Mirror slap an issue?

No, no Hasselblad EL model offers mirror lock up. Only prerelease.

I agree that if it's possible to eliminate mirror-induced vibration from the imaging equation it's prudent to do so. Whether it will actually be germane to sharpness of the images involved is another point. But given the choice between living with or managing, a source of vibration, or eliminating it—I'll nearly always choose the latter. Granted—lifting the mirror might not help. But maybe it would, and it can do no harm—so, if the feature is available—why not use it?

 

That said, (as far as 35mm SLRs are concerned, at least) most manufacturers did not include a mirror lock up to help reduce vibration—at least not primarily. The function was usually included to facilitate the use of one or more non-retrofocus wide angle lenses, the fitting of which to the camera without first locking the mirror up would damage same. That the MLU would also be of particular benefit with long lenses or great degrees of subject magnification was surely of secondary importance.

 

Getting back to medium format SLRs, historically, relatively few models have actually been fitted with a genuine mirror lock up. Eg the 500C, C/M and their derivatives are oft-said to have MLU, but in fact, this isn't the case. A pre-release button permits the reflex mirror and rear shutter to be pre-fired before using their lens shutters. But on winding the film to the next frame, it is impossible to stop the mirror from descending. "Mirror lock up", as the words "lock up" suggest, means exactly that—the reflex mirror is mechanically locked in the retracted position. and until it's unlocked by the photographer—it stays locked.

 

There have been certain MF SLRs manufactured with true MLU capability. Some focal plane shutter Hasselblads Eg. their 2000FC and FC/M have various mirror operating modes apart from mirror instantly returning after exposure; one of these is mirror remains up after exposure and wind on. The 500EL & EL/M may have had a similar option—can't recall offhand.

 

Purely as far as vibration reduction is concerned, of course, a pre-release confers all of the benefits of MLU to a camera fitted with the function.

The Mamiya 645 system features MLU, despite having a fairly well damped mirror, and no lenses that protrude into the mirror box.

 

All of Nikon's pro level film bodies and DSLRs also offer MLU, and only one or two ancient Nikkor lenses would need the mirror locking up. AFAIK all Nikon lenses produced after the mid 1960s were sufficiently retrofocus that there was no danger of them interfering with the mirror.

 

In all my experience, nobody has suggested that an MU facility was there solely to accomodate oddball lenses. I have always understood, and been taught, that its purpose is to get rid of mirror slap.

Edited April 23, 2021 by rodeo_joe|1

The Mamiya 645 system features MLU, despite having a fairly well damped mirror, and no lenses that protrude into the mirror box.

 

All of Nikon's pro level film bodies and DSLRs also offer MLU, and only one or two ancient Nikkor lenses would need the mirror locking up. AFAIK all Nikon lenses produced after the mid 1960s were sufficiently retrofocus that there was no danger of them interfering with the mirror.

 

In all my experience, nobody has suggested that an MU facility was there solely to accomodate oddball lenses. I have always understood, and been taught, that its purpose is to get rid of mirror slap.

To get rid of mirror slap you do not need lock up. A simple prerelease would do.

So why lock up anyway, do you suppose?

A simple prerelease would do.

Except a prelease mechanism isn't simple. It requires some form of timing between mirror-lift and shutter triggering. Whereas lifting the mirror out of the way mechanically, using a lever, really is simple. That this also locks up the mirror is incidental to its simplicity.

 

Designed many cameras have you, Q.G.?

Edited April 26, 2021 by rodeo_joe|1

Except a prelease mechanism isn't simple. It requires some form of timing between mirror-lift and shutter triggering. Whereas lifting the mirror out of the way mechanically, using a lever, really is simple. That this also locks up the mirror is incidental to its simplicity.

 

Designed many cameras have you, Q.G.?

A mirror prerelease puts a pawl in the way at the right moment of a camera's normal release cycle. Very simple.

Simpler than a lock up, which needs disengaging the mirror mechanism from the normal cycle.

Which is also evident from, indeed, the number of cameras designed to offer lock up vs. those who only offer prerelease.

 

Why lock up, when a simple prerelease would do, Cowboy?

What is your answer?

A mirror prerelease puts a pawl in the way at the right moment of a camera's normal release cycle. Very simple.

