RE: slightly OT - lenses and closeup

OK, since we've ventured this far afield. What about the use of
"close-up" filters on larger view camera lenses. I recently purchased
a 300mm Nikor M for my 4X5 field camera - a Tachihara which has barely
enough bellows extenstion to focus the lovely piece of glass at
infinity. I am using a Nikon +1 closeup filter and having a good deal
of success using this lens in many more scenes. QUESTION: Is this
heresy or just a slight optical compromise? I've nothing to really
judge against, since the lens was never able to focus this close
before... everything looks pretty sharp to my eyes.

Darryl

-----Original Message-----
From: Ryuji Suzuki [mailto:rs@silvergrain.org]
Sent: Sun 12/7/2003 10:28 PM
To: alt-photo-process-l@sask.usask.ca
Subject: Re: slightly OT - lenses and closeup
 
Lenses can focus at any close distance you want as long as the lens
barrel can extend enough. The required extension is determined by the
focal length of the lens and the distance. As the photosensitive image
transducer size shrunk from 35mm to digital (most consumer digital
cameras have image sensors smaller than the image size of 35mm
format), required focal length to achieve the same angle of view is
much reduced. This in turn reduced the required lens extension
required to focus on a close subject, thereby allowing greater closeup
focusing capability with a limited physical dimension. It's more
analogous to the fact that 35mm cameras can usually focus at objects
much closer than what 8x10 cameras are capable of, rather than
advancement of optical technology.

--
Ryuji Suzuki
"Reality has always had too many heads." (Bob Dylan, Cold Irons Bound,
1997)