russellhq Posted August 24, 2012 Share Posted August 24, 2012 I'd like to add an occular to Stellarium to get an idea of the field of view of my guide scope but I don'tknow what the focal length is.By any chance does anyone know what the focal length of the skywatcher 6x30 guide scope is? Link to comment Share on other sites More sharing options...
JamesF Posted August 24, 2012 Share Posted August 24, 2012 A quick test of mine would suggest the focal length is about 125mm.James Link to comment Share on other sites More sharing options...
squeaky Posted August 25, 2012 Share Posted August 25, 2012 You'll then need to set up an "eyepiece" for it.When I did my 9x50 I had no idea what the apparent field of view or the focal length of the eyepiece was. (Still have no idea). But what I DID know was that my finderscope has a field of view of approximately 5.5 deg. So I set up an "eyepiece" using mostly defaults and just tweaked the focal length value until, when in telescope view I had an FOV of 5.44 deg. It says the magnification is 12.5 rather than the 9 that it really is - but the Field of View is what matters and it fits what I actually see.The FOV for your finder is about 7 deg. Link to comment Share on other sites More sharing options...
squeaky Posted August 25, 2012 Share Posted August 25, 2012 Actually that 7 deg figure is for the Orion 6x30 finderscope - but yours is likely to be close to that. Link to comment Share on other sites More sharing options...
russellhq Posted August 25, 2012 Author Share Posted August 25, 2012 Thanks squeaky, I was just needing a number to get me close so I could have play about with Stellarium and plan for when the skies eventually clear! They will clear won't they?! Link to comment Share on other sites More sharing options...
squeaky Posted August 25, 2012 Share Posted August 25, 2012 You're welcome I did mine pretty much by guesswork and the only figure that really needs to be right is the final FOV that you get when you select your finderscope in Stellarium.If you get somewhere around 7 deg you'll be able to compare it with your actual view and tweak it from there until it fits.Yes, we WILL get a clear sky... 1st April 2027 Link to comment Share on other sites More sharing options...
cantab Posted August 26, 2012 Share Posted August 26, 2012 The most up-to-date version has a "Binocular" option, in which the "AFoV" setting is instead treated as the true field of view and other figures are ignored. Link to comment Share on other sites More sharing options...
squeaky Posted August 26, 2012 Share Posted August 26, 2012 Oh! Hadn't considered that since I don't have binoculars.... must go and have a play.Thanks for that Link to comment Share on other sites More sharing options...
squeaky Posted August 26, 2012 Share Posted August 26, 2012 Just tried it. All you need to do is to put the FOV of your finderscope into the aFOV box and check the Binoculars checkbox.The only downside is that the aFOV can only be entered in whole lumbers. Still, it gives a pretty fair view - and you don't have to research loads of numbers and fiddle with settings; so if you're not too fussed about comparative accuracy this is a quick and simple option. Link to comment Share on other sites More sharing options...
squeaky Posted August 26, 2012 Share Posted August 26, 2012 Oops....That is: You don't need to set up a Telescope.Just go to Eyepieces...click on Add... Name it "Finderscope" and put your known (or guessed) FOV into the aFOV input box, and check "Binoculars".So it's easier to set up and use.Even if you don't know the FOV of your finderscope - the vast majority of them appear to be between 5 and 7.5 deg, so it wouldn't take long at all by trial it and see to get close. Link to comment Share on other sites More sharing options...
cantab Posted August 27, 2012 Share Posted August 27, 2012 The only downside is that the aFOV can only be entered in whole lumbers.Ah yes, I remember now this is a bug. If you find the actual configuration file Stellarium uses (~/.stellarium/modules/Oculars/ocular.ini in Linux, I can't speak for other systems) you can put in a decimal value there. Link to comment Share on other sites More sharing options...
The Sailor Posted August 27, 2012 Share Posted August 27, 2012 I used the occular on Stellarium, checking every input was correct and yet if never looked the same as what I seen through an eyepiece, don't use it now .Jim Link to comment Share on other sites More sharing options...
squeaky Posted August 27, 2012 Share Posted August 27, 2012 That's odd, because mine are pretty much spot on. Link to comment Share on other sites More sharing options...
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