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900mm mirror lens + 2X Tele Converter vs. Mak-Cassegrain

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#1 DonBoy

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Posted 23 April 2019 - 03:35 PM

So how would a 900mm f/8 mirror lens plus 2X tele converter stand up against a 102mm or 127mm Mak-Cassegrain?


Edited by DonBoy, 23 April 2019 - 03:36 PM.


#2 photoracer18

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Posted 23 April 2019 - 05:53 PM

Mirror lenses have large central obstructions, which is why they are often F8 (there have been a few fast ones over time at F6.3 and faster but are rare and not recently), and designed to be used in sunny conditions. A 2x TC is going to make it F16 but with no decrease in the CO as an F16 true MCT would have. So contrast at least will be much better in the MCT than the mirror lens. Often mirror lenses suffer from some CA since they have extra lenses in the light path.

Having tried both in my more photographer days if you have one already don't buy the other, but if you have neither I would prefer the MCT depending on how you plan on using it.


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#3 DonBoy

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Posted 24 April 2019 - 11:54 AM

Thanks for the information.   I think I'll plan on a MCT, probably a 102mm or 127mm.



#4 luxo II

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Posted 25 April 2019 - 03:47 AM

No contest. The mak will win easily.

Mirror lenses are not diffraction limited whereas a visual mak is, and the mak has greater aperture (and resolution).

To make matters worse the mirror lens has a huge central obstruction which further degrades image quality.


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