When to use Mirror Lockup (MLU)?

Scott_Quier

I was reading around the various forums (not on DGrin) and ran across this,

Mirror lockup prevents mirror slap, which manifests itself mainly in exposures between 1/5 and 3 seconds or so. After that the exposure is long enough that the initial slap is muted, and shorter than that the slap doesn't have enough time to move the camera out of alignment.

which caused me pause. My understanding, based on my reading (a couple of years ago now) on this subject, is/was that the mirror slap can impart enough vibration to be noticable when the shutter speed was anything slower then the rule-of-thumb 1/FL [or 1/(FL * cropfactor), for crop cameras]. Because this statement wasn't contested in that other forum, I thought I would bring it here and see what people smarter and more experienced than me had to say. My practice has been to use MLU whenever practical, especially with longer lenses, regardless of the shutter speed. Have I been working harder rather than smarter? :dunno :scratch

catspaw

I was taught to think of it as a percentage of shutter speed. For example, at a three minute exposure, the lock up isn't needed, since it's such a small part of the total exposure time.

pathfinder

Scott,

My general thoughts for MLU, are 1/30th to about 1/2 to 1 sec. Shutter speeds of 1/15th to 1/4 are the worst I believe. Depends on focal length to a certain extent, wider lenses significantly less than very long lenses. Theoretically, a long lens if held perfectly still, should not require a faster shutter speed than a wider lens, but tripods are just never that good for most of us.

Longer or shorter shutter speeds than stated above are less affected by the mirror movement for normal to wide lenses.

One thing not mentioned, but I'll bet some bodies ( better or pro ) are somewhat less affected than others. Full frames MAY be worse due to a larger, heavier mirror to move. I wonder if this is less of an issue for the 4/3 system, and the new Micro 4/3 does not have a mirror at all.

Canon used to make a pellicle mirror based system years ago that the mirror did not move also if memory serves.

That is why MLU with a 2 or 10 second delay before shutter activation is so worthwhile for maximum image sharpness.

Scott_Quier

OK - well I'm not yet convinced. The 1/30s for the upper limit just doesn't feel right. So, when in doubt test it. I have a new tripod (arrived last week) and a new ballhead (arriving today). I'll experiment with my 70-200 (as that's the longest lens I have right now) and post the results!

Candid Arts

I normally use MLU on any macro shot I take (assuming I remember to turn the MLU on) or on longer exposures. As for me, any movement is bad movement. I don't nessecarily have an exact number that I would turn MLU on, but if I'd have to guess, I'd say somewhere in the 1/15th. Pretty much if I have to put it on the tripod, and I remember to use it, I'll use it.

Testing sounds like the best, most surefire way to figure this out though. I'm interested in seeing the results.

Scott_Quier

Candid Arts wrote:

I normally use MLU on any macro shot I take (assuming I remember to turn the MLU on) or on longer exposures. As for me, any movement is bad movement. I don't nessecarily have an exact number that I would turn MLU on, but if I'd have to guess, I'd say somewhere in the 1/15th. Pretty much if I have to put it on the tripod, and I remember to use it, I'll use it.

Testing sounds like the best, most surefire way to figure this out though. I'm interested in seeing the results.

Didn't think about macro but that would/could be an even more critical test of MLU. Hmmmm ... such fun in store for me this afternoon!

Candid Arts

Scott_Quier wrote:

Didn't think about macro but that would/could be an even more critical test of MLU. Hmmmm ... such fun in store for me this afternoon!

Yeah, Macro is one of the most important uses for me as the DOF is usually fairly narrow and with a 1:1 magnification (or higher with the MP-E), even a little bit of movement can and will be detected.

SUCH fun! Can't wait to see them.

pathfinder

Scott_Quier wrote:

OK - well I'm not yet convinced. The 1/30s for the upper limit just doesn't feel right. So, when in doubt test it. I have a new tripod (arrived last week) and a new ballhead (arriving today). I'll experiment with my 70-200 (as that's the longest lens I have right now) and post the results!

I think of 1/30th - 1/60th for normal or wide lenses typically used for landscapes or product shots. There are those who refuse to hand hold less than 1/125th, but that is pretty confining as I am sure you know shooting weddings.

