aperture masks

asimov (John) · #1 03-09-2005, 11:00 PM

Just thought I'd throw this on here. The mask on the left for the 6" achro & the other for the reflector. They help on bright objects like jupiter & venus.

davidpretorius · #2 03-09-2005, 11:20 PM

i was just about to ask for a picture, you beat me to it. Thanks

happy fathers day for tomorrow old boy!!!

netwolf · #3 04-09-2005, 12:27 AM

Thanks asimov, i assume the penciled lines are to match your spider vane positions?
Have you tested this for spliting multistars like Antares etc.

asimov (John) · #4 04-09-2005, 01:27 AM

Yes Wolfie, that's where my vanes are in relation to the mask. Split antares with this mask and a contrast booster on the 12.5" @ 212X It was impossible to do without these 2 items on the same night.

ballaratdragons (Ken) · #5 04-09-2005, 01:34 AM

I'll have to try one, for when the sky eventually comes back. Ta!

netwolf · #6 04-09-2005, 01:43 AM

asimov is it special material or just any bit of cardboard will do. My friends imported some solar filter material from astrophysics to make a mask. Is this a similar material??
I have been able to split one of the Centarus pointers (rigel i think) but its still a litle fuzzy. And have not had a good enough try at Antares, but it is more difficult than rigel.

asimov (John) · #7 04-09-2005, 02:03 AM

Any old cardboard is fine. Mine were made out of pizza boxes! As you can see, their not even painted flat black as yet. I've been using them as is for 2 years.

The pointer you split is apha centauri. (Rigil Kentaurius) which is actually a triple star system.

asimov (John) · #8 04-09-2005, 02:31 AM

If you make one, make sure you don't put the holes too close to the outside (see pic)

Also do use a compass to make sure your holes are evenly spaced around the circumference. Make your holes big enough to just mask off the primary mirror by about 3-5mm. This will 'hide' any turned down edge you may have on the mirror. At the same time as hiding your vanes obviously. If you have a 4 vaner, use a four hole mask.

RAJAH235 · #9 04-09-2005, 02:34 AM

Hey John, I used black cardstock from the newsagents. Sprayed it matt black & clear lacquer for waterproofing. Have included a selection of shaped masks to place over the hole & rotated to move the diff. spikes. When nec. I use both holes for focusing. The shaped masks & the 'dust plug' are simply 'blue tacked', (actually, I use 'UHU' which is yellow), to the underside of the main mask when done. Been using mine for about 3 yrs.
Works well...

L.

asimov (John) · #10 04-09-2005, 02:43 AM

Yep! There's all sorts of weird & wonderful designs for masks on the internet hey!? L

I went this design cos' it allowed a bit more light in. I have tried the one you use as well though.

davidpretorius · #11 04-09-2005, 08:12 AM

nice one rajah, actually, thinking of the magnetic adapter for toucams gives me an idea of magnetic shapes???

asimov, you cheeky bugga, you can't just throw in a new term "contrast booster" and not expect me to ask you what it is?

now get out of bed (placing aside a wonderfully cooked breakfast hopefully!) on this loveley fathers day and let us noobies know what is a "contrast booster" and pics too.

having a laptop is wonderful $5

having a laptop with wireless broadband $500

having a wireless laptop with broadband and sitting up in bed $5000

having a wireless laptop with broadband and sitting up in bed and on the ICEINSPACE.COM.AU website and stirring asimov - absolutely priceless!!!

asimov (John) · #12 04-09-2005, 11:11 AM

A contrast booster, my dear young astronomer is a 1.25" filter (bought from AOE) screw the lil' beggar on your EP & awayyy you go!

netwolf · #13 04-09-2005, 01:03 PM

What would be great is if there were a PDF Template that printed on paper. Use paper as guide to cut cardboard. Something like that..

davidpretorius · #14 04-09-2005, 01:03 PM

cool thanks

davidpretorius · #15 04-09-2005, 01:04 PM

there is netwolf in the resources section i think , the one for the hartmann mask, ?????

[1ponders] (Paul) · #16 04-09-2005, 02:51 PM

Was just going to post that David. http://www.iceinspace.com.au/index.p...ae9502d7b7ef1c. The article is aimed more at focusing for astrophotograpy but the aperture mask design layout is down near the bottom.

[1ponders] (Paul) · #17 04-09-2005, 03:10 PM

If you have a refractor you might want to consider these designs. While not strictly designed for visual work you may find that they increase contrast as well as settle down some of the seeing.

They are from one of my current projects. I'm trying to design an autoguiding mask to reduce flaring of the guidestar which can at times cause an autoguider to send unnecessary commands to the telescope. Initial responses look good but one of the side effects was that on one particular night I happened to look at Jupiter through one (The one with the second most holes, bottom right) and I noticed a considerable increase in contrast. Now whether this was just from the mask or because of condition that night (I didn't look at Jupiter again that night) I can't really say. But they are so easy to make why not give it a try.

These masks were made for a 60mm refractor and the various hole sizes are 20mm, 12mm, 8mm, 6mm (or corresponding imperial sizes

) They were all cut from the lid of a 20 liter plastic bucket and have a ring of styrene cut from the top of a broccoli box to fit over the dew shield. Held on with a couple of pieces of double sided tape and tidied up with electrical tape around the top.

asimov (John) · #18 04-09-2005, 04:01 PM

Thats right,

I forgot you wrote that hartmann article Paul...

Nice article

The one you mentioned that 'may' have given you more contrast, I'm gonna try that one! I'm a contrast junkie, lol

I forgot to mention...that one I made for the reflector? does produce more contrast on jupiter, it's quite a noticeable difference visually.