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Posts Made By: William Paolini

December 7, 2006 10:17 AM Forum: Chinese Optics Imports

Performance of the Glass

Posted By William Paolini

Well, there's been it seems some real keen interest in routing out exactly what may or may not be special about this new market entry - the TMB/BOC Planet Hunter. Seeing as I'm the only one that has one, anyone wanting to give me some observing tests for me to do I'll be more than happy to try smile

To date I've done these:

Mag -1 @ 180x - CA
Mag 0 @ 180x - CA
Mag +1 @ 180x - No CA
Mag +2 @ 180x - No CA
Mag +3 @ 630x - No CA

Lunar Limb - Always This line CA

Terminator 180x - No CA
Terminator 225x - No CA, but some yellow?
Terminator 300x - No CA
Terminator 360x - No CA
Terminator 450x - No CA
Terminator 630x - No CA

Saturn 180x - No CA
Saturn 225x - No CA
Saturn 360x - No CA

M42 Nebulocity - Fine details emerged starting at 130x

All mags stars show classic airey disk and one diffraction ring, even at 630x.

Lunar details continued to reveal at least thru 257x, remaining sharp and contrasty. 257-630x some new details appears, others got lost, depending on contrast level of detail as image dimmed.

December 7, 2006 08:20 PM Forum: Chinese Optics Imports

Forum rules and conduct.

Posted By William Paolini

All,

I would like to remind everyone of the AstroMart terms of usage. A pertinent excerpt is:
“Users may not use the Astromart services for any illegal purpose or for transmitting material that is unlawful, harassing, libelous, invasive of another’s privacy, threatening, harmful, vulgar, obscene, tortuous, infringes the intellectual property rights of another, or is otherwise objectionable.”

As a forum monitor, I will be enforcing this best practice. As a general rule, please limit discussions to the topic at hand, and never bring into your discussion personalities or people. If you wish to reference any manufacturer in a negative light, please be factual in your presentation, do not be emotional, do not be personal, and please state how what you are presenting may be relevant to current or future conduct of that manufacturer. For the most part, I would imagine that contributors will be talking about products offered by these manufacturers. As such, it is never correct to assume that performance on one product offering, may be indicative of all their product offerings, as most businesses in today’s global environment utilize parts and processes from then global market as a whole.

Anacortes, through their generous sponsoring of Astromart, is allowing our community of users the opportunity for constructive comment and discourse to benefit not only ourselves, but the community as a whole. So again, if your issue is personal and not indicative of what the general community is experiencing, then please keep it offline between you and the person or company with whom you are having issues. To extrapolate that you negative experiences are indicative of what thousands of consumers are experiencing is not acceptable without supporting facts.

While these rules of conduct to some may feel restrictive, they are not. As long as you can be factual, non-emotional, and provide constructive criticism in a professional manner, then the community at large will only benefit.

I thank you all for your attention to these rules, and look forward to many fruitful and constructive forum posts that will benefit the entire community of users.

Appreciated,
-Bill (forum co-monitor)

December 24, 2006 09:02 PM Forum: Religion

Merry Christmas...

Posted By William Paolini

“… in that region there were shepherds out in the field, keeping watch over their flock by night. And an angel of the Lord appeared to them, and the glory of the Lord shone around them, and they were filled with fear. And the angel said to them, "Be not afraid; for behold, I bring you good news of a great joy which will come to all the people; for to you is born this day in the city of David a Savior, who is Christ the Lord. … And suddenly there was with the angel a multitude of the heavenly host praising God and saying, ‘Glory to God in the highest, and on earth peace among men with whom he is pleased!’ “ (Luke 2)

This night I recall all the wonderful places reason has taken me and our civilization…indeed this very technology being used is a prime example. It has taken us places and given us things that no other process could probably do. But with all this, we cannot reason ourselves into joy, nor use reason to comfort our grief, nor reason the grandeur of love, and least of all can reason find God – for this, we have faith as a process. Through faith, we are able to find that which we seek, and after we find our God, faith turns to trust and communion with that which we once sought.

For those in faith or seeking it, I pray this night and season brings to you all the blessings and promises of God heralded by this event so many centuries ago – His peace is yours! To those of you who are happy in life without faith or God, I wish for you all the warmth and peace and love from those closest to your life this night and always.

Merry Christmas Bobby, Samantha, Gary, John, Clyde, Mike, Eric, Steve, Jim, and Patrick grin
-Bill

December 26, 2006 12:33 PM Forum: Refractors

Re: Testing of optics through magnification

Posted By William Paolini

James Fusco said:
I'm posting this question here because I have not found a straight answer. Testing a lens with high magnification untill the image breaks down, this limit is it a test? Does this indication a quality of optics or design. ... My impression is magnification will increase error. Error of what, in what I do not know.

