Most current commercial refractors have the tube length set to give 5.5 to 6" of back focus with the focuser all the way in. The TEC 140 has 7" with the...
... their ... Harveys scope is pretty special and very configurable in that he can on the fly adjust the tube length ahead of the focuser. His OTA is therefore...
Hi,Joe I am owner of D&G 5"f20 in selfmade tube with Zeiss old focuser I have a pertinax tube-this is 270 mm shorter than focal lenght-thats enough,because you...
I am trying to locate the former owner or an employee of the telescope firm Cheshire Instruments of Georgia. They used to advertise heavily in Sky & Telescope...
I am trying to track down the history of a 5" f/12.6 Astro-Physics, Inc. apochromatic refractor tube assembly and need to look at back issues of the now...
Fred, a very detailed review but let me point out that it is taking 3.5MB of 20MB file space which is almost full. Maybe you should web publish it. David...
Hi David, Yes, I could just that, or I can try to bring it back to an acceptable level
.. I'll try this weekend, okay? Kind regards, Fred ... Van: David Datum:...
Fred, maybe redo the pictures only with lower dpi settings before making the pdf file. I suspect the pictures take most of the file. Your joy of the instrument...
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Anybody else out there have one of these? This was touted early on as "semi apo." While not an apo by any stretch of the imagination, the CA is remarkably good...
... The CA is noticeably less than my Synta 6 inch f/8. I read somewhere that one of the elements is a special high dispersion glass.>> If it has a high...
... Thanks for raining on my parade....I stand by my assertion that the CA is noticeably better than my f/8. Special "magic glass" aside,I'll settle for a...
... Thanks for raining on my parade....I stand by my assertion that the CA is noticeably better than my f/8.>> So what? What makes your Synta F8 the standard...
... I didn't realize this was a "scientific" forum; I was just posting my impressions from an aesthetic point of view. My point comparing it with the Synta was...
I have always been amazed at how quickly some will jump on others... and it is ususally anytime someone tries to tell a good story or compare a lesser piece of...
No jumping down the throat was intended. No trying to disuade from cheap to mega expensive. Just trying to tell you that an achromat is an achro, no matter how...
I'll state it another way if the previous explanation was too technical. There are two ways to reduce the color error that you see as color fringing in the...
... I certainly am not crossing swords with you on what you say above; I sit at your feet when it comes to optical theory. I've learned loads reading your...
Every Synta I have ever looked through had quite badly corrected color due to poor matching of the crown to the flint. I would not hold them up as an example...
... Didn't say that I don't see any color; I have excellent eyes. The color that I see in the Antares is about half that of the slower Synta at the same...
... Synta ... And ... point? ... The 5"F6.45 Antares achromat is on my short list of scopes to replace my Burgess 102F6. I've followed the very long thread on...
... To me it's a matter of the point of diminishing returns....if a lot more money will yield only a little improvement, that's where I draw the line. Frankly,...
... Of course, to each their own. For visual use, you don't need perfect color correction to see detail on the planets, nor do you need it for low power wide...
... I agree with everything you say above.... IMO the tremendous attention paid to using refractors for viewing the planets and double stars ( with the...
