focal plane v diaphragm

cowanw · Dec 2, 2014

cowanw said:
Which makes me wonder how graduated filters work?

I still wonder? Why does a graduated filter block a portion of a scene and a shutter or stop not?
When I had a portrait done with my wife in a daguerreotype, I needed less exposure and the photographer blocked half the lens for a period of time. How is that different from a f stop obstruction?

Peltigera · Dec 2, 2014

cowanw said:
I still wonder? Why does a graduated filter block a portion of a scene and a shutter or stop not?
When I had a portrait done with my wife in a daguerreotype, I needed less exposure and the photographer blocked half the lens for a period of time. How is that different from a f stop obstruction?

If you put the grad filter right up against the glass, it will not work significantly. The filter holder keeps it some distance from the front surface of the lens. The further the grad filter is from the lens, the clearer the filter will be in the final image. Shutters (leaf type, any road) and diaphragms should ideally be at the node of the lens - that is, inside between the glass elements - where they do not obliterate parts of the image.

Sirius Glass · Dec 2, 2014

film_man said:
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.

I use the 45 degree PME which means that they eye piece also stabilizes the Hasselblad. I have shot 1/30 hand held with 80mm lens a few times without a problem, but since I usually use ISO 400 film that rarely happens. Then of course I keep a tripod in each of my vehicles.

Kirks518 · Dec 2, 2014

While I have nothing to add to this, simply because I don't have an answer, I do have a question.

How does the mirror/shutter work in a leaf shutter system that is an SLR? What's acting as the 'closed shutter', since you can see through the lens to focus/compose/etc.? I have an RB67 (very new to me), and this thread and the camera have me pondering this, and I can't get my head around it.

Is the series of events as follows:

Shutter release button pressed
Leaf Shutter Blades close
Aperture blades move (close) to chosen setting
Mirror lifts
Leaf Shutter blades open
Leaf shutter blades close

If that is how it happens, seems like an awful lot of stuff happening in shirt a short period of time.

elekm · Dec 2, 2014

There were several cameras that had leaf shutters with speeds exceeding 1/500. However, it's doubtful that any of them reached their marked speeds.

MattKing · Dec 2, 2014

Kirks518 said:
While I have nothing to add to this, simply because I don't have an answer, I do have a question.

How does the mirror/shutter work in a leaf shutter system that is an SLR? What's acting as the 'closed shutter', since you can see through the lens to focus/compose/etc.? I have an RB67 (very new to me), and this thread and the camera have me pondering this, and I can't get my head around it.

Is the series of events as follows:

Shutter release button pressed
Leaf Shutter Blades close
Aperture blades move (close) to chosen setting
Mirror lifts
Leaf Shutter blades open
Leaf shutter blades close

If that is how it happens, seems like an awful lot of stuff happening in shirt a short period of time.

You are correct (although the lifting of the mirror and movement of the aperture blades may be slightly different).

Now go through the same process with a focal plane shutter - it is simpler, but only just.

Brett Rogers · Dec 2, 2014

Kirks518 said:
While I have nothing to add to this, simply because I don't have an answer, I do have a question.

How does the mirror/shutter work in a leaf shutter system that is an SLR? What's acting as the 'closed shutter', since you can see through the lens to focus/compose/etc.? I have an RB67 (very new to me), and this thread and the camera have me pondering this, and I can't get my head around it.

Is the series of events as follows:

Shutter release button pressed
Leaf Shutter Blades close
Aperture blades move (close) to chosen setting
Mirror lifts
Leaf Shutter blades open
Leaf shutter blades close

If that is how it happens, seems like an awful lot of stuff happening in shirt a short period of time.

A few designs use the mirror to double as a capping plate (or rear shutter if you prefer), when the lens shutter is open for viewing through the finder. Others such as Voigtlaender's Bessamatic/Ultramatic, the various Zeiss Ikon Contaflexes and, of course, the V series Hasselblads use a dedicated capping plate (or plates, in the case of the Hasselblad) to shield the film gate when the leaf shutter is open.

Your description of the sequence of operation is basically correct, except that where there is a separate capping plate near the film plane, after the mirror retracts upwards, the capping plate normally retracts towards the front of the camera to rest beneath the mirror (prior to the leaf shutter re-opening and then closing for the exposure, of course). The main point to appreciate is that at any given time either the main leaf shutter or the capping plate will be closed to shield the film from light. The only time both are ever open simultaneously, is during the actual exposure.

There is a lot of stuff happening in not very much time, however this can be achieved with a delay only fractionally longer than the release of a typical focal plane shutter design. It's a great credit to the Zeiss Ikon designers that their original Contaflex (which had a fixed 45mm Tessar lens) was able to pack all this into a body that is substantially smaller than most conventional SLRs--at a pinch one can slip the original model (or a C II) into a jeans pocket.

