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80mm F10 Telescope for PST Mod and Baader TZ Quark?

Posted: Tue Mar 30, 2021 10:01 pm
by AndiesHandyHandies
Hi

Whilst there are conflicting statements in TZ advertising I believe they are designed for a 800mm FL, as in Zeiss APQ 100mm F8, or is it a F10 beam as in this telescope which is also 800mm FL?

https://www.firstlightoptics.com/stella ... cuser.html

It could be used with a standard PST F10 mod or a TZ Barlow with Quark.

Anyone got one or seen one?

Cheers. Andrew.

Re: 80mm F10 Telescope for PST Mod and Baader TZ Quark?

Posted: Wed Mar 31, 2021 7:48 am
by AndiesHandyHandies
Hi

Doing more searching Baader mention for one TZ model about F10.

Astrograph mentions the 800mm FL.

My recollection about the APQ seems to be wrong.

And my Rumak180 is F10 for those few days of good seeing.

Would I be using a 80mm stopped down mostly for imaging in the UK?

Cheers. Andrew.

Re: 80mm F10 Telescope for PST Mod and Baader TZ Quark?

Posted: Wed Mar 31, 2021 7:50 am
by AndiesHandyHandies
Hi

And which TZ model would be best for imaging with the 80mm?

Cheers. Andrew.

Re: 80mm F10 Telescope for PST Mod and Baader TZ Quark?

Posted: Wed Mar 31, 2021 3:51 pm
by marktownley
TZ4 I would say for the 80/10

Re: 80mm F10 Telescope for PST Mod and Baader TZ Quark?

Posted: Wed Mar 31, 2021 4:34 pm
by Bob Yoesle
Telecentrics are very simialr collimators, and are designed for specific focal lengths and positioning to render precise telecentricity, not focal ratios. That said, Christian's evaluations show using longer focal length objectives work quite well, shorter not so much:
Even if they are optimized for a specific focal length, telecentric systems can be used with some flexibility regarding focal length. Telecentric lens systems with higher magnification factor have more flexibility on the focal length.

Degradation of performance comes first for short focal lengths.

Re: 80mm F10 Telescope for PST Mod and Baader TZ Quark?

Posted: Wed Mar 31, 2021 6:55 pm
by AndiesHandyHandies
Hi,

I thought Mark would say the TZ4. And what aperture would be typical to use in the UK?

Thanks for the link Bob.

I am a bit confused as Baader say F10 in one of the TZ adverts. Astrograph says 800mm fl and CV has done his calculations on 800mm fl.

Is there any official Baader document which says it should be 800mm. So I could be right about them being designed for a 100mm F8 APQ?

Cheers. Andrew.

Re: 80mm F10 Telescope for PST Mod and Baader TZ Quark?

Posted: Thu Apr 01, 2021 6:52 am
by marktownley
You could ask them Andrew, tbf, the TZ3 would work just as well with the 80/10 when seeing doesn't cooperate. When seeing isn't playing ball a 60mm stop would work with the TZ2 - all £££££££ though!

Re: 80mm F10 Telescope for PST Mod and Baader TZ Quark?

Posted: Thu Apr 01, 2021 9:52 am
by AndiesHandyHandies
Hi

Thinking about it.

I can use the PST mod in the refractors as vignettes to F10:
80mm F5 = 40mm AKA PST
100mm F5 = 50mm
90mm F6.7 = 67mm
127mm F7.5 = 95mm
So can choose one for seeing.

Edit:

127mm with -150 and +150 lenses for 127mm
Rumak180 at 180mm for those few days of excellent seeing. Hopefully the Baader TZ4 would work well with it.

***

Bob points out CV says the Tele-centrics work OK over 800mm FL so should be OK in the 127mm which can be stopped down to 95mm and get F40 with TZ4.

Give those a go.

Cheers. Andrew