Pete D Posted October 3, 2011 Share Posted October 3, 2011 I am having trouble getting focus using my webcam SPC900 on a Skywatcher 200p unless I use a barlow lens. Does anyone know if a 1.25 diameter extention tube will work and can anyone reccomend one. Link to comment Share on other sites More sharing options...
ronin Posted October 3, 2011 Share Posted October 3, 2011 I think that the problem is that you cannot get the webcam in close enough to where the prime focus is. The barlow will have it's object plane on this prime focus and in order to magnify the image will create the second image further out, so this image will be far enough out from the barlow to fall on the web cam.An extension tube would not therefore be of much use.Sorry I cannot draw the optics to show what I mean.I would suggest that you ask somewhere like FLO concerning what you are finding and ask what they suggest. However I think that an extension tube is not what is required. A shorter focusser is what I suspect is wanted. Why not use a good barlow and simply have a magnified image on the webcam? Link to comment Share on other sites More sharing options...
todd8137 Posted October 3, 2011 Share Posted October 3, 2011 a would think its the other way round i could not get focus with a rack and pinion focuser theres not enough inwards travel well thats was the prob on my sw300p Link to comment Share on other sites More sharing options...
Mr TamiyaCowboy Posted October 3, 2011 Share Posted October 3, 2011 had the same problem with a converted webcam. could not get close enough to the focal plane. took me about 5 mins to work out that the eyepiece holder was the problem. removing this gave the camera the added few mm drop to focus perfect. was the most effective way to get camera and telescope to focus. Link to comment Share on other sites More sharing options...
pritc Posted October 3, 2011 Share Posted October 3, 2011 I purchased one of these for my 200P:Orion Precision Centering Adapter - SCS AstroSlots into the 2" adaptor.Never get an issue achieving focus now with my SPC900 webcam or DSLR Canon 1100D.Wayne Link to comment Share on other sites More sharing options...
tiredboy Posted October 4, 2011 Share Posted October 4, 2011 I have the same problem with my Meade ETX80. I can use the webcam with the barlow flipped in but not with it flipped out....the eyepiece holder was the problem. removing this gave the camera the added few mm drop to focus perfect. was the most effective way to get camera and telescope to focus.Might have to look into this. Any other solutions greatly received. Link to comment Share on other sites More sharing options...
Stephen Posted October 4, 2011 Share Posted October 4, 2011 The only other solution to lack of inward focus is to move the mirror up the tube.You can do this by either chopping some off (bad idea) or using spacers, springs and / or longer bolts between the mirror cell sections. Link to comment Share on other sites More sharing options...
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