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William Optics Bahtinov Mask

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#1 Svalbard

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Posted 24 April 2019 - 12:42 PM

Anyone have one and wish to comment on this?  Are they really superior to the metal ones? The price is pretty steep compared to others, before I take then $68 plunge on my first Bahtinov mask I figure I'd check with the good folk here on CN.

 

I'm looking for a quality mask, if anyone has other recommendations feel free to chime in also.

 

This will be for my TS130 photoline APO, I'm not sure what the outside diameter of the dewshield is but I'm guessing around 170 mm (my Seymour Helios glass solar filter is 178mm).

 

 



#2 wrnchhead

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Posted 24 April 2019 - 01:09 PM

I got one 3D printed by DrBenway (CN member) and it's excellent, and not overpriced. 



#3 scadvice

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Posted 24 April 2019 - 02:22 PM

I don't believe they will fit. I have a Stellarvue 130 that is about 168 mm on the dew shield OD and the WO mask for their 132mm was too small. The one your talking about I have. The flat of the plastic 172mm to 235mm mask which is without the aluminum frame works but it is a little too big and I had to modify it. Their next one down was too small.


Edited by scadvice, 24 April 2019 - 02:27 PM.


#4 Stelios

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Posted 24 April 2019 - 02:49 PM

Waste of money, IMO. Any Bahtinov mask will get you pretty close to perfect focus. The issue is that the focus keeps changing--if you take a video, you can see that clearly, and it's because of seeing variations. 

 

Eventually you will end up using some auto-focus system anyway, so save money for that, and get an inexpensive mask. 



#5 Svalbard

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Posted 24 April 2019 - 03:03 PM

Waste of money, IMO. Any Bahtinov mask will get you pretty close to perfect focus. The issue is that the focus keeps changing--if you take a video, you can see that clearly, and it's because of seeing variations. 

 

Eventually you will end up using some auto-focus system anyway, so save money for that, and get an inexpensive mask. 

I'm all fine with inexpensive, however I'm not a fan of low quality.

 

I see Astrozap ($45) makes one, and Farpoint ($20) I see those pop up on my search most frequently.



#6 Svalbard

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Posted 24 April 2019 - 03:07 PM

I don't believe they will fit. I have a Stellarvue 130 that is about 168 mm on the dew shield OD and the WO mask for their 132mm was too small. The one your talking about I have. The flat of the plastic 172mm to 235mm mask which is without the aluminum frame works but it is a little too big and I had to modify it. Their next one down was too small.

Good point, they might not even be an option. My solar filter is a little big, but it does fit. I'll measure tonight.



#7 wtd1114

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Posted 24 April 2019 - 03:09 PM

Right after I got my ZS61, WO came out with the Bahtinov mask built into the lens/dust cap. I felt a little slighted.  Anyway, I got the small mask to try.   I find that typical Bahtinov masks are kind of hard to use with small aperture scopes and camera lens, because the defraction pattern is so close, it does not let much light in.  What is cool about the WO Bahtinov mask is that there is an etching of the defraction pattern on the clear plastic as well as the typical slots.  So instead of blocking the light, the plastic is clear and allows a lot more light in while also integrating the defraction pattern.

 

Personally, I think the small WO Bahtinov masks works great for small apertures.  However, I do not know if there is much benefit of the WO mask for a larger aperture device.  The etching on the plastic does make the spike more prominent... So for me, for something like 130mm, I would probably make a mask.  I have a hand made one of cardboard for my 102mm refractor.

 

Willis



#8 Endymion

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Posted 24 April 2019 - 04:16 PM

The WO mask for my 80mm refractor works MUCH better than my old slotted mask. You get a much brighter and longer spike pattern. Was worth it for me.

#9 Svalbard

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Posted 24 April 2019 - 04:21 PM

Right after I got my ZS61, WO came out with the Bahtinov mask built into the lens/dust cap. I felt a little slighted.  Anyway, I got the small mask to try.   I find that typical Bahtinov masks are kind of hard to use with small aperture scopes and camera lens, because the defraction pattern is so close, it does not let much light in.  What is cool about the WO Bahtinov mask is that there is an etching of the defraction pattern on the clear plastic as well as the typical slots.  So instead of blocking the light, the plastic is clear and allows a lot more light in while also integrating the defraction pattern.

 

Personally, I think the small WO Bahtinov masks works great for small apertures.  However, I do not know if there is much benefit of the WO mask for a larger aperture device.  The etching on the plastic does make the spike more prominent... So for me, for something like 130mm, I would probably make a mask.  I have a hand made one of cardboard for my 102mm refractor.

 

Willis

Good point, with the larger aperture the benefit might not be needed or noticeable. 




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