Mirror lock up and when?

Discussion in 'Medium Format' started by jim_gardner|4, Jan 30, 2021.

  1. Having not been working much recently due to Coronavirus, I have had a lot more time for photography. Apart from testing cameras and trying to get some new prints I have also been reading and processing (mentally and in the darkroom). Having been using various cameras for 30+ years I have generally used mirror lock up to minimize vibrations on longer exposures and especially with medium format cameras.
    MLU has always been second nature. If exposure times are getting longish, use MLU to eliminate that vibration when the shutter fires, but,,,,Thinking about it recently, and possibly thinking about it too much and confusing myself, I now have a question that may be better in the beginner forum. MLU is something I have used forever but cant for the life of me now see why only at long exposures.

    When we make an exposure, the mirror lifts up which may cause some vibration and thus negatives that are not as sharp as they could be. Lets say the mirror vibration lasts for 1/4 of a second (complete guess on my part as to the duration) and the exposure is 4 seconds. Disregarding the delay between the mirror going up and the exposure starting, the mirror vibration would then last 1/16th of the exposure time.
    With an exposure of many minutes, the vibration would only last a tiny fraction of the exposure time and may not be recorded on the negative at all.
    If the exposure was 1/4 second or faster, then the entire exposure would be made during the vibrations.

    Why then is MLU used on longer/slower exposures, when the vibration could be present on only a small part of the shutter open time, and generally not on shorter/faster exposures, when the vibration could be present for the entire exposure time?
  2. In my experience you are correct. MLU has meaning mostly on less than 2 secs up to even 1/125 if we are talking for a long telephoto. Exposures over 4 secs usually a small vibration will not get recorded. I use MLU on all long exposures though just to be on the safe side. Mamiya AF cameras have a combination of mirror lock up + timer where you only have to press the shutter once. The mirror goes up immediately and the shutter goes off after the time chosen. In my case usually 4 secs, longer with a tele lens.
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  3. what I remember there was a special dual release cable for the RB
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  4. Whenever your subject isn't about to run away?
  5. I have found little reason to worry about mirror shake with lenses below 500mm, especially on lenses with image stabilization. However, at 500mm and above, there is no denying that results are much better with a stiff, heavy tripod and mirror lockup.

    I also have no doubt that a decent tripod, used carefully, will produce better results below the one-over focal-length shutter 'safe' speed rule of thumb, and even at faster shutter speeds, but I don't think mirror slap is the key element in this.

    I'm a big fan of Herbert (Burt) Keppler, here's what he had to say about camera vibration way back in 1985:
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  6. It used to be discussed more in terms of very slow shutter speeds, esp among amateurs, but in practice many experienced photographers relying on tripods would lock the mirror for all (or nearly all) speeds, certainly speeds at or below the "handheld limit formula". Lessons learned in the digital era have made many more photographers rely on lockups or electronic shutter whenever possible, given hi res sensors magnify mirror/shutter shock effects that were not as apparent with film.

    Medium format can be more unpredictable vs smaller or larger formats: some MF cameras behave completely counter to how you would assume from their appearance. Mass plus a well damped mirror can be hugely beneficial: the Mamiya RB67 is a handheld champ in this regard, competing favorably at 1/15 and 1/8 against fixed-mirror TLRs like Mamiya's own C220/330 and various Rolleiflex, Yashica, etc. With Hasselblad, I get less mirror shock issues from the heavier noisier motorized 500ELX than the smaller lighter 500CM. Some 'blad photographers have trouble with mirror/flap shock, while other (quite vocal) photographers claim they can balance a 500CM on one fingertip and get tack sharp 24 x 24 prints shooting at 1/30. So "the rules" generally seem to apply until they randomly don't, much depending on the individual photographer and circumstance.

