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Author Topic: Mirror Lock-up is a bigger deal than previously thought  (Read 10416 times)
GaRP
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« on: April 16, 2009, 10:30:23 AM »
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I found this while surfing this AM.

http://techon.nikkeibp.co.jp/english/NEWS_...0090413/168663/

Highlights directly from the article:

The results of measurements using the new tool are as follows. The resolution of an SLR camera was substantially reduced to 1/4 or lower by the mirror shock (vibration generated when the mirror bounces up).
Next, it was confirmed that the vibration generated by releasing the shutter remains even when a picture is taken after a certain period of time from the mirror lockup to prevent a mirror shock.
Then, the Nishi Lab and Tani Electronics found that camera shake significantly worsens when a lighter tripod (approx 1.5kg) is used. Also, they conducted a quantitative investigation about the influence of the installation direction of the tripod.
"There is no point in enhancing resolution unless we take some measures to reduce the vibration of a camera unit as a whole including a tripod," said Kazuki Nishi of UEC.
When a tripod is used, the above measurements were carried out after disabling the image stabilizer, as directed in instruction manuals of cameras and lenses. And, to make sure, the researchers conducted the measurements using several cameras with the image stabilizer function turned on and confirmed that camera shake worsens.

This may be old information but I could find no other references on the forum.
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EricV
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« Reply #1 on: April 16, 2009, 11:17:02 AM »
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A fancy lab is hardly needed to see the effects of vibration.  Michael recently suggested the simple demonstration of attaching a laser pointer to the camera and watching the beam vibrate as the mirror bounces or the shutter is tripped.  An even better demonstration would be to mount the laser pointer off the camera, pointing stably at a distant wall in a dark room, then take pictures of the laser dot under varying conditions and examine the images at high magnification.
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250swb
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« Reply #2 on: April 16, 2009, 04:06:50 PM »
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Mirror lockup, or at least a shutter delay, has always been a big deal. Which is why it should be higher in most camera menus. Unfortunately it isn't 'sexy' because mirror lockup implies negative overtones that you need a special function to stop the camera 'f ing' up your photo's.

Steve
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DarkPenguin
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« Reply #3 on: April 16, 2009, 04:34:08 PM »
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Quote from: 250swb
Mirror lockup, or at least a shutter delay, has always been a big deal. Which is why it should be higher in most camera menus. Unfortunately it isn't 'sexy' because mirror lockup implies negative overtones that you need a special function to stop the camera 'f ing' up your photo's.

Steve

What!?!?

Are you sure it just isn't something that most people don't use and never would no matter how easy you make it for them?  kind of like using a tripod?
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Nick Rains
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« Reply #4 on: April 16, 2009, 11:57:16 PM »
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Quote from: DarkPenguin
What!?!?

Are you sure it just isn't something that most people don't use and never would no matter how easy you make it for them?  kind of like using a tripod?

LOL - yes indeed.

I remember watching a guy shoot images of a rainforest waterfall. He stood there with his camera, taking pics in the deepest shade and then left,  with a tripod still strapped to his backpack. It was a 10k round trip to this waterfall - WTF!

I don't think MLU would have helped.
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Nick Rains
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BernardLanguillier
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« Reply #5 on: April 17, 2009, 12:27:07 AM »
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Quote from: GaRP

Any idea whether the original Japanese article is available online? This abstract is too vague to figure out the details of their findings.

My personnal experience shows:
- Tripod without MLU is the stupidest thing to do, whatever the shutter speed
- Handheld without MLU is a reasonnable option when the shutter speed is high enough
- The weight of the tripod in itself means little without looking at its vibration behavior
- The shutter itself is also an important source of vibration when it is large (like plane shutter MF for instance)

Cheers,
Bernard
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Nick Rains
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« Reply #6 on: April 17, 2009, 01:11:41 AM »
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I don't doubt the theory of this but I've just been tinkering around with a laser pointer...35mm camera only as I don't have an MF system to hand (unless I used my old RZ).

Canon 400D (lightest body I could find), 17-40L.
Gitzo 4 section carbon fibre tripod with full leg extension (2540LVL)
Crappiest tripod head I could dig out of my cupboard, a Manfrotto 141RC with a small cork faced QR plate.

