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Lawrence Parchman

Sculptor Galaxy (NGC 253)

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Posts Made By: Mark Holden

May 3, 2006 01:23 PM Forum: Eyepieces

5mm eyepiece choice...

Posted By Mark Holden
Peter Hallock said:

Any Glowing reports on Burgess Planetary 6mm, 5mm, 4mm? I have all three...No Nagler, Radian, whatever can beat the 4mm in IMHO.

Pete

The 6 that's available used is not up to full spec - but folks do seem to love them. I have the 4 and 5 and while they're the least expensive eyepieces I own, I find they're the first ones I reach for when I'm using higher powers.


May 7, 2006 11:43 PM Forum: Eyepieces

Best daytime eyepieces

Posted By Mark Holden
Dmitri Kulginov said:

What are the best eyepieces for daytime observing, if money is not an issue,
- for an 5" refractor?
- for an 8" SCT or Mak?

And why?

Dmitri

The 2" 32mm widefield Vernonscope is a good daytime eyepiece. So are the 1.25" Brandons.

I also like the Nikon 7mm and 9-21 zoom. These were made for the Nikon Fieldscopes, but you can get adapters give them a standard 1.25" barrel.


May 8, 2006 03:21 PM Forum: Digital SLR AstroPhotography

Nikon D50 experiences anyone?

Posted By Mark Holden
Keith Proctor said:

Any experiences from anyone with the Nikon D50? Just picked one up for myself and would love to play with it under the stars this summer. Barndoor already being built, just curious what others may have tried or done with the camera.


The D50 is supposed to have less thermal noise than my D70.

I've taken a fair number of shots through my TMB 115 (f7) and a friends 175 (f8) and find I can get nice images of brighter DSO with exposures between 2 and 8 minutes.

A friend has used his on a barn door and gets very nice milky way shots - though light pollution is often a limiting factor.

May 11, 2006 08:30 PM Forum: Politics

This Thread May Be Monitored By The NSA

Posted By Mark Holden
jess tauber said:

Remember the 'meaning of 'is' is' argument from a couple of years ago? The semantics of semantics may allow the NSA and the President to claim that nobody is listening to average Americans' phone calls- but of course this might not cover automated keyword recognition systems. After all, such a system would literally be 'nobody'.

Jess Tauber

Todays "news" isn't about listening in - it's logging what phone numbers are dialed by other phone numbers.

But before getting excited about these "new" intrusions into our private lives, you might want to read about the Echelon system of monitoring phone calls that has been in operation since around the end of World War II.

This is very old news. It's been happening for decades, and it's been public for more than a decade.




May 16, 2006 02:53 PM Forum: Telescope Making

Perplexing Refractor

Posted By Mark Holden
Hi

Two thoughts

1. The lens you have may not be a complete lens.

2. If you tested it in daylight, and haven't flocked or baffled the tube you may have problems from stray light.

May 18, 2006 07:54 PM Forum: Equipment Talk

Carry-on vs checking on airplane

Posted By Mark Holden
I fly with a TMB 115 CNC as carry on, and I check my GM8 mount head as luggage.

I keep a spare tripod, counterweight, and battery at the destination I fly to.

Last time, TSA damaged a servo motor on the mount. My best guess was they took it out to inspect it, and dropped it back onto the mount instead of putting it in it's cubbyhole. (though perhaps they threw it against the wall, the drive shaft on the motor was bent 30 degrees)

Fortunately, it was only a $50 repair, and it happened on the way home from my vacation.

But part of the problem is the GM8 won't fit into the Losmandy suggested case with the servo motors attached - so I had to remove them for shipping.

You can buy extra insurance for your luggage. You can also "schedule" your telescope equipment on your homeowners policy. (It's treated as "camera equipment" and I think I pay about $16/$1000 per year)

If you must check a scope, look into getting something like a scopeguard ATA case.


May 19, 2006 07:45 PM Forum: Digital SLR AstroPhotography

Astrophotography with Nikon D70

Posted By Mark Holden
The ground glass on the D70 doesn't have as much resolution as your eye.

If the focus is right, the image will be pretty good, but the image scale will be small. In round numbers, a D70 will give an image scale about like using a 28mm eyepiece.

There are various tools to make focusing easier. The simplest is a hartman mask.

May 28, 2006 02:53 PM Forum: Beginning Astronomy?

Attaching SLR film camera to telescope...

Posted By Mark Holden
Lee Spain said:

Last week, I was really fortunate to get a nice 35mm Canon EOS Elan 7e camera from a friend who is a semi-pro photographer who has gone all digital.

If I wanted to attach it to my Observer 70 and try my hand at long distance terrestrial photos, is this what I would need?

http://www.buytelescopes.com/product.asp?pid=591

You'd also need a 1.25" camera adapter.

This will screw into the T ring, and give you a 1.25" diameter tube that'll go in the scope where you'd normally put an eyepiece.

June 13, 2006 02:47 AM Forum: Telescope Making

Blackening Aluminum

Posted By Mark Holden
Here's an alternate way if you're looking for something easier:

http://yarchive.net/metal/aluminum_black.html

June 14, 2006 06:39 PM Forum: Eyepieces

Air Glow

Posted By Mark Holden
What you're talking about is commonly called "scatter".

As Floyd mentioned, dirt on the lenses can make this more of a problem.

Otherwise, some eyepieces are better than others at reducing scatter.

Better coatings, smoother polishing, and fewer air to glass surfaces will reduce scatter.

The eyepieces I use for observing planets are TMB Supermonocentrics (least light scatter), BO/TMB Planetaries (most eye relief), and Clave (an excellent but rare top quality plossl).

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