focal plane v diaphragm

[pdeeh]

All this anxiety can be avoided by the simple expedient of using one's opera hat to cover and uncover one's lens.

 

[cliveh]

All this anxiety can be avoided by the simple expedient of using one's opera hat to cover and uncover one's lens.

Quite, but what does an opera hat look like?

 

[flavio81]

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.

And this is also an "un-honest" way of freezing time, since what it is done in this case is to have the flash emit bursts of brief pulses.

Consider 1/1000 speed again in this camera. Think of it -- the narrow slit of the focal plane shutter travels horizontally while several separate burts of flashes are emited... OM-4 TRUE sync speed is 1/60. So what is really happening is that in the amount of 1/60 seconds, many vertical slits that represent a different point in time are joined together left to right in a poor excuse for an image. Yucky yuck.

While, again, a machine with a leaf shutter at 1/500 will expose ONE full flash burst at the ultra quick speed of 1/500 with total honesty, truth, and humbleness.

Say NO to the conspiracy created by a company that fooled us previously with the idea that "compact" and "smaller" is better, spawning generations of whiney photographers that complain of camera weight and such nonsense!!

We won't get fooled again!! Reject the slow focal plane shutters and embrace the POWER of the LEAF!!

 

[cowanw]

That's nonsense though. All parts of the lens transmit light to all parts of the film.

As an inquisitive child, I once covered up half of the projector lens during one of my father's slide shows expecting half of the image on the screen to disappear. That doesn't happen though. All you do is reduce the intensity of the whole image.


Steve.

Which makes me wonder how graduated filters work?

 

[Steve Smith]

Quite, but what does an opera hat look like?

Like a top hat - but it can do a special trick...




Steve.

 

[cowanw]

I also now wonder if Depth of Field varies with shutter speed as the relative time spent at full aperture would then vary with how much time the shutter took to get to full aperture.

 

[Les Sarile]

And this is also an "un-honest" way of freezing time, since what it is done in this case is to have the flash emit bursts of brief pulses.

We won't get fooled again!! Reject the slow focal plane shutters and embrace the POWER of the LEAF!!

I prefer to give ourselves the benefit of the doubt. As knowledgeable photographers, we are masters of compromise (light, speed, focal length, dof, etc.) and so we all use what is available to us to get the results we want/need.

It is easy to say something is limited but it is more useful to understand the limitation and use it for its advantages.

 

[cliveh]

Is it just a question of leaf v FP, or is there another way? What would a perfect shutter look like and how should it function? Can quantum physics throw some light on this?

 

[Steve Smith]

Can quantum physics throw some light on this?

... for a specified length of time!

I also now wonder if Depth of Field varies with shutter speed as the relative time spent at full aperture would then vary with how much time the shutter took to get to full aperture.

This is what I was alluding to in my earlier post.

Something else to consider is that if you are using a very fast shutter speed, i.e. one which requires the shutter to open then immediately close again without delay, then with the aperture blades wide open, the actual exposure is made at all apertures from wide open to pinhole. The longer the shutter speed, the less this will have any effect.

Steve.

 

[erikg]

A shutter could be made from a special type of glass that is opaque until you don't want it to be, then it becomes perfectly clear for a specified amount of time. Similar to the glass used in high rises to pass or block sunlight. It could be built into the lens or live at the FP.

 

[Sirius Glass]

Which makes me wonder how graduated filters work?

It depends on where they graduated from. Some schools are better than others.

 

[Sirius Glass]

I also now wonder if Depth of Field varies with shutter speed as the relative time spent at full aperture would then vary with how much time the shutter took to get to full aperture.

The Depth of Field is not a function of shutter speed however it is a function of the f/stop.

 

[wombat2go]

The penumbra of a leaf shutter recorded from a high speed photodiode with a 5 degree angle of view measuring scatter off a ground glass. In this shot the shutter speed was 1/30th s . Th ripple while the shutter is open is from the incandescent light source.
Unknown to me in this relative light amplitude is the light level that will be above the reversible re-halogenation.
That is, I wonder how far up the slopes does the film start/stop to irreversibly record the image?

