Re: Exact fl of lenses... 220 VR

[Andy Buck <buckwiet@xxxxxxxxx>]

All this work just to figure out how to use a camera
that costs *that* much? Unbelievable. For that much
money, I'd expect to set it up and use it, or at
least, find complete instructions and charts included.
IMMHO!

--- Bill Glickman <bglick@xxxxxxxx> wrote:
> 220 VR users:
> 
> Here is the results of my testing....
> 
> After extensive testing I have concluded the
> following... I would hate for
> anyone to have to go through 60 rolls of film like I
> just did.
> 
> Mr. Seitz says that one needs to determine the exact
> fl down to .05mm for
> images to be sharp.  As I mentioned in prior posts,
> I felt the best way to
> accomplish this was shooting a building with a known
> aspect ratio and then
> match this ratio on film.
> 
>       I succesffuly accomplished this down to .1mm
> per lens.  However, I was
> suspicious if under different rotational speeds the
> same exact fl would hold
> true.  It would take some really precisioned motor
> gearing for this to
> occur.    For example, at 1/15 speed, my 150mm lens
> computed consistently
> out to be 146.3mm.   However at 1/125, the lens
> computes out to be 149.0mm.
> So, as you can see, to have an exact fl for a lens,
> one must test this for
> each shutter speed.  Then enter into your brain box
> the fl value that
> matches the shutter speed selected.  In other words,
> you would need about 9
> exact fl values for each lens to be sure you are
> accurate, at any shutter
> speed.  (to be fair, I did not test at all ss, just
> a few, but the pattern
> was obvious)
> 
>       So all my testing was in vain, because at
> different shutter speeds the
> exact fl varies ... I can't spare 2 weeks and  200
> rolls of film to figure
> this out for each shutterspeed.  Therefore, to me,
> it does not make sense to
> try to nail each fl so exact, unless you are willing
> to do it for every
> shutter speed you plan to shoot at.
> 
>          So for me, its boiled down to an
> estimate....  Sure wish this was
> in the manual?  Bottom line, .05mm is a unrealistic
> goal, and even .1mm will
> only reproduce itself at the shutterspeed it was
> tested at.
> 
>       Anyone have a different experience?
> 
>       I also tested different film speeds and the
> auto exposure... the auto
> exposure it apperas requires much tweaking to
> prevent banding.  As for the
> different shutter speeds, at 1/250 and sometimes
> 1/125, uneven film uptake
> can be seen... It seems best to shoot at slower
> shutter speeds...
> 
> Hope this can benefit some users....
> 
> Regards
> Bill G
> 


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