Focal plane vs. leaf shutters in MF SLRs

wrote in message
...
Enough with the design details - which one provides the sharpest image
overall?

Thanks

Leaf shutters typically vibrate less- certainly comparing my 'Blad or
Bronica lenses with a Pentax 67, it is a tangible difference. So in that
scenario, the leaf shutter would provide sharper images. But a rangefinder
with a FP shutter might vibrate less than an SLR with a leaf shutter, and
hence be sharper still. And a rangefinder with a leaf shutter might
potentially be even sharper...

Personally i'd aim for a camera whose shutter is moved by faeries on rocket
boots. Failing that, I don't much notice the vibes from a leaf shutter SLR.

--
- Martin Francis

"Two hundred channels, and nothing but cats"
- Jasper

wrot

Enough with the design details - which one provides the sharpest image
overall?

Sharpness is in the lens. It doesn't matter what shutter you use.

Some people (myself, for example) feel that the leaf shutter has less
vibration and it's a good thing. I won't get into arguments about this.
Suffice to say, I always pre-fire the 500c when shooting on a tripod. If
you feel the same way, then a leaf shutter is the way to go - IMHO.

Yesterday I walked down the photogaphy aisles in the university library and
found a book that showed how shutter speed related to sharpness. There were
noticable differences (at admittedly ridiculous magnification) in hand-held
1/250th pictures compared to tripod shot 1/250th, but it makes sense - a
fraction of a millimeter of movement at the camera is hugely magnified.

shutter and related camera vibration sources can be significant limiting
factors at the higher resolution levels; Dr. Skudrzyk's Photography for
the Serious Amateur notes that his results for lenses were typically 1/3rd
higher than often reported in other tests, which was largely credited to
using short duration studio flash for exposure, thereby minimizing camera
related vibration (and these tests were on seriously heavy tripod setups).

as jjs noted, tests show some degradation at speeds as fast as 1/250th
See chart at http://medfmt.8k.com/mf/vibration.html

even more shocking, the value of mirror lockup may surprise many
photographers, including many whose current cameras don't offer this once
common feature, see http://medfmt.8k.com/third/mlu.html chart of Pop tests
telephotos gained circa 100% (135mm) to 170%+ (300mm) when used with MLU
on sturdy tripods at speeds around 1/15th to 1/60th second etc. Yeech! ;-)

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

Thanks all. I learned a lot.

"KM" wrote in message
...
I was cleaning my RZ and began wondering why each lens must incorporate
its
own leaf shutter, then began wondering why we find leaf shutters only in
lenses. I understand why the shutter has to be in the lens for rangefinder
systems (proxmity of wide-angle rear elements to focal plane =
insufficient
space), but why couldn't they be incorporated into SLR bodies?

In current leaf-shutter systems like the Bronica ETR and Mamiya RB/RZ,
doing
so would make the lenses smaller and lighter. In focal-plane systems like
the Pentax 645N, you'd get flash synch at any speed.

I'm sure there's a perfectly good explanation I'm overlooking.What is it?

In article , (Bob
Monaghan) wrote:

[...]
even more shocking, the value of mirror lockup may surprise many
photographers, including many whose current cameras don't offer this once
common feature, see http://medfmt.8k.com/third/mlu.html chart of Pop tests
telephotos gained circa 100% (135mm) to 170%+ (300mm) when used with MLU
on sturdy tripods at speeds around 1/15th to 1/60th second etc. Yeech! ;-)

Thanks for the pointer to the excellent articles, Bob.

One more thing - I can show how the wrong cable release can lead to camera
shake. My favorite release is the long (about 12") thin type, however I
got a 'deal' on some short, high-tech heavy releases. What a huge mistake.
Sighting down the side of a 500mm lens I could see the lens and camera
move as I depressed the release. Bad! I switched to using the camera's
self-timer and the differences in the negatives were profound.

jjs wrote:

Sharpness is in the lens. It doesn't matter what shutter you use. [...]

That doesn't quite tally with the rest of what you wrote, i.e. that shutter
caused vibration can indeed reduce sharpness.

One other thing to consider is that SLR cameras using leaf shutter lenses
must have a second "shutter" to shield the film while viewing through the
open leaf shutter. That thing too will cause vibrations, so it's design too
will matter very much.
In some SLRs using leaf shutter lenses, this extra shutter even is a focal
plane shutter.

Use of a tripod and prereleasing the camera is the only way to benefit from
the relative lack of shutter induced vibration associated with use of leaf
shutters.
(And anyway, use of a tripod is far more important than choice of shutter
type.)

Martin Francis wrote:

Personally i'd aim for a camera whose shutter is moved by faeries on
rocket
boots. Failing that, I don't much notice the vibes from a leaf shutter
SLR.

Kerr-cell type electronic shutters don't move at all. Capable of
fantastically fast speeds too.
With (slow) liquid crystal technology where it is today, i can't help but
wonder why we haven't seen any developments in that direction.

I hate to play devil's advocate (OK - I like playing that role) but as most leaf
shutters are designed in between the lens elements, doesn't that inhibit lens
design? Could the anecdotal stories of Biometars outperforming Planars could be
as a result of the Biometars being mounted to a camera using a FP shutter and
the Planars using between the lens, leaf shutters?

jjs wrote:

wrot

Enough with the design details - which one provides the sharpest image
overall?

Sharpness is in the lens. It doesn't matter what shutter you use.

"Martin Francis" m wrote in
message ...
[snip]

Personally i'd aim for a camera whose shutter is moved by
faeries on rocket boots.

Didn't Black Sabbath write a song about that?


Peter

Kerr-cell type electronic shutters don't move at all. Capable of
fantastically fast speeds too.
With (slow) liquid crystal technology where it is today, i can't help but
wonder why we haven't seen any developments in that direction.

How about 'Because the light has to go THRU the device, and that itself
degrades the image. And it provides additional surfaces on which dust
collects. Digital SLR suffer from the need to keep the CCD clean of dust, so
imagine how a light-shutter would affect things, too!