Solomark Bahtinov Focus Mask for Telescopes 80mm-Suitable for 78-103mm Diameter Telescope

Used this and it led to a "perfect" focus. Amazed at how easy it is to get a precise focus. Recommend you use with a camera having live view so you can adjust the focus while watching the diffraction pattern. The attached photo was from my first time use. Star = Altair and the telescope was an AstroTech 80mm EDT. The camera was a Nikon full frame DSLR (D750). I'm very pleased with the effectiveness of this product.

Still had drawing marks on it so they could make the cutouts. It didn't fit the OD of my dew shield which I had measured and ordered to fit. It did fit the ID, so I can make it work. One of the slots for the screws is not regular, the screw won't slip through the whole length of the slot. I would think with automation being what it is, it wouldn't be that hard to mass produce these with perfect dimensions. I recently used it and it does help achieve near perfect focus. Notice in the bahtinov star image that the diffraction spikes are not perfectly centered, I could have done better.

Came super quickly with amazon shipping. Product was precision cut with the protective paper/film still on both sides/surfaces. Posts are solid brass and have a clear "rubber" coating to prevent any chance of damage to your optics/scope.Fit perfectly. Performed perfectly as well. Highly recommended for the price. Should last pretty much forever if you use it (take 30 seconds to install and focus if you take your time) and then take it off and store it properly. Honestly, I can't see ever needing to purchase another one for this scope.Hope this helps.

Works great for Orion 4" refractor. I cant' believe I didn't use a Bahtinov mask for 2 years I had this telescope. This makes focus possible, and thus makes astrophotography possible. I bought this after buying one for my 6" SCT telescope and seeing the massive improvement in focus accuracy.But lets be honest..... this is just laser cut plastic in a mathematically proportioned pattern. The only thing that can go wrong with this is if it is brittle (it is not), or if the packaging caused the product to arrive broken (it did not). The padded screws are a great touch to protect the housing of the telescope.

I had only been using this for 3 months and it started to come apart. Where the adjustable mounting screws are is the weak point for the mask. I had the mask break at the outer edge of the adjustment notch and lost one of the adjustment screws. Shortly after that, a second break occurred but I managed to retain the adjustment screw.If you choose to buy this, I would recommend reinforcing the outer edge around the adjustment screws with some electrical tape or some black duct tape.I can still position it and obtain a sharp focus, but am extremely disappointed in poor quality of the design and manufacturing. The only reason I gave it 3 stars instead of 2 is that I am able to obtain a good focus.

I ordered a 100mm and use it on smaller scopes via some foam padding. After focusing it's easy to remove. For the correctly sized scope the provided adjustment screws easily hold it in place while focusing.

I purchased the 100 mm Bahtinov mask. It fits outside my 90 mm Celestron telescope. It's high quality and does what it says it would do. It has padded screws to prevent scratching the telescope. It comes with a protective paper covering which can be removed prior to use.

Excellent product. I use it with my Meade Series 6000 80mm scope and this is the second one I've ordered after I stepped on my first in the dark.