[MF3D.FORUM:1209] Re: Sputnik focus fix

["Don Lopp" <dlopp@xxxxxxxxxxxxxxx>]

Sorry about the slow responce but  my mental capabilities have been greatly
deminished of late ,my responce as reguards to to adjusting the focus on
sputnik cameras I indicated  should be a simple proceedure if a ground glass
is used at infinity , I do not seehow it can take more than one minute per
lens to make this adjustment if focussing on infinity which should allow for
the mosst precise adjustment which is not a quick and dirty adjustment as
indicateted.--do we have the blind leading the blind again or what? I am not
sure . My mental problems are the result of not being able to sit or stand
any more except with much pain after visiting tthe pain clinic at ythe
University of Washington, at Seattle , Washington ..I will try to end this
by saying that there is only ONE infinity point but there is there are many
15 ft points depending on the accuacy required-- 15.0 ft, 15.01 ft , 15..02
ft. or 14.99 ft or14.9999ft but there are many points close to 15 ft but
there is only one point at infinity from your  position. I can still
remembering measuring points on B 52 s to an accaracy of 23.049 ft but we
were using quite elaborate equipment. What I am trying to say is that
infiity is a precise point whereas 15 .00 ft is not a precise point unless
one has the equipment to make it so. I can see Mt.Rainier which is about 40
miles away which I consider to be to be " near infinity ". I dont measure
it. It is either sharp or it is not sharp assuming the lens iscapable of
being sharp which can be a question with Sputnik optics.  May be that in
Austin, Texas --because of haze and flat countryside [ I have never been
there] infinity is difficult to find or see!!
                               Don
----- Original Message -----
From: "Paul Talbot" <ptww@xxxxxxxxx>
To: "Medium Format 3D Photography" <MF3D.Forum@xxxxxxxxxxxxx>
Sent: Tuesday, August 22, 2000 5:24 PM
Subject: [MF3D.FORUM:1134] Re: Sputnik focus fix


> Don Lopp wrote:
>
> > Sputnik focus first $35 seams a bit high to me,
>
> Based on how long it took me to do a few of them the last
> couple days, it would have been a superb bargain when
> calulated as an hourly rate!  I was on the steep part of
> the learning curve, and working on developing my techniques.
>
> > in any event  it is best to determine focus at
> > infinity, not at any inter mediate distances because of
> > depth of focus problems.
>
> Most sources talk about setting focus based on infinity, but
> I'm not sure I understand why, except that it seems to be far
> less demanding.  Setting focus based on, say, 15 feet, requires
> far more precision.  It seems to me that two lenses that appear
> to be in synchronized focus at infinity could easily be off by
> several feet when focus is changed to a closer distance.
>
> So my tentative conclusion is synchronize focus at infinity
> for a "quick and dirty" solution, but synchronize focus at
> a much closer distance for pinpoint accuracy.  Am I going
> wrong somewhere?
>
> Paul Talbot
>