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Your cart is empty.Product Description
- The Bahtinov mask has become the preferred method of focusing a telescope, either visually or when imaging with a CCD camera, DSLR or webcam.
- Bahtinov masks take the guesswork out of focusing and even get over the seeing conditions as it is a mathematical type approach to the task. The best focus for your telescope quickly and easily.
- They are an inexpensive tool which will allow you to achieve pin-sharp levels of focus, saving you time and improving your work. Simply place the mask over the front of your ‘scope, align the scope towards a star.
- 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.Whether you’re doing planetary visual observing, planetary imaging, or deep sky imaging, the Bahtinov Mask is a great accessory to get the best focus for your telescope quickly and easily.
Two Installation Modes
Inside the Dew Tube
- Place the brass screw on the inside of the dew tube. Slide each of the three grip pegs inward until they cling to inside of the telescope’s front cell or dew shield, then tighten the thumbscrews. Suitable for use with telescopes with inter diameters ranging from 92mm to 130mm, the max inter diameter is 130mm.
Outside the Dew Tube
- Place the brass screw on the outside of the dew tube. Slide each of the three grip pegs inward until they clamp outside of the telescope’s front cell or dew shield, then tighten the thumbscrews. Suitable for use with telescopes with outer diameters ranging from 80mm to 118mm, the min outer diameter is 80mm.
Specifications:
- Nominal Size: 85-120mm
- Material: Sturdy Plastic
- Thickness: 2mm
- Telescope Min Outer Diameter: 80mm
- Telescope Max Inner Diameter: 130mm
3 Holes and 3 Set Screws
There are three holes on the mask,which can be gently but firmly connected with the telescope through three brass screws. There is a scratch free silicon sleeve on the metal column to protect your precious telescope surface. Because of this 3-post mounting, the mask remains centered, whilst fitting a wider range of telescopes.
Made of High-Quality Materials
The mask is made of Acrylonitrile Butadiene Styrene and it is cut into 2mm thickness by precision laserr. It has the advantages of high strength and toughness, and is resistant. They will never be brittle in the cold, unlike some other masks which are made from normal plastics.
Strong Versatility
These high quality Bahtinov masks are adjustable to fit a wide range of optical tubes, unlike masks which are only able to fit one telescope. They have adjustment latitude of about 85-120mm, depending on model, in aperture making them very versatile. Suitable for use on all types of telescope - reflectors, rafractors, Dobsonians, Mak-Cas and SCTs.
How to use it?
- Place the Bahtinov Focus-Mask over the end of your telescope; then locate a bright star near your target; take a 3-5 second picture and view the diffraction spikes.
- Change your focus; take another picture and again; view your diffraction spikes. Is the center spike moving further from center?
- Then change the direction your focusing and try another picture. Watch the direction the spikes are moving and when the center spike passes the middle of the other two spikes; change direction and fine tune your tuning knobs until the center spike is in the middle; Your now in perfect focus.
Make sure the mask is centered.
- To ensure a tight grip, loosen one thumbscrew slightly, then push the grip peg inward while pulling the mask gently toward the loosened grip peg. This will make sure that the other two grip pegs are contacting the telescope when you retighten the third thumbscrew.
Robert
Reviewed in the United States on August 16, 2023
The 3 screws didn't fit in the slots had to force them in but I got them in and it works I cant adjust it so it's only suitable for the one scope.
LestersOfTheForest
Reviewed in the United States on May 4, 2023
Wrongly advertised - it states it will fit Orion ED80 CF T - it is too small. I retuned the 80-110 and got the 85-120mm and it fit, but as others have stated - Holes too small for the retaining bolts and had to force them in. Luckily mine did not break, warmed it up a bit with a hair dryer. And remember - you are sizing the dew shield - not the lens. So for 80mm scope with dew shield you need 95mm. All good now, with McGyvering.
Sam Snow
Reviewed in the United States on December 12, 2022
The brass screws are way too big to fit into the slots on the mask. While trying to fit one in, it snapped the thin plastic mask at the edge. I guess you could still get some use out of it by throwing some tape to hold it on or just manually holding it?
M. Dickerson
Reviewed in the United States on October 4, 2022
Product was advertised to fit 85-120. However, this would not fit 102. Additionally, the screws are oversized in diameter to even fit in the slots making it a pain to even be adjusted from 85-120.
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