Astrophotography Focus With a Bahtinov Mask

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Mike Farley
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Astrophotography Focus With a Bahtinov Mask

Postby Mike Farley » Sat 24 Jun 2017, 08:32

A focussing aid for the astrophotpgraphers. Necessary, I suppose, as lenses can focus past infinity.

https://petapixel.com/2017/06/23/improv ... inov-mask/

It reminds me of when I was in Norfolk during the club's recent trip there and the moon was visible in daytime. I noticed that I could see it between some branches of a tree which were 15' - 20' feet away. However much I tried with my Fuji XF 50-140 lens, I could only get either the branches or the moon in focus. Not both at the same time. Even at f/22. Depth of field, it seems, does not extend 250,000 miles. :?

The shot did not work, so I forgot about all about it until now. Perhaps if I had had a tripod with me and focussed manually, I might have found a point of focus where both were sharp simultaneously. Does anyone have an explanation of why I could not get the shot with a single exposure?
Regards

Mike Farley
(Visit my website and blog - www.mikefarley.net)
Rose
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Re: Astrophotography Focus With a Bahtinov Mask

Postby Rose » Sun 25 Jun 2017, 10:28

Focus stacking would be one answer...
Rose
Mike Farley
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Joined: Tue 11 Sep 2012, 16:38
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Re: Astrophotography Focus With a Bahtinov Mask

Postby Mike Farley » Sun 25 Jun 2017, 21:20

Rose wrote:Focus stacking would be one answer...

That is what I resorted to. One shot with the branches in focus, the other where the moon is sharp. Had I thought that the shot actually worked, it would have been a simple matter to combine them in Photoshop.

I was intrigued that despite the principle of hyperfocal focus, it seemed to reach its limit at some point before 250k miles.
Regards

Mike Farley
(Visit my website and blog - www.mikefarley.net)

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