ChrisEdu Posted September 8, 2011 Share Posted September 8, 2011 The C11 comes with a 1.25" visual back and EP. However, the C14 has a 2" set-up. I have seen that a 2" set-up can be used on the C11, so, the question is, is it worth it? Does a 2" EP / visual back set-up provide a significant gain / advantage over a 1.25"? Link to comment Share on other sites More sharing options...
riklaunim Posted September 8, 2011 Share Posted September 8, 2011 C11 has actually a ~3" SCT thread (+ the standard ~2" SCT thread reduction). 2" EP can give you widest fields (for example Erfle eyepieces - WO SWAN and their cheap clones). If you want to use the f/6.3 reducer then the 1,25" eyepieces may suffice. Link to comment Share on other sites More sharing options...
ChrisEdu Posted September 8, 2011 Author Share Posted September 8, 2011 So, what would use the ~3" thread?In terms of the FOV, does this mean that, for example, 68 degrees on a 2" appears as more than on a 1.25"? Link to comment Share on other sites More sharing options...
riklaunim Posted September 8, 2011 Share Posted September 8, 2011 1,25" maximum is around 20 mm at 70 deg FOV, while 2" may have that 70 deg FOV even at around 38-40mm (Erfle/SWAN) or 50mm 51 deg GSO SuperView Erfle Link to comment Share on other sites More sharing options...
ChrisEdu Posted September 8, 2011 Author Share Posted September 8, 2011 1,25" maximum is around 20 mm at 70 deg FOV, while 2" may have that 70 deg FOV even at around 38-40mm (Erfle/SWAN) or 50mm 51 deg GSO SuperView Erfle So, ultimately, given any FOV, like for like, the 2" will appear bigger? (not sure if I have phrased that particularly well). By bigger, I don't mean that the object appears bigger, rather the 'view' in the eyepiece appears larger in size. Link to comment Share on other sites More sharing options...
riklaunim Posted September 8, 2011 Share Posted September 8, 2011 The magnification will be smaller (like 38mm vs 20 mm EP), but you will also see more sky. The 2" allows you to see more sky at even lower magnifications than 1,25" would allow. For eyepieces at short focal length 1,25 vs 2" doesn't means much. Link to comment Share on other sites More sharing options...
ChrisEdu Posted September 8, 2011 Author Share Posted September 8, 2011 So, the most benefit is at lengths like 25mm+? Link to comment Share on other sites More sharing options...
riklaunim Posted September 8, 2011 Share Posted September 8, 2011 For C11 if you want decent-big FOV for "big" DS objects you will probably need those 2" EP or f/6.3 reducer for 1,25". I'm using only 20 mm 1,25", but with reducers (now with the 0,5x Optec NextGen reducer - before imaging the object). Link to comment Share on other sites More sharing options...
m.tweedy Posted September 8, 2011 Share Posted September 8, 2011 Go for the 2 inch diagonal. You can always put 1.25" eyepieces in it but not the other way round. I often use my 50mm 2" celestron eyepiece and it gives lovely views. Of course now I have the ethos's I need the 2" diagonal.Remember in a previous thread I mentioned thisFirst Light Optics - MoonLite CS Dual Rate SCT Crayford Focuser for large 3.25 inch thread for a totally unrestricted view with a 2 inch diagonal Link to comment Share on other sites More sharing options...
John Posted September 8, 2011 Share Posted September 8, 2011 I think a 2" diagonal would make a lot of sense in a C11. The standard 1.25" diagonal is rather cheap and cheerful as you have found so you will want to upgrade that soon and you might as well go for a 2" one. The wider field of view is the benefit that the 2" format brings - the 1.25" eyepieces being limited by the internal diameter of their barrels. In one of the the pictures you posted of your new scope showed the standard 40mm 1.25" plossl that came with the scope - that will have a field of view of around 43 degress. A 40mm eyepiece in the 2" format can have a field of view of 72 degrees and so it will show a lot more sky. Translate that into true field of view (how much of the sky you actually see through the scope) and the 40mm 1.25" will give a magnfication of 70x and show .61 degrees of sky wheras the 40mm 2" I mention would also give 70x but show just over 1 degree of sky - nearly 70% more.Of course you will need to budget for 2" filters when you start to consider those as well Link to comment Share on other sites More sharing options...
ChrisEdu Posted September 8, 2011 Author Share Posted September 8, 2011 cool - that's cleared things up for me, thanks. Link to comment Share on other sites More sharing options...
