Quote:
Originally Posted by OzStarGazer
Thanks for the replies. I will have a look at the Tele Vue eyepieces.  Yes, Malcolm, that's what I meant. It can be useful because prime focus is good, but the magnification is not so high, so using a camera adapter with a compact camera can also be an option, particularly at high magnifications. |
You mention prime focus; how are you doing this? What camera do you have?
If you are using a DSLR then an alternative and preferred method to afocal is eyepiece projection and for that you need a different adapter. See
http://www.bintel.com.au/Astrophotog...oductview.aspx
For eyepiece projection you mount the eyepiece (slim 8mm Tele Vue Plossl is ideal) inside the adapter. One end goes into the focuser and the other end connects to the T-ring which is connected to the DSLR camera (without lens).
The afocal method may not work all that well if at all with an 8mm Plossl due to insufficient eye relief.
See
http://www.televue.com/engine/TV3b_p...5#.U8b7CJSSy5I for a discussion on different imaging methods.
Note an alternative to eyepiece projection is by using a Powermate and no eyepiece. This is probably the most common method now. A Barlow can be used in lieu of a Powermate but the latter are available in 2.5x, 4x & 5x with the 5x model capable of over 7x depending on focal plane distance.
A DSLR with lens would be too heavy for the afocal adapter originally referred to. These adapters suit small compact digital cameras and work well with 32 to 40mm Plossl eyepieces with good eye relief, (they will work with any eyepiece with a good 20mm of eye relief). To increase the image scale you use the compact camera zoom feature.
When using eyepiece projection method the magnification factor is determined by the distance from eyepiece to focal plane and the eyepiece used. Meade make a variable eyepiece projection adapter with sliding section to vary the eyepiece camera distance. See
http://www.meade.com/products/access...pter-1-25.html
Most eyepiece projection adapters require slim eyepieces and Plossls or Orthos work very well.