this but if you are interested then Steve Richards (Steppenwolf on SGL) has written a book length explanation which would have been a great help to me had he written it before I started! Making Every Photon Count is available from FLO, the forum sponsor, and would save you a lot of wasted time and cash on the road to building a deep sky imaging rig. 

This stuff is complicated but fun - and intensely rewarding. Take small steps.

Olly

[Nadine2704]

Thanks guys!

I've fiddled about with my scope (which is a 200P dob, Dan!) and I think I've sussed out how to attach my DSLR.  Just need to wait for the t ring to arrive now!

Bit sad that I won't be able to do any sort of DSO imaging until I invest in an EQ mount, but I pretty much knew that anyway, so I was prepared for the disappointment!  I'll no doubt still attempt to get some afocal shots of M42 with my Canon, because I'm stubborn, and I did manage to get a vague image with my Samsung Galaxy, so can only assume that the image would be better with a DSLR (although obviously nowhere near what others would consider a decent photo!!)

It's all a learning process and I'm very excited to get started!  Have been doing a lot of daytime imaging just to get used to the way my camera works.  Will wait for a clear night and try my hand at some basic photos and see what the results are!

Thanks for all the info, Olly!  'Making Every Photon Count' has been mentioned so many times, so I will definitely be checking that out!

[Physicist13]

dont be afraid of trying to get DSo esp brighter ones. Play with exp and ISO to see how long(or rather short) an exp you can get without too much drifting. worth a play just to get familiar with it all and you might get some good results.