    35mm SLRs are more consistent than medium format, as Keppler's 35mm SLR shock comparos demonstrated over the years. He can be a little opaque in his phrasing, tho: the Nikon EM mirror mechanism is at least as sophisticated as the FE and has less moving baggage than the F3, so it isn't the EM mirror causing Keppler's sharpness loss but its tiny weightless slippery plastic body. Mass of 35mm SLR body + steadiness of human body determines most of the mirror shock outcome: for Keppler the tiny EM gives worse results than the FE, which in turn is bested by the larger F3 with its grippier grip. Unexpected discrepancies do sometimes arise in 35mm: the "crude" original Nikon F is less shock prone than the "sophisticated" F2, and for some the Olympus OM-1 retains the negative impact of small light slippery body despite its advanced mirror damping mechanics.
    Last edited: Jan 30, 2021
  7. As you explained, MLU probably has most benefit at let's say 1/2, 1/4 or 1/8 for the reasons you mentioned. I remember reading a test that was done that proved this. Not necessarily for a MF camera.

    I always shoot my RB67 on a tripod with MLU. I have their dual cable release. But I stopped using it. I only use a single release cable connected to the lens shutter. I release the mirror with my finger. Then using a single cable to release the shutter works better. The only time I use the dual cable release is when I'm shooting people. Then as I push the release so the main mirror lockup activates, the people hear that. They think I shot them and relax rather than pose. So when they're unsuspecting, I just press a little harder to release the shutter and catch them better.
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  8. Some interesting replies there, thank you all. I can’t say I have noticed any loss of sharpness when hand holding medium format but then I don’t use it without a tripod very often. When it is on a tripod I do generally use mlu.
    It’s interesting to hear different views but for now I will still use my Mamiya C330 when out for a walk without tripod. Obviously no moving mirror in the C330. I am happy to use 35mm handheld without mlu certainly down to a 1/60 and 50mm lens but the Hasselblad and Bronica have big mirrors that make the camera feel like it is moving. Thanks again.
  9. William Michael

    William Michael Moderator Staff Member

    I ran a series of tests using Canon a DSLR and long, heavy lenses (e.g. 400/2.8) on a (sturdy) tripod: we were looking at the relationship between the mirror slap and the pitch (movement) of a long lens about its tripod mount.

    Simplified conclusions
    - necessary to use MLU at Tv between 1/125s and 2 seconds
    - advised to use MLU always, if you can

    BTW - MLU is sort of pointless unless you use a Remote Shutter Release - OR - Timer Release, plonking your finger into the 'GO' button can create a vibration, too.

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  10. And now that this question has been answered, time, perhaps, to point out the difference between mirror lock up and mirror prerelease.
    Very few cameras offer mirror lock up, i.e. allow to put the mirror up until you decide to have it come down again.
    Many offer mirror prerelease, with the mirror coming down again after every single exposure.

    Lock up is used when attaching lenses that protrude into the camera, or when the viewfinder isn't used.
  11. William Michael

    William Michael Moderator Staff Member

    Good point! -

    That's interesting isn't it? "Mirror Lockup" is the term regularly used in DSLR and SLR manuals, yet, as implied, many medium format cameras have a different cocking and shutter mechanism and "Mirror Prerelease" in Medium Format gear, is for the same reason, to reduce vibration effecting the image, yet, for example Hasselblad, use a different term for this similar process.

    Arguably, it would have been very good to have kept these two terms separate and distinctive.

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  12. Using a digital back (CFV16), I found a noticeable loss of sharpness at any shutter speed unless the mirror were pre-released or locked up (both features of a 555 body). This was in addition to using a heavy tripod and remote or delayed release. In other bodies, using the focal plane shutter produced similar camera shake issues.

    The mirror position prior to manual release is the important issue, not what we call it.
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  13. Just out of interest I looked in the manuals for Hasselblad and Bronica. Hasselblad call in Pre release. Bronica call it Mirror lock up, but they do have the option (on SQAi) of keeping the mirror up for all exposures.
  14. It's not an medium format v. 35 mm format thing. Some 35 mm cameras do offer lock up, not just prerelease. And some MF cameras do not.

