happy-kat Posted May 6, 2018 Share Posted May 6, 2018 I tested an erect image diagonal is that not a prism? Link to comment Share on other sites More sharing options...
Merlin66 Posted May 6, 2018 Share Posted May 6, 2018 I think the optical path length may be different to a basic prism diagonal...... Link to comment Share on other sites More sharing options...
Rick_It Posted May 7, 2018 Share Posted May 7, 2018 (edited) Shortest optical path is with a 90° 1.25" prism diagonal. - Celestron 1.25" prism diagonal (it comes with SCTs) - Takahashi 1.25" prism diagonal - Baader T2 prism diagonal - Vixen 1.25" prism diagonal Optical lenght of all of these should be around 60mm. They provides an upright but mirrored image. An erecting prism uses a totally different optical layout; it's generally a 45° diagonal and provides a completely erected (correct orientation) image. Edited May 7, 2018 by Rick_It 2 Link to comment Share on other sites More sharing options...
happy-kat Posted May 9, 2018 Share Posted May 9, 2018 Just for info my Skywatcher finder shoe arrived today and it does fit the Evoguide foot, so now I can mount the Evoguide on the finder shoe into my eqclamp. 1 Link to comment Share on other sites More sharing options...
Oldfort Posted May 12, 2018 Share Posted May 12, 2018 For visual use, straight through, I have found a 15mm spacer works great. This is with a televue 32mm plossl, or 19mm panoptic. Inevitably, the skies have been obscured since I got all the bits. Link to comment Share on other sites More sharing options...
happy-kat Posted May 13, 2018 Share Posted May 13, 2018 (edited) 22 hours ago, Oldfort said: For visual use, straight through, I have found a 15mm spacer works great. That's the same as my findings using it straight through with the rear section attached. Though I don't have a spacer so was testing using hand held eyepiece. I'll have to rumage around to see if I can find something I can use. Something like this @Oldfort do you think please? Link here Edited May 13, 2018 by happy-kat Link to comment Share on other sites More sharing options...
Oldfort Posted May 13, 2018 Share Posted May 13, 2018 4 hours ago, happy-kat said: That's the same as my findings using it straight through with the rear section attached. Though I don't have a spacer so was testing using hand held eyepiece. I'll have to rumage around to see if I can find something I can use. Something like this @Oldfort do you think please? Link here Yes, that's the one I have used. It weighs next to nothing. 1 Link to comment Share on other sites More sharing options...
happy-kat Posted May 15, 2018 Share Posted May 15, 2018 My spacer arrived today. Goody goody. Link to comment Share on other sites More sharing options...
DRT Posted May 17, 2018 Share Posted May 17, 2018 I received my ED50 today and tested it with a Baader 45 degree Amici Prism (which I think is identical to the William Optics) and a TV 32mm Plossl and it would not reach focus. It would be good to know of a prism or diagonal that works with this little scope. 1 Link to comment Share on other sites More sharing options...
happy-kat Posted May 18, 2018 Share Posted May 18, 2018 That's quite a few diagonals tested now with no luck. I'll be using mine straight through. Link to comment Share on other sites More sharing options...
LukeSkywatcher Posted May 18, 2018 Share Posted May 18, 2018 Love the colours. Nice price too. Any good for use with a Quark. Link to comment Share on other sites More sharing options...
Rick_It Posted May 18, 2018 Share Posted May 18, 2018 (edited) Quote Baader 45 degree Amici Prism (...) That's quite a few diagonals tested now with no luck If I have not miss something, anyone has tried the ED50 with a 90° 1.25 prism diagonal. Those are the diagonals with the shortest optical path. Amici prisms have a very long optical path. To be clear, the Celestron prism diagonal which comes with all SCTs is a very common example of a 90° 1.25 prism diagonal. Baader T2 prism is another example. A barlow should also extract focus a little bit. Edited May 18, 2018 by Rick_It Link to comment Share on other sites More sharing options...
happy-kat Posted May 18, 2018 Share Posted May 18, 2018 The diagonal would need to be less than 60mm more like 54mm to allow for focus travel I think. Link to comment Share on other sites More sharing options...
