astrophotography on Celestron 102SLT need advice

[biffidum]

First off, I am new to this hobby.  Yes, astrophotography is like hitting the ground running.... that being said, does anyone have any suggestions for the following combination:

camera:  Olympus DSLR E-610

telescope:  Celestron 102SLT

I understand that I could do something called "prime focus" photography with just a simple T-ring adapter at the base of the tube (remove diagonal mirror).

Will this lower my magnification too much?  Better light collection allowing for shorter exposures.  Can I rely on the digital resolution of the camera to make up for the lost magnification?

Would a 1.25" DSLR adapter be the better way to go?

I do want to do this on the cheap

[Cornelius Varley]

A lot will depend on what you wish to image. The SLT mount isn't ideal for DSO imaging due to the way it tracks across the sky, exposures of more than 30 seconds or so will show field rotation. This field of view calculator will give you an impression of how big various objects will appear with your camera and telescope http://www.12dstring.me.uk/fov.htm

[biffidum]

The link is cool, thanks.  I still am not sure of what setup to go with though.

[ronin]

The 102SLT is a short achro refractor so expect chromatic  aberration on brighter objects such a the moon and planets.

For long exposure DSO imaging the mount is not really suitable, you really need an equitorial mount for that aspect.

There is no magnification in imaging, you get an image size on the sensor that is dependant on the focal length of the scope and the size of the object.

So a 500mm FL scope on say M42 which is about 1 degree will give an image of about 8.7mm, the moon at half a degree would give an image of around 4mm.

To run a DSLR you will need a remote timer, this makes getting multiple images a lot easier.

Imaging is generally not a cheap option.

At present the mount will be the item that makes imaging difficult, it tracks wrong for long exposure (DSO) imaging. The scope will give coloured rings on the stars but that can be lived with, within reason.

[dph1nm]

I use a Canon 1000D at prime (without the diagonal) on the 102SLT for holiday imaging. See http://community.dur.ac.uk/nigel.metcalfe/astro/slt_canon.php. The ones with "SLT" in the description were taken using the SLT mount (the others are on an HEQ5). I stack lots of 30 sec exposures - field rotation is not a problem, but the tracking accuracy of the mount is, so you have to throw maybe 20%  away.  The native pixel scale for this combination is about 2"/pixel. I invariably bin this up to 4"/pixel for final display to hide any non-roundness in the stars. One 'advantage' I find with an alt-az over an EQ is that the tracking errors tend to be in random directions, so if you stack the images regardless they tend to average out (you get fuzzier stars as a result of course)!

On the whole I have been fairly pleased with this as an imaging set-up. One think I did do is fit a Skywatcher dovetail and tube rings onto the tube, because balance is an issue with the out-of-the-box mount if you stick a camera on the end.  Also, weight the mount down with something heavy. I put a 12v battery on the tray.

NigelM