Lens testing old glass on film and digital.

[Stephen]

I had started to test a selection of lenses on Leica thread, and compare to original Leica and use a TTH as reference standard.

But I was surprised at the performance of the Ilford Advocate, checked with FP4, which turned in sharpness at very good levels, frankly as sharp as any lens of it's type.

Most of the Leica thread lens tested recently, along the lens from a Foth camera under repair, test very sharp indeed on digital.

But a couple of Industars and an Exa standard lens turned in poor sharpness, when tested on film.

I tried the TTH on my Leica and a Zorki and got variable sharpness at first..but then tried the lens with the camera on Heavy tripod.

The sharpness shot up.....

When tried on the Olympus 4/3 both lenses are very sharp. Then I realised it is the image stabilisation that is cutting in, and covering up the real performance.

In effect it is getting the most from the lens, and what was happening with the film tests was camera shutter vibration affecting the sharpness.

When the Leica and Zorki were bolted down they gave good results, but hand held it took the edge of the performance. The sharpness varied in proportion with the shutter speed.

The only Leica thread camera that gave similar results to digital consistancy was the Periflex, which has a well damped shutter and a front camera release.

I am now pretty certain that the shutter can make or break the overall sharpness of the lens.

It does go to explain slight differences between major makers, when in theory the lenses were as good as each other. Nikon's titanium shutter and the OM1 shutter being pretty vibration free explains why simpler shuttered camera could not compete despite excellent glass.

The Advocate I was testing has a very simple rotary plate shutter, rather like a sophisticated box camera shutter. It means no vibration in operation, and combined with the front release being soft gives such good results.

Testing all the lenses at F 8 on digital with IS on and fitted to a heavy tripod, then repeated with IS off......the results are all in the exellent range.

So there is little point in film testing, unless bolted down, and with a high shutter speed.

The best test is on Digital, any format. I have not got a full frame, but even this may be only comparable with 4/3 etc due to lower pixel density.

At least it also shows that sharpness is not the only important parameter, and that using older lenses on digital really shows the best the lens can deliver.

Stephen.

[philbirch]

I have had practical experience of this, and wondered why my lenses were not up to scratch. I guess it could be called 'shuttershake'

The image taken here has shuttershake. I used the kit lens on my NEX5 on a tripod, lightweight with a ball & socket head, the vibration of the shutter caused the shake, it's a real clunker! The exposure was about 1 second at about F11, I still got shake even with the 2-second timer or remote release. My Sony A6000 on the other hand has a very quiet, smooth shutter and has almost no shake.

I'll use my heavy duty Manfrotto next time

Thanks for this post, very informative - as yours always are.

[mickeyobe]

Thank you, Steven, for this very detailed and enlightening test.

Your statement "The Advocate I was testing has a very simple rotary plate shutter, rather like a sophisticated box camera shutter. It means no vibration in operation, and combined with the front release being soft gives such good results." aroused my curiosity about the two Universal Mercury cameras that I have.

They have rotary shutters with a full range of speeds up to 1/1000 second. Unlike other none rotary cameras, regardless of the speed used, the sound emitted does not vary with the speed. They give a soft purr with a slight tap at the end of their travel.

It occurred to me when I first got them that these cameras are not going to destroy themselves as their shutter actions are so gentle.

Admittedly the cameras' design is unconventional but I still wonder why more manufacturers did not/do not adopt the rotary shutter.

I have not performed lens tests on my cameras. I have neither your skill nor patience. I have only your curiosity.

The Mercurys made their first appearance in 1938 and were in production, as far as I can find out, until 1945. I have seen a number of Mercurys. Some were in poor condition but the shutters always worked.



Mickey

[Stephen]

Yes the Univex Mercury was a good design, as it is virtually a standard cine camera shutter, with the pawl to move the film removed. Not so surprising as Univex were cine camera makers.

It performs in a true rotary movement, like the Berling Robot.

The Advocate uses a plate with a standard size hole, and pivots it across the light path, with variable pressures to get the speed range.

As the plate has return to the start, during the film transport a second masking plate with no hole covers the hole up, as it returns to the cocked position.

