Aperture stop

[RAJAH235]

Hi Guys,
Mike, I noticed that you use a full,(almost), aperture solar filter on your 10" DOB. A few of us W.A.A.C.ers use a full aperture cover made of thick card stock, with an 80mm hole in it, must clear the spider/secondary etc,and just solar film that. The same principal applies to planetary viewing, get really good contrast. I have made an 80mm ap/stop, makes my f4.5 into an f14.25, and I have split Antares with this set up. Mag about 234x/308x with good/calm conditions. It will test out your collimation and fine focus as well.
I made up some different shaped masks,(square/octagonal etc),which I rotate to get the diff./spider spikes out of the way. These shapes must fit inside the 80mm hole.
Another project to try.
ps. Can't quite get Sirius's pup!!!(need 2 eyepatches).

[iceman (Mike)]

Hey Laurie. I was going to make my solar filter like that, but some advice from people more experienced than me (on CN) suggested:

By the way, there's no real need to make an off-axis mask with a 10". Full aperture will be just fine and will allow to see the most detail possible when seeing allows.

Ditto, on the full aperture... seeing permitting, you'll grab a lot more detail. If conditions are mediocre, I simply lower the power rather than use an aperture reduction mask...

I don't do a lot of white light observing at the moment, but now that there's a few more sunspots rotating around I might pull it out this weekend.

[rmcpb (Rob)]

How would that setup go (unfiltered) on the full moon? Would it cut down the glare and allow for more comfortable viewing?

Cheers

[RAJAH235]

Hi Rob, Yes it would work,(heaps of contrast), but you will still need an ND/Moon filter. It's -12 mag. remember. Best moon viewing done when it's partially illuminated. (1 to 5 days old or thereabouts).

[ving (David)]

I am so going to do that!!!

[ving (David)]

ok i did it...

I got my old PS2 box and cut a circle about 1cm bigger that the diameter of my ota. then about 1.5-2cm from the edge I cut a 8cm diameter hole... placed the card on top of my ota and headed outside with it...

I have to say that from planetary work it is great... of course saturn ws the only one up at the time of testing but it is such a worthy subject.
The seeing was really bad but saturn looked better than I have seen for quite a while. the increase in contrast with the mask was really noticable.

A really big thanks for the tip rajah.

at zero cost it was well worth the money

hey ice, you might want to try this for your saturn and jupiter photography for more contrast... it doesnt cost anything to try. Id be interested in seeing results too

[ballaratdragons (Ken)]

The dust cap on my 12" (brag, brag) doubles as a solar/contrast mask as it has a 55mm hole in it with a cap. They work excellent.

Can't try mine tonight as it is raining! (typical)

[RAJAH235]

Hi Ken, I thought that's what you bought the shower caps for----- just singing and viewing, in the rain?????? da de da de da daa, da de da de da daa.....

[RAJAH235]

Just looking at your lovely shower cap, when I thought, If you put a light under it and project it onto the ceiling. Hey presto, instant indoor star gazing with no weather to worry about!

[RAJAH235]

Ving, You're welcome.
See, who said Astronomy is an expensive hobby? An old cardboard box finally has a use!

[ballaratdragons (Ken)]

Cardboard and PVC.

Where would we be without them?

[ving (David)]

hey ken, why didnt you just cut a hole in your showercap?

[bytor666]

actually an apodizing screen works far better on the planets as it pushes the outside diffraction on the outside of the airy disk right back into the center of the image again ...
--------------------
markus
12" GSO SCOPE

[ving (David)]

er... what do they look like and where do you get them?