Posts Made By: Alex McConahay

I believe I saw it last night at about 10:00 at our deep sky site in the desert (Landers, California). I did not bother turning a telescope to it at the time, since I was doing other things.

Alex

First, have both mirrors tested (or use both of them for a bit) to make sure that one mirror is in fact better than the other.

Then, it is just a question of the mechanics of the thing. As I understand it, you need to move the focuser and the mirror about 1.25 inches further apart.

Before you make any modifications, you may want to check things out. When you use your eyepieces, how racked out is your focuser? It could be that you have enough out-travel to accomodate your eyepiece collection without any modification, even if you change the mirror.

If you still want to change your mirror, and you need to make other modifications, you can get that distance several ways.

The easiest is to do what you suggest--use an extender at the focuser. Just an additional 1.25 inch (long) tube stuck in the focuser tube, and from that point on, just fit your eyepieces to that.

Another way to do it is to raise your focuser up off the tube by inserting a couple of spacers (or something).

With both of the above solutions, you may experience some vignetting--although I doubt it would be noticeable. Some loss of stability may happen, also, but on a good old 8 inch F6--you'll be fine.

A third way to do the trick is to cut a new hole for the focuser 1.25 inches further forward. This can get messy quick, involving a change of the secondary spider, etc.

Another easy way to do it--if your tube and how it swings through the base will accommodate it, is to move the mirror cell back a bit toward the end of the tube. Be careful to re-balance when you do this, perhaps moving the bearings.

And if it turns oout you just need a bit of movement, you may get this with just changing where your collimation screws are set.

(I'd either get some focus tube extenders or put the focuser on stilts.)

Alex

Flats are dependent on the optical system and dust bunnies--looking for shadows, bright spots, etc. They stay essentially the same regardless of binning.....So, yes you can re-use them, assuming they have been properly resized.

Darks, however, are dependent on pixel to pixel correspondence. They are correcting each pixel for whatever errors they are making. Therefore, you should use the same binning to calibrate.

Alex

There is a new Yahoo group for SOuthern California Astroimagers....They might have good info for you.

You are always welcome at Goat Mountain Astronomical Research Station. (Dark Sky site for Riverside Astronomical Society. ) We have some local lights, but they can be controlled by proper placement of your scope to avoid them. And our skies are not as dark as we would like, but better than either J Tree's main campgrounds or Cottonwood at the other end of J Tree. More details at the GMARS links on rivastro.org.

Alex

This is as good a time to announce it as any----

The Pacific Astronomy and Telescope Show (September 26-27) will feature Rusty Schweickart, an Apollo astronaut. I am sure he has many interesting things to share with us.

Alex

Are you talking about personal messages or email responses to astromart ads?

Alex

You have gotten into a problem that many others have faced before.

You will be told over and over again that the information must match 100%. And you will try over and over again, making sure it matches correctly. And you will get the same error, and think it is your fault somehow. You will be told that over and over again.

Fact is, it happens. The several people I have heard from with this problem have all just given up eventually, lost to Astromart.

I hope you find a way around it. When you do, please post so that we can share it.

Alex

The LA, Orange County, San Bernardino, and, of course, Riverside clubs have all responded favorably so far. SO, we have an interest, and commitment. We should be able to get on the agenda this Memorial Day weekend. Keep the ideas coming. We do want it to be something we can benefit from.

Alex

The powermate is meant to keep things parfocal. That is, when you have an eyepiece in focus, and put in a Powermate, the eyepiece is still in focus (or very nearly so). If you put need your diagonal in the train with the eyepiece to get the eyepiece to focus, then you will need it in the train with the Powermate.

There are extension tubes that you can use in place of a diagonal. They give you the extra length of the diagonal, without the optics.

Alex

I have been using Images Plus for acquisition and processing for some time. It is quite powerful, and about half the cost of Maxim, from what I understand (or at least used to be). However, it takes some getting used to. It's automated image processing routines get you something to work with very quickly--but from there, it can be slow going.

Craig Stark's suite of software (PHD guiding/Nebulosity/etc.) is pretty good, and much less expensive. It does not, however, have the same top end as IP. I have not used the other products.

Eventually, from what I have seen, both need Photoshop to really finish off the picture.

As for your cable, I don't know. I know the 20D needed one cable (a simple usb cable--provided with the camera) to run the shutter and download short exposures (under 30"). It used another (put together by Hap Griffin among others) to download the long exposure image. The 450 D, on the other hand, apparently uses only the simple USB cable for both functions.

Alex