 

[lxdude]

I also now wonder if Depth of Field varies with shutter speed as the relative time spent at full aperture would then vary with how much time the shutter took to get to full aperture.

I asked that question somewhere here, and the answers were that it is insignificant.

 

[Steve Smith]

The Depth of Field is not a function of shutter speed however it is a function of the f/stop.

The point was that if the shutter takes a significant part of the time opening and closing, it is effectively being the aperture whilst moving and will expose a range of DOF.

I asked that question somewhere here, and the answers were that it is insignificant.

Yes because for every doubling of diameter, the exposure is two stops higher so the wide open part of the exposure will have much more effect and will hide the closed down exposure.


Steve.

 

[film_man]

The vibrations are damped out before the shutter opens. The war on reflex cameras is based on bunk to push an agenda for rangefinder cameras.

https://www.youtube.com/watch?v=CkKcbyh2CrA

I'll tell you what I have used and how it works for me: Right now if I take a shot with a Canon EOS 300 the vibration/torque of the mirror moving is felt quite a bit more compared to an EOS 3 which I have sitting right next to it. I also have a Leica R8 right here and the vibrations on that are even less, I can shoot 1 stop lower with that than the EOS 3 which is similar to a 1V which I also had in the past.

Move to medium format. A TLR gets you 1 stop or more over an SLR, at least. On the Hasselblad I can get 1/60 at best. I just got a few rolls back shot with the Rollei 6003 and 1/30 is doable all the time. Even shots at 1/15 were acceptable and I managed to squeeze one at 1/8 that come out great that that was probably more luck than fact. Then again, with my RB67 I can shoot 1/15 all day long and even 1/8 if I am careful.

Last I heard a Pentax 67 can be tricky to hold still when that mirror moves up once you get to the slower speeds but never used one myself.

So...is that bunk? Don't know, but not for me. The mirror hits the top, the shutter opens. The mirror momentum is still in action unless you delay the shutter, which I think is what Mamiya did with the RB, at least it feels slower.

On the other hand, I have an old TLR and a folder, when it goes click it just goes click and nothing else is felt moving. 1/8 is not a problem, assuming the subject stood still.

 

[Steve Smith]

The mirror momentum is still in action unless you delay the shutter, which I think is what Mamiya did with the RB, at least it feels slower.

I think the RB67 mirror is damped so it slows down towards the end of its travel.


Steve.

 

[Brett Rogers]

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.

I'm very much an observer rather than a participator at this site, but because of the subject matter I will wade in for once.

Firstly, relative efficiency. I thought Ansel Adams covered the pros and cons of leaf vs focal plane shutters, including their efficiency, pretty well in "The Camera". So I'd recommend that as a primer to anyone wanting to understand some of the practical considerations.

Secondly, re the above (quote) I don't really agree that leaf shutters are not practical with interchangeable lenses. Hasselblad, Mamiya, Bronica and others have proven beyond a shadow of a doubt that their equipment can deliver the goods, over decades. It's certainly true that limitations are imposed on lens design, particularly including how fast lenses can be, or how closely they can focus. But that does not mean, per se, that they are not practical. However as has been pointed out, this is a 35mm forum. And I note that most of the conversation seems to have been around single lens reflexes, but don't forget that leaf shutters were also fitted to a number of other types of cameras.

Thirdly, there's no doubt that competition from the Japanese camera industry decimated German manufacturers including Zeiss Ikon. As the context is leaf shutters SLRs, and Zeiss Ikon, I can only presume Ian must be referring to the Contaflex SLRs in his remarks above. Personally, I'd argue it was their inability to compete on quality and price that was a major factor, and that the Japanese were making 35mm SLRs with instant return mirrors, something the Contaflex never got. There's no doubt the German makers (including ZI and ZI/Voigtlaender) lost market share to the Japanese. But with the best part of a million Contaflexes sold by them, (800,000-odd of all types from memory, I can look up the exact number, if anyone really wants to know) I'm not so sure the decline was as rapid as Ian suggests, or that it was down to the Contaflex either, for that matter. Rather, I would argue the reverse, Ie. that, if not for all those Contaflex sales that actually made money for ZI/V (unlike the focal plane shutter Contarex) ZI/V would have collapsed years before they finally did.

