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false color

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#26 Guest_**DONOTDELETE**_*

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Posted 26 November 2003 - 04:38 PM

Tom,

I am looking forward to seeing the 2 scopes side by side. I was very close to buying the one you bought just because I wanted to see the differences. :question:

Now I can and I saved a bunch of Cash. :roflmao:

Thanks!! :bow:

#27 Guest_**DONOTDELETE**_*

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Posted 26 November 2003 - 07:14 PM

So did I! :smirk: :D

#28 Guest_**DONOTDELETE**_*

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Posted 27 November 2003 - 11:16 PM

Hi Chris,
Regardless of quality, all achromats(not APOs) will have the same color correction given the same aperture/f-ratio. It doesn't matter if its Sunta, Vixen, or SV, etc,etc.

A common criteria for decent color correction is to triple the aperture(in inches)and that is a good f/ratio for low color error perception. Examples 3"(f/9), 4"(f/12), 10"(f30). As you can see this can get out of hand and you'll end up with enormous telescopes real quick.

There is a fudge factor of tolerance. My 5" f/9.3 is pretty good as an AT1010 at f/6.2. At moderate to dim objects its barely noticeable. On bright planets and bright stars the blue fringe will be easily seen.

BTW, Saturn is very forgiving in that you won't see too much of the blue fringe. Regardless these refractors of moderate to long f/ratios can be superb performers. For 95% of the objects observed the achromats will hold their own against APOs. Don't go to the very short f/ratio refractors and you'll be just fine.

The Meade AR5 is a superb performer optically. Its LXD55 GOTO mount, though, has had a few problems.

Al M

#29 Guest_**DONOTDELETE**_*

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Posted 27 November 2003 - 11:19 PM

C'mon Tom,
You know that the Orion ED80 will easily win that one! Don't be so smug ... oh heck .. be smug!

Al M

#30 Guest_**DONOTDELETE**_*

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Posted 27 November 2003 - 11:23 PM

Hi Keith,
A difference of 1 f/ratio can be easily noticed at the short end. Compare your AT1010(f/6.2) against a ST80(f/5) and you'll know. as the f/ratios increase such a difference will become harder to distinguish.

Al M

#31 Nebhunter

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Posted 28 November 2003 - 01:54 AM

I finally bit the refractor bullet a month ago. I purchased the Konus 120, 1000 mm f8.3. Came with a 19 & 10 mm Plossl. First light was at a dark site - deer camp - during a full moon with the eclipse to follow Nov. 8. Brief view of the moon Nov. 5 evening - then clouds. Left the scope outside, and had a gorgeous view of Jupiter at about 05:30 hrs with the 10 mm at 100x. Easily see banding and 4 moons. Clear, crisp, with a very dark background. Both poles (very white) and banding was bluish as sunrise started to show. NO PURPLE or violet until the sun got brighter, and I guess the angle of light made a small ring appear - but it went away after about 2 minutes.

That night under a full moon - came Saturn. The seeing must have been 6 out of 6 because the Cassini division was sharp and distinct at 100x (that's all the power I had). The rings were white with slight tan ring nearer the globe of the planet. The globe was white, with tanish banding. No violet or false colour visible to this nubie at least. Moon was a bright (what else) white. Gray colour to the sea's and visible craters on the top corner gave very good contrast with the dark shadows. No violet ring around the edge or anywhere during viewing. Orion - gasp - but no nebula filter to improve the view - but a nice gray nebula with trapesium easily visible - under a full moon high in the sky. Eclipse night - not a cloud - cool, crisp air. The Milky Way just expoded under full eclipse. I went nuts trying to look at everything during that 1/2 hour. Ended up in a lawn chair with a good set of binoculars and just could not believe my eyes. I digress.

Home - London, ON - backyard view of the moon the next week with a 2x Barlow. I also purchased a 2" diagonal. I put the Barlow after the diagonal for 200x with the 10 mm Plossl. Great view of crater and shadow - white and black contrast. Barlow before the diagonal for 300x - WOW. What detail going down the crater walls. No false colour, no violet on the tops of the craters or around the moon - as I looked for it - because they say it should be there - right? Saturn even held up at 300x with much more detail visible in the tanish banding and black Cassini division. Some of the double stars had the colour mentioned in the magazine - one was an ice blue, the other an orange - red. No yellow on the moon either. Used the motor drive that night and viewed from about 1:30 to 4:30. It was cold.

Went back to the moon, and it was getting very difficult to focus and get a sharp image. Went down to 100x and bingo - violet ring around the moon, and lousy contrast. Problem was - a skating rink on the lens as it was frosting up quickly. I called it a night of grate viewing, and was not disappointed one bit. Not many good nights since, due to rain, and cloudy conditions. Bright stars are just that - white, ice blue, or redish orange. Star clusters are amazing with the variety of ice blue to white stars, and they stay that colour as I go inside with 200x or more.

I'm sticking to 3 - max. 4 element Plossls for my planetary viewing. I want all the light I can get, and never mind the light robbing 6 to 8 element heavy weights. Barlow is OK on very bright planets etc, but not for faint stuff as it does cut down the light. I'm going to try a different Barlow - 1.6x next time. I digress.

My enthusiasm know no bounds for the treasures of the heavens. Yes, it's an achro. Where's the colour? I don't know, and I don't care. Did I luck out with a well made and properly spaced lens cell? Don't know, and I'm not about to take it apart. Slightly over corrected with a brighter image focus out - nice round rings. Focus in produces a star image a kid would draw with lots of spikes inside the ring.

I'm going to slowly add to this Konus, and IF a Chromacor system will improve the contrast and image, as they say, then I will test one - once I save up that is, and buy it. I figure that if it improves my seeing even more, then it's worth it regardless what I paid for the original outfit. I'm here for the long run, and this baby is a keeper. FYI.


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