    Out of all the V system Hasselblads, only the focal plane shutter models offer lock up. The rest only prerelease.
    Contrary to what you say, Ed, none of the EL models offer lock up. Only prerelease, and automatic prerelease. The mirror always goes up and down between exposures.

    What we call it, Ed, does matter. You can't mount one of those old Nikon fish eyes, for instance, on a camera that doesn't offer mirror lock up without doing serious damage.
    Prerelease and lock up are different things and it can be important to know which one there is.
    Last edited: Jan 31, 2021
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  15. There is a curious lack of consistency over the range of medium-format SLRs when it comes to mirror control.

    Early Kowa and Bronica 6x6 SLRs have no mirror lockup or pre-release whatsoever. The Kowa has leaf shutter lenses and is fairly well damped, so OK. But the Bronica (S2 etc) is the loudest, most mechanically convoluted SLR ever made: it will almost leap out of your hand when fired if you don't hold it tight. I was quite surprised when I owned one that mirror shock was not much different from my Hasselblads: probably because despite the cacophony all the mechanics are moving in opposite directions and may be neutralizing each other (i.e. the mirror flips down instead of up, while a roller blind races across the focus screen from back to front and the huge focal plane shutter snaps open at the rear).

    Rolleiflex SL66 and Hasselblad crank-wound leaf shutter models both have a similar mirror "pre-release" function triggered by a separate switch button: you can't lock it up in fixed position for a series of shots (mirror comes down after each exposure and must be pre-released again before each succeeding shot). Hasselblad variants with electronic focal plane shutter do have a full-time lockup option.

    Mirror pre-release operation in the motorized Hasselblads like 500ELM and 553ELX can seem downright bizarre to the uninitiated: just like the manually-cranked Hasselblads and the Rolleiflex, the mirror cannot be locked in a fixed upward position for a series of shots. Instead, the motor snaps the mirror down and back up for each and every shot (leaving it in the up position before shutter release until you change modes). This seems reasonable in the single-shot mode but almost nonsensical to watch in the continuous shooting mode: one really needs to use the camera to understand it.

    Mamiya RB67 requires a single or double cable release to operate mirror pre-release (here again, you can't lock it up in fixed position for a series of exposures). The leaf shutter in the lens has a switch for MLU function (newer lenses just sense the presence of a cable release and auto-activate MLU mode). Pressing the body release trips the mirror, pressing the cable release cycles the lens shutter to open/close.

    Bronica electronic focal plane shutter (EC. EC-TL) and electronic leaf shutter (ETR, SQ, GS) have the full time lockup feature. Early Pentax 67 had (amazingly, considering the huge mirror) no lockup or pre-release, but full time lockup feature could be retrofitted and was included in newer versions.

    Some 35mm SLRs had an indirect mirror pre-release feature tied to the self timer (i.e. Nikon FE, FM series). With these cameras, the self timer is actuated by the shutter release button instead of a separate self timer button. After winding the self timer lever (or its electric switch equivalent), pressing the shutter button pre-releases the mirror to up position, stops the lens aperture down and begins the self timer countdown. During the countdown any mirror-induced vibration presumably dissipates, then the shutter fires to make the exposure. As with the medium format pre-release function, the cycle must be repeated for each succeeding exposure (mirror won't stay up in fixed position for more than one shot).
    Last edited: Jan 31, 2021
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  16. The Olympus OM-1 was very quiet, no 'slap' at all. It has a true mirror lock up.
  17. ^ One of the reasons it was so popular with astro-photographers decades ago :) . Peter
    Last edited: Feb 1, 2021
  18. And from these focal plane shutter models, only the 2000-series cameras, not the 200-series models, offer mirror lock up.
  19. I uses a 555ELD. The mirror stays up.
  20. Then you have a very special ELD, Ed.
    None of my ELDs behaves like that. In all, just as in any other EL model, the mirror always flaps up and down.
    Take the lens and back of your ELD, put it in RS or AS mode, and watch what happens through the lens mount. No lock up. Just instant prerelease, i.e. mirror down and up again without a pause.
    Last edited: Feb 2, 2021

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