Re: lens questions

----- Original Message -----
From: "Barry Kleider" <bkleider@sihope.com>
To: "alt-photo-process-l@skyway.usask.ca"
<alt-photo-process-l@sask.usask.ca>
Sent: Tuesday, July 05, 2005 11:31 PM
Subject: lens questions

> Last week, I was shooting some welders.
>
> My ultimate goal was to shoot them with a Hasselblad and a
> 150 f4 lens.
> (No internal meter.)
>
> Since these exposures are obviously tricky, I started with
> my Nikon D-1
> and a Tamron 28-70 f2.8
>
> I was getting some decent exposures - nothing great, but
> certainly
> within tolerance for a first attempt. So I decided to
> switch over to the
> Hassy using the same readings.
>
> Since the Nikon was running at ISO 200 and my provia is
> 100, I gave it a
> full stop. I got the lab results today: $%#^$%.
> (Translation: way too
> dark and looks like s**t.)
>
> So my question is: what's the relationship between a
> medium format Hassy
> with a 150 f4 lens, and a 35mm Nikon with a 28-70 f2.8
> lens (running
> close to 70 if not full on)?
>
> I assume there's a very straight-forward (though possibly
> hard to
> follow) explanation having to do with the difference in
> lens designs
> rather than a format comparison or a digital vs. analog
> thing (as my lab
> guy surmised.)
>
> Barry
>
   Re-reading this at a decent hour I see I misinterpreted
it before. The difference in exposure between modern coated
lenses at the same f/stop should be minimal regardless of
any difference in the design of the lens or format or
maximum speed of the lens. I think that the difference is
either something in the way the digital camera adapts to
exposure or, perhaps, the Hassy shutter is fast (unlikely
IMO). Its certainly not the lenses unless one of them is
defective.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com