It is classed as rotary, but only over a short segment of a circle. This type of shutter was very common in box cameras and early Kodak etc.

The Advocate is a bit more sophisticated, balanced parts, and better design, but the simplicity pays off with zero vibration, there is a slight noise as the plate hits the stop, after the exposure is over. It must be one of the quietest cameras!

Old reviews of the Advocate made quite a lot about the smoothness of the shutter, and its front release position.

I noticed in the Olympus Pen digital shutter that they have selectable lag position that delays firing for a moment to minimise shutter shake.

And the original Pen used a rotary shutter as well.....

PS I have the early Mercury with the special canisters, a right nuisance!!!

[daveh]

"I am now pretty certain that the shutter can make or break the overall sharpness of the lens."
No, it can't. What it can do is make or break the sharpness of the final image

It is not exactly a new concept that a big heavy well-braced tripod, preferably weighted down, will be more stable than a flimsy affair.

[Stephen]

But there is bit of a difference between camera shake and shutter vibration. Both are helped by a good tripod, but the shutter induced vibration is the factor here, and almost impossible to remove if the camera is badly designed in the first place.

Many reflexes are poor on the mirror damping, and leave the mechanism still vibrating as the shutter operates. It helps explain the good performance from older leaf shutter cameras, where vibration must be very low.

The main point is it explains why old lenses come up trumps on digital, especially with IS switched on.

And shows why the early reflexes with a slowly raised mirror that fired the shutter after it was raised worked well.

Camera makers knew about it as why did top makers offer mirror lock up.

It ties in with the opinion of my old boss in Lens making, that most lens design peaked in the 1900's and really did not get better till aspheric surfaces and multi coating. When you look at old glass plate negatives for, say, landscapes the degree of detail is astonishing.

I would dearly like to try the Advocate with Kodachrome, impossible now, but I will try it with Tec Pan to see how near it comes to a good TTH 50mm or a sound tested 35mm Russian lens. Dallmeyers lens being good may explain Wray having trouble matching it in later production.

Stephen.
I do wonder whether the focal plane shutter was such a good idea when made like Leica where an awful lot of mechanism is under movement during operation. They solved it with damping as did most other makers, but then came the mirror!

Anyway all usable at high shutter speeds, or firmly held!

[genazzano]

I would assume that a traveling slit FPS, such as that used in old Graflex models like my 3A, would produce less vibration at all exposures since the speed of the mechanical components is lower and more easily dampened. What are your thoughts?

we usually think of tripods in terms of eliminating hand movements during longer exposures. However, what you describe is a quite different matter. It would appear the you are doing two things by mounting a camera on a heavy tripod: First, you are locking all components such that all elements in the system tend to vibrate with the same characteristics. Second, you are tremendously increasing the mass that must be set in motion by the shock waves caused by shutter elements rapidly starting and stopping.

[mickeyobe]

I am probably wrong but I'll give this a try.

It seems to me that shutter shock would occur not when the shutter opens or travels but when it slams shut.

That should not degrade the image.

OK. Have at me.

Mickey

[genazzano]

For SLR designs, the mirror must move up and hit the dampening material. Then the the first curtain begins its trip to fully open. Then the exposure of the film or sensor begins.

[Stephen]

All tends to show Zeiss were right to use leaf shutters! and, yes, it's to first blind and mirrors that are behind the vibrations...as much as a one third loss of lines per mm in the test shots.

The first Russian Zenit was OK, along with other early reflexes, the mirror rose slowly as the first part of the pressure was applied, so any vibration was down only to the first curtain.

Alpa seem to have sussed it out, they damp the first blind, same as late Leica. And even Praktica damped the shutter blind on the vertical metal shutter, but have a clunky mirror.

The Exakta has longer overlap of the frame, and had a gap between the rise and the first blind that is longer than most.

The main offenders seem to be the metal shuttered Japanese Reflexes, shutters from both Seiko and Copal, that had damping, but left the mirror trip to the camera maker, often relying on as little as a foam buffer to damp the mirror.

I don't think the effect is massive at higher shutter speeds or a well held camera, but it can take the edge off the performance, or give the max lens performance all the time, like the well designed Nikon shutter.

