MidAtlantic Posted June 25, 2017 Share Posted June 25, 2017 I purchased (and received) a 10" (254 mm) reflector optical tube assembly. (I'm hoping build a Dobson mount for it). SPECS: 254 mm x 1200 mm, f/4.7 However, I failed to purchase an eyepiece and would like to test the tube before the 30-day return window closes (it's a clearance "second" from the manufacturer). I tired a 25 mm EP from a friend's Gskyer with terrible results, but I really don't think I should use this as a fair assessment (it's basically a toy scope). I'm looking at ordering ordered two EPs to get an idea of the scopes performance: First, the Celestron X-Cel LX 25 mm eyepiece Second, the Celestron 93230 8 mm -24 mm zoom eyepiece Should either of these EPs yield good views in a 10" dob without much experimenting? The Gskyer 25 mm EP wouldn't focus on anything and the stars looked like fuzzy cheerios (at best) - I tired for a while with no luck. I can have the Celestrons in a couple days. Any good ways to easily test if a reflector tube assembly is suffice for a dobsonian setup? Any other advice? I'm stoked about this project (I'm a civil engineer) but don't want to wait too long to learn I'm hundreds of dollars into a dead-end project. i.e. I ain't no chicken, but I know when to ask for help!! Thanks - MidAtlantic Link to comment Share on other sites More sharing options...
Moonshane Posted June 25, 2017 Share Posted June 25, 2017 pretty much any Newtonian tube can be used for a dob project. can you post a pic of the scope with the eyepiece in so we can see possible reasons for your problem? I presume you are turning the wheels at the side of the focuser to focus and looking as you do? it sounds like you are out of focus to me. the eyepieces mentioned should give reasonable results assuming the scope is in working order and focused. Link to comment Share on other sites More sharing options...
MidAtlantic Posted June 25, 2017 Author Share Posted June 25, 2017 Thanks moonshane. I attached a pic... 2" Crawford with the included 2" receiver (threaded onto the focuser tube), 1.25" reducer inserted. 25 mm Gskyer EP Link to comment Share on other sites More sharing options...
Dave In Vermont Posted June 25, 2017 Share Posted June 25, 2017 May I ask where you purchased the OTA from? I'm in the US, too - and know a good many of the shops. I'd like to take a look at the 10" F/4.7 on their site. Dave ps - we posted in the same minute! Your photo shows an Orion sticker. Is it an Orion OTA from Orion? Link to comment Share on other sites More sharing options...
MidAtlantic Posted June 25, 2017 Author Share Posted June 25, 2017 1 minute ago, Dave In Vermont said: May I ask where you purchased the OTA from? I'm in the US, too - and know a good many of the shops. I'd like to take a look at the 10" F/4.7 on their site. Dave Directly from Orion... http://www.telescope.com/Telescopes/Reflector-Telescopes/Reflector-Optical-Tube-Assemblies/Orion-254mm-f47-Reflector-Telescope-Optical-Tube-Assembly/pc/1/c/11/sc/345/p/9959.uts Link to comment Share on other sites More sharing options...
Moonshane Posted June 25, 2017 Share Posted June 25, 2017 On the assumption this is the same as many skywatcher units I think you might need a 2" extension to to get focus for now, try pulling the reducer (the bit the eyepiece is in) out as far as safely possible, and bring the focus out as much as you can and then see if the eyepiece gets closer to focus if you pull it out slightly when looking through it. all this supports needing an extension tube. Link to comment Share on other sites More sharing options...
ronin Posted June 25, 2017 Share Posted June 25, 2017 Fuzzy Cheerio's sounds like out of focus. Now Orion use Skywatcher/Synta items and on those you have to remove the eyepiece adaptors and operate with only one of them in the focuser. I am wondering if that is why you cannot get a good focus. Basically look at the focuser, and if possible remove the 1.25" eyepiece adaptor, then look again and see if there is another 2" eyepiece adaptor in there. If so remove that and put back in only the 1.25" item. Then try with the eyepieces again. The X-Cel should be OK ar f/4.7 but as I do not own any cannot say with 100% certainty. Someone else will likely have experience. A TV plossl say 15mm should be a safer option. Link to comment Share on other sites More sharing options...
Dave In Vermont Posted June 25, 2017 Share Posted June 25, 2017 Orion is top-notch - congratulations! Another good thing about Orion is that their tech. support is also top-notch. Give them a call and ask if you need an extension for the focuser on this scope. If the first person you speak with doesn't know - just ask to speak with someone who will there. "Supervisor, please." - works. Let us know how it goes? Thanks! Dave Link to comment Share on other sites More sharing options...
Peter Drew Posted June 25, 2017 Share Posted June 25, 2017 +1 for Moonshanes post, it highlights the usual "problem". In addition, I don't think the zoom eyepiece you specified is particularly suitable for F4.7 optics. Link to comment Share on other sites More sharing options...
