#1  
Old 07-05-2021, 03:26 PM
xelasnave's Avatar
xelasnave
Gravity does not Suck

xelasnave is offline
 
Join Date: Mar 2005
Location: Tabulam
Posts: 14,134
Filters for RASA 11 inch

I asked the following in the Equipment section but given that thread has probably run its course and really my question is best asked here I repeat my question.

I plan to buy a RASA 11 inch and a ZWO 2600 mono and filter draw...I recall that one should buy a particular brand to minimise reflections or something so I ask... what brand of filters and what size should I buy?
Also which ones? Can I get by with Ha, S and O or should I get the lot? Is there a "set" that would be sensible...as anyone can tell I really dont know what I am doing so any guidance will be much appreciated...any help at all
Thank you.
Alex
Reply With Quote
  #2  
Old 07-05-2021, 05:24 PM
Zuts
Registered User

Zuts is offline
 
Join Date: Mar 2007
Location: sydney
Posts: 1,725
Can't help much but the little I know points towards you needing a set of 'fast' filters due to the speed of the scope.

https://www.cloudynights.com/topic/7...s-for-rasa-11/

Cheers
Paul
Reply With Quote
  #3  
Old 07-05-2021, 06:12 PM
kosborn (Kevin)
Registered User

kosborn is offline
 
Join Date: Mar 2018
Location: Canberra
Posts: 346
HI Alex,


I started with 31mm ZWO narrowband filters with an ASI1600mm and found there were horrible internal reflections as the filters are anti-reflective on one side only. I ended up replacing them with Astronomik filters which work really well. From the reading I've done, 31mm filters are the smallest possible for the ASI2600mm, depending on your focal length. Probably 2" is the best way to go. This web page: https://astronomy.tools/calculators/ccd_filter_size has a good calculator to work out minimum filter size for your set up.


Kevin
Reply With Quote
  #4  
Old 07-05-2021, 09:37 PM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 2,975
I reckon unless you want to go all false colour, you will want an RGB set too. but at least RGB are pretty cheap. GIven the exposure times you would be talking about from a RASA, you might even go the whole hog and do LRGB-NB.
Reply With Quote
  #5  
Old 08-05-2021, 06:25 AM
xelasnave's Avatar
xelasnave
Gravity does not Suck

xelasnave is offline
 
Join Date: Mar 2005
Location: Tabulam
Posts: 14,134
Thanks to everybody for helping.

Given all the sound input I will buy the 2 inch Astronomik filters ...all of them...I am not even going to think about the cost ... I will place my order with John at Bintel on Monday even though I am not sure I will be able to get back to astrophotography but one must remain positive and make plans based on positive outcomes ...And a big thank you to John who has been and is always so helpful when I ring him..I will probably regret being so hasty and ambitious but hopefully not.

Thanks again I really appreciate the guidance and help you wonderful people give me..sincerely thank you.
Alex
Reply With Quote
  #6  
Old 08-05-2021, 08:48 AM
Emuhead
Registered User

Emuhead is offline
 
Join Date: Oct 2019
Location: Melbourne, Australia
Posts: 90
Believe the Baader fast filters are designed with the Rasa in mind, and it's where i would head if & when i go the 11" f2 route, just need the mount for it.

Also, some people have success using the Rasa 11 with the mini zwo efw, so you won't have to manually change the filters which i could only guess would become a chore after a while, especially if you also have a dew shield in the way. The mini doesn't have a very large foot print either so whilst it does block some of the light & introduce a slight change to diffraction shape, its not a deal breaker. Pros & cons.
Reply With Quote
  #7  
Old 08-05-2021, 08:59 AM
The_bluester's Avatar
The_bluester (Paul)
Registered User

The_bluester is offline
 
Join Date: Feb 2011
Location: Kilmore, Australia
Posts: 2,975
I reckon the way to go with a RASA would be a flat panel. That way you could shoot a target with one filter, shoot flats to go with it, change filters and keep going.
Reply With Quote
  #8  
Old 29-05-2021, 12:53 PM
srmnm (Will)
Registered User

srmnm is offline
 
Join Date: Aug 2019
Location: Caloundra, Queensland
Posts: 18
Hi Alex,

I know question was asked a few weeks back, but perhaps not too late to give some more input. I've been using Baader F2 high-speeds. They are very good although the Oiii really gives a lot of halo around bright stars. I've got the cables even going away in arcs and still doesnt fix the issue. Not getting this with Sii or Ha.

Also, i use Baader R, G & B filters with same setup (mono 1600mm pro) when I want to shoot galaxies etc.

Hope this helps.

Thanks,
Will
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 03:50 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Advertisement
NexDome Observatories
Advertisement
Testar
Advertisement
Bintel
Advertisement
Limpet Controller
Advertisement
Astronomy and Electronics Centre
Advertisement