Moon focusing

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Originally Posted by wfwhitaker

While it sounds like most of your sharpness issue may be related to hand-holding the 300mm lens, don't forget that the moon is a moving object. Motion is magnified along with the image when using a long lens.

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For a full sense of this motion: the moon subtends half a degree of arc in the sky and 'moves' at about 15 degrees per hour. The full moon will move it's own width every two minutes.

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Originally Posted by modafoto

So the conclusion must be to manual focus at infinity, use a tripod and expect tack sharp slides?
Morten

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Almost. The only variable is the focussing, whether or not infinity is at the far mechanical stop, or if the infinity mark on the lens barrel is accurate, etc. You should be able to get very close by looking in the viewfinder. If your camera has an "in focus" indicator, it should work or at least get you close enough that DOF will cover any errors (DOF at 250K miles is pretty big!)

Quote:

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Originally Posted by wfwhitaker

While it sounds like most of your sharpness issue may be related to hand-holding the 300mm lens, don't forget that the moon is a moving object. Motion is magnified along with the image when using a long lens.

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From "Astrophotography for the Amateur" by Michael Covington, the rule of thumb for fixed-tripod shots of astronomical subjects:
Longest shutter speed = 250 / Focal length in mm.
For a 300mm lens, 1/2 second or faster will be enough to prevent motion blur of the Moon. You should be using mid-apertures (f/8 or f/11), so your shutter speeds should be 1/125 to 1/800 depending on film ISO, much faster than the 1/2" maximum.

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Originally Posted by Dave Mueller

From "Astrophotography for the Amateur" by Michael Covington, the rule of thumb for fixed-tripod shots of astronomical subjects:
Longest shutter speed = 250 / Focal length in mm.
For a 300mm lens, 1/2 second or faster will be enough to prevent motion blur of the Moon. You should be using mid-apertures (f/8 or f/11), so your shutter speeds should be 1/125 to 1/800 depending on film ISO, much faster than the 1/2" maximum.

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Thank you. I go out tonight and shoot a test roll of the moon. I'll use tripod and all the kinds of focus I can. I'll shoot it at 1/125 @ f/8. Looking forward to try the advices from the replies to my question.

Greetings Morten

"auto-focus" what the f is that? must be a miniature format thing. :)

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Originally Posted by mobtown_4x5

"auto-focus" what the f is that? must be a miniature format thing. :)

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You only use that when shooting cars.:p

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Originally Posted by mobtown_4x5

"auto-focus" what the f is that? must be a miniature format thing. :)

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Blah blah!

A few of the pictures from the film. No keepers. I am forced to use a tripod...

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Originally Posted by modafoto

A few of the pictures from the film. No keepers. I am forced to use a tripod...

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Looks kind of grainy.

What developer did you use :D

Amazing! I think if you kept the shutter open a little longer the moon may have spelled "modafoto"! Without the quotes of course(that would just be ridiculous :) )

Mike

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Originally Posted by mikeb_z5

Amazing! I think if you kept the shutter open a little longer the moon may have spelled "modafoto"! Without the quotes of course(that would just be ridiculous :) )

Mike

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And dropping one picture and rearranging the others (15,9,10,13) spells MOON...