#1  
Old 19-02-2019, 11:17 AM
Mokusatsu (Australia)
Registered User

Mokusatsu is offline
 
Join Date: Nov 2014
Location: Leeming
Posts: 125
Filter slides

I'm thinking of getting a 2" filter slide, something like the Moonlite one, to pair with my 20" Skywatcher Dob. Ideally one with a dew heater element built in.

https://focuser.com/products/focuser...lterslideA.jpg

Does anyone have any recommendations? Are there any local suppliers or is ordering direct from Moonlite (or others) in the US the only option?
Reply With Quote
  #2  
Old 19-02-2019, 11:34 AM
gaseous (Patrick)
Registered User

gaseous is offline
 
Join Date: May 2016
Location: Brisbane
Posts: 463
I can't offer any advice sorry, but I'd be interested to hear if you have any success as I've got the same scope.

I looked at a filter slider like these (as the "outside" mounted slider I have won't allow me to reach focus), but I thought it'd clash with either the spider vane or the inside of the curved focuser mounting plate.

Also, I assume you'd either have to use it without the light shroud, or be putting your hands through the spider vanes to slide it.


Good luck!
Reply With Quote
  #3  
Old 19-02-2019, 03:57 PM
astro744
Registered User

astro744 is offline
 
Join Date: Apr 2007
Posts: 783
There is also Astrocrumb. See http://www.astrocrumb.com
Reply With Quote
  #4  
Old 19-02-2019, 04:24 PM
gaseous (Patrick)
Registered User

gaseous is offline
 
Join Date: May 2016
Location: Brisbane
Posts: 463
Yeah, the Astrocrumbs sure are a nice looking unit. Unfortunately, for some reason Skywatcher have placed the spider vanes in such a way that one of them is directly above the focuser draw tube, so any filter slider would need to run at 90 to the Astrocrumb images.
Reply With Quote
  #5  
Old 19-02-2019, 10:09 PM
Mokusatsu (Australia)
Registered User

Mokusatsu is offline
 
Join Date: Nov 2014
Location: Leeming
Posts: 125
I exchanged some emails with the astrocrumb guy, who quickly pointed out that as the Skywatcher spider lines up with the focuser a slide cannot be used.

Probably the easiest mod would be to move the plate that the focuser is installed on just enough to clear the spider vanes. We'd need to drill four new holes, tap a thread into them, and cut a new notch in the eyepiece plate to clear the spider vain. Only question is whether I could do it with the required degree of precision. It's not like I can stick that whole thing in a drill press vice.

Is this something a machinist would be equipped to do?

Edit: on further consideration, it shouldn't be a difficult thing to do, a jig could be built to facilitate precise hole drilling, and cutting out the notch would be 15 minutes with my Dremel.

I'll continue to exchange emails with Astrocrumb guy, and see if we can figure out a technical solution.

Any other 20" Skywatcher owners interested in a purchase if we figure it out, i.e. for group buy purposes?

Last edited by Mokusatsu; 20-02-2019 at 02:57 AM.
Reply With Quote
  #6  
Old 20-02-2019, 04:13 AM
Allan's Avatar
Allan
Registered User

Allan is offline
 
Join Date: Feb 2013
Location: Newcastle
Posts: 876
I faced the same issue on a previous Orion dob. The fix is quite easy by rotating the spider veins 45 degrees in orientation. That gets them clear of the focuser so you can install the filter slide under the focuser.

I have the Moonlite slider on my dobs. It is a high quality machined aluminium and black anodised slider. The Astrocrumb is a timber slider. It is nice but not anywhere near the quality of the Moonlite.
Reply With Quote
  #7  
Old 20-02-2019, 07:36 AM
gaseous (Patrick)
Registered User

gaseous is offline
 
Join Date: May 2016
Location: Brisbane
Posts: 463
Looking at my UCA here, and I'm not exactly sure how you can rotate the spider vanes to make this work, unless you can rotate them yet keep the secondary mirror in the same orientation somehow. Otherwise if you rotate the spiders, you'll be rotating the secondary as well, which'll put everything out. Same goes for slightly shifting the position of the focuser mounting plate so the focuser clears the spider - you'd also have to slightly rotate the secondary mirror somehow, while not moving the spider, to keep the optics aligned. Or am I missing something simple?
Reply With Quote
  #8  
Old 20-02-2019, 07:49 AM
gaseous (Patrick)
Registered User

gaseous is offline
 
Join Date: May 2016
Location: Brisbane
Posts: 463
Actually it seems like the secondary could be possibly rotated and refixed in position with the locking nut, so it may be feasible if you feel like cutting into metal to rotate the spider - bit beyond my skillset judging by all the areas that seem to need adjusting.
Reply With Quote
  #9  
Old 01-03-2019, 09:55 PM
aperturefever (Sean)
Registered User

aperturefever is offline
 
Join Date: Nov 2010
Location: Eleebana, NSW
Posts: 21
I have been using the Astrocrumb for years now. Works a charm and the woodwork on the storage box is sensational. Highly recommended.
Reply With Quote
  #10  
Old 17-03-2019, 11:52 AM
gaseous (Patrick)
Registered User

gaseous is offline
 
Join Date: May 2016
Location: Brisbane
Posts: 463
Mokusatsu, did you end up having any success with your filter slider venture?
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 08:40 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Advertisement
Interest Free Finance
Advertisement
OzScopes Authorised Dealer
Advertisement
SkyWatcher WiFi Adaptor
Advertisement
SkyWatcher 2018 Catalogue
Advertisement
NexDome Observatories
Advertisement
Bintel
Advertisement
Lunatico Astronomical
Advertisement
Astronomy and Electronics Centre
Advertisement