MidAtlantic Posted June 25, 2017 Author Share Posted June 25, 2017 1 minute ago, Moonshane said: On the assumption this is the same as many skywatcher units I think you might need a 2" extension to to get focus for now, try pulling the reducer (the bit the eyepiece is in) out as far as safely possible, and bring the focus out as much as you can and then see if the eyepiece gets closer to focus if you pull it out slightly when looking through it. all this supports needing an extension tube. I've read that on some forums... However, for some reason I was thinking the opposite - that I needed to be closer (especially given all the talk about DSLRs being "too far away" to be in focus). Here's a pic of the attachments included (T ring adapter not pictured). Left to right: 2" (threaded) tube, 2" (threaded, longer) tube, 1.25" reducer. Link to comment Share on other sites More sharing options...
MidAtlantic Posted June 25, 2017 Author Share Posted June 25, 2017 14 minutes ago, ronin said: Basically look at the focuser, and if possible remove the 1.25" eyepiece adaptor, then look again and see if there is another 2" eyepiece adaptor in there. If so remove that and put back in only the 1.25" item. Then try with the eyepieces again. The 1.25" isn't threaded and needs a 2" threaded adapter with screws to stay in place. Link to comment Share on other sites More sharing options...
MidAtlantic Posted June 25, 2017 Author Share Posted June 25, 2017 11 minutes ago, Peter Drew said: +1 for Moonshanes post, it highlights the usual "problem". In addition, I don't think the zoom eyepiece you specified is particularly suitable for F4.7 optics. Pardon my ignorance, but why is that? Link to comment Share on other sites More sharing options...
wookie1965 Posted June 25, 2017 Share Posted June 25, 2017 Here is mine with the 2" riser then the self centering adapter and eyepiece. Link to comment Share on other sites More sharing options...
Peter Drew Posted June 25, 2017 Share Posted June 25, 2017 @Midatlantic. Most reflecting telescopes these days are designed to be photo compatible, this requires that the camera can be focused nearer to the telescope than an eyepiece. To allow the eyepiece to be focused instead, an extension piece is usually supplied to position the eyepiece further out. The "problem" is when the new owner is unaware with this. Link to comment Share on other sites More sharing options...
Pondus Posted June 25, 2017 Share Posted June 25, 2017 If its the XT series it does not need an extention to achieve focus. The eyepiece looks to be in the correct position on the image. Link to comment Share on other sites More sharing options...
MidAtlantic Posted June 25, 2017 Author Share Posted June 25, 2017 Thanks everyone... I'll call them tomorrow. I guess the part that confuses me is that the same OTA is sold with the XT10 dob and the Atlas 10 EQ and neither seems to mention or list an extension; but both include eyepieces. The XT10 includes a 25 mm EP. Hard to believe they would sell an complete kit that still requires an extension to use... However it does appear that the 2" Crayford is the same as the Skywatcher, so now I'm confused (cause I don't see how removing the 2" threaded adapter is an option). Link to comment Share on other sites More sharing options...
MidAtlantic Posted June 25, 2017 Author Share Posted June 25, 2017 7 minutes ago, Peter Drew said: @Midatlantic. Most reflecting telescopes these days are designed to be photo compatible, this requires that the camera can be focused nearer to the telescope than an eyepiece. To allow the eyepiece to be focused instead, an extension piece is usually supplied to position the eyepiece further out. The "problem" is when the new owner is unaware with this. OK, I understand. I was just following the directions supplied and the photos from the website. Just to confirm, this photo shows a setup that won't work without a longer 2" adapter? (It's from the Orion site). Link to comment Share on other sites More sharing options...
Pondus Posted June 25, 2017 Share Posted June 25, 2017 Correct position of 1,25" eyepiece. For 2" the 1,25" adapter is removed, nothing else. (8" Orion XT) No extender is needed. Does Your focus 'travel' inwards/outwards or is it locked? Edit : I seriously doubt its any different on the XT10 Link to comment Share on other sites More sharing options...
MidAtlantic Posted June 25, 2017 Author Share Posted June 25, 2017 2 minutes ago, Pondus said: Correct position of 1,25" eyepiece. For 2" the 1,25" adapter is removed, nothing else. (8" Orion XT) No extender is needed. Does Your focus 'travel' inwards/outwards or is it locked? It travels fine. Link to comment Share on other sites More sharing options...
Moonshane Posted June 25, 2017 Share Posted June 25, 2017 Sounds like it may be the other eyepiece then. see how you go when they arrive. Link to comment Share on other sites More sharing options...
wookie1965 Posted June 25, 2017 Share Posted June 25, 2017 I could not reach focus without the 2" extension strange. Link to comment Share on other sites More sharing options...
Dave In Vermont Posted June 25, 2017 Share Posted June 25, 2017 I have an Orion 200mm F/4 scope - in my case - it was made by GSO (and then branded Orion). No extension here at all. Focuses just great! And my Vixen LV 8 - 24mm Zoom has no problem in it. The Vixen LV is optically the same as most others - including the Celestron 8 - 24mm Zoom EP (Eyepiece). Your Mileage My Vary, Dave Link to comment Share on other sites More sharing options...
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