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RASA 8 filter holder/slider options

accessories Celestron astrophotography
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#1 harshad.savant

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Posted 25 February 2020 - 01:20 PM

I recently got a RASA 8 and ZWO 1600 cam along with a 2" 12nm Ha Astronomik filter. I also ordered the Starizona filter slider for this setup. Unfortunately, the Starizona filter slider for rasa 8 has a lead time of 4-6 weeks. I was told that they are custom made as per orders.

Do you guys have any suggestions on other possible filter sliders for this setup which are readily available? I don't mind just an adapter which excepts a 2" filter as long as it meets the spacing requirements. It will be cumbersome to thread in and out each filter but it will atleast get me going. smile.gif
It sucks that the Celestron optical window doesn't accept standard 2" filters! That would have made it much easier for people to start imaging narrow band without having to wait for third party accessories. 



#2 bobzeq25

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Posted 25 February 2020 - 01:48 PM

People use the Starizona.  There's a new Baader FCCT due out, but it's been delayed, with no end in sight.  The Baader has the _serious_ advantage of tilt adjuster built in.  Tilt is a real issue with the scope.  So I'm just waiting for the Baader.

 

I have both 183 cameras and 2 Precise Parts adapters (requires no additional spacers, which can cause tilt, and has no felt).  One uses the standard 2 inch ring on the 183.  That ring accepts an adapter for a 1.25 inch filter, although the adapter must be modified to fit the RASA.  I've done that.

 

Then, you have to decide what spacing to use with a filter, and whether to leave in/remove the Celestron window.  All is debatable.

 

Bottom line.  Great scope, but all the issues are not worked out.  It took me about 3 months to get it working well.


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#3 Brule

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Posted 25 February 2020 - 06:39 PM

Sorry to hear about them being out of stock, I got lucky when I ordered mine I guess as it arrived in a few days.

 

For an alternative have you looked at the Artesky 2" Filter Adapter for Celestron 8" RASA? You can screw in 2'' filters, it basically replaces the stock M42 adapter, while being thicker which helps getting to the proper backfocus. It claims to change the needed backfocus to 17.5mm, which is exactly what your 1600 should have with the stock 11mm T2 spacer on (11mm spacer + 6.5mm camera window to sensor), so you just screw it on. It also comes with a 0.5mm aluminum spacer. I'm a little confused on whether that's needed or not. Measuring the thickness of the adapter it's 11mm, so that would be 11 + 11 + 6.5 = 28.5mm, and the RASA 8 manual states 29mm is needed, so that would mean it is required, but it's odd as they don't mention it being needed. Of course, there's a number of other factors like whether you kept in the clear window, or the thickness of your filters, etc... There's a whole thread here on finding proper backfocus with the RASA 8, so expect to play around with it, but it should get you close.

 

I also must apologize that I ordered the last one off agenaastro (just received it today), however it looks to be in stock on teleskop-express -- that would ship from Germany. I got it to possibly shoot OSC during galaxy season as I'm not sure I want to switch out 4 filters, or maybe shoot OSC one night and Mono the other for luminance. In both cases I wouldn't need to switch my astronomik L-2 filter. Also wondering if the Artesky adapter will improve any tilt/backfocus issues since it's just one solid piece.

 

Finally, if you're feeling particularly adventurous and want something right now, here is a DIY video by Roswell Astronomy on replacing the clear window in the rasa with your own. I'd probably only do that if I was only shooting OSC, or if I wasn't going to use the clear window anyway, but it is possible.


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#4 Topographic

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Posted 03 March 2020 - 10:06 AM

Artesky tell me that it will also fit the ASI 071 Pro. Logical as the backfocus is 17.5 mm, T2 thread, you just don't need an 11 mm spacer like with the ASI 183/1600 et al.

 

Sorry to hear about them being out of stock, I got lucky when I ordered mine I guess as it arrived in a few days.

 

For an alternative have you looked at the Artesky 2" Filter Adapter for Celestron 8" RASA? You can screw in 2'' filters, it basically replaces the stock M42 adapter, while being thicker which helps getting to the proper backfocus. It claims to change the needed backfocus to 17.5mm, which is exactly what your 1600 should have with the stock 11mm T2 spacer on (11mm spacer + 6.5mm camera window to sensor), so you just screw it on. It also comes with a 0.5mm aluminum spacer. I'm a little confused on whether that's needed or not. Measuring the thickness of the adapter it's 11mm, so that would be 11 + 11 + 6.5 = 28.5mm, and the RASA 8 manual states 29mm is needed, so that would mean it is required, but it's odd as they don't mention it being needed. Of course, there's a number of other factors like whether you kept in the clear window, or the thickness of your filters, etc... There's a whole thread here on finding proper backfocus with the RASA 8, so expect to play around with it, but it should get you close.

 

I also must apologize that I ordered the last one off agenaastro (just received it today), however it looks to be in stock on teleskop-express -- that would ship from Germany. I got it to possibly shoot OSC during galaxy season as I'm not sure I want to switch out 4 filters, or maybe shoot OSC one night and Mono the other for luminance. In both cases I wouldn't need to switch my astronomik L-2 filter. Also wondering if the Artesky adapter will improve any tilt/backfocus issues since it's just one solid piece.

 

Finally, if you're feeling particularly adventurous and want something right now, here is a DIY video by Roswell Astronomy on replacing the clear window in the rasa with your own. I'd probably only do that if I was only shooting OSC, or if I wasn't going to use the clear window anyway, but it is possible.




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