Bahtinov mask has become the preferred method of focusing a telescope, either
visually or when imaging with a CCD camera, DSLR or webcam. 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.
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.
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 30-60mm, depending on model, in aperture making them very
made from precision laser cut enforced plexiglass, which is stiff and long lasting.
They will never be brittle in the cold, unlike some other masks which are made
from normal plastics.
grip the telescope tube gently but firmly with three metal posts which have
non-scratching silicon sleeves to protect you valued telescope surface. This
prevents slippage, whilst allowing the mask to remaining perfectly central.
Because of this 3-post mounting, the mask remains centered, whilst fitting a
wider range of telescopes.
There is a myth about different Bahtinov grating
pattern is required for different focal length telescopes. There is no real practical reason for the use of
special patterns for different telescope types and focal lengths. In fact, the
frequency and angle of Bahtinov mask patterns aren’t really that important. The
diffraction effect is so sensitive to changes in focus, that the results are
excellent regardless. Please be assured that these focusing masks will work
excellently for both reflectors and
refractors with whatever focal length. All you need to do is to measure your
telescope tube size and choose the right size of the mask.
The sale is for ONE Bahtinov mask and you can chose from 8 different products:
FM60mm for a tube outer
diameter (OD) from 65mm-90mm.
FM80mm for a tube outer
diameter (OD) from 90mm-120mm.
FM100mm for a tube outer
diameter (OD) from 110mm-150mm.
FM140mm for a tube outer diameter (OD) from about 150-205mm
FM150mm for a tube outer
diameter (OD) from 160mm-195mm.
FM180mm for a tube outer
diameter (OD) from 195mm-240mm.
FM200mm for a tube outer
diameter (OD) from 200mm-260mm.
Please be advised that the bigger FM180mm focusing mask have a different patterns as shown by the pictures.
Please also visit my shop at http://stores..co.uk/Joys-Optics
for more bargains!
Delivery: FREE P&P for UK buyers. The item will be posted to you the same day by Royal
Mail First Class Post when your payment is received before 13:00
O'clock. Otherwise, it will be posted the next day. Please note that all
payment received over the weekend will be posted the following Monday. International Buyers please see postage details.
Buy from a UK PowerSeller with more than 30,000 happy customers and buy with TOTAL confidence!