Farpoint Tri-Bahtinov Mask for Celestron 9.25" SCT

SKU: FP415HT
Tri-Bahtinov Mask for Celestron (6795857985689)
P1140021 (6795857985689)

Farpoint Tri-Bahtinov Mask for Celestron 9.25" SCT

SKU: FP415HT
Regular price $30.00 Sale price $21.00 Save $9
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Customer Reviews

Based on 8 reviews
63%
(5)
13%
(1)
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(0)
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25%
(2)
J
JAMES LONG
Very high quality

Ordered a tri-Bahtinov Mask for my 9.25 SCT, it came pretty quickly. It's been cloudy since, so I don't know how effective it is, sorry.

m
mike close
Have not received it yet

Wish I could rate it but I don’t have it. I left a message to you a few days ago and have not received an answer back . Item was ordered 2/26 today is 3/12 how do you think I should rate you and it? Just checked and it usps says item was picked up today coincidence? Payed 13.62 shipping….

K
Kevin Price
Perfect fit!

Works super well and fast delivery!

M
Mark Johnston
It works!

I was never satisfied with the traditional way to collimate an SCT. Seemed like it relied too much on eyeball judgement. So when I saw this I had to try it. After some trial and error I dialed it in and my subsequent Jupiter photo was the sharpest I've ever taken, even in average seeing. A great investment.

S
Steve Andrews
INSTRUCTIONS COULD BE BETTER

I’ve used Bahtinov masks for focus and a Duncan mask for collimation. The Tri-Bahtinov mask performed well to accomplish both tasks in less time. The enclosed instructions were for a Bahtinov focusing mask and did not provide guidance on the need to center all three center spikes to improve collimation.

The Tri-Bahtinov Mask is an advanced version of the Bahtinov mask that allows for even more precise adjustments and can also be used as a collimation tool

Tri-Bahtinov Focus and Collimation Mask for Celestron 9.25" SCT with Hyperstar or Fastar is an ingenious new way to easily focus a telescope. Pavel Bahtinov, a Russian amateur telescope maker and astronomer, created this simple, very intuitive method and the device has universally been named after him: The Bahtinov Mask.

It does NOT fit with the Hyperstar or Fastar camera installed. But if you look carefully, you will see a slit that goes almost all the way across one side. Just complete that slit and you can flex (twist) the mask to open it up to get around the camera. The OD is 10.25" and the ID is 3.375".


Tri-Bahtinov Focus and Collimation Mask for Celestron 9.25" SCT with Hyperstar or Fastar


Tri-Bahtinov Focus and Collimation Mask for Celestron 9.25" SCT with Hyperstar or Fastar based off the classic Bahtinov mask: it allows to focus a bit more objective compared to visual star focusing.

The Bahtinov will produce Cross-shaped stars, with one clear line that moves along the cross as you focus. When the line is centered on the cross, you should have achieved perfect focus.

What is the Tri-Bahtinov?


It essentially three Bahtinov masks in one, rotated over 120 degrees. It gives you three lines and three crosses to check collimation, along three axis simultaneously.

In addition to focusing, the tri-Bahtinov so also indicates collimation status along three axis.

This is interesting for e.g. Schmidt-Cassegrain telescopes, where the collimation is done by push-pull screws of the secondary mirror along three axis.

When you position the tri-Bahtinov alongside these axis, it will give you insight not only per axis of the focus but also how different these focus points are for each axis.

Bahtinov mask is a less expensive method of getting focus on objects in the night sky compared to a standard motor focuser.

With the right mask and setup, it’s easy to get crystal clear focus on a star in less than 90 seconds.


Star in focus via a Bahtinov mask



How it Works


The slits in the mask are the focus assist, when the star is in focus it will appear on your screen display as an “X” with a line through the center (see above).

These mask will work equally as well on the end of a scope or on the end of a dew shield on top of that the mask itself does not need to be perfected centered on the scope this is due to the angle of the slits themselves.

Select a bright star, this will be your guiding object. Place the Bahtinov focusing mask on your telescope’s lens and secure it into place using the provided rubber tabs.

The slits in the mask design create a set of diffraction spikes on the star that will assist in the accuracy of our focus. It will appear on your DSLR display screen or computer as an “X” with a line through the center (when in focus).


The diffraction spike pattern from a bright star using a Bahtinov mask


As you adjust the focuser of your telescope, the central spike will move in and out of the X-pattern. If you are using capture software be sure to compensate for the lag time between exposures on the screen, typically 4-5 seconds.

The same process applies using Live view display on your DSLR camera. The difference is, the image will be much dimmer, as you are essentially looking at a live video feed rather than a short image exposure.

You can read how to collimate using the Tri-Bahtinov Mask here: https://github.com/cytan299/tribahtinov

or here https://www.cloudynights.com/topic/536410-a-tri-bahtinov-mask-for-sct-collimation-and-focusing/page-16?hl=+tri%20+bahtinov

You can read how to collimate using the Tri-Bahtinov Mask here: https://github.com/cytan299/tribahtinov

or here https://www.cloudynights.com/topic/536410-a-tri-bahtinov-mask-for-sct-collimation-and-focusing/page-16?hl=+tri%20+bahtinov



be sure to check the rest of our bahtinov masks

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