Daz Type-R Posted April 21, 2014 Share Posted April 21, 2014 All. I can not use 2" ep's (currently) as there is not enough back focus on my focuser. When I purchased my Moonlite I went for the standard 50mm focuser tube, tried my 13mm Ethos on its 2" fitment setting and then found out I could not rack the focuser tube out enough. Simply fixed this by using the Ethos on its 1.25" setting, as on the 1.25" setting it does not fit inside the focuser tube as much as it does on the. 2" fitment. Now my issue is, the next ep I'm getting is a 2" ep with no option of using a 1.25" fitting, so I'm going to have the same issue but this time be unable to simply fix it. As far as I am aware, there are 2 options to fix this. 1, get a longer focuser tube. 2, (and I don't understand this option) get a low profile focuser. Now I'm sure the Moonlite I have is a low profile one but when I fitted it, I fitted all the risers that came with it, would removing one of these help, (either the 1" one or the 1/2" one) and if it would help, how, as far as I see it, by doing that you are moving the ep even further away from the focal point. I guess I am either missing something here or I have got it all horribly wrong, proberbly the latter, over to you lot for help! Cheers. Link to comment Share on other sites More sharing options...
Guest Kheldar Posted April 21, 2014 Share Posted April 21, 2014 Option 2 is backwards - why would you want a lower focuser than you have? Answer is option 3 - buy a 2" extension tube Link to comment Share on other sites More sharing options...
Daz Type-R Posted April 21, 2014 Author Share Posted April 21, 2014 (edited) Option 2 is backwards - why would you want a lower focuser than you have? Answer is option 3 - buy a 2" extension tube I blame Google for my number 2 option, saw a few posts on other forums etc that said fitting a low profile focuser would cure back focus issues, I couldn't see how myself hence why I posted my dillema on here, off to look at 2" extension tubes now, cheers matey. Edited April 21, 2014 by Daz Type-R Link to comment Share on other sites More sharing options...
catman161 Posted April 21, 2014 Share Posted April 21, 2014 I only fitted the 1/2 inch riser Daz and have no problems with back focus even when I use the 4x powermate. I do use a combo of extension tubes ranging from 1.5-3.5 inches and anywhere in between to get focus for different situations though. Link to comment Share on other sites More sharing options...
Daz Type-R Posted April 21, 2014 Author Share Posted April 21, 2014 I only fitted the 1/2 inch riser Daz and have no problems with back focus even when I use the 4x powermate. I do use a combo of extension tubes ranging from 1.5-3.5 inches and anywhere in between to get focus for different situations though. Ok, cheers, so from the sound of it, without the extension tubes you would be in the same boat as me. Telescope house do a 50mm extension tube with compression rings for £16, just need to get out and measure how much extra back focus I need, may need the 80mm? Link to comment Share on other sites More sharing options...
Guest Kheldar Posted April 21, 2014 Share Posted April 21, 2014 I think 50 (or 35) will sort it - I never used the 80 and I had same problems with Panaview plus Oiii filter Link to comment Share on other sites More sharing options...
Daz Type-R Posted April 21, 2014 Author Share Posted April 21, 2014 I think 50 (or 35) will sort it - I never used the 80 and I had same problems with Panaview plus Oiii filter Cheers matey. Link to comment Share on other sites More sharing options...
Brantuk Posted April 21, 2014 Share Posted April 21, 2014 Low profile focusers usually fix "inward focus" issues - often experienced when attaching a dslr. Link to comment Share on other sites More sharing options...
+Ibbo Posted April 22, 2014 Share Posted April 22, 2014 this is the reason I prefer the terms inward focus travel and outward focus travel back focus has as far as I can tell, different meanings to different people esp our cousins across the water Link to comment Share on other sites More sharing options...
philjay Posted April 22, 2014 Share Posted April 22, 2014 Yep, inward focus for stuff like dslr and outward focus for 2" eyepieces. I went for a 2" extension with the old OO next I had so my vixen 2" eps would work but had to maje a low profile adapter so I could get focus with my canon. Link to comment Share on other sites More sharing options...
