Ad Astra Observatory

Art Morton wrote:

>> It’s continually amazing to me how close our FOVs are. That’s totally random, given that we’re using different size chips and different focal length scopes. Or maybe it’s not so surprising; 1deg is a nice, comfy FOV where you can be off by a little and still get your object in the FOV. shrug.

>

> This was calculated. This is the core of the Nyquest Sample Theory. I can not imagine your have not done this for a reason?

So far, everything that I have done in astronomy in general and astrophotography in particular has been “do the best you can with what you have”, followed closely by “see if you can sell some stuff to make a little extra so you can afford X without incurring The Wrath”.

I bought the 8” scope because it was my first scope and my wife wanted “a scope for backpacking”, and I thought “8 inches isn’t that big”. As soon as it showed up, we both realized my error. I offered to send it back, but she was having none of it.

3 days later, I got into photography by holding my Kodak point-n-shoot up to the eyepiece to take a picture of the moon. By a month after that, I’d modded a QC Pro 3000 and was shooting high-mag photos of Jupiter and Saturn. By 3 months after that, I was figuring out how to drive a Pentax K-1000 with whatever film I had lying around. Note I had these cameras lying around, “just need an adapter”.

At this point, I started having to make choices to push my rig towards photography in particular. I bought an ST-4, an autoguideable mount, a reticle eyepiece, guide scope and rings, etc. Still, everything was based on “what I can afford”, not “what would be best for {FOV|sharp stars|personal sanity|…}”

When I got the DSLR as a graduation present, it both changed my life (photos easier to get, but FOV slightly smaller than 35mm), and maintained the status quo (still big FOV, heavy camera, bulb cables, and snobbery from the “real astro CCD” crowd).

I decided at some point that I needed “a little more magnification” than the ED80. So I tried out the 8” (which had been gathering dust as my “planetary” scope while I was keeping the load light on my not-really-suitable mount), discovered that: 1) 8” rocks compared to 80mm, 2) f/5 rocks compared to f/7.5, and 3) 8” scope way too heavy for my mount.

So I scrimped, saved, went to Europe and lived on expense accounts for awhile, and sold every piece of unused astro gear I could, and took an IOU from the wife, so I could afford a G-11 (which I consider my first “serious” astrophotography purchase). Couldn’t afford Gemini. So I learned to use (manual) setting circles, sufficient to put things into my generous DSLR FOV.

Went a little crazy, bought a 8” f/10 SCT to get more magnification on those teeny spring galaxies, MSC no longer working (not accurate enough to put things in the now-smaller FOV). Right about here is where an old friend turns up, upsells me to about $2k worth of new gear, and completely throws my astrophotography hobby under a train while I figure out which way is up.

You will note that, at no time, did I mention anything having to do with “this would be the perfect FOV for…” or “with my camera, I should pair this scope…” or…

I’ve just been floating along, making the best decision I could with the information I had at the time, and learning that a lot of the accumulated wisdom of the ‘net is pure unadulterated BS that doesn’t apply to my situation.

And I reconnected with an old friend who’s helped my rig join the 1% club. I mean, seriously, I read stuff about people and photography, and I realize that they are still having problems with things like “can’t find the object” or “can’t focus on something dim” or “how to stack 20 images”, and I realize I’ve come a long way.

…

and we have strikingly similar FOVs. How odd. (:

>> Anyway, it’s a nice Rosette. If you can figure out a way to rotate the camera a little, you might be able to kill the blooms with a median combine. M42 is a little on the underexposed side, but a very pretty shot, nonetheless.

>

> I tried to do a sum add and the noise is just to much, so, I am doing what you suggested, median. As for the blooms …

Median is good for stuff like planes and cosmic ray hits; stuff that’s in one frame but not the others. So if you had a shot that was about 5° rotated from the others, and median combined them, it would probably kill the bloom spikes (which are in different places because of the rotation) pretty effectively.

That’s some tough stuff to do, though. Shoot, rotate the camera, refocus, shoot. You could automate it all except the rotation part, but.

>> I am so jealous of your unguided shots. My setup would run off the rails if I tried that.

>

> My dear man, you are close. You just need to work it a bit more.

yes, I have this feeling that you’re right. I just have no idea how to get that last bit. I do wonder whether the additional software would help. I don’t know if you’ve been reading the Yahoo group about Gemini, but your meridian flip thing is probably because of CCD Commander, not the Gemini itself. Nobody else (who’s not using CCDC) is claiming “spot-on” meridian flips.

I wonder if the tracking/unguided behavior is the same thing. I mean, you were getting stunning tracking before PemPro. But totally unguided? That’s just wrong.

I need your help, Obi-Morton. You are my only hope.

> PemPro has made my life so easy. The north alignment is so easy. and once that is done the systems just works.

sigh. I need you to come down and I’ll take a few days off work and we’ll go at the thing with toothbrushes and wrenches, and I’m sure I’ll be in hog heaven afterwards.

> The Sky just puts things wherever I want on the CCD.

I have no problems with Goto. It’s just tracking.

> It is raining here too.

We’re finally getting the winter storms that I have been expecting for 3 years. We need more of this. But of course it’s happening when I’d love to be under the stars. I’m spending my time cleaning off the hard drive and getting ready for the next round.

Might clear up on Wed.

J