Focusing Device for Astro Cameras

[AstroTasmania]

Hi All,

Here is a link to a useful device called a Hartman Mask, a simple device to make at home, which will take the hassle out of CCD image focusing.

http://rao.150m.com/Focusaid.html

Clear skies...

[Radar]

Yeah Hartmann masks are good for focusing film cameras to. I bought one a few years back for me LX 50. Are they any good for colimation?

Cheers

Ray

[Tony Leece]

Hartman masks are brilliant things, especially for those of us who have canon 300's, with their tiny little (very dim) frame viewer.
Here is a very useful link for anyone wanting to make their own.

http://billyard.servehttp.com/Hartmann.html

The template shows circles and triangles, try a mixture of both, perhaps two circles and one triangle. Depending on your setup mixing them can give better results.

Another, but much more expensive way is to buy a Stilleto focuser.
It consists of a 'Ronchi Screen' and is supposed to give knife sharp focus.
I have never used one, but know a few people that have and they wouldn't get rid of them at any price.

Tony..........

[Radar]

Hi Tony,

I have a stilleto focuser. They make life easy for people with refractors and SCT's. Before I had one, focusing was a "get on the ground and try and look upwards" effort. The stilleto allows me to plug my ronchi screens into a diagonal and focus comfortably. Just in case anyone is wondering, Stilleto's are not used or needed for newtonians. :pipethinker:

[Draig]

Hi All,

Silly question, but can you use a Hartman mask on Newtonians?

Cheers Colin

[AstroTasmania]

Hi Colin,

You can use a Hartman mask on any scope. However, it is of no use for collimating a scope.

Clear skies...

[Draig]

Thanks Shevill.

Cheers Colin