Daz Type-R Posted April 22, 2014 Author Share Posted April 22, 2014 Thanks for all the replies guys, everyday is a learning day! Link to comment Share on other sites More sharing options...
Guest devil74 Posted April 22, 2014 Share Posted April 22, 2014 Daz I have the same trouble with my new focuser...I discovered up Belper that I just run out of back travel when using 2" EP's, literally about 2mm from focus. As mentioned above have ordered myself a 2" extension tube. Link to comment Share on other sites More sharing options...
+Graham Posted April 22, 2014 Share Posted April 22, 2014 (edited) Maybe I am having a blond moment here but I always thought 'back' focus was inward travel, hence the word 'back'. Which is why you fit the low profile focuser to move the DSLR closer in especially if using an OAG. If you get stuck for an extension Darren drop me a pm and I will soon have one knocked up for you. Edited April 22, 2014 by Graham Link to comment Share on other sites More sharing options...
Guest Kheldar Posted April 22, 2014 Share Posted April 22, 2014 (edited) Just don't use the term back focus Edited April 22, 2014 by Kheldar Link to comment Share on other sites More sharing options...
+Graham Posted April 22, 2014 Share Posted April 22, 2014 Just don't use the term back focus Link to comment Share on other sites More sharing options...
Guest Kheldar Posted April 22, 2014 Share Posted April 22, 2014 To be serious it's usually used completely wrong anyways. It's far more accurate to say "I don't have enough inwards travel" or "I don't have enough outwards travel" to reach focus Link to comment Share on other sites More sharing options...
Guest devil74 Posted April 22, 2014 Share Posted April 22, 2014 To be serious it's usually used completely wrong anyways.It's far more accurate to say "I don't have enough inwards travel" or "I don't have enough outwards travel" to reach focus I don't have enough outwards travel to reach focus Link to comment Share on other sites More sharing options...
Guest Kheldar Posted April 22, 2014 Share Posted April 22, 2014 I don't have enough outwards travel to reach focus Link to comment Share on other sites More sharing options...
+Ibbo Posted April 22, 2014 Share Posted April 22, 2014 :good3: :clap2: Link to comment Share on other sites More sharing options...
Toymaster Posted May 5, 2014 Share Posted May 5, 2014 Thanks for the posts as I was confused about Back Focus when I was struggling with not enough outwards travel on the DOB. Didn't have the right tubes / adaptor fitted for the eyepiece being used. Sorted now... Ade Link to comment Share on other sites More sharing options...
+Bino-viewer Posted May 5, 2014 Share Posted May 5, 2014 If upgrading a focuser on a Newt with something like a Moonlight, its always best to go for the longer draw tube option. Think they do a 75mm option. Worth calling FLO and seeing if they can order you the longer dedicated tube from Moonlight, rather than rely on a third party add-on. On my refractor i was a bit miffed to discover, despite upgrading to a Feathertouch, (with a 115mm draw tube !! ) i still didn't have sufficient out / front focus to get my big 2" eyepiece to focus. I then had to put a 50mm extender on the focuser to get it to focus. Thats one of the plusses with SCTs i guess, with a moving primary. No focusing issues at all. I agree with the confusing wording though. I think it's American terminology to use the term 'back' focus meaning back in (focuser fully racked in ) and we automatically think the opposite. Link to comment Share on other sites More sharing options...
catman161 Posted May 5, 2014 Share Posted May 5, 2014 Having spoken extensively with Martin at FLO regarding draw tube length and and Newts he said after speaking with Ron at moonlite that anything over the 50mm option for the CR1 and CR2 is likely to protrude into the OTA in certain focus situations which can impair the view and especially problematic if trying to image. Link to comment Share on other sites More sharing options...
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