Astrophotography Focus With a Bahtinov Mask

[Mike Farley]

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?

[Rose]

Focus stacking would be one answer...

[Mike Farley]

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.