The Bahtinov mask allows digital astrophotographers and visual observers to get razor sharp focus in seconds!
The difference in focuser position between the
four pictures shown below is very small, a few tenths of a mm. The method
is very fast and incredibly sensitive. There is no guessing when you are
focused during times of poor to moderate seeing. Simply put the mask and
the status of your focus will become immediately apparent.
The masks have a series of slots that create a
unique diffraction pattern that can be used to quickly bring your telescope
to focus with an absolute minimum of fuss.
Note: Unlike the Kwik Focus HARTMANN MASK, a Bahtinov
Mask is not a multi purpose tool and is designed specifically for achieving
sharp focus.
PLASTIC FILM MASKS
These flexible plastic masks are constructed of
an opaque black plastic film that is very tough yet very flexible. When
rolled up and released, it will revert back to its natural flat state.
This makes for very easy storage as they will fit easily into many accessory
cases once rolled up.
How it works
They come with three tabs exactly the same as our aluminum masks but unlike the aluminum masks, we do not provide rubber bumpers with them. The tabs can be used as an aid in connecting the mask to your telescope per a method of your choice. If the tabs are deemed undesirable, they can be trimmed off with a pair of scissors. Also, the plastic masks can be glued into one of our R-60 aluminum rings if you prefer a more rigid, but still lightweight, set up. A list of rings to fit the various plastic masks is provided below in the technical spec section.
First of all, the aluminum masks come with three adjustable rubber bumpers. This allows them to fit to a wide variety of tube diameters. Simply push the bumper to the desired location on the slot to ensure that the mask is properly centered over your optic. The plastic masks will require the user to devise a method of attachment. We suggest masking tape.
Then focus. The graphic below describes visually
what you will see on either side of being focused. This graphic represents
movement of the focuser in very small amounts (fractions of a mm). It is
extremely sensitive.
The Bahtinov Mask is probably the easiest product
on the market to achieve tight focus for digital astrophotographers.
TECHNICAL SPECIFICATIONS FOR THE FLEXIBLE PLASTIC
MASKS:
Material: .010" thick plastic film.
Colour: Black
Weight: negligible
TUBE DIAMETER FITTING DIMENSIONS:
# BM-6004-P...Fits tube ODs 80mm to 164mm
# BM-6006-P...Fit tube ODs 108 mm to 172 mm
# BM-6007-P...Fit tube ODs 112mm to 186mm
# BM-6008-P...Fit tube ODs 133 mm to 207 mm
# BM-6011-P...Fit tube ODs 158 mm to 232 mm
# BM-6013-P...Fit tube ODs 202 mm to 276mm
# BM-6015-P...Fits tube ODs 244 mm to 318 mm
# BM-6016-P...Fit tube ODs 258 mm to 342mm
# BM-6017-P...Fit tube ODs 288 mm to 362 mm
# BM-6018-P...Fit tube ODs 314 mm to 388 mm
# BM-6020-P...Fits tube ODs 358 mm to 442 mm