hartman mask on a skywatcher 200

[proflight2000]

On my skywatcher I have a front plastic pushin protective plate, it is possible to remove a small front circular cover to cut light down entering the mirror.However directly across from that cover is another circle, the same size but is covered in plastic so it cannot be opened. If I was to make a hole in this, would that be the same principle as a hartman mask? two holes, the same size on opposite sides of the plate, or would the holes be too big. Cheers.

[Jamie]

Hi Terry

The hole that is already there and the one marked out on the opposite side of the

cover are the correct size for use as a Hartman mask. (Thats what they are there for)

[proflight2000]

Thanks Jamie, yep that works a treat, I took the other side out and have tried it this evening on Venus and it works a very well indeed.

[Greg]

Have a look here...

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

Will produce a template for any scope....You'll need Adobe Reader

[Dangermouse]

Ah so that is what that is for you learn something every day.

[Albireo380]

Great link Phattire, I will pass it on to my local Astro Soc - and make up a few "blanks" for them.

Tom

[The Warthog]

Actually, the purpose of the unopened circular thingy opposite the aperture mask is so that you can put the aperture mask there and not lose it while you are using the scope cover as an aperture mask.

It will work, but you lose the ability to seal your scope tube. Better to make a cardboard aperture mask with smaller holes. I did one with triangular holes once - you are supposed to get a six-pointed image when the star is in perfect focus, but it was hard to use that way, so I just focused until the two images came together. Worked fine.

I was looking for an image of my Hartmann mask, but I've deleted it. Nuts!

[proflight2000]

Lucky the scope came with another cover for the hole and after removing the selaed plastic I was able to cover both holes so it stay as a dust cover also. I am a bit suprised though that seeing as that was the intended use for the front cover that they did not allow it to be removed a little easier, push out sort of thing rather that scribe and cut.

[The Warthog]

Lucky the scope came with another cover for the hole and after removing the selaed plastic I was able to cover both holes so it stay as a dust cover also. I am a bit suprised though that seeing as that was the intended use for the front cover that they did not allow it to be removed a little easier, push out sort of thing rather that scribe and cut.

Once again, this is the first time I have heard of anyone doing this. It is intended to be an aperture mask, and the hole is somewhat larger than most people put in a Hartmann mask. The second boss on the front is there to hold the cap from the aperture mask. Full stop. If it works, it works, though.