What is the Purpose of this Adapter?

[Renato1]

A dealer in the US sent me the wrong adapter, and then told me to keep it and, that he would send me the correct one. So I wondered what on earth this half inch SCT spacer would be useful for. So I then looked up the ad for the adapter.



SCT Schmidt Thread Extension Tube / Spacer Ring, 1/2 inch

This spacer has male SCT Schmidt threads on one side, female SCT
threads on the other side. Spacing is 1/2 inch, center opening is 1.77",
outside diameter is 2.175". Black anodized alumium, interior is
baffled. Great for adjusting SCT focal reducer spacing.


Which in turn leaves me wondering why one would want to change SCT focal reducer spacing.

Any ideas?
Regards,
Renato

[Dennis]

Hi Renato

I have found that if I place my Celestron x0.63 Reducer Corrector (RC) between my optical tube and motorised focuser, and then fit my DSLR to the focuser, it behaves like an x0.5 RC. The RC to sensor distance is approximately 130mm in this configuration.

When I fit the x0.63 RC directly to the DSLR with the appropriate adapter, then slide it into the focuser, I get the x0.63 reduction at a RC to sensor distance of 105mm.

The recommended distance from the x0.63 RC to the sensor is 105mm to obtain the desired reduction and correction. I guess the spacer would be useful in the image train if someone wants to adjust it for optimal placement.

Cheers

Dennis

[Merlin66]

Handy when using CCD's with the x0.63 reducer to get the "optimum" spacing.

[Renato1]

Thanks very much Ken and Dennis,
Regards,
Renato