Quote:you really do need to look at pictures that smaller aperture scopes have taken. Pictures on Amart of the planets with high end APO's sure are awesome. I would have to argue that with some of them I have never seen anything better with a C14. Having a couple of C14's I know there limitations.
I only know, i know nothing.
Quote:Terra had the answer: "All this however is highly subjective and arbitrary."
Nothing would be done at all if one waited until they could do it so well that nobody could find fault with it.
Quote:Those canals got removed because of urban renewal by NASA.
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Quote:There is of course the quote from Suiter: "the best way to get a perfect 12" is to make a good 14".
If you look at the theory, the Modulation Transfer Function (MTF) captures the differences between different telescopes very well. For reasonable optics you can see how optical quality can be traded for aperture. The bigger optics will be better in resolving small high-contrast objects like very close doubles. But at the scale of details on planets there is much leeway, and smaller, better optics can compete with bigger and worse. But not with bigger and as good optics.
Quote:Oh, I can definitely say that people have different perceptions of what they see, hear, smell, & taste -- regardless of the source -- how else to explain Nickelback fans??
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Quote: Yes, but what are the margins??? I mean, we´re talking about a 4" refractor in comparison to a C14? or are we talking about a 6" vs 8" scope? What you say, can be true between small differences in aperture, but not between important ones.
Quote:I have the answer to that!Jim
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ALL my posts should be considered as opinions shaped by MY experiences and understanding of the facts.
Quote:That is quite a scope! Can it reach zenith?
Quote:A 6" APO could be very well color corrected down to about f/5. A Newtonian on that same focal ratio would get absolutely hammered in terms of contrast, fine resolution, details etc...
Quote:Here is a 6incher on a short FL:http://www.teleskop-express.de/shop/product_info.php/info/p5630_TS-PHOTOLINE-...
Quote:Of course all the data that has been presented are theories that were developed many years ago. I have always wondered if these same theories still hold true with all the advancements in lens making and the exotic glass that is used today.
It's actually a 130mm f/7 with a field flattener that can be screwed into the focuser. It's a 5 inch along the lines of the NP-127 but less intergrated and possibly not capable of visual use .
I don't know of any "native" 6 inch F/5 apos. It might be possible but the ones I see are relatively slow and within range of focal lengths where a planetary 6 inch Newtonian is possible.
Quote:In saying that, your TV 100mm f/5 APO does a good job on color correction - correct?
It is excellent, even out of focus. But it's not really a 4 inch F/5.4, or at least the objective is not. It's a bit of a simplification but it's basically a long focal length apo double with a fancy ED focal reducer/field flattener at the rear of the scope. NP stands for Nagler-Petzval.
You could do a similar thing with a 6 inch apo but then you could do a similar thing with with a Newtonian but neither makes much sense.