Tweedledee Posted March 22, 2015 Share Posted March 22, 2015 It would be good to have some eyepieces to fill the gap above the 12mm up to a maximum of about 30mm. The 40mm will have too wide an exit pupil on the ST102 so light will be wasted. The ST102 will allow the use of 2" or 1.25" eyepieces using the adaptor supplied with the scope. A 2" diagonal would be preferable to the 1.25" in case you ever want to use 2" eyepieces. With a 2" diagonal you can get the best out of both sizes. A 1.25" will only allow the smaller ones to be used. 2" eyepieces allow you to take advantage of really wide fields of view. Higher powers (smaller fields of view) don't require 2". Quality 2" eyepieces are generally more expensive than 1.25" but they do have big advantages on low power wide angle views. If you get a 2" diagonal, you can always upgrade to 2" eyepieces later, or just get the cheaper 1.25" diagonal and sell it if you want to go up to 2". Hope this helps. Link to comment Share on other sites More sharing options...
Seamaster Posted March 22, 2015 Author Share Posted March 22, 2015 (edited) Update, it looks like the scope does not come with any other eyepieces, just the two TMB eyepieces (3.2mm and 5mm) I understand these are good quality eyepieces? The 5mm may be worth keeping? (Or would it be too much and useless on a ST102?) but the 3.2mm would be too much for sure on a ST102 and I would think I'd want to sell or swap for something more useable on my set up? From what I can gather, the scope does not come with a star diagonal from new so does the diagonal/eyepiece adaptor come with the scope or the diagonal? If it comes with the scope itself then it should hopefully come with this one but if it comes as part of the diagonal then it won't so I won't have one. Of course I will know more when I collect it but I was hoping to get things ordered so when I pick it up I have everything I want or need for now. Thing us that until I know for sure if it has (or still has) the adaptor I dare not buy a 2" dielectric in case I can't use it! Edited March 22, 2015 by Seamaster Link to comment Share on other sites More sharing options...
Seamaster Posted March 22, 2015 Author Share Posted March 22, 2015 I suppose I need to sell the TWB 3.2mm and fill the gaps with a 10mm a 25mm and a 30mm? Link to comment Share on other sites More sharing options...
Tweedledee Posted March 22, 2015 Share Posted March 22, 2015 (edited) Those TMBs are quite good, so try them and see what you think. The 3.2mm might be a bit overpowered giving dim views with the ST102, but give it a try. It will provide 156x with a tiny field of view. The 5mm at 100x should be good on planets and the moon or splitting double stars. The scope will probably have the adaptor if the previous owner has been using the TMBs with it. You can get the adaptors very cheap off astroboot secondhand or £10 to £20 new. The scope normally comes with the adaptor and a new 2" star diagonal might come with the adaptor, you would need to check. Most people have spare adaptors kicking around, so you might easily scrounge one . Edited March 22, 2015 by Tweedledee Link to comment Share on other sites More sharing options...
Seamaster Posted March 22, 2015 Author Share Posted March 22, 2015 Would a Barlow be a cheaper way of filling those gaps than 3 separate eyepieces if used in conjunction with what Zi already have? Link to comment Share on other sites More sharing options...
Tweedledee Posted March 22, 2015 Share Posted March 22, 2015 (edited) Some people don't like putting extra glass in the path, but a barlow could save you some money and effectively double your eyepiece collection. Do the calculations and make sure you are not duplicating magnifications with the barlow. Magnification = focal length of telescope / focal length of eyepiece. If you use a 2x barlow, the telescope focal length is effectively doubled for the above calculation. The ST102 is 500mm focal length. Edited March 22, 2015 by Tweedledee Link to comment Share on other sites More sharing options...
Werisit Posted March 23, 2015 Share Posted March 23, 2015 If you buy the 102 on an alt az mount it's normally supplied with a 45 degree prism diagonal. Ok for stars but hard on your neck when looking at anything above about 45 deg elevation. Good for terrestrial. The EQ version comes with a 90 degree mirror diag as standard. Both are 1.25". The focuser is 2" and has a 2" to 1.25" adapter so you can fit the 1.25" diagonal. If you want to fit a 2" diag just take out the adapter. You can fit the adapter on top of the diag to convert it back down for your 1.25" EP's. Link to comment Share on other sites More sharing options...
Werisit Posted March 23, 2015 Share Posted March 23, 2015 Update, it looks like the scope does not come with any other eyepieces, just the two TMB eyepieces (3.2mm and 5mm) I understand these are good quality eyepieces? The 5mm may be worth keeping? (Or would it be too much and useless on a ST102?) but the 3.2mm would be too much for sure on a ST102 and I would think I'd want to sell or swap for something more useable on my set up? See my earlier post (No 46) regarding the 5mm EP. Providing it's of decent quality it'll make a good planetary EP and is certainly worth keeping. The 3.2 will certainly be too much for the 102. Link to comment Share on other sites More sharing options...
Seamaster Posted March 31, 2015 Author Share Posted March 31, 2015 Now sorted and thanks to all who contributed their opinions and advice, much appreciated. I ended up finding a great deal on a used set up from Astro buy and sell. Skywatcher Star Travel 102 9x50 finder scope in matching livery AZ4 mount. 2" Quartz dielectric diagonal 2x TMB planetary eyepieces (3.2mm & 5mm) (They look unused to me) Semi-Apo filter I doubt the TMB 3.2mm will be much use on my scope so I am trying to sell or swap it. I have also acquired a 2x Barlow (Orion Shorty Plus) and a 25mm eyepiece to compliment what I already had before (Vixen NPL 40mm, Celestron X-Cell 7mm and 12mm,) I also have a new/unused solar filter that despite being adjustable will not adjust enough to fit the 102 (was for my now sold Mak 127) http://astronomia.co.uk/index.php/accessories/filters/solar-filters/front-mounted-solar-filters/emc-solarfilter-sf100-129-170-mm.html So I am now trying to sell or swap it for one that will fit my 102. All in all I am very happy and looking forward to actually using it if the sky's ever clear! Neil. tuckstar and BAZ 2 Link to comment Share on other sites More sharing options...
Tweedledee Posted March 31, 2015 Share Posted March 31, 2015 Looks like you've finally got the right setup for you, and at the right price. Well done. Link to comment Share on other sites More sharing options...
Werisit Posted April 8, 2015 Share Posted April 8, 2015 Hi Neil. Have you managed to get out with your 102 yet? I'd be interested to hear how you're getting on with it. Link to comment Share on other sites More sharing options...
Seamaster Posted April 9, 2015 Author Share Posted April 9, 2015 Hi, I've not really had chance to take it out yet although I had a quick (drunken) go through the window last weekend (yes I know but as I said I'd had a few beers) and managed to see a few stars but of course the views were not good due to thermals and me being drunk! I am intending to have a more serious attempt soon though and will update as and when. Neil. Link to comment Share on other sites More sharing options...
Werisit Posted May 3, 2015 Share Posted May 3, 2015 How's it going Neil? Link to comment Share on other sites More sharing options...
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