I would never choose to shoot a tripod mounted 400mm lens at 1/40th given any other choice. I would strongly prefer to stay close to 1/400th or 1/200th for a 400 mm lens. For your 200mm, I might accept 1/100 with MLU on a good firmly based tripod.

Baldy did his pano shots with a 600mm lens on two tripods heavily weighted - I am not certain about his shutter speed and use of MLU though.

Maybe he will give us his experience here.

This image is from a small portion of a 40 D image I shot with a 200-500mm at 500mm lens firmly sitting on a rock for stabiity at 1/250th at f8 at ISO 800. The deer was in the deep shade. No MLU was used nor was a remote shutter release. I did not like the choice of shutter speed, but the deer would not wait while I set up a tripod and activated MLU, so I did the best I could. I did not want to go to ISO 1600, but maybe that would have been a better choice than 1/250th. Maybe not. I have a print of this image at 16x20 and it does not suffer from blurring; a bit of grain, but not blurring from the mirror movement. That's my opinion, and I am sticking to it!!:D

Unless you can convince me otherwise, Scott!

Scott_Quier

pathfinder wrote:

Unless you can convince me otherwise, Scott!

No "convincing" intended. I'm still not totally convinced ... though more so that I was before - that image is very telling/convincing. I'll just be more comfortable once I have done my testing.

More later

Candid Arts

pathfinder wrote:

FWIW, I absolutely LOVE this photo. If it were mine (thus making printing it cheap) I would have printed this as a b-day present for my dad two weeks ago. But no money means no print...:-/. Anyways...beautiful photo.

Nikolai

Scott,
here's my take on the subject. Please take it with the grain of salt since I'm trying to avoid MLU usage like a plague, hence my actual experience with using it is minimal.

• it's primarily related to the shutter speed and the effective duration (and strength) of vibration. My unsderstanting is that it becomes dangerous around 1/4 sec on a "fast" side and becomes irrelevant after 2-3 sec, with the "worst peak" being 1 sec.
• since it's caused by the vibration, the longer lens may prolong the duration due to the sheer mechanics (especially if a flimsy tripod is used), hence making an impression that the effect is increased along with the focal length used.
• the strength (or the initial amplitude) of the vibration plays an important role in this. We all remember the loud "slap" of Canon 20D. Since that time Canon engineers spent a lot of efforts dumpening the mirror, so the effect was gradually becomeing less ans less noticeable.
• the introduction of a LiveView mode pretty much nullified the effect, at least on a most recent crop (50D/5D2). I didn't use it much, but I did use it, and I yet to get a blurred image even though my shutter speed was quite often in the middle of the "danger zone".

HTH

Scott_Quier

OK - Here we go, some results
Macro: Canon 50D and Canon EF 100 f/2.8 Macro lens. All images are without MLU as I'm trying to determine when it might be useful.

The method: Mount the camera/lens on the tripod in the most "technique lacking" manner I could think of...



and position the camera/lens at an appropriate macro distance from the target (a bunch of intersecting black lines on white paper). Manually focus on the target using LiveView. In Tv mode and with EC set to +1.5 (shooting white paper, we want it to be white, not gray!) shoot with shutter speeds from 1/6 all the way up to 1/400. In multiple tries, I failed to get any of the images to exhibit blurring due to camera motion.

Distance: Canon 50D and Canon EF 70-200 f/2.8 IS at 140mm and IS NOT engaged - the idea was to avoid the end of the focal range

Method: Again ... Mount the camera/lens on the tripod in the most "technique lacking" manner I could think of, LV manually focus, turn off LV, fire off exposures, change Tv between exposures ...



Shooting from 1/400s all the way to 1/6s. Things were looking pretty good from 1/400 all the way to 1/100

Here 100% at 1/125s


Here's 100% crop at 1/100s


Heres' 100% at 1/60s


Here's 100% at 1/50s


Same blurring can be seen at any speed less than 1/60. BTW - some may question the fact that the camera strap was on the camera and that it might have caught some air movement - nope, still air.

So, now I know the limits of my equipment. Your's may (probably will) behave in a different manner. And, I'm sure that I could proably change the outcomes shown here had I used a bit better tripod technique (load the tripod a bit more, not use the center column extended, that sort of thing).