Using 10 sec self timer and no MLU and at a range of 10m I got a deflection of less than one mm on shutter firing at 1/15th sec which would be one of the worst shutter speeds to use (I tried other shutter speeds and there's not much difference). That's less than 1:10000. Not sure what that is in angular deflection but it's not much. Using MLU reduced that to zero, or certainly not discernible to the naked eye.

The worst result I could get was with a 5D on a Kirk B+S with the tripod centre column at full extension (!). Then the deflection was about 1.5mm. With MLU it was barely perceptible.

What I did notice though was that the barest touch of the tripod sent the spot wiggling around like mad.

My conclusions for now are that in the absence of wind even a half decent tripod holding a DSLR it will be completely stable if you use MLU and an electronic cable release. Even without MLU it's still almost perfect. Shutter bounce, in these two cameras at least, has negligible effect. But if you use your finger without MLU then you will be very likely to get an soft image, and with a tele lens this is obviously magnified.

When I get my hands on a medium format system I'll try the same test and see how it goes.
« Last Edit: April 17, 2009, 01:13:37 AM by Nick Rains » Logged

Nick Rains
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Henry Goh
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« Reply #7 on: April 17, 2009, 01:13:30 AM »
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Quote from: BernardLanguillier
Any idea whether the original Japanese article is available online? This abstract is too vague to figure out the details of their findings.

My personnal experience shows:
- Tripod without MLU is the stupidest thing to do, whatever the shutter speed
- Handheld without MLU is a reasonnable option when the shutter speed is high enough
- The weight of the tripod in itself means little without looking at its vibration behavior
- The shutter itself is also an important source of vibration when it is large (like plane shutter MF for instance)

Cheers,
Bernard

Hi Bernard,

May I clarify: are you saying w/o MLU even at higher speeds on a tripod, you are seeing image degradation from vibrations?  Is this observation from all cameras?

Thank you.


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David Sutton
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« Reply #8 on: April 17, 2009, 01:35:05 AM »
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So many variables to consider when trying to get really sharp images. For the life of me I've never been able to get the laser pointer thing to work. Even running the beam back and forth across the room with mirrors to amplify any movement. But I have seen obvious horizontal blur in an image, even with MLU, when using a tripod on a wooden floor at shutter speeds of about half a second (part of the same experiment). A bean bag on the camera solved the problem. I've always felt my tripod to be a little lightweight ( Velbon Sherpa) but since fitting it with a hook and hanging my backpack there, the whole thing now feels rock-solid. But for anything under about 1/30th second I'd still use the beanbag if handy.
David
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Henry Goh
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« Reply #9 on: April 17, 2009, 01:49:31 AM »
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Can you guys please try this.  I don't have a lightweight tripod so need you to test:

Instead of hanging heavy bags or other things under your CF tripods, could you hang a bottle of water say 1 litre or 1.5 litre bottle of Coke or something.  Now repeat your tests and see if you find significant improvement.

Please report.

Thanks.
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Ray
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« Reply #10 on: April 17, 2009, 05:40:26 AM »
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Quote from: BernardLanguillier
My personnal experience shows:
- Tripod without MLU is the stupidest thing to do, whatever the shutter speed

My experience is quite different, Bernard. I've never found MLU to be necessary outside of a shutter speed range of 2 seconds to 1/60th. The most critical shutter speeds are 1/15th to 1/30th. At 1/60th and 2 seconds, the benefits of MLU would only be noticeable (if at all) at print sizes far greater than you would likely make, or at 200% on the monitor.

I've heard reports of images from long telephoto lenses benefitting from MLU with shutter speeds as fast as 1/125th. But I've never experienced such a benefit with my 100-400 IS. On the other hand, that's not a particularly sharp lens, so maybe a razor sharp long telephoto actually can benefit from MLU at 1/125th.

I once tested the effects of MLU on my Canon 20D with 50/1.8 II lens, using a lightweight travel tripod and remote cord. I could not detect any benefit from MLU at any shutter speed, yet when using the 5D with the same lens on the same tripod, same position and same target, there was a very noticeable benefit to MLU at 1/30th.

