Just a change for those who are interested: I have a new 'colour' for the masks. Most have been silver / black or black / gold in colour, but if you wish, you can purchase a fluoro pink / white mask as an alternative. The interesting thing is that it is easier to spot on a dark night in your accessory box. Still is very light and bends easily - not like the acrylic that breaks if dropped.
Use the mask with the pink side down.
Order info: measure the size of your OTA dewshield and give the INNER diameter, and the resulting mask will be around 0.7mm smaller than this - to mount with blu-tack or just use gravity inside the dew-shield / cover as required - that is what I do. Specify an inner diameter for SCT/RC / modified Newts if you wish to have it fit over the secondary.
Happy for pickup ex Sydney, and prices are:
$40 + $10 freight etc 3-4" OTA (up to 110mm diameter)
$50 + $10 freight 5-6" OTA (up to 180mm diameter)
$60 + $15 freight 8-10" OTA (up to 300mm diameter)
$80 + $20 freight 12-14" OTA (up to 450mm diameter)
Larger sizes on request
$25 freight internationally
Multiples: 15% off for 2 or more, 25% off for 5 or more, so please gather multiples if you wish - better for me, better for post, better for everyone.
Could I please ask this question, dose this mask have to be positioned on the objective lens, or can it sit half way down the dew shield, or on the end for that matter.
I ask this as my Tak 106 dew shield, although the same diameter all the way down it dose have a small ridge half way down the shield, so if one had to place this mask on the objective it would not be possible unless the mask was made considerably smaller.
I use the one on my C11 about 1" from the corrector, The one for my Megrez 102 about 4.5~5" from the objective on the end of the extended dew shield... Both seem 100% spot on..
Heres a pic, Focused through the camera view finder (no angle adapter, so 0x magnification) with the mask 4 or 5 inches from the objective.
Hi there Leon,
Sorry I didn't check the messages here yesterday.
But it is a really interesting point. I had only experience with pretty much on-the-objective , but I would have thought that no matter where the mask is, it would still generate parallel light patterns that would be focussed at the film plane regardless.
For my Newtonian, the primary mirror doesn't know where the mask is, and doesn't care, as long as it is sitting relatively square to the incoming light.
It would vary if the mask was INSIDE the objective, probably, but for instance you could incorporate the mask into the end cap of the scope, so that it would not have the possibility of touching the objective on a refractor.
I think I have two TAK refractors with the masks, and they have reported that they work well.
Many thanks for your reply, I reckon if it goes down the dew shield and rest on the ridge I was talking about in the last post it might just do the trick.
That would place it about 50 mm from the objective.
I will PM you if I intend to purchase.
I have added a few options that people might be interested in: For Hyperstar / large SCT users, I can halve the mask so that you can use the mask without removing the camera. Call it HALF-MASK. Price is the same
Secondly, for users who have trouble getting the masks out with the tight fit, I can do a custom radius tab - a reverse arc that allows you to slip a fingernail under the edge to remove the mask more easily - you could get a fingerprint on the objective if you . Just call it a REMOVAL-TAB, and let me know your clear aperture as well (just let me know the actual scope - that makes it easy), so the tab doesn't intrude on the function of the mask.
Thirdly, for those who want finer focus control, I can do a special mask at a lower degree. I already use a slightly finer angle than recommended by Mr Bahtinov, but I want some feedback on this going forward, so if any new orders want to try one then just call it the HI-RES mask, and for the next 4 orders I will supply a standard mask of the same size as well.
Existing mask users: If you want to try a HI-RES one as well, let me know and we will work something out.
Thanks for all the encouraging feedback, by the way, and for the samples of work that you have sent.
I just picked up a new 50D (which will stay unmodded), and with live focus and the new hi-res 920,000 pixel screen at 10x magnification the diffraction spikes are just unbelievably clear. I can highly recommend the 50D, except that I have seen evidence of the 'dark-river' problem that I fortunately did not see on my 2 20D and 2 40D bodies.
This may sound dumb but I assume the masks have to sit exactly level with the objective to get the proper reading as the diffraction spikes can still appear even if the mask is slightly askew.
I haven't really tested it, but it would be easy to do so. I suspect that it would not be sensitive to that sort of distortion, however, if you tilted it so that the effective angle of the two angled patterns were different, then it might be harder to accurately bisect the two angles with the major spike in the middle.
Hey there Clinton. Just a quick note to say thanks for the mask you sent me for the Tak. It works a treat.
Now - can you do a small one that fits snugly into a 50mm camera lens filter ring - either with the filter glass in or not? I'd like to be able to use it for my widefield setup.
Glad to be able to help, and glad that they do the job. It seems like the faster scopes in particular really go well, since the focus point is so tight on those FS series scopes. You must have quite a 'tak club' down there, with a couple more of the tak club receiving theirs last week. Thanks for the demos!
Chris (omaroo) requested a 'filter-ring' mask, and I have experimented with different materials to come up with something.
I found a very hard wearing 'rip-stop' laminate (uv treated so they won't degrade), that I think will last a long time. It is also self adhesive at any time, so you could stick it to the filter glass and you would have a screw in mask, as well as being able to be just placed on the filter.
I am really happy with them - the corners are unbelievably sharp because they are thin.
Price is $40 including freight up to 82mm filter ring size. ring if you need larger, and you can use the material for standard masks if you wish as well.
Sounds great Clinton - I can't wait to try it out! I have a dedicated daylight filter ready to go now, and this will make using camera lenses so much easier. As filters just screw into each other, it'll be super easy just to screw the mask on, set focus with a couple of quick three second shots and then remove it.
I have rubber bands on my lenses so that the focus ring doesn't move easily. I think that if loosely screwed on just a quarter turn to hold it there, the removal process won't move my focus at all. I'll eventually make up a robo-focus stepper-driven system any way.
Received the masks, thanks Clinton your a legend
Can't wait to try them out.
It was a stunningly clear night last night first time in ages but I was out at a Christmas party till very late, Thought that'd be right.