Fourthly, as is usually the case whenever this topic arises on the web, people are not considering the historical context. Exakta and others had been making SLRs with focal plane shutters dating back to the 1930s; it is not as though the configuration was unknown when ZI designed their first Contaflex. So why did they choose a lens shutter? When you look at things as they were in 1953, their reasons weren't as silly as some people seem to think they were today. In my experience though, these up to sixty year old cameras invariably get judged against modern standards, somewhat unfair when their historical merits are being discussed.

Owners of 1960s or later 35mm SLRs might be forgiven for wondering why the additional complexity of a lens shutter would even be considered but, generally speaking, by then the FP shutter had really come of age. Most designs included an instant return mirror, and Nikon, Canon, Pentax and others offered examples with instant return mirrors, accurate speeds and longevity. But it wasn't always so.

A decade or so earlier the 35mm SLRs that were on offer without exception did not have instant return mirrors. As any classic Leica owner should be aware the possibility of holes being burned through curtains was (and is, for those who still use them) very real. Well, older SLRs without instant return mirrors used to have precisely the same problem. But unlike rangefinder designs, only the second curtain was vulnerable, the first being shielded by the reflex mirror.

Cloth FP shutters had other reliability problems detractors of the lens shutter conveniently often forget to mention. Capping and tapering were issues that were not exactly unknown. Far from unknown.

In this context, Zeiss Ikon's decision to use a tried and proven Compur light proof shutter in their new 35mm reflex makes a lot more sense. Years of reliability were assured, with the bonus of full synchronisation with the new electronic flash tubes that were hitting the market. Granted, the mechanism is more complex than a typical FP shutter design. But this is only a problem if quality and reliability is not present. Something the Contaflex features in abundance. Yes, I'm serious.

I've been fortunate to acquire a fair cross section of the different Contaflex types and have worked on most Compur variations (I have no interest in Pantar lenses). In almost every single case, nothing more than a cleaned shutter and some minor adjustments were needed to restore them to full working order. There were two or three examples with unhealthy selenium or CdS cells, admittedly. But this is scarcely an issue specific to the type of shutter fitted to period cameras.

I've also sorted out a couple of Exakta Varex IIas that I also use sometimes. The Exaktas are without question some of the most beautiful and interesting SLRs ever produced, and I love using them, but in terms of what has been needed to get a 1950s camera working reliably and consistently, it's a no-contest. The Contaflex wins, hands down. No curtains or ribbons to be replaced or timed. Clean the Compur shutter, lube, reinstall, check and adjust lens focus and mirror and rear shutter setting, load film. So please, don't argue the reliability case to me, because I've worked on FP and lens shutter SLRs, and I can't think of too many FP shutter SLRs that can be put back into regular, reliable service, without replacing a single mechanical part. This is the rule not the exception with a Contaflex. Even the magazine backs actually work. Many other manufacturers tried and failed to make reliable, quality lens shutter SLRs in the 35mm format. It is interesting to note that Japan had little to no success with this configuration (although I'd quite like to try a Fujicarex one day) whereas Zeiss Ikon and Voigtlaender respectively (and to a lesser extent, Nagel) were able to manufacture cameras that performed and lasted well.

Like any rangefinder or TLR with a Compur shutter in 2014, the Contaflex you buy Eg. online, is very unlikely to work very well, because the reflex shutter Compurs are not as different to the standard types as one might expect. Hence, they suffer from the same need for cleaning and lubrication any Rolleiflex or Voigtlaender RF would have. The difference is that, whereas many Eg. Rolleiflexes get a CLA, the reputation of the Contaflex dissuades most owners from getting this done. I'll let you in on a secret here. They are quite complex mechanisms. This is true. But the complex bits almost never give any grief. 9 times out of 10, all they need is a cleaned shutter, and they'll spring into life as good as new again. Owning thirty plus examples, and having successfully serviced a good two dozen or so, I believe I am qualified to speak from experience.

