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Posts Made By: Charles Hakes

November 15, 2003 01:54 PM Forum: Telescope Making

Bent Newt secondary question

Posted By Charles Hakes
I am finally bending the light path in my 10" f9.6 dob. I am going to put the focuser at 45 degrees, so the secondary will be tilted at 22.5. My question is about the secondary size. I have played with "Newt" a bit and obviously Newt wants a 90 degree bend in the light. (I must use the at-work computer until he comes up with the Mac version.) Does it work to just say the focuser is just sqrt(2) farther away? Are there other considerations I need to make?

I have a Surplus Shed "oval" flat mirror that I got for this project. I guess I will know when it all gets put together how it will work. I just wanted a little more "theory" behind my construction effors to know if I need a different secondary.

Thanks,
Charlie

December 14, 2003 02:15 AM Forum: Equipment Talk

GM headlights - help!

Posted By Charles Hakes
Someone else must have encountered this. How do you turn off the headlights in GM cars at night. A while back I got to visit a stargazing party in a GM rent-a-car and couldn't figure out how to leave without shinig headlights on everyone there. (*&#^$@!!!

Now the problem is closer to home. We got a new (used) Olds and I now have the same problem. The users manual tells you how to turn them on during the day, but I don't see an option for turning them off at night. Anyone solve this problem yet?

Thanks,
Charlie

March 19, 2004 09:11 PM Forum: CCD Imaging and Processing/Solar System

limiting magnitude question

Posted By Charles Hakes
Is there a convenient table as to what kind of limiting magnitude can be expected with a given CCD/scope/exposure. I can do the calculations just fine for naked eye observing. I have also taken enough film photos to do a good job guestimating my limiting magnitude there. But I was wondering what I could expect if I get a nice CCD that can take long exposures?

Thanks,
Charlie

March 20, 2004 01:33 PM Forum: Equipment Talk

question on dimmest stars visible

Posted By Charles Hakes
I posted this on the CCD forum too, but thought the question might get more visibility here...

Is there a convenient table as to what kind of limiting magnitude can be expected with a given CCD/scope/exposure. I can do the calculations just fine for naked eye observing. I have also taken enough film photos to do a good job guestimating my limiting magnitude there. But I was wondering what I could expect if I get a nice CCD that can take long exposures?
Thanks,
Charlie

March 23, 2004 01:33 PM Forum: Equipment Talk

CCD question for Maurice Clark (or anyone else)

Posted By Charles Hakes
If you were taking 60 minute exposures with your ST9, what magnitude stars could you see? What size scope were you using? Maybe I could scale to apperture and exposure. I am trying to figure out what we can see through a 16" SCT.

The "calculator" you directed me to looked great, but I don't know what I should enter for all the boxes.

Thanks,
Charlie

May 4, 2004 01:40 AM Forum: Telescope Making

Cooling idea - great or nuts?

Posted By Charles Hakes
Reading some recent posts got me wondering...

Why not attach aluminum (or some other high-heat-conduction metal) fins to the back side of a mirror using whatever appropriate thermal grease. Think of your computer CPU. In this case the supports would need to be "taller" than usual, and go through those cooling fins to reach the glass. Fans would then be just that much more effective.

Has anyone tried this? Why not? Is this idea totally whacko? Or do I need to run down to the patent office?

later,
Charlie

May 12, 2004 01:51 PM Forum: Equipment Talk

refractor diagonal comments?

Posted By Charles Hakes
I am looking to purchase a 2" diagonal for a Meade 5" acromat. I have heard good things about the Williams Optics 2" diagonal, but there are two options. Would it be worthwhile to get the one with dielectic coatings? (more$$)

Also, I would like to get some sort of minus-violet filter to keep permanently installed in this diagonal. Are any better than the others? Are there any I should avoid? Any other options I should be considering?

Thanks,
Charlie

May 26, 2004 08:19 PM Forum: Telescope Making

My ATM project

Posted By Charles Hakes
This is by far the most complex truss design I have ever tried to build. Having taken "the plans" as far as they go, my next step will be to attach the structure in the photo to a suitable Azimuth bearing and find a "dome" the proper size. Of course then I would need to start on a matching scope so I can do proper interferometry.

Has anyone else built one of these?

Charlie

June 9, 2004 01:16 PM Forum: Equipment Talk

16" image shift - too much?

Posted By Charles Hakes
I got a 16" LX200 out of storage the other night. The focus was surprisingly stiff and there was lots of mirror image shift. Close to 1/2 degree when I started! A bit less after some "exercise." How much should I expect? And how much is too much? I do want to get a rear Crayford-style (electronic) focuser, but I also want to make sure the mirror is aligned properly when I use it. Wouldn't image shift like this cause astigmatism? It sure looked like it. Are the 16" scopes typically lots worse than the smaller ones? A couple of 10" I have used weren't nearly this bad. Does anyone else on this forum use the 16" version?

Thanks,
Charlie

June 11, 2004 02:37 PM Forum: Equipment Talk

Please help with statistics

Posted By Charles Hakes
I like to get some statistics on SCT focusing image shift. How is your scope? Instead of just "good" or "bad," how good or how bad is it in arc minutes or arc seconds? I guess for completeness we should know Meade, Celestron, or "other" and what size scope it is. Maybe with enough responses we can quantify some of the Celestron/Meade discussions I have seen here. I hope this thread will be useful to others on this forum and not just something to satisfy my curiosity.

To get things started, I have a 16" Meade showing (at latest test) 3 minutes of shift. For those who followed a previous thread this shift got significantly better after lots of focuser "exercise" by moving through its whole range several times. I'll post results for other local scopes I know of as I get the information.

Thanks,
Charlie

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