Putting a pawl in the way wouldn't make the mirror start rising any sooner, and wouldn't delay the shutter from firing.

 

And that 'simple' pawl would also prevent the mirror from dropping again. That's what a pawl is, it engages with a gear tooth to prevent reverse rotation.

 

Get some engineering knowledge Q.G. before trying to pick a spurious argument on a subject you obviously know little about.

Mirror lockup is essential if part of the lens extends into the body. The original (c1960) Nikon 21 mm lens is an example. It would be helpful for digital live-view for uninterrupted se, but perhaps not essential. Pre-release worked well enough for me when a Hasselblad was my main choice for travel photos. The 555ELD seems to work as an automatic pre-release, in that the mirror returns to the up position without any action on your part. There are three seddings for that - off, one-time, or "lockup". The shutter release is an electric contact, rather than mechanical, which gives a soft release. It also works with an remote switch, which is handy for portraits and group photos. as well as for super-precise landscapes and closeups. Edited April 28, 2021 by Ed_Ingold

Putting a pawl in the way wouldn't make the mirror start rising any sooner, and wouldn't delay the shutter from firing.

 

And that 'simple' pawl would also prevent the mirror from dropping again. That's what a pawl is, it engages with a gear tooth to prevent reverse rotation.

 

Get some engineering knowledge Q.G. before trying to pick a spurious argument on a subject you obviously know little about.

Don't be such a simpleton...

The mirror doesn't need to start going up any sooner. It always goes up before the shutter is triggered. All that is needed is to insert a pause at precisely this moment. And that is rather easy to make.

 

And don't be such an extremely annoying simpleton!

Of course would such a pause not prevent the mirror from dropping down again. It always does in prerelease.

 

So why, again, lock up when a simple prerelease would do, Cowboy?

No answer? You don't have a clue, do you?

Mirror lockup is essential if part of the lens extends into the body. The original (c1960) Nikon 21 mm lens is an example. It would be helpful for digital live-view for uninterrupted se, but perhaps not essential. Pre-release worked well enough for me when a Hasselblad was my main choice for travel photos. The 555ELD seems to work as an automatic pre-release, in that the mirror returns to the up position without any action on your part. There are three seddings for that - off, one-time, or "lockup". [...]

Indeed. It behaves as you describe, Ed: that "lock up" actually is an automatic prerelease. The normal cycle (in any camera) begins with the raising of the mirror. When that is finished the shutter does what it has to do. Mirror prerelease halts the cycle at this moment, needing a trigger (usually the release button tripping the thing that blocks the cycle at this point) to set things in motion again. And when the shutter has done what it had to do the mirror comes down again. In the AS or RS setting in Hasselblad EL-models, the cycle goes on for one step, and the mirror is raised again.

If or when the mirror slaps down again is irrelevant. That occurs after the shutter closes, and for 500 series bodies, only after you wind the camera. As an aside, I found that I could wind a 500cw body and shoot faster than the digital back would recycle, losing some important images in the process (i.e., a steam locomotive roaring past a crossing).

If or when the mirror slaps down again is irrelevant. That occurs after the shutter closes, and for 500 series bodies, only after you wind the camera. As an aside, I found that I could wind a 500cw body and shoot faster than the digital back would recycle, losing some important images in the process (i.e., a steam locomotive roaring past a crossing).

Yes. That's what the communication between back and camera through the ELD's rear contacts is for. The camera will only respond to your input if and when the back is ready (and it will wind on as soon as the back says it can, ignoring the input of your finger).

You didn't lose the images due to winding and shooting faster, though, but due to the back not being fast enough.

 

Obviously, when shooting is rapid succession (AS on EL models), without time for any vibration to settle before the shutter operates, there is little point in using (automatic) prerelease.

You didn't lose the images due to winding and shooting faster, though, but due to the back not being fast enough.

That's what I said. However It's good to know about the ELD/CFV interlock..

Not necessarily Bronicas in particular are really noisy with mirror slap. Yet the Mamiya RB 67 is REALLY WELL damped

 

 

I'm not sure the "sound " of the mirror is the issue, more about when that sound (and vibration) occurs in relation to the actual exposure.

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