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Lion Nebula SH2-132 - RC71

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Posts Made By: Timothy Iafolla

January 8, 2006 06:16 PM Forum: Telescope Making

image quality of optical fiber for astro use?

Posted By Timothy Iafolla
Jeff,

interesting idea in theory, but I think it would be very difficult to execute.

The first thing that comes to my mind is the information loss caused by packing inefficiency: since the fibers are circular in cross section, when they are bundled together there are significant spaces with no fiber "receptors". If memory serves I think the most efficient packing of tubes results in something like a 72% fill. So right off you lose over quarter of the light, and whatever visible features fall into those spaces are lost.

Interesting idea though. But I think the inherent problems account for why images are carried over fiber only when there's no practical alternative (endoscopes, etc).

Just remembered: Melles-Griot makes a line of small aspheric lenses that are made from bundled fibers. They allow extremely low focal ratios (f/0.3 and the like), because the focusing of the light doesn't rely on lens refraction, but on the physical direction that the fibers are oriented.

So you're not completely in left field here (g).

Tim Iafolla

January 10, 2006 02:22 PM Forum: Equipment Talk

Any Plettstone owners out there?

Posted By Timothy Iafolla
FYI, over in the Zambuto mirrors user group I just learned that Carl Zambuto mirrors are now available on Plettstone scopes.

Tim Iafolla

January 27, 2006 02:02 PM Forum: Politics

Hamas Victory

Posted By Timothy Iafolla
I've heard a couple of analysts cast it this way: that, in addition to its less savory activities, Hamas has been supportive of poor Palestinians with food distribution, running schools, supporting the families of dead fighters, and other 'making the trains run on time' types of activities. The previous government had distinguished itself with corruption and tribalism. It wasn't so much the struggle with Israel that determined the outcome....it was the failure of simple acts of governance.

If true, there's a lesson here for those who would try to influence other contries by force of arms rather than by economic and social means.

Tim Iafolla

January 27, 2006 05:23 PM Forum: CCD Imaging and Processing/Deep Sky

M42 with New Eyes

Posted By Timothy Iafolla
I found this DVD to be helpful for monitor calibration:

http://tinyurl.com/bsjzf

It's indispensable for home theater calibration (it's amazing how far off most TV's are), which means it includes some functions that don't apply to computer monitors. However it's excellent for grayscale adjustment, brightness/contrast setting, geometry, and color calibration (it comes with a set of gel filters to help with this aspect). HTH,

Tim Iafolla

January 27, 2006 05:39 PM Forum: CCD Imaging and Processing/Deep Sky

A rediculously simple question... *grin*

Posted By Timothy Iafolla
I think globulars would present an interesting test case. I agree with what the others say when it comes to nebula imaging.

But it might be true that imaging a globular is more like imaging a planet: lots of detail to resolve along with fairly high surface brightness. I'd like to see a comparison between the 'traditional' ways of shooting globs (say a dozen 30-second images) vs a stack of 1000 images of 0.36 seconds each....both methods with the same total exposure time of 6 minutes. A control shot of a single 6-minute exposure would be nice too.

Or is my premise of imaging a glob being similar to a planet completely faulty? Thanks,

Tim Iafolla

February 7, 2006 06:16 PM Forum: Politics

Good news from the Middle East!

Posted By Timothy Iafolla
Jim Babcock said:

Support for the President's bold actions in the Middle East are beginning to be understood by those most impacted in that region of the world. That is fantastic news for everyone!

It is unfortunate that "the loyal opposition" continues to be on the wrong side of this issue, just as they were against President Reagan when he ordered the Kremlin to tear down the wall. As they like to tell us, if you do not study history, you are doomed to repeat it. wink

Whoa! That is quite a leap of logic to assert that the quoted poll results mean that the president's "bold actions in the Middle East" are now being supported by middle easterners. I think it's pretty safe to assume that our Iraq policy is still deplored by most people affected. I think the pol results may reflect that the actions of the terrorists and insurgents have become so heinous, so random and unrelated to their stated policy objectives, and have adversely impacted on so many lives, that some people are finally starting to complain. To say it's in support of Bush is insane....the man doesn't even have the support of a majority of Americans, for heaven's sake, and his policies have even less support than the person.

Jim, based on your last few posts, I think your logic circuits sustained some solar flare damage.

Tim Iafolla

February 7, 2006 06:29 PM Forum: Telescope Making

Off axis Newtonian Binoscope

Posted By Timothy Iafolla
Stu Lieberman said:

I am interested in off axis reflectors.

Has anyone modified (or knows how to) a Newtonian to a non-obstructed instrument?

I have several 4.5 f8 Meades (parabs) to play with.

I would like to make a 4.5 binoscope.


Stu,

If you simply use a standard parabolic mirror and tilt it so that the diagonal is off axis, huge aberrations are produced by the tilt. There are only a couple of ways to move the diagonal off-axis, and they are technically difficult and expensive.

The first is to make the primary mirror an off-axis section of a larger parabola...so for a 4" mirror you would need to atart with at least an 10" parabola. This is the approach that D&G uses with its off-axis scopes. They perform very well, but are as expensive as apo refractors of the same diameter.

The second way is to use a flat that is asperically ground into a sort of saddle shape. This is done in the Yolo design, and again is technically very difficult.

No free lunch.

Tim Iafolla

February 8, 2006 04:46 PM Forum: Equipment Talk

What's your "travel scope"?

Posted By Timothy Iafolla
For air travel, it's a Lumicon 80mm f/4 Superfinder and a light camera tripod, along with 25mm, 10mm, and 2x Barlow EP's. It's small (it all fits in a camera bag), light, decent aperture and optics, and if it all gets lost or stolen it's only $300 or so.

Tim Iafolla

February 8, 2006 05:54 PM Forum: Politics

Should we sell the moon?

Posted By Timothy Iafolla
That brings up a question: assume some private commercial entity wanted to land on the moon and build a base. Would they have to get permission; if so from whom? Would it make a difference whether or not the entity was American or not? Just curious,

Tim Iafolla

February 23, 2006 05:12 PM Forum: Politics

How to make a purse out of a sows ear!

Posted By Timothy Iafolla
Darrell,

I strongly recommend a book by Thomas Friedman called "The qWorld is Flat". He makes a very convincing case, backed up with lots of data, that outsourceing is VERY good for America, in fact in the long run it is absolutely necessary.

It may not be good for the individuals who are replaced, but for the overall economic health of the country, and for the young people who are tomorrow's workforce, it is vital.

On this single solitary matter I agree with Bush.

Tim Iafolla

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