Jim,
Hi. In the strictest sense of the word, I don't think this is a test. I'd classify it more as a general performance test. That is, all other things being equal, 2 identical scopes on the same night on the same object, but one with a better corrected lens, the one with the better corrected lens should achieve higher magnifications better. Not only color correction though, but spherical as well. Once the design corrects the color sufficiently, then the better spherical correction should allow you to use higher powers more effectively -- until you hit other barriers, like the atmosphere and all the many less than well understood things it does to the optical path. smile At least, this is my understanding.

However...in practice, I have seen what you say. Generally each telescope I have they tend to have their own general limit for the average day. Further, the limits are different in terms of x/inch for each.

Finally, as far as observational experiences, even though there is the general truism that as you push mag, at some point it becomes empty mag as no new details are revealed just bigger image, I have recently poked a hole in that concept. Several weeks ago I decided to push and push magnification on the Moon and do some detailed observing. What I discovered was interesting...even at rediculous magnifications, while I did of course get to a point of losing details, in other places more details did indeed reveal themselves! I went up and down in powers on the particular spot where I noticed it happening and what I "think" was probably at work was how contrast is related to resolution. So as I pushed the mag and the image got dimmer, lower contrast details started to wash out then disappear all together. However, in very high contrast areas, whose brightness was extreme, more details popped up. So what I learned for me in this exercise, that you will miss new details if you are looking at a high contrst object and you never go past that point where you start to see a general fading or softening of detail due to supposedly excessive magnifications.

Anyway, the reason you've probably not found a straight answer on this is probably because there is none?! 8O But the fun is in the experimenting grin

-Bill

January 12, 2007 10:04 AM Forum: Celestron

Celestron SS60 Spotting Scope from the 80's

Posted By William Paolini

I have an old SS60 spotting scope from the 80's in classic Clestron Orange. The objective and eyepiece (25x) are fixed and it focuses via a ring in the middle of the tube in front of the erecting prism.

Does anyone know how the focusing is accomplished since neither the object or eyepiece move?

I was thinking about demounting the objective and making it into an convention 60mm telescope. As a spotting scope it produces really sharp images and when I unscrew the eyepiece and place an unscrewed RKE 15mm in it's place, the image scale is the same although very much sharper. So I estimate it is an f/6. With an 8mm RKE in place all 4 trap stars are visible and no CA on Rigel (although this is only approx 50x).

Anyway, anyone have any thoughts on taking this thing apart. Was curious how the focusing was accomplished though before I did and assume the main objective is a standard achromat.

-Bill

January 25, 2007 10:57 AM Forum: Eyepieces

Baader Zeiss Barlow

Posted By William Paolini

Does anyone have experience with the Baader 2x Zeiss Barlow? How does it compare to other mainstream barlows?

I guess my ultimate question is what is considered the best 2x barlow. By best I mean providing sharpest image with least light loss from the added lenses.

January 31, 2007 08:07 AM Forum: Telescope Making

Hershel's Telescope Making

Posted By William Paolini

Ran across this article and thought those here would find it interesting. Has a photo of a 10" reflector he made. The 7 footers seemed to be the most popular ones he made and sold.

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?db_key=AST&bibcode=2004JHA....35...45S&letter=.&classic=YES&defaultprint=YES&whole_paper=YES&page=45&epage=45&send=Send+PDF&filetype=.pdf

February 6, 2007 05:55 AM Forum: Beginning Astronomy?

Resolution Question

Posted By William Paolini

Hello all. Didn't know where to post this so chose this forum since none of the others seemed appropriate.

My question is if optical resolution behaves the same way that radio resolution does. As we know, with radio telescopes if you build an array or have two scopes separated by some distance, the resolution of the combination of scopes is determined by the baseline of their separation.

Would optical scopes behave similarly? So in a practical example, if I had a 20" Newtonian, if I placed a mask with two 3" apertures with the outside of the holes 20" apart (i.e., the centers 17" apart), what would be the theoretical resolution of this masked setup vs the full resolution of the 20" opening?


February 21, 2007 01:06 PM Forum: Eyepieces

Re: TeleVue Radians

Posted By William Paolini

$160-$190 each seems to be the avg price range going back to Nov 06 on AMart. The $160-$170 seemed to be lowball prices, so $180-$190 each should sell reasonably quickly if they are in Excellent or LNIB condition with caps and original boxes.

February 21, 2007 01:37 PM Forum: Celestron

XLT Coatings

Posted By William Paolini

FYI - I've recently acquired a C6-S w/XLT. In doing some compares between it and my Orion 10" XTi (F/4.7) I was quite surprised with its light thruput...much more than I expected from a 6". In my neck of the woods, usually Limiting Mag is 4 and 4.5 on a good night, this little 6 stayed surprisingly close to the 10" relative to faint stars and DOS (although of course slightly higer mag with the C6 - 80x vs 63x).

Attached is a drawing of the heart of Pleiades showing TFOV differences -- I was testing out an Antares 19mm W70 on loan from Jon Isaacs. Within the C6-S's TFOV, I marked the stars with hashes to show the only extra ones that the 10" showed. I would have expected much more. Aparrently the XLT coatings are doing a good job.