Focal reducer question

[Kai]

I have read on here about the impoetance of getting the correct spacing between a CCD and a Focal Reducer.

The question is how do you calculate this ??

I plan on using a 6.3 reducer with my SxvfH9.

Cheers

Steve

[Merlin66]

No calculation require, only some measurements. The distance is defined in the design of the reducer lenses and spacings to give " optimum" performance.

The x63 reducer ideally should be positioned 110mm infront of the CCD chip. Depending on the type of scope you have, you made some adaptors to hold the reducer and spacer adaptors between the camera and the reducer. T2 spacers come in various lengths from 6mm to 40mm.

[RobH]

Basically, the closer the reducer to the chip/eyepiece, the less the reduction. Too far away and you start to get vignetting and field curvature.

I have various reducers and a few experiments will give you the correct spacing for your setup.

As said theough, the correct spacing for the .63 is 110mm.

Cheers

Rob

[Kai]

Okay.......... :scratch:

But how do you get 110mm ???? ,where do you get that info ???

[Merlin66]

It's from both the instruction manual issued for the Meade 0.63 reducer and various write-ups on the MAPUG support site. I can scan the instruction sheet for you. Drop me a PM.

[MikeP]

You could try here ..... http://www.rc-astro.com/resources/reducer.html

Mike

[Helen]

I'm looking to do the same Steve with the C8. So guys, how do you work out how far in the tube the chip is? (is that in the manual somewhere too?)

Helen

[Merlin66]

Helen,

Should be specified in the camera's manual. I have the old MX7c and the manual ( p12) gives 22mm as the "CCD to adaptor flange distance"

[Jeff RV]

I also have a Meade f3.3 reducer, but the manual states it needs to be mounted straight onto the threaded rear cell of the scope, which means you cannot theoretically mount it onto the "Micro Focuser", But i had a play with it in this position and it seemed OK without any vignetting using a ccd with terrestrial.

Here's a link to the CCD instructions for the F6.3, F3.3.

http://www.californiastars.net/lx200gps/tips.html

Likewise! What should the ideal distance be?

Jeff.

[Merlin66]

I use my X0.63 reducer with the #1209 micro focuser by using the Orion 2" to SCT prime focus adaptor. ( BTW this also allows me to use all the SCT flip mirrors etc etc on the ED80 etc)

Jeff, The distance for the X0.33 is variable, the manual shows a 30mm spacer and a Pictor camera gives X0.33, and with the 1 1/4" spacer unit it give X0.3.

[Merlin66]

Jeff,

Checking Doc G's notes on MAPUG, he gives 59mm as the " calculated distance for a reduction of 0.33".

[Jeff RV]

Jeff,

Checking Doc G's notes on MAPUG, he gives 59mm as the " calculated distance for a reduction of 0.33".

Thanks Merlin, I thought MAPUG was no more, as last time i tried to go into i couldn't get in?

Must have been my old link, no problems now.

Cheers.

Jeff.