The Tessar lenses used in the Contaflex line are capable of very good results. It is a pity more people do not give them a chance, however I accept that given the absence of repairers willing to think outside the square and repair them few people will undertake to learn to work on them themselves. This is what I did. I'm happy to take questions from owners of Contaflexes or Bessamatics with problems, as I would like to see less of them sitting in cabinets, and more of them being used for imaging.
Cheers,
Brett

Kevin Caulfield · Dec 3, 2014

I disagree, Tom.

flavio81 · Dec 3, 2014

Kirks518 said:
While I have nothing to add to this, simply because I don't have an answer, I do have a question.

How does the mirror/shutter work in a leaf shutter system that is an SLR? What's acting as the 'closed shutter', since you can see through the lens to focus/compose/etc.? I have an RB67 (very new to me), and this thread and the camera have me pondering this, and I can't get my head around it.

Is the series of events as follows:

Shutter release button pressed
Leaf Shutter Blades close
Aperture blades move (close) to chosen setting
Mirror lifts
Leaf Shutter blades open
Leaf shutter blades close

If that is how it happens, seems like an awful lot of stuff happening in shirt a short period of time.

Yes, the sequence of events is more or less that list, but if i recall correctly on the RB67 the mirror lifts first (and the light trap behind it opens), and then the events are as you describe.

In the case of the Mamiya this takes time and makes the camera have a noticeable lag between hitting the shutter button and having the actual picture taken. Moreover because of the mirror dampening, which makes the mirror-up time considerably longer compared to a camera where the mirror goes up with brute force. Granted, the shutter lag it is one of the very few defects of that camera, and i haven't found it too problematic yet.

flavio81 · Dec 3, 2014

APUGuser19 said:
The Hasselblad 500 series(...) rates as a very guilty offender in vibration from mirror slap and barn door action. Even Adams made note of the Hasselblad problem. (...) A necessary evil; flaw in the physics of cameras. The alternative being pretty much, no camera at all.

Not exactly correct; as indicated before the Mamiya RB solves this problem by using a mirror de-acceleration device, just like every decent 35mm camera does. So it's not a necessary evil, and the alternative is... using a different medium format SLR.

My guess is that the hasselblad 500C doesn't have this device basically simply because it was designed in 1957, when SLRs were in their infancy!!

cowanw · Dec 3, 2014

Peltigera said:
If you put the grad filter right up against the glass, it will not work significantly. The filter holder keeps it some distance from the front surface of the lens. The further the grad filter is from the lens, the clearer the filter will be in the final image. Shutters (leaf type, any road) and diaphragms should ideally be at the node of the lens - that is, inside between the glass elements - where they do not obliterate parts of the image.

The early landscape lenses had apertures a couple of inches in front of the glass.
The common filter contraptions put the filters pretty close to the front of the glass and front mounted home made f stops work OK.
There must be more to it?

Dan Fromm · Dec 3, 2014

Peltigera;1732024Shutters (leaf type said:
This depends on the lens' design. For an extreme example, my 200/4 MicroNikkor AI's diaphragm is well behind all of the bits of glass.

cliveh · Dec 3, 2014

erikg said:
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.

Good idea and there is a form of technology that does this, but not sure if it could make the glass opaque. I sometimes wonder why this technology is not employed in car windscreens as a form of variable graduated filter instead of a sun shade.

E. von Hoegh · Dec 3, 2014

erikg said:
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.

Old news.

http://www.eastwood.com/auto-darken...ode=ga220010&gclid=CM666dHfqsICFWcLMgodZDkAxQ

That's tech from the last millenium.

Peltigera · Dec 3, 2014

Dan Fromm said:
This depends on the lens' design. For an extreme example, my 200/4 MicroNikkor AI's diaphragm is well behind all of the bits of glass.

I suspect that is where the node of the lens is. The node is usually inside the lens but always with complex designs.

cliveh · Dec 3, 2014

E. von Hoegh said:
Old news.

http://www.eastwood.com/auto-darken...ode=ga220010&gclid=CM666dHfqsICFWcLMgodZDkAxQ

That's tech from the last millenium.

So why is it not used in car windscreens?

Sirius Glass · Dec 3, 2014

Kevin Caulfield said:
I disagree, Tom.

I am with Kevin on this one.

Sirius Glass · Dec 3, 2014

APUGuser19 said:
Who's Tom? Oh well. I still believe what I wrote. Hasselblads do vibrate and leaf shutters lose accuracy worse than focal planes from all I've been able to tell. Except maybe 1/1000 and 2000. They tend to drag a good bit all these years after manufacture dates. I haven't come across a trustworthy iris shutter yet. And worse, I've seen marked speeds so far off the next speed on the dial was more in keeping with the marking of the former, and the former more accurate to the latter, or some other marking. They can be very oddball. Seems like 1/100 is about all you can really trust when no checking or servicing has been done.

I find this is disingenuous considering:

[*=1]The Series V Hasselblad have a top shutter speed of 1/500 of a second. That would rule out 1/1000 and 1/2000 second shutter speeds.
[*=1]I can find no reliable documentation on

drag

Click to expand...

