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Canon 200mm f2.8L NB filter options?

astrophotography LP
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#1 GTom

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Posted 14 December 2019 - 04:36 PM

Has anyone tried the Baader filter holder or any other solution mounted in front of the 2.8/200 lens? This one is for 2" filters, meaning the aperture will be stopped down to f4, which is exactly the WO redcat physical aperture.

I'd use the kit on a 6D, eventually on my z6 once it retires from daylight duties.

 

baader-ufc-universal-filter-changer-282.


Edited by GTom, 14 December 2019 - 04:37 PM.


#2 Samir Kharusi

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Posted 17 December 2019 - 05:06 AM

I used simple step-down rings. You'll probably need to use 2, one from 72mm(?) to around 55mm and a second from 55mm to 48mm. Standard astro 2" filters have a 48mm thread but you may not be able to find one ring that reduces from 72mm to 48mm. I picked the intermediate diameter to fit my other, shorter lenses. Step down rings are very inexpensive. Anyway, with the 2" filter at the front of the 200mm lens you end up working at around f4.5, with the lens set at f2.8; no diffraction spikes.



#3 2ghouls

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Posted 17 December 2019 - 09:53 AM

Sorry if I am missing something, but why not use one of the many clip-in filter options from Astronomik, Optolong, etc.?


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#4 GTom

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Posted 17 December 2019 - 01:05 PM

Sorry if I am missing something, but why not use one of the many clip-in filter options from Astronomik, Optolong, etc.?

Just ordered a UVIR block filter but I have a full set of NB filters for my refractor - forgot to tell, I have 90% of the necessary gear (filter drawer, square filters) and I don't necessarily want to invest in a second full set bow.gif . The useful aperture of the 2.8/200 is so close to the available filter dimensions that I am considering reusing my existing filters.


Edited by GTom, 17 December 2019 - 01:33 PM.



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