Author Topic: Focal ratio and Coma.  (Read 259 times)

excunisep

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Re: Focal ratio and Coma.
« Reply #15 on: February 03, 2018, 07:39:05 AM »
I would much rather have slower optics. No Paracorr, collimation is not as tricky and no shallow focus problems and i can use higher power with whatever eyepiece i am using. I am a planet guy 90% of the time.

lorndwatassi

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Re: Focal ratio and Coma.
« Reply #16 on: February 03, 2018, 12:18:47 PM »
The OP was never asking for a fast Newtonian. Re-read post #1.

closfockralperp

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Re: Focal ratio and Coma.
« Reply #17 on: February 03, 2018, 12:38:08 PM »
Quote
I had a F4.9 Z10 that seemed a little large for me. I would like to hear from people who have had  8" F6s and 6" F8s. I am trying to decide between the two dobs or a C8 Edge. Of those three which will have the "refractor like" stars. I understand the aperture effect. Would a Coma Corrector make the dobs as good or better than a C8 Edge? I want something with a little more aperture to compliment my C102.

I've had versions of all (3) scopes mentioned, except the 8" SCT was not an Edge model. The 6" f8 will be slightly more refractor like than the 8" f6 (no CC), but not a huge difference. I would probably go with the 8" f6 given your criteria. Keep in mind that I would always choose a Newtonian over an SCT due to the thermal issues (it's cold where I live). YMMV.

David Allen

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Re: Focal ratio and Coma.
« Reply #18 on: February 09, 2018, 06:13:57 AM »
Jeff's descriptive term "convenient medium aperture " perfectly describes what I was thinking. I am looking for the "CMP" scope that has "refractor like" stars. Thank you for the input. I am leaning towards the dobs, I have had a 8SE and an 8CPC I don't think of them as convenient.

consmagestma

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Re: Focal ratio and Coma.
« Reply #19 on: February 09, 2018, 11:06:45 AM »
Quote
Jeff's descriptive term "convenient medium aperture " perfectly describes what I was thinking. I am looking for the "CMP" scope that has "refractor like" stars. Thank you for the input. I am leaning towards the dobs, I have had a 8SE and an 8CPC I don't think of them as convenient.

Bill:

This one is really calling out to me:

http://www.astromart...ified_id=937983

It's set up for photo and visual and could be easily converted to Dob use. But the second-to-last-thing-in-the-world I need right now is another scope!

Do you use bino-viewers?

Jeff