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Hi,

Thanks.

As I am trying to compare 'like for like' would it be possible to do the spot diagram for a 6" as its got a lens at the front. What are the F no limitations and what is required at 6".

Cheers. Andrew.

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Here is a spot diagram of a 6" f/12 which a friend owns. Note that it is again diffraction limited for all colors at a field of view of over 1/2 a degree and has polychromatic Strehl ratio of 0.995.
Schupmanns can be made as fast as f/9.75, maybe even faster. Gerry Login displayed a 10.25", f9.75 at Riverside about 10 years ago were it received excellent reviews.
The largest Schupmann is the Swedish 0.97 meter used for solar work.

- Dave

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Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schief. 60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4.5" f/16 Schupmann Medial refractor, 14 Stellafane awards 7 in optics

Engineering = Taking what you have and making what you need.

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