Classic Bahtinov mask which is custom-made by your parameters. A storage box is included and can contain custom text on the cover. 

After quite a long trial-and-error (8-10 different masks with different patterns and manufacturing methods) and researching what fits best, I developed a design of a Bahtinov mask that meets all the characteristics so that I finally don't have to worry about focusing anymore.

Here, the Bahtinov pattern will be calculated according to your parameters: the diameter and the focal length. Most other masks on the market are actually designed for larger telescopes with very long focal lengths and so have a much too coarse pattern.

Please select parameters according your needs:

• Tube outside diameter at the front edge in mm. This is where the mask will be put on. Note that a certain tolerance will added to this size so that the mask can put on for sure and will be not too small. The maximum diameter is 200mm. See my other offerings for masks in the size 200-250mm and Tri-Bahtinov masks. Please note that the price is higher for larger masks.
• The focal length. If you use a reducer with your telescope, consider using the reduced focal length. This will generate a finer pattern and work with the regular focal length well too. It does not work well other way around.
• Optionally, if you are familiar with this, or just want to try it out, you can specify an individual Bahtinov factor. By default, the factor of 150 is used.
• Custom text to put on the cover of box for the mask. If you leave this field empty, the diameter will be used, e.g. "85mm"

Please note that the material of the mask is heat-sensitive and starts deforming at 50˚C and hotter. Thus, the mask should be not left in the sun, for example. At night, however, this should not be a problem 🙂

Customers from Germany have one correction sample free of charger. Customer from other countries should cover only shipping costs.  In return, we would ask to send the exact name of the telescope and picture of the final setup.