The Canon 20D has a very noisy mirror slap. My theory is that the energy of low frequency and inaudible vibrations which would normally cause a problem with most DSLRs when the mirror is rapidly lifted, has been transformed into less harmful, higher frequency vibrations on the 20D. Whilst such higher frequency vibrations are very audible, they are too high to cause physical vibration of the camera.
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BernardLanguillier
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« Reply #11 on: April 17, 2009, 05:50:28 AM »
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Quote from: Henry Goh
Hi Bernard,

May I clarify: are you saying w/o MLU even at higher speeds on a tripod, you are seeing image degradation from vibrations?  Is this observation from all cameras?

Yes, I have not done rigorous tests on this, and have not taken a single shot on tripod without MLU for years, but I did see such things a few years back (I believe with a SLR/n at the time).

Regards,
Bernard

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JeffKohn
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« Reply #12 on: April 17, 2009, 12:22:16 PM »
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Quote from: Henry Goh
Hi Bernard,

May I clarify: are you saying w/o MLU even at higher speeds on a tripod, you are seeing image degradation from vibrations?  Is this observation from all cameras?

Thank you.
Not to speak for Bernard, but if you're going to take the trouble to use a tripod and cable release or timer, there's really no reason _not_ to also use MLU if your camera supports it.
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Ray
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« Reply #13 on: April 18, 2009, 05:25:22 PM »
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Quote from: JeffKohn
Not to speak for Bernard, but if you're going to take the trouble to use a tripod and cable release or timer, there's really no reason _not_ to also use MLU if your camera supports it.

That's not necessarily true if your camera does not support Live View. If your camera does support Live View, and, if you go to the trouble of using a tripod and cable release, you might as well enable Live View so you can be sure of accurate focussing. In which case, also enabling MLU is no longer necessary because in Live View mode the mirror is already flipped.

However, if your camera does not support Live View (as the Sony A900 doesn't), then there may be circumstances when using MLU for no good purpose puts you at a disadvantage. Consider the procedure. Press the shutter button once to flip the mirror. Wait a couple of seconds for any vibrations to subside. Press the shutter again to take the shot. There's at least a 2 second period during which time you are unable to see through the viewfinder. Any person or animal in the scene, buffalo or large bird, might suddenly turn its/his/her head during that 2 or 3 second interval. Photgraphy is often about capturing the moment.

Consider also the cumbersome procedure of autobracketing exposure with MLU enabled. It could take up to 10 seconds to take 3 shots even with fairly fast exposures. A lot can happen in 10 seconds.


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Peter McLennan
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« Reply #14 on: April 19, 2009, 10:50:33 AM »
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Quote from: Ray
...Consider also the cumbersome procedure of autobracketing exposure with MLU enabled. It could take up to 10 seconds to take 3 shots even with fairly fast exposures. A lot can happen in 10 seconds.


Indeed, Ray.  It's a frequent annoyance for those of us addicted to HDR.  Clouds move much faster than you think.

Perhaps it's time to reconsider the mechanical shutter.
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JeffKohn
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« Reply #15 on: April 19, 2009, 12:08:16 PM »
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Quote from: Ray
That's not necessarily true if your camera does not support Live View. If your camera does support Live View, and, if you go to the trouble of using a tripod and cable release, you might as well enable Live View so you can be sure of accurate focussing. In which case, also enabling MLU is no longer necessary because in Live View mode the mirror is already flipped.
I can understand how you might feel that way shooting Canon. In Nikon-land, live-view is no substitute for MLU, because with live-view the camera still drops the mirror down before taking the exposure and then operates as normal. This means that mirror-slap can be even more of an issue with live-view than with out. Stupid I know, but that's how it works. So my habit is to use live-view for focusing, then switch to MLU mode to take the exposure.

