Focal plane vs. leaf shutters in MF SLRs

Hi David ;-)

There is an easy way to see the difference between 30 lpmm images and
those well above that point for any film using photographer with the
interest and a softening filter (and if you don't have one of those, I
have a page telling how to make some at:
http://medfmt.8k.com/bronfiltersp.html#homebrew

After all, a softening filter acts like a low pass filter such as the ones
used for anti-aliasing effects in the majority of current DSLRs

you can "calibrate" your softening filter(s) by shooting a free test chart
(download from http://medfmt.8k.com/mf/resolution.html - USAF 1951 series
I find it takes at least a mid-strength (as in #2 fog) softening filter to
cut resolution down into the 40-50 lpmm range, but YMMV. The same test
chart can tell you how well and where your lens performs (try a few stops
down from wide open aperture esp.).

At this point, you only have to shoot some of your favorite subjects with
and without the softening filter in place. The shots with the softening
filter in place shows you what a 40-ish lpmm resolution limit looks like.
This level corresponds to the 50% MTF contrast or 40 cycles/sec or 40 lpmm
range David L. advocates for useful photography (or even lower, 30 lpmm?).

Now compare the same scenes shot without a softening filter in place. The
difference is the effect of adding in fine contrast and high resolution
data above 40 lpmm, up to the working limit of your lens(es) [as you found
out in your test chart series shot without filters from charts]. Simple!

For MF pro lens users, you will need to use really good fine grained
slower (slide) films, not prints, for a valid "first generation" test.
You also need to use good technique, including a sturdy tripod and the
right exposure (bracket if in doubt).

Now it is up to you to decide if there are useful improvements in your
images above 50% MTF, that is, without the softening filter in there.

Most of us who use softening filters know that there are differences, and
many pros can spot which softening filter they used on a given shot from
the amount of softening or lowered resolution/contrast they see on a shot.

If you want to see what 30 lpmm looks like on MF, you may need a #3
softening filter ;-)

grins bobm
--
************************************************** *********************
* Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 *
********************Standard Disclaimers Apply*************************

"Bob Monaghan" wrote in message
...

Hi David ;-)

There is an easy way to see the difference between 30 lpmm images and
those well above that point for any film using photographer with the
interest and a softening filter

That doesn't work, since one can't produce an image _with decent contrast_
at anything higher than 30 lp/mm.

David J. Littleboy

Tokyo, Japan

Yes, I often bring a manual with me in the camera bag; given I have over a
dozen MF cameras and more 35mm kits, it is handy to have and weighs only a
few ounces. And if somebody steals my kit (again), at least they'll be
able to use it right ;-)

I see China as really two countries, 150-250 million along the coast with
incomes now over $3.5K, and the rest in the rural countryside with average
incomes now still hovering around $350+. Once you get out of the big
cities and the coast, you are out of the first world infrastructure. As
noted, there are few computers and fiber networks in the hinterlands.
China has 8,500 of the world's 9,000+ large cement factories because the
roads are so bad in the hinterland that you can't ship heavy goods far.
The fastest way to send packages to the next town is often by air - by way
of Beijing or Shanghai, which may be a loooong trip ;-)

Mail order might work - for film. Would you mail off your digital hard
drive? Your costly memory sticks in an envelope? Or would you have to
setup your own PC and printer and get in supplies and all that, if you
lived there? If you were traveling thru, you could download to a portable
PC and various drives, and manage and review and edit your images etc. But
you would have to carry it along to do that. But for the billion folks who
live in those hinterlands, the infrastructure remains a critical issue...

# of MF in china, MF film processing etc.

From Modern Photography of March, 1982, p.70, SLR Notebook by Herbert
Keppler, 500,000 cameras were made in China in 1981; of which 90% or
450,000 were medium format TLRs (seagull, peafowl, pearl river TLRs); by
comparison, only 100 or so clones of the Hasselblad 500 series known as
East Wind were ever produced at the Shanghai Seagull factory, with only
the 50/80/150mm lenses ;-) [from my http://medfmt.8k.com/mf/seagull.html
pages] The cloning of the minolta SR-2 35mm cameras (of 1959 design) was
an increasingly popular alternative to those who could afford them too.

I have the seagull 203 folder (120 rollfilm) and the Great Wall DF-4 SLR
(which had only the 90mm lens for it readily available) which is a clone
of the German Pilot 6 from the 1930s. Excluding the export model Seagull
TLRs (with the japanese made shutter and 4 element lenses), most of these
Chinese made MF cameras would be decidely low end and 1930s technology,
with considerable quality control variations, and lack accessories etc.

So yes, there really is a base of low end MF cameras and 120 rollfilm
users, but import restrictions and tariffs have kept higher quality MF
cameras and resources like interchangeable lenses (even on the low end
Great Wall DF series SLRs) unavailable to Chinese pro and serious amateur
photographers. It would only take one tenth of the State biz enterprises
(100,000+) buying a single MF SLR to produce those 10,000 MF SLR sales ;-)

grins bobm
--
************************************************** *********************
* Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 *
********************Standard Disclaimers Apply*************************

In article ,
Gordon Moat wrote:

Fil Ament wrote:

All optical? For mini labs to survive they need some digital
capability. There are quite a few that still print from film, and
don't scan the negatives, but that justs a portion of their over all
process.

