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Charlie
Tinkerer
Username: Charlie
Post Number: 102
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, October 01, 2007 - 06:21 am: | 
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The thread on focus shift reminded me of a topic which has always puzzled me - if you are designing a fixed focus lens for a Baby Brownie, box camera or a low end digital camera how do you get reasonble sharpness from 3 feet to infinity? Will intentional S/A plus an f11 diaphragm give you reasonable sharpness over the entire range as opposed to a sharper image at a specific distance? |
Adrian
Tinkerer
Username: Adrian
Post Number: 87
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, October 01, 2007 - 07:18 am: |
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Given the plethora of cameras with "in for places, out for faces" lenses and portrait attachments, I suspect that a range of three feet to infinity is stretching it a bit - I suspect that something close to eight to ten feet outwards is more like it for most cameras, which was probably rather easier to design for.
It would also be quite easy to extend the depth of field using Waterhouse stops, as the pre-620 No2 Box Brownies did. With three apertures approximating f10,f20 and f30 you could get very good sharpness over quite a wide distance - see this for one I took, on 100-speed film and almost certainly at f30.
http://ph.groups.yahoo.com/group/browniecamera/photos/view/bf3a?b=3
Adrian |
Charlie
Tinkerer
Username: Charlie
Post Number: 103
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, October 01, 2007 - 08:53 am: |
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The digital fixed focus cameras, such as the Kodak C530, don't have waterhoue stops but advertise a range of 3.3ft. to infinity. It does have a short focal length lens (36mm equivalent) which must help.
Also I don't think th Baby Brownies had stops. |
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