Acceptable DOF is calculated based on the circle of confusion which varies by format.
At 08:20 AM 7/24/03 -0400, you wrote:
Isn't DOF computed via f stop, regardless of format? I do know that a 165mm lens projects an image the same size on the film regardless of format. In other words, if a 165mm lens forms an image 1cm high on 35mm film, it will also form an image 1cm high on 120 film, the difference being that the image comprises a larger area on 35 than on 120.
Bill
----- Original Message ----- From: "Steve Larson" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, July 24, 2003 7:28 AM Subject: Shallow DOF with 6X7 lenses (was: 6x7 lenses - Brotherhood comments solicited)
> Why do 6X7 lenses have a shallow depth of field even stopped down > all the way? Chris mentioned it with the 165/2.8. Are they all like that? > I could understand it if it was at close focus with tubes WO, but for a > landscape shooting at infinity? Please enlighten me. > Steve Larson > Redondo Beach, California > > > Chris Stoddart wrote: > > Well I have the old Tak 105/2.4 and it's really sharp - not a complaint > > against it. My 165/2.8 (newish model) is also sharp, but it has a shallow > > depth-of-field, even stopped right down which makes it a bit of a pain > > for landscapes. I also have the final model 75/4.5, which is just > > excellent apart from a dimmer viewfinder. One difference between the three > > is weight - as they get newer they seem to get lighter, so the 75, depite > > having the largest front element, is by far the lightest of my lenses. > > The build quality doesn't seem to suffer though as the 75's focus is the > > smoothest of any lens I've owned. Next purchase will be a late model 45 or > > 55 - by all accounts the newest 55 is among the sharpest lenses Pentax > > have built. > > > > > Regards, Bob S. (considering joining the Brotherhood) > > > > Join, you won't regret it! > > > >
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the post office, even the sleaze.
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