Some industry and company reports indicate that the photo finishing business in
China is largely switching to a digital mini lab system. I would think these
types of places would be much more common in China than purely optical labs.

I would think that to be smart business. In general the chinese are a highly intelligent/
industrious people I am sure MMV. In general I have a great deal of respect for
their culture.

So you decide to download to a PC and store on CDROMs. You go around town
looking for CDROMS. What are these plastic things used for, tea coasters?
No CDROMs.

Why do you suppose these would have to be purchased
on location?

It depends on where the photographer lives I guess. It depends on alot of
factors. I would think that major cities one could get just about anyting one
desires.

A casual look at retailers in China reveals these to be easy to get items, so I
think Bob M. was stuck in the past with the CD-R comments. Computers are still
very expensive, relative to income, in China, and not even close to the density
per capita as anywhere in North America, Europe, or Japan.

Yep the west undoubtably has it easy "for now".

Take care.
--
The joy of a forever Unknown Artist is the mystery and potential
of a Blank canvas.

This is a provision for the mind's eye.
I see the lights go on, but realize of course no one's home.

quoting David:
That doesn't work, since one can't produce an image _with decent contrast_
at anything higher than 30 lp/mm.
end-quote:

Well, David, this will be really bad news to all of us shooting MF with
pro lenses then ;-)

My view is that you can't produce an image with decent contrast unless you
have fine contrast detail, which requires pro quality MF lenses.

If this were true, then wouldn't we all be shooting with low end brownie
cameras and one element lenses? ;-)

grins bobm
--
************************************************** *********************
* Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 *
********************Standard Disclaimers Apply*************************

my impression is that Foveon feels that its X3 technology has such
benefits (vs. Bayer pattern chips) that they opted to pursue that path
instead of waiting until 0.18 micron IC fab lines could mass produce their
16 MP chip (when others were producing 3.3 MP chips in small volumes in
1998...). That may be a marketing error, or it may reflect the reality of
costs to bring these products to market, and the uncertainty of that
market. Foveon doesn't have the deep pockets or existing base of (Nikon..)
users to fund their R&D and create volume sales for new technology
roll-outs. So yes, they may remain a minor market element if they stick
with X3 sensor designs.

But somebody is going to produce a full-frame 16MP chip, and then we will
see if there is a market for a 32 or 64 MP sensor of MF size, for digital
backs or MF digital cameras or not? If not, then MF looks to remain a film
based enterprise. If yes, then we may see it as a niche market, but for
high end digital users as well as film types ;-) Or it may be that 16MP
will be "good enough", and a "medium format killer", as some here predict

time will tell ;-)

bobm
--
************************************************** *********************
* Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 *
********************Standard Disclaimers Apply*************************

"Bob Monaghan" wrote in message
...

quoting David:
That doesn't work, since one can't produce an image _with decent contrast_
at anything higher than 30 lp/mm.
end-quote:

Well, David, this will be really bad news to all of us shooting MF with
pro lenses then ;-)

Huh? You're the one who points out that people can't tell the difference
between different MF lenses!

I thought we were here doing MF because we understood that film can't
withstand a 10x enlargement without begining to lose quality. Presumably,
you've compared 11x14s from 35mm and MF? Did you see a difference? If you
didn't, why do you bother with MF?

If you did, what does that say to the claim that film resolves 100 lp/mm?

My point here is that limiting resolution is a meaningless measure. The only
reason we even bother with it is that we're too lazy to measure the MTFs.

David J. Littleboy
Tokyo, Japan

"Q.G. de Bakker" wrote in message li.nl...
Dan Fromm wrote:

Interesting that they claim better resolution for TMX than Kodak does.

Hm...
It would be highly surprising if two people measuring the same thing would
come to the excat same result. Even if one and the same person measuring one
thing twice would come to the same result.
So look at the relative values, how Kodak and Zeiss place for instance TMX
relative to other films.

I don't have the figures at hand, maybe you do? I'd be interested to know!

QG, I'm at home and my good bookmarks are, naturally, at work. On
Monday I'll direct you to the EKCo site, which is where I got the
info. If I recall correctly, Zeiss' claim for TMX beats what EKCo
claims for TP. Very curious indeed, if my memory is still working.

Cheers,

Dan

Dan Fromm wrote:

QG, I'm at home and my good bookmarks are, naturally, at work. On
Monday I'll direct you to the EKCo site, which is where I got the
info. If I recall correctly, Zeiss' claim for TMX beats what EKCo
claims for TP. Very curious indeed, if my memory is still working.

I'll find the EKCo site. Thanks!

Numbers that don't match are not that unusual. After all, test methods
rarely match too.
The thing is how the rate different films relative to each other.
Difficult to compare perhaps, since Zeiss rates only TMX, not TP (at least
not in CLN19). But then, they do have a number of Kodak films in their list,
so it should be possible to check the worth of the Zeiss numbers against the
Kodak numbers.

China has 8,500 of the world's 9,000+ large cement factories because the
roads are so bad in the hinterland that you can't ship heavy goods far.

Hi Bob. I don't fully understand what the connection is between cement
factories and bad roads, can you clarify please?