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11" RASA + ZWO mini filter wheel?

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#1 andysea

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Posted 11 December 2018 - 10:11 PM

Question for the group: has anyone used the 11" Celestron Rasa with a ZWO mini filter wheel and a ZWO mono camera?



#2 akulapanam

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Posted 12 December 2018 - 06:12 PM

I think you are going to have significant issues with that setup. Really the only option for filters on Hyperstar or a RASA is a qsi or filter slider. Even an Atik One is problematic. It’s not just diffraction either but also vignetting at corners of the field even on a 1” chip like a 694

Full 2” filters are ideal here

Edited by akulapanam, 12 December 2018 - 06:16 PM.


#3 andysea

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Posted 12 December 2018 - 08:31 PM

Yeah full 2" filters and a filter drawer should work as I have seen some images taken with that setup. ZWO says that the 31mm unmounted filters can be used with f/2 systems so that's why I was thinking of the mini FW.

The other issue that I was worrying about tho was the FW sticking out into the light path. Do you know how large is the secondary assembly on the 11" RASA?



#4 akulapanam

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Posted 12 December 2018 - 08:36 PM

Yeah full 2" filters and a filter drawer should work as I have seen some images taken with that setup. ZWO says that the 31mm unmounted filters can be used with f/2 systems so that's why I was thinking of the mini FW.
The other issue that I was worrying about tho was the FW sticking out into the light path. Do you know how large is the secondary assembly on the 11" RASA?

115mm . The diffraction artifacts can be an issue but it isn’t horrible. On my F3 RH200 I need a 36mm filter with the 694. On Hyperstar I needed 2” for the identically sized 814. However distance to the chip is a big consideration, the closer it is the smaller the filter needed.

Edited by akulapanam, 12 December 2018 - 08:37 PM.


#5 andysea

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Posted 12 December 2018 - 08:43 PM

Hm thanks! Lot's to think about. Off topic question: is your RH200 the new one with the carbon fiber tube or the original one? And what focuser do you use with it?



#6 akulapanam

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Posted 12 December 2018 - 11:55 PM

Hm thanks! Lot's to think about. Off topic question: is your RH200 the new one with the carbon fiber tube or the original one? And what focuser do you use with it?

I use an Optec Leo.  Easy to access the tilt adjustment screws, can handle a large train, very thin, and uses the same controller as my existing feathertouch focusers.

 

Mine is a MY2017 and the shell is carbon fiber.  Focus shift over the past couple of nights has been about 200 steps (.079 microns each) over about 5 hours with 10 degree temp drop.




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