6.3 Focal Reducer

[mick pinner]

does anyone know if placing a focal reducer in different positions in the imaging train (SCT) effects the actual focal reduction.

[asimov]

Hi Mick.

Not sure about that one but an F-0.6FR will produce F-0.3 if a 1.4" extension is used to get the FR away from the chip on a toucam.

But when you look at it, it is actually putting the FR closer to the SCT corrector & the chip remains the same distance away IF your seating the webcam into the focuser all the way on both occasions..

http://webcaddy.com.au/astro/adapter.htm

I could be looking at all this in the wrong aspect though..

[Gama]

The simple aswer is YES.
When i used it with my SCT i used a diagonal then the ccd camera. This lowered the f ratio even more. Try it..

[Lester]

Hi Mick,

I am led to believe that there are different kinds of Meade f6.3 focal reducers. When I mounted mine at the rear of the SCT and then the flip-mirror, and the camera, I couldn't get focus. I had to get adapters made up by Steve Mogg. Now I have the focal reducer after the flip-mirror and then the camera, and focus is achieved.

When Meade got the focal reducers made in China some of the characteristics changed eg focus point.

[Striker]

Yes Mick it does.

The further the camera is away from the reducer the lower F ratio...but it does have an optimal distance...something around 100mm from the reducer to the chip is F6.3.....I dont think you would want to push it any further then that.

[mick pinner]

thanks guys.

[rogerg]

I find the focal reducers quite sensitive to position in the imaging train. Not only in the focal reduction provided but the quality of image (edge distortion, non-flat field, etc). I find the 3.3 reducer much more fussy than the 6.3 which is really quite tollerant of positioning (and distances).

Roger.