I hope that Mike D. would be kind enough to tell us what was nmeant by
the following:

"Stop Near Focus Far

f2.8 62.8 125.7 Infinity", etc.


Best regards,

DON

Don Lopp wrote:

> I hope that Mike D. would be kind enough to tell us what was nmeant by
> the following:
>
> "Stop Near Focus Far
>
> f2.8 62.8 125.7 Infinity", etc.

It looks like columns of data to me.

At f/2.8, when focused at 125.7 the depth of focus ranges
from 62.8 to infinity.
________________________________________
John Thurston
Juneau, Alaska
http://stereo.thurstons.us

Hi Don,

At 04:12 PM 11/9/2006, you wrote:

>I hope that Mike D. would be kind enough to tell us what was nmeant by
>the following:
>
>"Stop Near Focus Far
>
>f2.8 62.8 125.7 Infinity", etc.

The spacing I had created between the four columns of my table got
reformatted. I should have used underscore characters, like this:

Stop______Near______Focus_____Far

f/2.8______62.8_______125.7_____Infinity

The first column is the f/stop, second column is the distance to the Near
Sharp in feet, the third column is the distance to the plane of sharpest
focus in feet, and the fourth column is the distance to the Far Sharp
(Infinity for all stops in that table).

Here's the original paragraph that explained the table, followed by a new
table, with underscore characters inserted:


Assuming a desired resolution of 5 lp/mm as seen in a 75mm viewer that's
focused at Infinity, using a Maximum Permissible CoC Diameter of 0.059 mm
and a camera focal length of 80mm, here are the Near and Hyperfocal
distances (in feet) at various f/stops, for scenes that include Infinity
subjects:

Stop____Near____Focus____Far

f/2.8____62.8____125.7____Infinity
f/4______44.4____88.8____Infinity
f/5.6____31.4____62.8____Infinity
f/8______22.2____44.4____Infinity
f/11_____15.7____31.4____Infinity
f/16_____11.1____22.2____Infinity
f/22_____7.9_____15.8____Infinity

Mike Davis

John,

At 09:46 PM 11/9/2006, you wrote:

> >
> > "Stop Near Focus Far
> >
> > f2.8 62.8 125.7 Infinity", etc.
>
>It looks like columns of data to me.
>
>At f/2.8, when focused at 125.7 the depth of focus ranges
>from 62.8 to infinity.

That's right. (You had already answered the question...)

Thanks,

Mike Davis

After several emails to China about the 1 Fstop difference between my
lenses, I was told such a difference would not make it through their
quality control. Strange then that the difference in apertures is
exactly two clicks on the aperture ring or exactly 1 Fstop. In
frustration and not looking forward to more email volleys with the
inherent time and language difference delays, I removed the four screws
that hold the lens board in to have a look. The camera appears to be of
very simple construction so that repairs should not be too difficult. I
was interested in seeing if the gear between the lenses could be removed
so that I could align the apertures, but it appears to be attached by a
bolt needing a proprietary tool. However the lenses appear to be
mounted by three small screws, so removal of one lens to make my
adjustments should be an easy thing. However I will wait out the
frustrating email process before attempting anything other than the
opening -the-hood that I have already done.

Dale Yingst

> .
>
>