|
I should add the following.
Prime Focus
The telescope in the photos I posted is a Vixen 4 inch refractor with a focal length of 918mm (a focal ration of f9). In the 1st photo with the SLR connected to the focuser via a T2 ring, the telescope is acting like a “giant lens” with a focal length of 918mm.
This set up is the easiest to use and gives a Field Of View (FOV) of around 1½° x 1° so you can fit in around 3 full Moons. You would use this set up for nebulae like Orion M42.
Eyepiece Projection
You use an eyepiece (in my photo it is a 10mm Plossl) to literally project a magnified image onto the DSLR chip. This method is tough! The FOV is very small, typically less than 20 arc mins (2/3 size of a full Moon); the image is dim so it is hard to focus but before all of that, finding the object at such a high magnification is a challenge in itself, unless we are photographing something as big and bright as the Moon.
You really need a mount with drives to do Eyepiece Projection and stay sane.
Cheers
Dennis
|