Posts Made By: Alex McConahay

I'm about to get organized.

Anybody know if there is already a set of charts for the Herschel 400. I can get out the Sky Atlas 2000, and The Sky, but I figure somebody has already done most of the work here!

Alex

I've been disappointed in Roto-zip. All the bits break--even when I am real careful. I prefer a router.....

Have others shared this experience?

Alex

Someplace in the rating rules is a line that says you should rate only on "completed" transactions. So, no, you should not rate in this case.

ALex

Well, here it comes, the big conjunction between Saturn and Venus this Saturday evening.

So, who has some helpful hints as to how to capture it?

I'm proposing a TV-85 with field flattener, on an LXD-55 mount, and a Canon 20D.

Any hints? Any suggestions?

Alex

I spent the weekend getting my RoboFocus installed and tested. Seems to work right out of the box (once I figured out that I needed to buy new bearings for the focuser!). I did have to move the primary mirror and install a new focuser on the tube, though. That took some time.

There is really very little documentation on how large the "steps" should be. The instructions spend a whole lot more time talking about installation and communicating with the computer, than about the settings. Actually, counting what I already know about focusing, and such, I did figure the following:

First--determine how large the "Zone of Critical Focus" is for a given F Ratio/Aperture. Using formulae available in several places, I figured that for my Newt (10 inch F5), it is about .0009 inches.

Second--Figure how big a "Microstep" is. I ran the procedure to determine that there are about 3300 microsteps from top to bottom of the focuser travel. My micrometer says this was .55 inches. This gave me something like .000167 inches per microstep.

Third--From what I have been told, you want the focuser to stop at least once, and maybe twice within that Critical Focus Zone. There are 5 "microsteps" through that zone, therefore, I want to set my motor to, say, four "Microsteps" per "Step." This makes sure that it stops every four steps (in my case .0007 inches), and does its sampling. Alternatively, I could set microsteps to two, and then run the autofocuser program through two steps at a time.

Well, does all that sound about right?

Then, when I went out to the telescope, I focused as well as I could with my camera viewscreen, parfocal eyepiece, and ronchi-focuser. The Robofocus reported it was at 506.

I ran the focuser in to 460.

Using the Autofocus program in DSLR Focus, I stepped through 10 sets (of three) exposures. They were spaced 8 steps apart. It reported the best focus was at about 480. (I was using 2 microsteps each)

I then told Robofocus to go to 470, and stepped back though again. This time it reported it at 486.

And I did it again and again. Each time, the "best" focus was different. It varied from about 480 to 496. The difference here is only .005 inches. While this does not sound like much--it is about five times the "critical focus" zone. (And probably a lot tighter than I ever did before.)

Does this sound about right? Is it still too sloppy? Is it just seeing? When you run your focusing routine do you always get exactly the same number?

I should say that the mount was tracking, but not guided. The stars were not obviously twinkling, but other than that, I did not notice seeing. And I was averaging three four second exposure for each trial.

At any rate--How does this sound? Any advice?

Alex

Canon 20 D, 12 x 300 sec, 800 iso, 10 inch Meade F4.5 Newt, Losmandy, G11, St-4

The Riverside Astronomical Society's Astro-Imaging Group will once again sponsor a series of workshops at this year's Nightfall.

Registration and other information is available at

http://www.rivastro.org/ras_imaging_event.html

I know we got a lot out of Mike Unsold last year helping us learn how to image and process. This year we have expanded, and are offering two levels. A complete package allows one to work with Jim Burnell, who co-wrote "The Handbook of Astronomical Image Processing." Jim will be there as Mike was last year, with his major presentation on Saturday, but also on the field at night, and for the rest of the weekend just to visit and talk about imaging. Or, if you would like, there is another series of workshops on introductory imaging and other topics of interest to amateur astronomers. You can sign up to see just these if you like. The whole package, Burnell and the Introductory topics cost $50, and the Intro topics alone cost $20 for RAS members. Once again, seating at the Burnell workshops will be limited.

We all hope you can come back to Anza Borrego this October 11-14, and hope to see you at the workshops. (And bring a friend or two!)

Alex

The Riverside Astronomical Society's Astro-Imaging Group will once again sponsor a series of workshops at this year's Nightfall.

Registration and other information is available at

http://www.rivastro.org/ras_imaging_event.html

I know we got a lot out of Mike Unsold last year helping us learn how to image and process. This year we have expanded, and are offering two levels. A complete package allows one to work with Jim Burnell, who co-wrote "The Handbook of Astronomical Image Processing." Jim will be there as Mike was last year, with his major presentation on Saturday, but also on the field at night, and for the rest of the weekend just to visit and talk about imaging. Or, if you would like, there is another series of workshops on introductory imaging and other topics of interest to amateur astronomers. You can sign up to see just these if you like. The whole package, Burnell and the Introductory topics cost $50, and the Intro topics alone cost $20 for RAS members. Once again, seating at the Burnell workshops will be limited.

We all hope you can come back to Anza Borrego this October 11-14, and hope to see you at the workshops. (And bring a friend or two!)

Alex

The Riverside Astronomical Society's Astro-Imaging Group will once again sponsor a series of workshops at this year's Nightfall.

Registration and other information is available at

http://www.rivastro.org/ras_imaging_event.html

I know we got a lot out of Mike Unsold last year helping us learn how to image and process. This year we have expanded, and are offering two levels. A complete package allows one to work with Jim Burnell, who co-wrote "The Handbook of Astronomical Image Processing." Jim will be there as Mike was last year, with his major presentation on Saturday, but also on the field at night, and for the rest of the weekend just to visit and talk about imaging. Or, if you would like, there is another series of workshops on introductory imaging and other topics of interest to amateur astronomers. You can sign up to see just these if you like. The whole package, Burnell and the Introductory topics cost $50, and the Intro topics alone cost $20 for RAS members. Once again, seating at the Burnell workshops will be limited.

We all hope you can come back to Anza Borrego this October 11-14, and hope to see you at the workshops. (And bring a friend or two!)

Alex

Got a call from somebody today who inherited 14.25 inch SCT (F 6.7) on a Bill Schaeffer mount.

I know in general what it is, and I am going over tomorrow to see it. So, I don't know conditions, etc.

Anybody know how I can tell him how much it is worth and the best way to sell it (in addition to here on Astromart?)

SOunds like it is too heavy to move.

The fellow who called me did not know telescopes.

Alex