My prime focus setup
Hello, I have written another thread with my afocal coupling setup, with a Televue 76 scope, a Televue Radian 14mm eyepiece, and a Sony DSC-W7 compact camera.
I also use this scope for prime focus digiscoping, if it can be told that way, with this setup. From right to left:
- Televue 76 scope, f6.3 480mm focal length.
- A 2'' tube extender (the main body of the GSO 2'' 2x barlow)
- A 2'' tube extender with an integrated T thread
- A M42 to Canon ring with an integrated focusing chip (Big IS).
- A Canon 1000D
- Between the 701 RC2 header and the scope I use a cheap balance plate as you can see. It allows me to perfectly balance the whole setup in their different configurations: prime focus, prime focus with barlows or powermate, afocal coupling with the compact camera.
Please note that the M42 thread doesn't fit perfectly on the T thread due to its different pitch, but in my experience with this light camera body it is tight enough to hold it. It's not a good idea to tighten it a lot, but at the moment it is working for me.
The scope's focal length of 480mm tend to be more like a 510mm one when you focus to near objects, so with the 1.6x crop factor of the camera you have more or less 800mm of equivalent focal length.
Color rendering, image quality and details are fantastic for me. Smooth focusing, bright and crisp views through the finder, I am very happy with it.
I have learnt a lot reading you, so I have to thank to Mr. Paul Corfield and other guys for sharing their knowledge here and try to feedback all what I have tested.
I also have a 2x 2'' barlow from GSO, and a 1.25'' 2.5x powermate from Televue. I can use them with the prime focus setup or even with the compact camera, reaching insane magnification.
I am suffering big troubles with the barlow when you have shiny weather, (what is almost always here in Malaga at the south of Andalucia). I have baffled it, but it seems to be not enough yet, next time I have to try baffling directly the T ring attached to the camera with a rectangular window for the sensor.
I have also tested diaphragming the scope with great success, even for using the eyepiece + compact camera it gives you more deep of field.
Thanks again to everyone here sharing knowledge and experiences.
Cristobal