Ouroboros

Great idea. I'd love to know what ratio is 'good enough' too. 

Mine is 1:4.6   I get guiding of 1" RMS or better as long a s there's no wind. That seems to be just about acceptable for my set up on most frames. I did once try testing the guiding by putting the guide camera into the main scope just to see what was the best I could get. That improved guiding by about a factor of 2.  So I could gain a bit by using a longer guide scope.  Trouble is I'm using a Lodestar X2 guide scope, which has 8um pixels in a 9x50 finder scope. 

Just a note on the software interface. On iPad I can't see all of the calculated numbers like resolution. So for example I can see the resolution is 2 point something but not what the two digits are after the decimal point. 

Heres a pic. 

7 minutes ago, GalileoCanon said:

Good point Stu! Thanks guys! I REALLY appreciate the assistance. I guess this is a new language to me at this point.

It's a bit overwhelming at this point. The good news is that I'm a quick learner.

When I got a DSLR, all the language was new and overly complicated compared to a point and shoots I'd used previously (aperture, ISO, shutter priority, lens zoom measured in millimeters, f-stops, f3.5 vs f22, field of view, EF-S vs EF lens mounts, crop sensors vs full frame, STM, white balance, exposure, polarizers,  etc...)

That stuff all makes sense to me now.

Ouroboros, I have a Canon EOS Rebel XS DSLR. (or 1000D)

I checked and it has a 22.2mm X 14.8mm image sensor. In pixels it has 3888 X 2592 pixels.
My telescope is a Galileo brand 700x76mm reflector.

OK. So the same size sensor as mine. You'll get a slightly larger image size than I get with my 450D attached to my Evostar ED80 which has a focal length of 600mm.  So the full moon will look something like the lunar eclipse image I took below. M31 is about 3 times the apparent diameter of the moon and will be nicely framed if you place it on the diagonal of the frame. That should give you an idea of the image size you'll get. 

12 minutes ago, GalileoCanon said:

Thanks Luna-Tic!

That helps a lot!!

I guess the "proper" semantics for what I was trying to ask in the first place is, how large will the image of the moon look in my pictures compared to  how large it looks at 18mm and at 55mm with my camera's kit lens. OR How large will the image look compared to how it looks on my 50mm lens.

My camera has a crop sensor.  If I'm not mistaken isn't a 50mm lens pretty close to what the naked eye sees? If I hold my camera to my right eye with a 50mm lens isn't that pretty close to what I'd see in size if I looked at the image directly with my left eye?

So to filter past all the semantics couldn't we just say that the image that my DSLR sensor will view through the telescope will be magnified about 14x using the prime setup??  (700mm / 50mm = 14x magnification with the telescope in prime setup)

 

Maybe you've said but what sort of DSLR have you got? 

One way to think about it I suppose is that a telescope is really a modified microscope for looking at distant objects. An eyepiece is really a microscope. The purpose of the primary lens or mirror is to collect as much light as possible from the distant object and to focus and project an image of it at (or near) the focal plane for close inspection by the eyepiece (microscope). 

The size of the image formed by the primary lens or mirror is proportional to its focal length.   The longer the focal length, the larger the image.  With my Canon 450D DSLR attached to my 1000mm Newtonian telescope the full moon almost fills the short side of a full image. The same camera attached to 700mm telescope would provide an image in which the full moon was 0.7 times smaller. Just over half the size in other words. Of course the actual size of the full moon on the OP's DSLR will depend on the size of the sensor. But in approximate terms, even if it's a full frame DSLR, I would expect the OP's telescope to give an image of the moon about half (or slightly more) the size of the full image. 

7 hours ago, GalileoCanon said:

Do I simply look at the focal length of the telescope and compare that to any normal DSLR lens' length?  So 700mm will be 20x more zoomed in than a 35mm DSLR lens?! (for example)

Yep. You got it!

This discussion always focuses on OSC versus Mono.   But is this the only, let alone the right question/comparison?  Many of us use DSLRs because of convenience, ease of use, reliability, cost and because they provide surprisingly rewarding results  in the time available to us, especially considering astrophotography is not what they're designed for. 

However, DSLRs fall down because of noise.  A cooled OSC performs better in this regard. So the question might be: should the DSLR user move up to an OSC as a better way to do the sort of astrophotography they are already doing? 

Is it a camera problem?  The camera driver maybe? Have you tried testing the camera with another application like SharpCap?  

I see. Maybe you could let the person who wrote Gradientxtermintor know. He might have an answer and if he doesn't I'm sure he will want to find one since he's selling this software.

Another possibility is that the trial version has limited functionality of course.

That's a point. Though it struck me from Peter's post that he didn't know how to install the plugin rather than having problems with it. Hence my earlier link to the instructions in the xterminator website.

The Gradientxterminator website has instructions for installing the plugin. http://www.rc-astro.com/resources/install_plugin.html

I don't use GX personally but Doug German has produced some free videos on how to use Photoshop for astrophotography including how to apply Gradientxtermintor. They're available on his website http://www.budgetastro.net/photoshop-basics.html

I've wondered whether one of those little diddy wifi security cameras that works with an iPlayer or android device might do the job.

In fact does someone make an electronic polar scope that works in that way?

Unfortunately I'm going to have to carry everything out each night.

Even so it will be more convenient. Also some kind of waterproof cover might be worth considering, even if you only leave the mount in place over a run of nights that look like they might be clear. You could also leave the scope covered to take flats etc next morning if you're into imaging.

Is the idea to carry out the scope and attach it each time you use it? Or are you planing some kind of removable shelter so you can leave the scope set up?

Thanks, Bobmoss, for your excellent account. It was full of excellent tips for those of us who quite like the idea of doing something like this but are bit hesitant because we don't feel we've got the skills and know how. I liked the fact you didn't mind telling us bits you found a bit daunting. It encouraged me to think even I might have a go.

I've noticed this too, MonicaA. Sensible advise.

Glad to hear you're sorted out by the way. All you need is clear skies now.

I'm not sure a screw thread is the best design for this lever. More convenient might have been a dowel that fitted into a lined of round sockets. More easily lost though perhaps.

Looks nasty. But if you can get the snapped off bolt thread out, and a new clutch lever, you'll be away.

I'm surprised because it's not necessary to put much pressure on to tighten and loosen it is it? Maybe it was a flawed bolt.

I see you've got some additions to the Allen bolts on your polar scope. I can see they would help with centring the polar scope. But do you find it necessary to so it that often?