USING DSLR WITH CELESTRON 6.3 FOCAL REDUCER

[DAVE AMENDALL]

HI all, There is a Celestron video on you tube which recommends that the Camera Sensor should be 105mm from the focal reducer for best imaging results.

I find that at this distance some vignetting occurs at the edge of the field. Also some stars are slightly  vertical pear shape.

However, on increasing the distance between the reducer and the sensor to 110mm things improve all round with good star images right to the edge of the field and no vignetting to speak of.

I am using an IR/Cut filter with a modded Nikon  with a Celestron C11 SCT and wonder if the longer focal length of the scope has any influence on  the increased distance between reducer and sensor ?

Any comments and advice would be appreciated...........Dave

 

[michael8554]

Hi Dave

I'd expect the correction to work best with a specific FR, f/10 in this case.

How did you measure the 105mm ?

Canon flange distance is 44mm, but Nikon is 46.5mm.

In any case, the star shape is all that matters..... !

Michael

[DAVE AMENDALL]

Hello Michael, I must agree with you that F 10 is the best results

I use F 6.3 for the open clusters  ectc

I have the Celestron  SCT  adaptor which gives 105mm length  overall automatically for the canon.

I have added a spacer ring to the system to give me an overall 110mm from the Nikon sensor to the rear lens of the focal reducer.

However, I did not know that the Nikon flange distance was 46.5mm. I just carefully measured the overall distance.................Dave