selmslie Loc: Fernandina Beach, FL, USA

MT Shooter's explanation is spot on. Another way of looking at it might help.

Imagine this process happening in slow motion. At very high shutter speeds the second shutter is following closely behind the first, so a narrow slit of light passes over the image. Each pixel gets exposed for the same amount of time, but not at the same time.

If the subject is not moving, this makes no difference. But if you take a picture of a speeding car and your shutter moves vertically, the top of the tires will be captured at a different time than the bottom, so they will not appear to be round but leaning forward or back depending on the direction the shutter travels.

So to answer your question, the whole sensor is exposed for the same amount of time at 1/25 of a second, but just not the same precise point in time.

GoofyNewfie Loc: Kansas City

Some film camera examples: Hassleblad (not the 1000f), Mamiya RB 67, later Bronica, twin lens reflex cameras, Crown Graphic, most large format cameras, film point & shoot cameras, a few 35mm slrs...Topcon Unirex & 100, Kowa.

Advantage to the leaf shutter is that you could sync the flash up to the max shutter setting, usually 1/500th. (the Super Speed Graphic went to 1/1000) The max on horizontal focal plane shutters was around 1/60, until the invention of the vertical shutter.

GoofyNewfie Loc: Kansas City

GoofyNewfie Loc: Kansas City

Interesting question. I think because it happens so quickly (partly because a leaf shutter has a shorter distance to travel), that it probably didn't make much of a measureable difference.
The fastest lens I know of for a leaf shutter was 1.7 on a Yashica Electro 35. My Topcon Unirex SLR had an f/2 50mm.

wilsondl2 Loc: Lincoln, Nebraska

I do not think you can get the oblong tire effect with DSLRs. The sensor size is not big enough and the shutter is moving too fast. The old time pictures you see with this effect were taken with 4X5 film. Also the shutter went down not sideways as on DSLRs. Since the shutter started on the top and the picture was inverted by the lens the bottom of the car was taken first then as the shutter slit went down the top was taken last. - Dave

GoofyNewfie Loc: Kansas City

DSLR shutters are vertical.
Maybe the old Speed Graphic shutters just traveled slower.... We know they had a lot farther to go.

MT Shooter Loc: Montana

All DSLR shutters lay horizontally, but travel vertically. This is primarily to allow for faster shutter speeds as the vertical travel direction corresponds with the narrowest dimension of the sensor making for the shortest travel distance.

jerryc41 Loc: Catskill Mts of NY

I like those pictures of the old racers. The tire illusion must have confused people back then.

selmslie Loc: Fernandina Beach, FL, USA

Yes, you can get the same effect with DSLR. The mechanics of a focal plane shutter are identical.

I have seen examples of it with modern racing cars. I just can't put my hands on a current example, maybe someone else will.

PhotoArtsLA Loc: Boynton Beach

This is a strange thread, with a mix of accuracy and lack of understanding. The problem is, weighing in on the side of accuracy, amidst a tide of lack of understanding, when accuracy has been mentioned... might just add to others puzzlement.

But, to have some fun... there are fast sync modes on most modern DSLRs allowing flash photography, ONLY WITH OEM SPEEDLIGHTS, at essentially all shutter speeds. Like 1/2500th. Or faster. This is very good for working with these tiny strobes, which really don't have sun crushing power, in sunny situations. The use of fast shutter speeds provides a workaround for the low power of the speedlight.

With professional strobes, you are limited by the given shutter mechanism. Focal plane shutters need to sync with the flash pulse to allow full exposure of the frame. Focal Plane Shutters are not fast enough for fast shutter speed shooting under pro strobes. With a DSLR, this limits the shutter speed to the rated "max" which is usually around 1/250th.

On cameras like the Hasselblad, with leaf shutters, which are sort of like a very fast iris which fully opens and fully closes for each shot. This type of shutter syncs at all speeds even with pro strobes because the mechanism is quick enough to allow it.

Simply put, the shutter must be open while the pro strobe is flashing.

It is not the case that each pixel "needs 1/200th of a second" even at fast shooting speeds.

selmslie Loc: Fernandina Beach, FL, USA

Leaf shutters are much slower (1/500 max) and much less precise. Even the best may be off as much as a half stop at the highest speed.

Since leaf shutters are normally used for longer exposures this is not normally an ssue.

wilsondl2 Loc: Lincoln, Nebraska

All DSLR shutters lay horizontally, but travel vertically. This is primarily to allow for faster shutter speeds as the vertical travel direction corresponds with the narrowest dimension of the sensor making for the shortest travel distance.[/quote]

I stand corrected. I thought DSLR shutters were like toh shutters on the old SLR. They do travel horizontally. - Dave

GHK Loc: The Vale of Eden

Agreed.
GHK

GoofyNewfie Loc: Kansas City

I sort of miss being able to open the back and see the actual shutter.
Bought a few Nikkormats recently to make some lamps.
(They still work!)
I took them to a boy scout photography merit badge class a few weeks ago and used them to show how the shutter works. Even hooked up a flash so they could see what happens when you pick a setting higher than the 1/125th sync setting. (The Nikkormat had a vertical traveling Copal shutter). They worked great as a teaching tool.

wilsondl2 Loc: Lincoln, Nebraska