The Pentax 67 units are very mechanical. The 67II give you some automation.
The Pentax 645 gives you a lot of automation and convenience features.
Then, there's the negative size.
35mm is 3.6 cm x 2.4 cm = 8.64 sq cm
645 is 6 cm x 4.5 cm = 24 sq cm
67 is 7 cm x 6 cm = 42 sq cm
4x5 is 12 cm x 10 cm = 120 sq cm
Obviously, the bigger the neg the sharper the print.
In results, you'll be hard-pressed to differentiate between a
6x7 neg enlarged to 16x20 and a
4x5 enlarged to 16x20.
A 4x5 can give you something fun to work with -- lens movements.
A 4x5 allows you to treat each frame differently. Over expose, underexpose,
process accordingly. Can't do that with roll film, at least not without
great expense.
A 4x5 can also be cheaper than a medium format.
Busch 'D' Pentax 67
Body $200 $400
Wide Angle 90mm $200 75mm $400
Normal 150mm $200 90mm $400
Portrait 210mm $250 150mm $300
===== =====
$ 850 $1,500
(Lenses chosen for 4x5 would be Schneider: 90mm Angulon, 150mm Symmar, 210
Symmar-S @ Ebay prices.)
You'll spend another $150 on film holders and a changing bag.
Film tends to run $1-$4 per shot, and that will add up quickly.
A 4x5 is a LOT more work.
You can pick up a 67 or 645 and just start shooting.
Can't do that with a 4x5, at least not very easily.
There are "cheap" lenses for 4x5 as well. Avoid them if you want to
justify the expenditure.
You might was well stay with 35mm as shoot with an Optar. (imnsho)
You can move the lens on a 4x5 for improving or manipulating DOF.
Just one movement (shift) on a Pentax 67 will cost you about $1000.
A little tilt on a 4x5 can enhance landscapes, allowing you to
shoot with a larger aperture, thus a higher shutter speed.
The cost of a good enlarger for either is about the same.
Expect to spend $300 for something nice, no matter the format.
Have fun,
Collin (the hobbyist with not enough tiem to shoot)
