Image of the day

Captured by
Arthur Hogan

Heart and Soul Nebulas

About Astromart

My Account

New to Astromart?

Register an account...

Need Help?

Posts Made By: John Holt

January 4, 2009 11:05 PM Forum: Reflectors

Mysterious optical phenomenon

Posted By John Holt
Atmospheric seeing.
Or more specifically, atmospheric turbulence effecting the "seeing".

January 15, 2009 06:42 PM Forum: Equipment Talk

Amici/correct image prisms

Posted By John Holt
For the astronomical purposes part, a half binocular makes a good inexpensive low power correct image finder.

January 26, 2009 12:12 AM Forum: Equipment Talk

It had to happen..bifocals

Posted By John Holt
Ivan Ong said:

Hi, well, I resisted long enough but it looks like bifocals are in the future for me! Question: I have astigmatism, and observe frequently with eye glasses on. I have been recommended the graduated bifocals (not sure what they exactly are but I assume it will not have that distinct half-moons on the lower part of the eye glass lens)...do any of you who wear them find them a hindrance to observing? If the far sight portion is on top, does that require peering from the top side at some angle? In astronomy you can easily run into imperfections and distortions from eye glass lens itself. Your thoughts are appreciated.
Thanks
Ivan



Plain old regular line bifocals work very well. You know exactly were you're looking through at the ep.

On a side note, if you spend time outdoors, then consider glass lenses. Small light weight glass. Small = fog up less, and glass = clean far easier.

Please note that glass lenses and volcano top ep's do not play well together. Plastic lenses work better if one bumps metal on ep's, or finders.

February 7, 2009 10:31 PM Forum: Deep Sky Observing

DSO binoculars.

Posted By John Holt
Paulo martin said:

Hello,

Is best a rich field telescope of 3"-4" with variable magnification for quick look DSO or a giant binocular 70-100mm with fixed mag.?

Paul


Scope.
Variable magnification does not need to be an entire case of eyepieces. This is particularly the case for quick look situations. But a mid to higher power magnification option (or a couple of them) in addition to that lowest power widest field view, is really nice to have.

February 22, 2009 11:39 PM Forum: Politics

I'm a Racist Coward!

Posted By John Holt
Here we go again?

February 28, 2009 04:14 PM Forum: Eyepieces

Best non-televue eyepiece collections

Posted By John Holt
GSO plossl's work very well if on a budget. And just plain work well.
RKE's are really nice with a bit slower focal ratio.
For wide field in slower focal ratios, UO Konigs were/are significantly better than most of the present day affordable wide field ep's in their fov range.
I'm using a lot of Sieberts nowadays.


March 7, 2009 08:44 AM Forum: Equipment Talk

A mounting conundrum for a newbie. "C-11A"

Posted By John Holt
Chris Deppe said:

I just picked up a nice C-11A OTA, but I'm stuck about what mount to get. The OTA is a newer #91036-XLT with the CGE dovetail bracket. I was told that this would also fit the CGEM EQ mount. The problem is that I can't afford either of these mounts. In fact, the CGE would be out of the question entirely, and the CGEM is out of my reach for at least a couple of years. I plan on doing some astrophotography with it. Probably about 70% viewing, and 30% imaging. At this point I don't have a preference as to weather I get an Alt/Az mount or an EQ mount, as long as it's stable enough to be useful. I'm not opposed to changing out the mounting bracket, if needed. I knew this would be a bit of an economic trap when I bought this thing, because you save so much money when buying the OTA and mount as a package, as opposed to seperately. But, I got it cheap, so I took on the challenge. If I can't find a mount by the end of spring, I will probably end up building my own manually operated mount so I can at least get some viewing in this summer. So my question is, does anybody have any reccommendations as to what type of mount I can get for less than 1200 bucks, that would be anywhere near steady enough for a 28Lb tube? Could I even get an Alt/Az mount for this scope? Any suggestions would be greatly appreciated.


For a short tube scope, even at 28 pounds, you should be able to build your own alt-az mount. With components from a local home improvement store.

March 21, 2009 05:33 PM Forum: Beginning Astronomy?

Dealing with eyepieces...

Posted By John Holt
Uncapped eps in cargo pockets when at the scope. I only use a few ep's at a time.
I spent some time looking at sporting goods and army surplus stores for vests or jackets. Found one with large pockets I've been using for years.

April 4, 2009 08:22 AM Forum: Equipment Talk

Life of a Telrad

Posted By John Holt
I have a 2 year old Telrad that suddenly died.


My experiences with sudden death of my telrad....have all been from the batteries losing good contact. Reinstalling them has fixed it each time.

April 16, 2009 11:18 AM Forum: Telescope Making

Slide Tube Focusing Design Ideas?

Posted By John Holt
Coulter made a sorta plumbing parts focuser on this order for their scopes. They worked. The biggest problem I ever had with mine was in cold weather. The coefficient of expansion/contraction between the plastic outer tube and the aluminum draw tube made it bind up in sub-zero temps.

For night time use, where the target isn't going to fly away any second, helical fine focus was not really required. One could actually get almost infinity fine adjustment simply by turning the draw tube ever so slightly between thumb and finger as you focuser in or out. Wiping down the draw tube from time to time helped.

There are 1.25" drain fittings available almost everywhere. One can make 1.25" focuser extensions from it. Cut it to length as needed.

You also may want to just put in a wanted ad for somebody's leftover Coulter focuser.

Funding Member

Sponsors


View all sponsors

Search