On 02/08/2001 17:58, Bill D. Casselberry opined:
> JoMac wrote:
>
>> If you're doing Macro, use a bellows instead of a Macro lens, and you've
>> got a Micro Focusing Rail built in with the bottom positioning block!
>
> Hmmmm, not *exactly* (at least w/ simple bellows :-)
>
> a bellows will replace the helicoid extension, but a rails
> will allow the entire body/bellows/lens assembly be moved
> into focus at whatever point a given extension dictates.
> (magnification is the "set factor")
>
> bellows alone permit focusing from the fixed position of
> the system, the magnification then falls into place w/ the
> amount of extension.
> (magnification is dependent upon camera distance at focus)
>
> rails make focusing easier while maintaining a particular
> composition, though the entire tripod can (sometimes) be
> moved to the same end effect as w/ a rails - much more of
> a nuisance, though.
What you're telling me, Bill, is that you own the only one of Pentax's
Bellows systems that DOES NOT have a tripod rail block as well as the
camera and lens rail blocks. That would be the Bellow1, address:
http://members.tripod.com/~McHil/gfx/bellow1.jpg
All the rest, screwmount and K-mount, do have the capability of moving
the entire unit forwards and backwards without changing magnification
using the separate geared tripod block (though, as with the Macro Rail,
it will change the image composition).
http://members.tripod.com/~McHil/gfx/bellslid.jpg
http://www.phred.org/pentax/k/macro/bellows_auto.jpg
http://www.phred.org/pentax/k/macro/bellows_III.jpg
The Macro Rail:
http://www.phred.org/pentax/k/macro/macro_rail.jpg
I made one out of an old Focobell A2 bellows that the camera body block's
upright had broken off (pot metal - I dropped it)). It is a two parallel
tubular rail design, with the lens block on it's own micro rail, as well
as the block itself being adjustable by sliding and locking, as is the
tripod and broken block.
So I ground off the rest of the body block that was sticking up, and
removed the lens mount upright (screwed in with 3 screws) and threw the
bellows cloth away. Now I have a 3" long steel plate on a micro adjuster,
5 mounting screws (the name plate has 2), and had machined an upside down
'U' with feet _O_. The feet are drilled and countersunk for the screws,
the top of the mod is tapped for 1/4 20, which has threaded though it a
long shaft wide knob head camera tripod socket screw with only 4 turns of
thread on the end.
Mount the camera (any) on the micro rail part, and you've got course
adjustment by moving either the (now) camera block, or the central tripod
block, and a fine adjustment for final composition.
I also have the Pentax Auto Bellows (for screw mount), the Auto Bellows A
(For K Mount), both full length (170mm) and will both take the either the
Asahi Pentax Slide Copier or the Pentax Slide Copier A, as well as the
same magnetically held extension length or magnification scales for
normal or reversed lenses. Both have reversible lens blocks to make
mounting any lens reversed easy. They also have interchangeable camera
body mounting rings (though not between the units, they are different
sizes and depths, wouldn't you know). So I can use either my Pentax K,
M-42 Screw, or Canon FD bodies, or any other if I purchase the proper
rings from Pentax.
I also have the smaller (130mm) Pentax Bellows Unit III, which has the
scale built in, a smaller slide copier unit, and none of the other
features of the larger units.
I once had a Pentax 6 x 7 bellows and slide unit (couple of feet long!)
that I picked up for a trade - only had $230 in this very expensive
accessory. Figured I'd never get into P 67, so I sold it for $850 on eBay
a couple of years ago. Of course, now I have a 67. It'll take me forever
to collect 67 pieces to make it more useful!
OK, enough rambling. Get a better Bellows Bill!
JoMac, Imagineer with Camera
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