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Model: bahtinov-72Part Number: ZS72
These are not generic masks, each mask is tuned to the telescope's focal ratio for the very best performance
The Bahtinov mask has become the preferred method of focusing a telescope, either visually or when imaging with a CCD camera, DSLR or webcam. Precise and repeatable focus can be achieved in under a minute, even in poor seeing conditions. The mask displays a unique diffraction profile, one part of the diffraction pattern moves in response to changes in focus and displays error as a displacement from a clearly defined point.
Straight sides ensure the focus mask will not roll away when stored on the shelf, matt-black surface prevents reflections and a reflective high visibility corner makes it easy to locate in the dark.
Credit goes to Russian amateur astronomer Pavel Bahtinov for creating the design and making it available to the astronomy community.
Made in the UK!
Got this with my first telescope purchase, and it is worth every penny, just zoom in on the brightest star one can find, then slip the mask over the telescope, and make align the bahtinov spikes (if that is what they are called), boom, you have prime focus!Remember that using if using a filter for imaging, to have the filter on when doing this, because that changes the focal point ever so slightly, it can be a bit hard if the filter is very restrictive, like certain wavelengths, one might have to resort to taking a few second exposures for each focusing-try, because it wont be enough light passing thru to show on the preview on the camera, I am sure this is adjustable in some cameras perhaps though! I recommend zooming digitally in on the live view to get the best view The mask has three holes in it, and is supplied with two nylon screws, which is enough to let the mask rest easy on the telescope (you will not need to attach it very sturdily, it is enough to have it rest flushly against the telescope opening usually it stays on for maybe 5 - 20 minutes, depending on filter use, if I am struggling to find a bright star etc etc.. it is quick work after a few sessions!It is made of cardboard, I did notice some of it starting to separate and fall off along the edges, so it looks a bit more rough now, I usually lay it on the ground if I am working quick and dont have any space nearby to lay it, but even so just catching the edge will make the paint come off an reveal the cardboardy interior of the mask, but it doesn't have any effect of the use of it. It would be better to have it in some kind of robust plastic instead of cardboard-ish material. But it does the job, absolutely worth the buy!
Does what I need it to do, screw plastic screws into mask put on scope simple. Quick delivery time as always.
Bought this item for my Esprit 150, I expected that it would be designed to fit over the dew cap of my Esprit 150 which has a diameter of 203mm, instead it is a flat piece of rigid plastic with 3 holes drilled in it, and supplied were 2 (not 3) threaded plastic pins, which I assume are designed to hold the mask in place over the dew cap, in any event the holes were drilled in the wrong place.Not at all what I was expecting,I will be returning the item for a refund.
Performs exactly as expected and is a great help assisting with focusing. Taking stock of other comments about potential structural weakness, I've been careful handling... but it feels solid.
I've tried this the last few nights, when it's been blessedly clear. It has definitely helped focusing. I'm using APT as my controlling software, which has a specific Bahtinov Mask focusing aid, but even without that the mask would definitely help to get sharp focus. I did find that for my setup at least I needed a bright star to use to focus on, which means re-focusing in the middle of a series of exposures on a DSO means pointing the scope at a nearby bright star, focusing, then re-pointing at the target DSO, which was somewhat fiddly to get exactly the same framing after the refocusing (using plate solving seemed to work best for me). I saw other reviews where they had dropped the mask and it broke. I dropped mine a couple of times and it was fine, so perhaps the product quality has improved - it certainly didn't seem brittle. Overall, this is an inexpensive tool, and a definite help.
Not the quality I thought it would be for the price paid.
Not a lot to say. Quick delivery, well packed and works well.
I would like to point out to people how fragile these things are. First night out with mine and it broke when it fell off the front of the scope.I think it will do the job of focusing once you make sure you have secured it to the scope.
This item really works, no more chasing focus. Precise focus is achieved in seconds even when using a dew shield. The two plastic screws used to hold the mask in place are simplicity’ itself.
Get perfect focus quickly every time simple to use ,a must have for imaging ,highly recommend use with Bahtinov grabber for even more accuracy http://www.njnoordhoek.com/?p=325
Read all 22 customer reviews...
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