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M20 Trifid Nebula in LRGBHa

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Posts Made By: Allen Tracht

March 8, 2006 10:47 PM Forum: CCD Imaging and Processing/Solar System

Stellacam Options

Posted By Allen Tracht
I have a Stellacam EX which I've used with a TV/VCR to capture a few images. I'd like to get images into my computer, but the recommended Imperx video capture (especially the 30 fps CardBus version) cards are relatively expensive, so I'm looking for alternatives:

1. Other digitizers: Anyone know anything about the Zarbeco VideoLink? What about consumer devices like ADS, Pinnacle, Plextor, etc.?

2. DV camcorder w/ analog input. Yes, it would be more expensive, but it would be usable as a camcorder as well. Is their digitizing quality adequate?

3. Replace the Stellacam with a digital-output astro camera. Recommendations for < $1000? No parallel-port, please. My laptop only has USB and FireWire.

I appreciate your comments and suggestions.

Allen

March 9, 2006 03:25 PM Forum: Equipment Talk

Stellacam Options

Posted By Allen Tracht
I posted this on the CCD/Solar System Forum and got no replies, so I thought it might be better addressed here:

I have a Stellacam EX which I've used with a TV/VCR to capture a few images. I'd like to get images into my computer, but the recommended Imperx video capture (especially the 30 fps CardBus version) cards are relatively expensive, so I'm looking for alternatives:

1. Other digitizers: Anyone know anything about the Zarbeco VideoLink? What about consumer devices like ADS, Pinnacle, Plextor, etc.?

2. DV camcorder w/ analog input. Yes, it would be more expensive, but it would be usable as a camcorder as well. Is their digitizing quality adequate?

3. Replace the Stellacam with a digital-output astro camera. Recommendations for < $1000? No parallel-port, please. My laptop only has USB and FireWire.

I appreciate your comments and suggestions.

Allen


October 16, 2006 05:16 PM Forum: Solar System Observing

Political Pluto Humor

Posted By Allen Tracht
http://www.leginfo.ca.gov/pub/bill/asm/ab_0001-0050/hr_36_bill_20060824_introduced.html

Read it and laugh.

January 18, 2007 09:40 PM Forum: Equipment Talk

Re: Superblack

Posted By Allen Tracht
I doubt it will ever be available as flocking
paper:

"A[n] ... electroless nickel process ... is used to plate ... a nickel-phosphorus alloy. ... [A] finely controlled etching procedure ... is largely responsible for the very low reflectance of the surface."

It only sounds suitable for rigid solids, probably
metals (though you mght be able to put the nickel-phosphorus alloy on plastic or glass).


October 12, 2003 03:46 AM Forum: Eyepieces

celstron x-cel experience?

Posted By Allen Tracht
My 12.5mm X-Cel's filter threads do not mate with my filter's threads, even though those filters mate with all of my other eyepieces and even with my TeleVue Barlow. The dealer suggested that this is a common problem with these eyepieces and has quite courteously agreed to replace it with one with the correct threads.

Has anyone else had such a problem?

April 21, 2004 05:51 PM Forum: Equipment Talk

Fan on Dob

Posted By Allen Tracht
In all of these discussions of tube currents and boundary layers, I haven't seen (maybe I missed) any mention of a way to tell if the fan is helping, other than the subjective quality of the image. Thermal distortion of the mirror figure would, I guess, have to be evaluated with a star test which, I understand, takes some study and skill to use correctly, but tube currents and boundary layer motion should be visible by looking for motion in a deliberatly defocused image at moderate power as described in the recent S&T article. Have you looked for this? Do the fans improve it?

May 13, 2004 03:05 PM Forum: Telescope Making

PLOP vs. Kriege

Posted By Allen Tracht
These calculations are really entertaining, but I wonder if they reflect enough of the true situation:

It looks like PLOP assumes that equal forces are applied by each mounting point. To achieve that, not only do the bars or triangle have to pivot, but their bases also need to be connected through pivots. Do real mirror cells do this?

The mirror cell chassis typically does not have the same rotational symmetry as the mouting points. Does this cause unequal distribution of the mounting forces?

Most observation is not done at zenith. Unless the mounting points have zero friction, there will be shear forces twisting the mirror. How much do these matter?

To the extent the mirror is not supported by such shear forces, the sideways (from the mirror's point of view)component of gravity is taken up by the sling/clips, etc. How do these affect the figure?

Finally, any advice for equatorial mounts? It would seem that the edge support of the mirror would be equally as important as the rear.

May 17, 2004 07:21 PM Forum: Equipment Talk

Mewlon

Posted By Allen Tracht
I notice in the ATWB product description, it specifies that the reducer increases the usable field diameter to 42mm. Have you tried that?

May 19, 2004 06:10 PM Forum: Equipment Talk

Who put the EQ in the EQ mount?

Posted By Allen Tracht
In a brief web search I found:

http://www.astrosurf.com/re/history_telescope.html

quoting KING,H.C. (1955). The history of the Telescope

The site has a link to a diagram of Scheiner's helioscope (the first equatorially mounted telescope) (ca. 1638)

http://www.astrosurf.com/re/king_042.jpg

This predates the link given to Newton's reflecting telescope on the same page (ca. 1671).

August 8, 2004 08:15 PM Forum: Equipment Talk

Please help me identify....

Posted By Allen Tracht
Thanks, everyone. I'm sure I'll be able to find a matchine mount.

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