All of this is just to tweak a bit more from older lenses, given good condition, and many an old camera holds surprises in performance.

Whilst servicing folders there is a chance to try lenses on digital, and even three element 1930's glass comes up trumps, failing only on light fall off away from the centre. It's rare a lens is un-sharp, unless a real cheap clunker like a meniscus single glass lens. Even here the old VP Kodak with two element is as sharp as modern lenses, but forget it for colour, there is fringing.

Stephen

[mickeyobe]

Oct 9, 2014 17:47:25 GMT -5 genazzano said:

For SLR designs, the mirror must move up and hit the dampening material. Then the the first curtain begins its trip to fully open. Then the exposure of the film or sensor begins.

David,

The mirror is fully open and finished its slamming before the shutter curtain opens.
It then rests silently until the second curtain closes.

Could a solid piece of equipment like most cameras continue to vibrate after the mirror hits the non resonant damping (Note: Damping) material?

Or, is there some other component of the shutter mechanism that vibrates enough to move the entire camera?

Mickey ( Devil's Advocate)

[philbirch]

Oct 10, 2014 6:19:41 GMT -5 mickeyobe said:

Oct 9, 2014 17:47:25 GMT -5 genazzano said:

For SLR designs, the mirror must move up and hit the dampening material. Then the the first curtain begins its trip to fully open. Then the exposure of the film or sensor begins.

David,

The mirror is fully open and finished its slamming before the shutter curtain opens.
It then rests silently until the second curtain closes.

Could a solid piece of equipment like most cameras continue to vibrate after the mirror hits the non resonant damping (Note: Damping) material?

Or, is there some other component of the shutter mechanism that vibrates enough to move the entire camera?

Mickey ( Devil's Advocate)

I'll answer this. The mirror slamming up will cause the camera to vibrate.  The shutter will open almost immediately the mirror bangs up, the vibrations actually still occurring as the shutter opens. Perhaps the vibration may have stopped when the shutter finally closes, but the damage is already done.

I get worse shots with myNEX5 and Nikon d3200 than my Sony A6000 using the same lens probably due to shutter shake, tripod or not.

When I used my NEX clamped to the bird watchers hide the clunk vibrated through the wood and startled the birds. My Nikon wasnt so bad and the A6000 is almost silent in comparison.

[genazzano]

I have never tried to test the roll of the mirror travel on the resolution of macro shots. However, the general claim is that the mirror lock-up option available on many DSLRs serves to eliminate any problem. The vibration cause by the shock of the mirror hitting its stop depends a lot on the mass of the mirror, the age of the camera and thus the efficacy of the dampening material, and whether the camera is locked down tightly to a high mass such as a heavy tripod.

Before my life with tractors and chainsaws, I was engaged in development of laser scanning imaging where vibrations were a major concern since image resolution was at the micron level. That's less than the size of the elements on a typical DSLR sensor. So we are talking about border line vibrations in the hands of the average photographer.

David

[Stephen]

To test this out a bit......modified a microphone with a tight low frequency filter, calculated to about 15hz to 300hz, and recording the sound with the mic clamped to the camera body.

The waveform can be looked at by any audio analyser, like audicity, which allows the wave form to be stretched to view.
First tests show it appears to show the impact noise and indeed trails away as fading vibrations. I am working on an optical sensor to check the point the shutter operates on in relation to the first blind, but it is near impossible with early Leica!!

First test shows leaf shutters are very quiet, and the trail away must be after the closure of the blades.
Focal plane are really clunky, and if on B, then the first blind makes a lot of noise and trail away that is longer than the blind travel.

At higher speeds the second blind is running whilst the first burst of vibration is still running, and the trace jumps as the second blind closes.

On the OMI the trace picks up the mirror slam, but then little vibration, as they have damped it ot, but the second blind shows a lot more,(does not matter).

For reference a Box Brownie barely registers anything! Same with the Ilford Advocate, no trail after the click.

So the first tests show the body does vibrate during the exposure, and must be affecting the sharpness, albeit at low levels, we are not talking camera shake, this is very tiny vibration shake. All it potentially does, is take the edge off max sharpness.

[genazzano]

You should publish this data.
David