focal plane v diaphragm

[cliveh]

I'm sure there are + and - points for each, but which type is more efficient?

 

[benjiboy]

I don't know but diaphragm shutters are quieter and will synchronise for flash at any speed.

 

[Ian Grant]

I have cameras with both, you chose at the time of exposure They aren't 35mm though.

Leaf shutters aren't practical with interchangeable lenses and Zeiss Ikon learnt the hard way losing market share rapidly to Japanese manufacturers of SLR's with focal plane shutters.

Ian.

 

[Arklatexian]

I assume we are talking about shutters here. To answer your question, my experience is that the focal plane shutter is technically more efficient while the blade type shutters are usually more useful, especially with flash, etc. I think this question usually comes up more with MF and with LF than with 35mm RF. I haven't seen very many blade type shutters in 35mm. A few, yes, just not very many...Regards!

 

[cliveh]

To answer your question, my experience is that the focal plane shutter is technically more efficient

But why?

 

[pdeeh]

Physics

 

[cliveh]

Physics

Please explain.

 

[MattKing]

Within-lens shutters have a limited range of short exposures, and constrain lens design options. They also add complexity with respect to camera to lens linkages and inconsistencies in exposure between lenses.
They also add expense for those who wish to own multiple lenses, because they force you to buy multiple shutters.
I expect that they also make it difficult to design large aperture lenses.

 

[cliveh]

Within-lens shutters have a limited range of short exposures, and constrain lens design options. They also add complexity with respect to camera to lens linkages and inconsistencies in exposure between lenses.
They also add expense for those who wish to own multiple lenses, because they force you to buy multiple shutters.
I expect that they also make it difficult to design large aperture lenses.

They don't seem to constrain lens design options for Hasselblad.

 

[Steve Smith]

Leaf shutters aren't practical with interchangeable lenses

Not practical but still possible. I have three Kodak Retina Reflex IIIs which remarkably, still work. The operating sequence for these is very complex as the shutter has to be open for the viewfinder to work. When the shutter button is pressed the shutter closes, the mirror swings out of the way, the light baffle moves away from the film, the shutter opens then closes after the required time then when the film is wound on, the light baffle closes, the mirror returns and the shutter opens ready for the next time.

By comparison, the focal plane shutter is much easier with a reflex camera. The Kodaks are some of my favourites though.


Steve.

 

[benjiboy]

They don't seem to constrain lens design options for Hasselblad.

You don't get 1/8000 sec. with a Hasselblad the top speed is only 1/500 sec as with all leaf shutter lenses.

 

[MattKing]

They don't seem to constrain lens design options for Hasselblad.

Ever see anything akin to a 24 - 105mm zoom for a Hasselblad?

This is the 35mm forum, after all.

 

[cliveh]

You don't get 1/8000 sec. with a Hasselblad the top speed is only 1/500 sec as with all leaf shutter lenses.

But that is not in real time, as a FP works within a time span.

 

[Dan Fromm]

Leaf shutters aren't practical with interchangeable lenses <snip>

Interesting. Why are there so few view cameras with focal plane shutters?

I agree with you with respect to 35 mm still cameras and cine cameras of all formats, although some (many?) cine cameras' shutters are better thought of as "behind the lens" than "focal plane."

 

[Dan Fromm]

http://www.1839.org/obtus/perf/rendement.html?lang=en

 

[cliveh]

http://www.1839.org/obtus/perf/rendement.html?lang=en

I have read the link, but not sure what the conclusion is.

 

[Bill Burk]

I have read the link, but not sure what the conclusion is.

It's an explanation with graphic representation of the efficiencies of shutters, as you asked.

So my opinion, in a 35mm camera, a focal plane shutter is about the best kind. I like when they are mechanical and of fine construction quality, but have to admit an electronic focal-plane shutter is probably the most precise.

I don't know any electric leaf shutters, so the only fair thing would be to compare mechanical to mechanical.

With a focal plane shutter, mechanically you need to get the base speed precise. Then the curtain openings are the only changes to make. So long as both curtains travel the same speed, and the first curtain starts rapidly, you will get an accurate exposure.

A leaf shutter needs to get its higher speeds through faster and faster action against resistance. Some achieve their high speed by an extra spring, whose tension might vary over its lifetime.

So I think focal plane shutters are more easily kept accurate at the higher speeds.

Slower speeds, I think both kinds would be the same, since it's the time for escapement to pass its course.

 

[Sirius Glass]

Lens shutters are limited to 1/500 second. Focal plane shutter can have shorter shutter speeds. My 1953 4"x5" Pacemaker Speed Graphic has both.

 

[Peltigera]

My Minolta Uniomat has a leaf shutter and a top speed of 1/1000. That is plenty fast enough for my needs - I generally use shutter speeds of between 1/100 and 1/300. I have never used shutter speeds in excess of 1/1000 even on my cameras that can.

I prefer leaf shutters because they are next to silent and cause no vibration.

 

[Dan Fromm]

I prefer leaf shutters because they are next to silent and cause no vibration.

Interesting. View camera users insist that some leaf shutters cause severe vibration.

About FPS vibration. I have a 2x3 Graflex RB Ser. B. Huge shutter and mirror in comparison with 35 mm SLRs. The mirror makes a thud when it hits its stop on the way up, the shutter makes a tremendous bang when it closes. I've shot it mirror up and then vibration during exposure is minimal. There's still the bang but since the shutter is closed before it stops it should have no effect on the image on film. Could wake the dead, though.

 

[Les Sarile]

The OM4+F280 combination allows flash sync across all speeds up to 1/2000.

I believe there are other focal plane cameras that do as well.

 

[cliveh]

If FP shutters are that good, why does my Hassy have a facility to lock the mirror up and use the leaf shutter for exposure? To presumably cut down on vibration.

 

[Sirius Glass]

If FP shutters are that good, why does my Hassy have a facility to lock the mirror up and use the leaf shutter for exposure? To presumably cut down on vibration.

I never had a vibration problem with a Series V Hasselblad.

 

[Bill Burk]

Hasselblad is a professional's camera. If you are shooting and one shutter malfunctions... There is always the other.

 

[lxdude]

I don't know any electric leaf shutters, so the only fair thing would be to compare mechanical to mechanical.

The RZ 67 and the leaf-shutter Bronicas use electronic Seiko shutters. Top speed is machanical-all others are are timed electronically.

With a focal plane shutter, mechanically you need to get the base speed precise. Then the curtain openings are the only changes to make. So long as both curtains travel the same speed, and the first curtain starts rapidly, you will get an accurate exposure.

Amazing how accurate they are over the frame, considering that the slit has to vary in width during exposure to account for the curtains accelerating during traverse.