nicoscy Posted May 20, 2018 Share Posted May 20, 2018 Possibly removing the extension tube, replacing with the below and using a 1.25” 90 degreee Baader T2 prism or a Tak Prism is the only way to reach focus... https://www.teleskop-express.de/shop/product_info.php/info/p9743_Baader-2458121-Ultrashort-1-25----T2-Clamp.html Link to comment Share on other sites More sharing options...
happy-kat Posted May 20, 2018 Share Posted May 20, 2018 That adaptor just takes away valuable distance and I don't think it is needed. Link to comment Share on other sites More sharing options...
nicoscy Posted May 20, 2018 Share Posted May 20, 2018 The point is to remove the extension after the focuser which is quite long and use this one which only eats 12mm... Link to comment Share on other sites More sharing options...
happy-kat Posted May 20, 2018 Share Posted May 20, 2018 And having used mine and tested it that is 12mm that is not free and is not needed as you still have everything the extension offers with it removed. Link to comment Share on other sites More sharing options...
nicoscy Posted May 20, 2018 Share Posted May 20, 2018 If I am reading you correctly, you removed the extension, installed this and there is still not enough in travel to reach focus with a 1.25” 90 degree Prism? Link to comment Share on other sites More sharing options...
happy-kat Posted May 20, 2018 Share Posted May 20, 2018 With the diagonals I own with the extension removed (39mm) there is still not enough back distance with the focuser fully wound in (focuser has 20mm of travel to fully wound out). Rick_it suggests a few other diagonal types to try but I don't have those. I don't have the prism diagonals suggested by Rick_it to test with and obviously neither does DRT. So still unanswered whether there is any diagonal that will. Link to comment Share on other sites More sharing options...
DRT Posted May 20, 2018 Share Posted May 20, 2018 32 minutes ago, happy-kat said: With the diagonals I own with the extension removed (39mm) there is still not enough back distance with the focuser fully wound in (focuser has 20mm of travel to fully wound out). Rick_it suggests a few other diagonal types to try but I don't have those. I don't have the prism diagonals suggested by Rick_it to test with and obviously neither does DRT. So still unanswered whether there is any diagonal that will. I'm trying to get a hold of a cheap prism to give it a go. If it works I might order a Tak or Baader equivalent but don't want to do that and find that it doesn't work. What was the configuration that worked for you when you said you could focus on leaves? Link to comment Share on other sites More sharing options...
happy-kat Posted May 20, 2018 Share Posted May 20, 2018 Back piece removed and focuser fully wound in The Orion erect image diagonal with the 25mm sw standard eyepiece was really close watching the ant brush it's teeth on the lawn being stood on. The unknown brand star diagonal with 25mm eyepiece focused on the hedge about 30+ feet away. In my image here the unknown diagonal is the one on the far left. 1 Link to comment Share on other sites More sharing options...
nicoscy Posted May 20, 2018 Share Posted May 20, 2018 Sigh... very disappointing that SW didn’t make it as a split tube model... Thanks for the photos - puts the whole thing into perspective. Link to comment Share on other sites More sharing options...
DRT Posted May 20, 2018 Share Posted May 20, 2018 I've just managed to modify (i.e. butchered!) a cheap 90 degree mirror diagonal to reduce the light path by around 10mm and it now reaches focus on terrestrial objects. There is still around 8mm of inward focus available to try to reach focus on infinity but can't test that until this evening. Whilst this isn't a long term solution it at least convinces me that a short light path diagonal or prism will work Here is what I did to the diagonal... 1. Cut out the internal lugs that set the position of the mirror 2. Raise the height of the mirror on the base plate using a sponge pad 3. Cut half the length of the eyepiece holder with a hacksaw and tap a new hole for the retaining screw 4. Hey presto! A cute looking wide field scope that actually reaches focus 3 Link to comment Share on other sites More sharing options...
happy-kat Posted May 20, 2018 Share Posted May 20, 2018 Looking good. I guess that's about the same length as my unknown star diagonal. Link to comment Share on other sites More sharing options...
DRT Posted May 20, 2018 Share Posted May 20, 2018 1 hour ago, happy-kat said: Looking good. I guess that's about the same length as my unknown star diagonal. It is now I’ve just bought a Meade prism diagonal from a member here so will report back on that later this week. Link to comment Share on other sites More sharing options...
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