David Hughes
David Hughes
The brochures tell me the camera is fitted with a "Universal Focus" lens and I -perhaps stupidly - think that means fixed focus.
Both the brochures and the instruction book tell me the programmed shutter works from f/4 to F/22 and, in use, everything from 5 feet to infinity will be in focus. The (1982?) brochure adds to that that it has "The bright and sharp f4 lens".
I cannot see how at f/4 the DoF can be from 5ft to infinity. Looking at DoF tables I see 5ft to infinity comes at about f/16 when focussed at 40 ft. Not f/4 by a long stretch, especially when 40 ft gives about 18 ft to infinity as the DoF at f/4.
There's another clue in the instructions; with flash you stand the subject 2.3m or 7'.6" away from the camera. The diagram suggest that this is where the fixed focus point is but 7'.6" at f/4 gives DoF from about 6ft to over 9ft. Nothing like 5 ft to infinity...
Most DoF tables use a CoLC of about a 1000th of an inch, make it bigger and the DoF might be obtained but what size print could you get? The brochure implies 5" x 7" based on implied sample shots...
Using the camera only on bright sunny summer days and with a fast 400 film (all the camera takes apart from 100 ISO) it might have the DoF they give but I can't see how it can be done any other way.
None of this bothers me in practice - it's a splendid carry all day camera and no batteries required - but the mathematics keep bugging me and give me sleepless nights now and then.
Regards, David
Both the brochures and the instruction book tell me the programmed shutter works from f/4 to F/22 and, in use, everything from 5 feet to infinity will be in focus. The (1982?) brochure adds to that that it has "The bright and sharp f4 lens".
I cannot see how at f/4 the DoF can be from 5ft to infinity. Looking at DoF tables I see 5ft to infinity comes at about f/16 when focussed at 40 ft. Not f/4 by a long stretch, especially when 40 ft gives about 18 ft to infinity as the DoF at f/4.
There's another clue in the instructions; with flash you stand the subject 2.3m or 7'.6" away from the camera. The diagram suggest that this is where the fixed focus point is but 7'.6" at f/4 gives DoF from about 6ft to over 9ft. Nothing like 5 ft to infinity...
Most DoF tables use a CoLC of about a 1000th of an inch, make it bigger and the DoF might be obtained but what size print could you get? The brochure implies 5" x 7" based on implied sample shots...
Using the camera only on bright sunny summer days and with a fast 400 film (all the camera takes apart from 100 ISO) it might have the DoF they give but I can't see how it can be done any other way.
None of this bothers me in practice - it's a splendid carry all day camera and no batteries required - but the mathematics keep bugging me and give me sleepless nights now and then.
Regards, David
petronius
Veteran
If you start asking ... (remember Elsa and Lohengrin?)
Seriously I thought similar about the XA2 and wondered why the pictures even in low light came out so good. Now I´m just enjoying it!
I don´t use the XA1 anymore, because I hate the low light release block.
Seriously I thought similar about the XA2 and wondered why the pictures even in low light came out so good. Now I´m just enjoying it!
I don´t use the XA1 anymore, because I hate the low light release block.
David Hughes
David Hughes
Thanks - nice to know I'm not alone...
Regards, David
Regards, David