Some Newbie Questions/Concerns

Hello everyone!

I am a newcomer to the whole astrophotography scene, but I am a veteran to astronomy. I acquired a used classic 8" LX200 from a guy here on astromart.

My questions are as follows:

1.) When polar aligning, I level the base pretty accurately. I set up the wedge so it's pointing north (I use the supplied compass to get a rough estimate and make adjustments as I go along). Then I set the DEC to 90 and RA to 0 as the hand controller says. I center Polaris making wedge adjustments only and press enter just as the manual says. Then it slews to a portion of the sky and says to center Enif. Now at this step, the scope is a good couple degrees away from Enif, but I use the hand controller to slew the rest of the way and center the star in the EP and press enter. So then I want to check the accuracy of my alignment. When I enter polaris, it slews right to it and usually nails it. Then I enter Altair and have the scope GoTO it, but it's still a good degree or two off. Shouldn't the accuracy be a little closer than this? I didn't get the chance last night, but should I try syncing on altair and bouncing back and forth between it and polaris making wedge adjustments on polaris and hand controller adjustments with Altair?

2.) Even though the tracking probably wasn't very good, I thought I would test out some film, the camera, get some practice with exposures, etc so I attached the camera to the visual back and planned on taking a few short exposures (3 minutes or so) of some brighter dense star fields in Saggitarius. I have an Olympus OM-1 with a Beattie Intenscreen. Now I know a very challenging part of astrophotography is focusing, but am I supposed to get pointpoint stars through the viewfinder or are they supposed to be out-of-focus looking even when it's the most in focus I can get it? The adapter I have has a small 2" or so tube extender which would increase the focal length of the system, right? I tried the camera adapter both with and without the extender and I noticed very slightly that without was easier to focus than with. So I guess focusing with a shorter focal length is easier than with a longer one.

3.) With all the accessories I got, there was an f/3.3 focal reducer. I tried it with the camera and all I saw was a huge out of focus star (and what appeared to be some serious vignetting). Well I tried focusing the blob, but the out-of-focus object was not focusing at all. Is this reducer going to be of any use to me?

I think that's all so far. I know I should be starting with piggyback photography, but while I wait for the mount to come in, I decided to try my hand at prime focus.

Any suggestions and all responses will be greatly appreciated!

Thanks!
Chris

Hi Chris.
1) For astrophotography, you really need very accurate polar alignment. Here are some pointers. USe the Itteration method first. With practice, this will get you accuratly aligned enough to shoot piggyback photography.
Itteration method:
Go through your normal polar alignment procedure.
Once you have synced on the 2nd star (Enif for example), go back to polaris. Note: for these next steps, your finder scope needs to be accuratly aligned with your scope.:
You should see Polaris in the finder. With the wedge's manual adjustments, move Polaris 1/2 distance from where it is at, towards the finder scopes center crosshairs. DO NOT HIT ENTER on the hand paddle. Select star, star name, enif, goto to go back to enif. Using the hand paddle, center enif in a high powered eye piece (I use the Celestron Microguide eyepiece, which I believe is a 12mm). Repeat these steps until your last adjustment on Polaris is done through the high powered eyepiece, go back to enif one final time and center and sync (remember to sync each time after centering enif). This will get you a real good (but maybe not exact) polar alignment. I have done this numerous times where I did not have to make any adjustments to my additional drift alignment (which you will need to learn if you want quality photos from your scope).

2) You probably should learn how to knife edge focus the camera, but it is challenging. You can go with the Stiletto, which I have used with some success. Again, this takes some practice to use.

3) My suspecion is that you will need a longer extension tube to bring the camera to focus with the focal reducer.
For more info, check out these web sites.
http://www.astrocruise.com/
http://www.astropix.com/HTML/I_ASTROP/TOC_AP.HTM

I hope this helps,
Don Spencer

Chris,

As for polar aligning--it must be done well. A couple of other respondents have given good advice.

As for focusing. You should see sharp stars in the viewfinder. However, even sharp in the viewfinder may or may not be at perfect focus. Make a Hartman mask (a front cover with two holes about two inches around). When something is out of focus, you will see double. When in focus--you will see single image.

The extender will help move the camera, but not change (practically speaking)_ the focal length. The focal length is set by the optics. Most SCT's have enough focus travel to handle the camera without getting fancy.
The question is simply one of whether you have enough travel in the focuser. As you focus, do you run out of travel? Do you get to what may be a focus, and then go past it?

An F 3.3 focal reducer will seriously vignette. (A 6.3 does some pretty strong vignetting.) And you do not want to use it with an OM-1.

Alex