Quote
However, if your camera does not support Live View (as the Sony A900 doesn't), then there may be circumstances when using MLU for no good purpose puts you at a disadvantage. Consider the procedure. Press the shutter button once to flip the mirror. Wait a couple of seconds for any vibrations to subside. Press the shutter again to take the shot. There's at least a 2 second period during which time you are unable to see through the viewfinder. Any person or animal in the scene, buffalo or large bird, might suddenly turn its/his/her head during that 2 or 3 second interval. Photgraphy is often about capturing the moment.
I don't see this as much of an issue for single exposures. You flip the mirror up in anticipation of the shot. I'm not suggesting MLU be used for action photography or BIF's, but for landscapes where you care about the getting the sharpest results possible (often at slowish shutter speeds), MLU becomes important.
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JeffKohn
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« Reply #16 on: April 19, 2009, 12:15:11 PM »
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Quote
Perhaps it's time to reconsider the mechanical shutter. rolleyes.gif
I wouldn't want to use an EVF camera for people, action, etc. But for landscapes I would definitely consider a live-view only camera with no mirror and an electronic shutter. Not only would it eliminate shutter slap but it should also make it possible to designer better wideangle lenses if there's no mirror clearance to worry about. Just think how nice it would be to shoot autobracketed exposures at 5fps without having to worry about any mirror- or shutter-induced camera shake.
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Rob C
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« Reply #17 on: April 19, 2009, 02:15:53 PM »
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I´m heartened to see that others have experienced the same strange effects that I have too: several different tests with cameras on tripod and mirror locked up or not locked up have not always delivered the expected results of the images WITH the mirror locked up being always better than the others.

As a matter of principle, when mlu is possible I´d use it, but it is no guarantee of best results. In fact, I have found that if I actually put some pressure down on the camera with one hand and trip the shutter with the other, a fairly good result will follow.

But with all of this, I believe that Bernard touched on a vital point: the intrinsic vibration-style of the tripod itself. And that seems to vary somewhat according to the material upon which its feet are based too: very hard floor tiles, for example, appear to set in motion a ´brittle´ sort of mechanics whereby the tripod feels very stiff but very movement-prone. Odd; has anybody else found this too?

Perhaps the worst case I´ve come across has been with the Pentax 67 ll, where with mirror locked up, on a heavy Gitzo, the shutter has bounced so much that the edges of the frame have been hopeless. Didn´t keep the camera long... a further big loss of money.

Perhaps we are nearing a situation where regardless of optics, sensor or film, mechanical limitations will bring us up against a brick wall which we will only pass by changing how we do things to capture images. Somewhere, I read of the idea of using no shutter at all, but of having exposure made via the trick of switching the sensor on and off for the time required to achieve exposure. Neat, if it can be done; fewer moving parts to go ass over tit. It might come from Canon, seeing how they don´t favour easy MLU ;-)

Just re-read JeffKohn´s last post: is this the same shutter you refer to as an electronic one? I have always assumed the exposing function of an electronic shutter to be exactly the same as a mechanical one: curtains.

Rob C
« Last Edit: April 19, 2009, 02:20:37 PM by Rob C » Logged

Wayne Fox
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« Reply #18 on: April 19, 2009, 03:48:16 PM »
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Quote from: Peter McLennan
Perhaps it's time to reconsider the mechanical shutter.

Ever observed the "shutter" action in one of the newer Canons ... 50d and 5dMk2?  

There is definitely no mechanical first curtain, and in fact in the correct Live View mode the curtain is open and the mirror up, and exposure begins without any physical movement other than the closing of the diaphragm ... perhaps the ultimate if trying to keep the camera still.

Wouldn't take much to eliminate the 2nd curtain ... perhaps they already have, maybe all it does is protect the sensor.

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KenS
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« Reply #19 on: April 20, 2009, 09:15:29 AM »
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Quote from: Rob C
...
Perhaps the worst case I´ve come across has been with the Pentax 67 ll, where with mirror locked up, on a heavy Gitzo, the shutter has bounced so much that the edges of the frame have been hopeless. Didn´t keep the camera long... a further big loss of money.

Rob C

Why would the edges of the frame suffer from vibration induced blur more than the center?
Was one side of the frame more blurry than the other?
The camera is a rigid body and all parts of the frame are exposed equally.
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