.
[*=1]May be you have not found a trustworthy iris shutter, but the rest of the world has.
[*=1]I can find no reliable documentation on

The point being that by reason an almost rudimentary engineering, the Hasselblad rates as a very guilty offender in vibration from mirror slap and barn door action. Even Adams made note of the Hasselblad problem.

Click to expand...

[*=1]In which universe have you found the physics for

A necessary evil; flaw in the physics of cameras.

Click to expand...

????
[*=1]I can find no reliable documentation on

Or, you have the leaf shutter, which is notorious with its drawbacks, not the least of which is time calibration.

Click to expand...

[*=1] I can find no reliable documentation on

1/25 can be 1/10 or 1/45th. 1/500 is more like 1/180th, and usually is. Compur, American made, Japanese made, whatever. Leaf shutters lose the accuracy race by a mile.

Click to expand...

erikg · Dec 3, 2014

E. von Hoegh said:
Old news.

http://www.eastwood.com/auto-darken...ode=ga220010&gclid=CM666dHfqsICFWcLMgodZDkAxQ

That's tech from the last millenium.

Isn't all this tech from the last millenium?

Anyway, no one has put it into a camera yet, at least as far as I know.

erikg · Dec 3, 2014

Sirius Glass said:
I find this is disingenuous considering:

[*=1]The Series V Hasselblad have a top shutter speed of 1/500 of a second. That would rule out 1/1000 and 1/2000 second shutter speeds.
[*=1]I can find no reliable documentation on .
[*=1]May be you have not found a trustworthy iris shutter, but the rest of the world has.
[*=1]I can find no reliable documentation on
[*=1]In which universe have you found the physics for ????
[*=1]I can find no reliable documentation on
[*=1] I can find no reliable documentation on

I guess that's why Hasselblad has a focal plane model as well.

Bill Burk · Dec 3, 2014

I'm trying to resist another Contaflex. First one I got on a whim for really cheap. I got it for the beautiful box, receipt and warranty with same serial number as camera. Such a nice presentation but the lens was so badly infected with fungus that I could not shoot with it. Gave to a friend who was collecting "Red things" for her 50's decor kitchen.

But Brett Rogers you make an interesting point that the Contaflex is underappreciated and highly reliable... I like the idea of a camera that can last a long time. And I think as far as flaws go, it would be better to have a leaf shutter that's a little slow... than a focal plane shutter that caps.

Of course there is the most efficient shutter I think exists: The EG&G Rapatronic.

http://edgerton-digital-collections.org/techniques/rapatronic-shutter

Sirius Glass · Dec 3, 2014

APUGuser19 said:
I can find no reliable documentation. Excellent. You should run for office.

Honest people are not allowed to run for office.

elekm · Dec 3, 2014

I've shot a number of photos with a Contaflex I, which uses the same Tessar that was used in the folding Ikonta 35/Contina, folding Contina II and folding Contessa. It's a very sharp lens.

Brett Rogers · Dec 3, 2014

Bill Burk said:
I'm trying to resist another Contaflex. First one I got on a whim for really cheap. I got it for the beautiful box, receipt and warranty with same serial number as camera. Such a nice presentation but the lens was so badly infected with fungus that I could not shoot with it. Gave to a friend who was collecting "Red things" for her 50's decor kitchen.

But Brett Rogers you make an interesting point that the Contaflex is underappreciated and highly reliable... I like the idea of a camera that can last a long time. And I think as far as flaws go, it would be better to have a leaf shutter that's a little slow... than a focal plane shutter that caps.

Of course there is the most efficient shutter I think exists: The EG&G Rapatronic.

http://edgerton-digital-collections.org/techniques/rapatronic-shutter

Good for you Bill. If I can help you need only ask.
My best picks for fully manual photography would be a good Contaflex I, II (essentially a I with selenium meter, they sometimes still work well), a Rapid (no meter, scarcest of all types) or a New Super. Later types incl. Super B; BC/S have very sharp lenses but are really geared to be used in shutter priority mode in the "A" auto aperture setting and have locking aperture rings. You can of course use them manually with hand held meter (which is indeed what I do). But the New Super, if you can find one, is a Super B without the auto exposure or locking aperture ring, and simply has a very accurate selenium meter and unlocked, uncoupled shutter and aperture setting rings, making it my pick of all the models for manual exposure imaging, and it also takes all Pro Tessars and magazine backs. Hope this assists.
Cheers
Brett

John Koehrer · Dec 4, 2014

Flutot's has a chart showing speeds in ms.
Tolerance is +/- 30% above 125 & +/- 20% below.

"Drag" can be defined as slow. Both leaf or FP can be slow when old lubricants are present. Old lube can also cause erratic or inconsistent shutter speeds that may or may not be apparent to the nekkid eye or by examining the negative. The exception to this would be dramatic variations.

focal plane v diaphragm

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