Cheers,
Brett

 

[flavio81]

Move to medium format. A TLR gets you 1 stop or more over an SLR, at least. On the Hasselblad I can get 1/60 at best. I just got a few rolls back shot with the Rollei 6003 and 1/30 is doable all the time. Even shots at 1/15 were acceptable and I managed to squeeze one at 1/8 that come out great that that was probably more luck than fact. Then again, with my RB67 I can shoot 1/15 all day long and even 1/8 if I am careful.

Last I heard a Pentax 67 can be tricky to hold still when that mirror moves up once you get to the slower speeds but never used one myself.

So...is that bunk? Don't know, but not for me. The mirror hits the top, the shutter opens. The mirror momentum is still in action unless you delay the shutter, which I think is what Mamiya did with the RB, at least it feels slower.

Agree with you. Mirror vibration is real and can be a problem in some SLR cameras. It's true that the shutter opens after the mirror has gone up, but this does not mean that any vibration caused by the mirror won't be there anymore.

The good news is that in quality SLRs (example: Nikon F3) this problem is solved for practical purposes.

I think the RB67 mirror is damped so it slows down towards the end of its travel.

Exactly. The mirror of the RB67 is de-accelerated using a centrifugal friction governor. This is a fact (i've seen pictures of the mechanism). As far as i know, the Hasselblad 500-series lacks such a device. The mirror slap, on the latter, is brutal, dramatic, and shocking (pun intended.)

Many 35mm cameras use some similar device or another. For example, a pneumatic device on the Olympus OM cameras; a clockwork governor on most Canon manual focus film SLRs, etc.

 

[flavio81]

Brett Rogers,

Great post and I agree with you. Most of such machines only fail due to lubrication issues. The Contaflex is a nice camera.
While i have found, on the user market, a good share of FP cameras with rotten, pinholed shutter curtains. A more difficult repair.

As for the fall of Zeiss-Ikon-Voigtlander, consider that at one point in time they had like 3 or 4 or 5 different SLRs with different, incompatible lens mounts (!!)

 

[John Koehrer]

I've never understood this because in an SLR by the time the mirror hits the bumper the picture has been taken.

Not so! The shutter is released when the mirror mechanism strikes the internal shutter release lever..All 35mm FP shutters work this way. In Electronic shutters only the timing is controlled electronically, not the release.

 

[John Koehrer]

I wonder if it would be possible to engineer a double leaf shutter, where one is closing as the other opens, with the time for each computer controlled to give an overall accurate exposure time?

Oh! You mean exactly like a FP shutter.

*** Now, i'm perfectly happy with the RB lenses, to be honest, and I haven't heard any Hasselblad or Mamiya user complain of having a slow 1/500 (or 1/400) speed, or complaining about the lenses' speed. Depth of field in Medium Format is extremely narrow at those apertures!

A sheltered life indeed.

***So I could argue that a camera with a FP shutter that tops at 1/2000 and synchs with flash at 1/90, is honestly a 1/90 speed camera, for moment-freezing purposes. While a camera with a leaf shutter that tops at 1/500 is really a honest near-1/500 speed camera.

And in daylight the leaf is still limited to what?

***Cloth FP shutters had other reliability problems detractors of the lens shutter conveniently often forget to mention. Capping and tapering were issues that were not exactly unknown. Far from unknown.

Still do. The metal horizontal travel though not vertical. But both metal/cloth can be adjusted


Was there ever a leaf shutter SLR with an instant return mirror made?

 

[cliveh]

Oh! You mean exactly like a FP shutter.

No, a leaf shutter operates more in real time.

 

[lxdude]

Was there ever a leaf shutter SLR with an instant return mirror made?

The Mamiya/Sekor 528TL is one.

 

[cowanw]

Quote Originally Posted by John Koehrer View Post

Was there ever a leaf shutter SLR with an instant return mirror made?

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