AztecastroMcJ Posted September 8, 2011 Share Posted September 8, 2011 Think it may be worth adding 2" star diagonal and nice widefield EP at some point, or like Rik has said u can also use reducer with 1.25" EP.Personally i would rather have nice widefield scope to complenent C11, the standard 1.25" 40mm (43AFOV) TFOV is 36.8 arc mins which is around 0.6 degree TFOVenough to fit Full moon and most objects if u used say 2" 40mm swan (70AFOV) u could get 60 arc mins which is full degree TFOVboth above would give 70x mag with 4mm Exit Pupil, for comparison a 2" 31mm Axium/luminos or Tevelue Nag with 82 AFOV would still give TFOV of 54.47 arc mins but at higher mag of x90 and smaller Exit pupil 3.1mmu can check true fov's herehttp://www.12dstring.me.uk/fov.htmthe 9x50 finderscope has around 5.8 degree fovJames Link to comment Share on other sites More sharing options...
ChrisEdu Posted September 8, 2011 Author Share Posted September 8, 2011 Personally i would rather have nice widefield scope to complenent C11, Shh!!! You never know who might be listening! I did mention getting another scope when I upgrade the mount - well, if I don't sell the CG5, it would be a shame to leave it empty! I think I got away with it but time will tell! Link to comment Share on other sites More sharing options...
m.tweedy Posted September 8, 2011 Share Posted September 8, 2011 Personally i would rather have nice widefield scope to complenent C11, JamesA WO Megrez 90 would (does) look good. You will then be pushing the limit for the mount. The NEQ6 PRO just copes with that load. Link to comment Share on other sites More sharing options...
AztecastroMcJ Posted September 8, 2011 Share Posted September 8, 2011 Very nice Michaelhopefully have something similar in few years loldo u have or use fastar btw ? another option for widefield ofcourse Link to comment Share on other sites More sharing options...
ChrisEdu Posted September 8, 2011 Author Share Posted September 8, 2011 Nice! Link to comment Share on other sites More sharing options...
m.tweedy Posted September 8, 2011 Share Posted September 8, 2011 To complicated. Have not yet taken an astro image despite having all the gear (and no idea) yet.my Primary objective is to have the C11 and 90 for contrasting views of the same object. For imaging I have the Astrotrac set up (but again not used yet)-hoping that will change from Saturday as going to Mauritius for 2 weeks. The C11 did not fit into the hand luggage so have packed astrotrac and WO66 instead. Link to comment Share on other sites More sharing options...
ChrisEdu Posted September 8, 2011 Author Share Posted September 8, 2011 The C11 did not fit into the hand luggage so have packed astrotrac and WO66 instead.You need to buy the lady in your life a larger handbag then! Link to comment Share on other sites More sharing options...
m.tweedy Posted September 8, 2011 Share Posted September 8, 2011 You need to buy the lady in your life a larger handbag then! Thought of that. Gillian's hand luggage is full with my eyepieces and camera lenses:D:D Link to comment Share on other sites More sharing options...
ChrisEdu Posted September 8, 2011 Author Share Posted September 8, 2011 Thought of that. Gillian's hand luggage is full with my eyepieces and camera lenses:D:DThen you need a bigger handbag! Link to comment Share on other sites More sharing options...
m.tweedy Posted September 8, 2011 Share Posted September 8, 2011 Then you need a bigger handbag! my own plane is the only thing that would hold everything I REALLY want to take with me Link to comment Share on other sites More sharing options...
m.tweedy Posted September 8, 2011 Share Posted September 8, 2011 Anyway we digress. I strongly recommend an ADM top rail as they are so versatile and can attach virtually anything you want from tube rings as I have my 90 on to camera adaptors .MDS Camera Mounta telrad was a must have for me. Link to comment Share on other sites More sharing options...
ChrisEdu Posted September 8, 2011 Author Share Posted September 8, 2011 Yeah - trying to get hold of a Telrad is like finding a certain Libyian ex-leader! I have been told they might be available from tomorrow or the start of next week - the Telrad that is! Link to comment Share on other sites More sharing options...
ChrisEdu Posted September 8, 2011 Author Share Posted September 8, 2011 Anyway we digress. I strongly recommend an ADM top rail as they are so versatile and can attach virtually anything you want from tube rings as I have my 90 on to camera adaptors .MDS Camera MountOk - so where do you start with that lot? Which bit is the top rail? Looking on their website I'm not sure which bit is which! Link to comment Share on other sites More sharing options...
m.tweedy Posted September 8, 2011 Share Posted September 8, 2011 MDS Dovetail Bar Link to comment Share on other sites More sharing options...
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