Help with Meade 0.63 focal reducer for visual use.

[Terry B]

Originally Posted by Inmykombi

Hi Terry, how did you measure the FL ?

Can you explain so I can do the same.

geoffro.

Using a tape measure and the moon.
I held the tape meaure against the side of the FR and projected an image of the moon onto a piece of paper on the ground. The distance from the reducer and the focussed image of the moon is the FL.
simple but does require the moon to be out.
I wouldn't try it with the sun as the image is quite bright and you will fry things.
Cheers

Terry

[Merlin66 (Ken)]

Geoff,
yes, you have to measure the focal length of the reducer lens to determine if it's one of the "short" or "long" types.......

[mithrandir (Andrew)]

Originally Posted by Merlin66

Geoff,
yes, you have to measure the focal length of the reducer lens to determine if it's one of the "short" or "long" types.......

Ken, measure from where? Terry said "the back of the flange".

Is that OTA side (which has a female thread and hence would include the physical length of the FR) or the CCD side (which has a male thread and would not include the FR)?

[Merlin66 (Ken)]

It's normal to take the measure from the bottom of the male thread..this is close to the optical centre... well close enough for the settings we're talking about.

[AndrewJ]

Gday Andrew

You point the female threaded side towards the moon or say a distant streetlight and then measure where it reaches focus on the male threaded side using a sheet of paper or a wall etc.
It doesnt have to be exact to tell if its the long or short version.

Andrew

[Inmykombi (Geoff)]

I'll try the focal length measurement and see what it is.
Hopefully I can actually use this thing for visual use.