Imaging with my 8' reflector

[Chris-B]

Hey guys,

Ive just got myself my first scope, an 8' 750mm reflector on an eq/azi mount (just a cheapy). Ive had a good play with it tonight and got some good views of the moon, jupiter and its moons so im a very happy chappy indeed! My friend has got an expensive canon dslr and im wondering what would be the best way to get good pictures of nebulae/galaxies/planets/moon etc... Ive already made a crude webcam mount that seems to work, but i have yet to download/learn about software. Now with the webcam, I can use diff eyepieces, but if I get the dslr to telescope adapter, how will I get the zoom I usually would with an eyepiece? or do I just take an ultra long exposure on the highest mp setting and zoom in digitally? When I get the hang of this, im planning on taking a trip to the darkest place this side of the country to try and get some good pictures, so any help will be much appreciated! I was also thinking of buying a zoom eyepiece, and nebula filter, any good?

lenses i have are 6.5mm (115x), 25mm (48x), 2x barlow, 1.5x erector

Thanks

Chris

[Capricorn]

You don't say what the mount is specifically. For imaging the mount is probably the most important aspect. It must be solid and stable also it needs to be motor driven to track the object you wish to image.

An 8inch reflector is fairly weighty, add a DSLR and that is more weight.

The term eq/azi appears to be a hybrid of EQ and Alt/Az. Which one is it EQ or Alt/Az.

[Chris-B]

'EQ4 dual purpose Equatorial / Azimuth'

yes i have a motor drive (well, in the post)

pretty much an eq mount, I cant see any real difference

[Capricorn]

Sorry, just never heard of an EQ mount described as dual purpose EQ/AZ. EQ4 is a rare beast, I have often wondered why there are 1's, 2's, 3's, 5's and 6's. Once in a while mention appears of a 4.

I see that the motors for an EQ4 are the same as those for an EQ5 (well that is what Sherwoods say).

I would say that the mount is "boarder line" for imaging. Simply because most use/recommend an EQ mount that will comfortably handle at least double the weight of the scope. So most imagers start at the HEQ5 size - heavy beasts.

For imaging you will need to spend time on getting the balance of the scope set up well. To take strain off of the motors. Worthwhile marking the CoG both with and without the DSLR attached. Also a set of batteries will be insufficent to drive it smoothly, power pack or car/mains converter.

After that it is a case of try it as see what comes out. Main concern would still be driving the mount smoothly with the weight of the scope and DSLR.

[Cornelius Varley]

Do you have a brand name or a link for the telescope ? Looking at the eyepiece / magnification info you have supplied there seems to be an error with the 25mm / 48x mag.

I think that the mount would not be suited to photographing DSOs. As others have already stated the mount is the most important piece of equipment for astrophotography. It would be OK for planetary and lunar photography using a webcam as the duration of the video capture would be relatively short ( 30 - 60 sec ) or lunar photography with the DSLR used at prime focus, but I would doubt that the mount would be able to track accurately for DSO photography.

To increase the magnification when taking lunar photographs with the DSLR you can use the barlow lens, you would also need to use it when using a webcam when photographing planets.

You may want to read this primer on planetary photography with a webcam.

http://stargazerslounge.com/primers-tutorials/40665-primer-planetary-imaging-toucam.html

Peter

[ollypenrice]

Zoom EPs are not popular amongst the experienced observers. They have smaller fields of view than EPs of fixed focal length and typically offer poorer views. I did look through one which was quite good, probably a TeleVue, but it would have been expensive. I would advise a small collection of fixed focal length EPs. Divide the focal length of the telescope by that of the EP to get the magnification. Treat 200x as probably as high as it is worth going for starters. Many objects are large so a magnification as low as 15 can be very useful - though to get 15 you need to pay quite a bit for a wide angle EP.

If using a DSLR you don't need to 'zoom.' The camera will be at prime focus which means the only 'lens' in the system will be the telescope. To get more or less 'magnification' - we would really talk about Image Scale - what we do is change the telescope in the way you'd change a camera lens. Not the cheapest solution!

Olly

[Chris-B]

Wow it does sound like I have a lot to learn! The only kind of name on it is zenith optics (cant find anything on google). I can see what you mean about the mount, it doesnt feel perfectly smooth as the whole thing is very heavy. I would love to image dso's really. What kind of mount would you suggest? or shall I just wait until I know what im talking about then spend money on a bigger/better scope and mount? Thanks for the link Cornelius, cheers Olly for clearing up my zoom confusion!