I would like to experiment with masking my 120mm, focal length 1000mm achromat. Any help or experiences would be welcome.
Aperture Masks
Started by mte1955, 11/07/2007 05:42PM
Posted 11/07/2007 05:42PM
Opening Post
Posted 11/07/2007 10:11PM
#1
Michael Tencza said:
I would like to experiment with masking my 120mm, focal length 1000mm achromat. Any help or experiences would be welcome.
It's worthwhile doing just for the experience. When I have done it have just used a cad program to print the mask(s) on a sheet of heavy paper and then cut them out.
I also made some masks that would mask off the center so only the outer edge of the objective was being used.
Jon
Posted 11/08/2007 06:57PM
| Edited 11/08/2007 06:59PM
#2
Michael,
Another interesting experiment to do with masks, is to mask the instrument down to other commonly available telescope sizes, like 114mm, 102mm, 90mm, then look at a variety of objects you normally observe on a routine evening to see if you still enjoy observing with that reduction in aperture (relative to light gathering loss and resolution loss). This would then tell you what is the minimum aperture APO you could really live with happily if you ever decide to spend all that cash on an refractor.
In my case, I have a 10" Dob which most of my observing is done in. However I have a 152mm Achro also and I did the downsize test for myself and determined for me, being used to a 10", that I could live with as little as 102mm but only for planets/lunar/doubles. If I was going to also use the scope for any DSO, nebula, clusters, Globs, then 127mm would be my minimum if I wanted to be marginally happy observing them with a refractor. So was an intersting experiment to ferret out exactly how I would feel using differing apertures as a general purpose observing instrument.
Another interesting experiment to do with masks, is to mask the instrument down to other commonly available telescope sizes, like 114mm, 102mm, 90mm, then look at a variety of objects you normally observe on a routine evening to see if you still enjoy observing with that reduction in aperture (relative to light gathering loss and resolution loss). This would then tell you what is the minimum aperture APO you could really live with happily if you ever decide to spend all that cash on an refractor.
In my case, I have a 10" Dob which most of my observing is done in. However I have a 152mm Achro also and I did the downsize test for myself and determined for me, being used to a 10", that I could live with as little as 102mm but only for planets/lunar/doubles. If I was going to also use the scope for any DSO, nebula, clusters, Globs, then 127mm would be my minimum if I wanted to be marginally happy observing them with a refractor. So was an intersting experiment to ferret out exactly how I would feel using differing apertures as a general purpose observing instrument.
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