Nikolai

Scott_Quier wrote:

Macro: Canon 50D and Canon EF 100 f/2.8 Macro lens. All images are without MLU as I'm trying to determine when it might be useful.
...

So, now I know the limits of my equipment. Your's may (probably will) behave in a different manner. And, I'm sure that I could proably change the outcomes shown here had I used a bit better tripod technique (load the tripod a bit more, not use the center column extended, that sort of thing).

Good test, Scott! I'll try ro follow!
One question: you said you failed to get a blur in macro mode and you also mentioned you were focusing in LiveView mode.. question: did you shoot in LV, too?

Scott_Quier

Nikolai wrote:

Good test, Scott! I'll try ro follow!
One question: you said you failed to get a blur in macro mode and you also mentioned you were focusing in LiveView mode.. question: did you shoot in LV, too?

No. Focus in LV. Turn off LV. Make sure AF (on the 70-200) is off. Adjust Tv between shots. Trigger shutter with wired remote.

pathfinder

Scott,

You didn't include the aperture you used for each shot as well with the 70-200 - as you close down the aperture from f5.6-f8 you will find less sharpness than the more optimal images.

Not enough to explain your results, but may contribute some.

I find it interesting that the 70-200 at 140mm was so different from the 100mm. Seems to me that the results relate more to the mass of the lens, than the difference in focal length. Both seem to be of very high optical quality normally.

I would have loved to see your results with a 35 mm lens, or a 28mm lens.

Before we assume your results are due entirely due to movement, it would have been nice to see a second shot with MLU engaged that was clearer, wouldn't it?

Art Scott

The only time(s) i would have even considered using MLU is during wedding ceremonies where the slap of the mirror was / could be recorded on the videographers tape.....but alais I have only owned one camera capable and it has long died.....for thse situations I just switched back to my handy dandy trust worthy TLR.....no moving mirror to worry about.

pyry

Good test Scott! I'll have to repeat for my equipment too.

One thing I have used MLU for a lot is when I've forgotten to pack a remote release. Set the timer and MLU on (to get the 2 second timer), press the shutter, let go of the camera...

Nikolai

A bit OT, but one of the things I like about 5D2 is the ability to use IR RC. Way simpler than RC cable. Of course, it can't do timed exposures, but that's a separate case. I find that the trigger-finger induced vibrations are like a tsunami compared to a regular mirror-induced storm.

I'll try to do my own set of tests soon.

LiquidAir

pathfinder wrote:

I find it interesting that the 70-200 at 140mm was so different from the 100mm. Seems to me that the results relate more to the mass of the lens, than the difference in focal length. Both seem to be of very high optical quality normally.

Here's my guess:

The 70-200 is mounted using a collar which means the mirror is not centered over the post. That means that when the mirror slaps it has a greater lever arm to set that tripod post a swingin'

pathfinder

I suspect you are correct, Ken.

I think the tripod setup contributes also, as Scott hinted at, as the center post is significantly extended, and I try very hard to NEVER extend my center post if at all possible.

I agree with Nik also about the IR remote for the 5DMkII - a very handy little gadget that I intend to use a lot. Mine arrived last week!

I think mirror slap is generally far less important than a heavy trigger finger,

Scott_Quier

pathfinder wrote:

Before we assume your results are due entirely due to movement, it would have been nice to see a second shot with MLU engaged that was clearer, wouldn't it?

Actually (and I may not have been clear on this), my purpose was to determine when I need to use MLU ... or put another way, when I don't need to use MLU. So, by determining when there was motion caused blur, I would also be identifying when MLU would improve image IQ. If I don't have motion blur, MLU would have only minimal impact on IQ. Obviously, my working assumption is/was that MLU would improve the situation by seperating any vibration induced by mirror slap from the exposure.

pathfinder wrote:

I suspect you are correct, Ken.

I think the tripod setup contributes also, as Scott hinted at, as the center post is significantly extended, and I try very hard to NEVER extend my center post if at all possible.

I agree with Nik also about the IR remote for the 5DMkII - a very handy little gadget that I intend to use a lot. Mine arrived last week!

I think mirror slap is generally far less important than a heavy trigger finger,

Just to be clear and to save my name from tarnish , extending the tripod center column was done to try to multiply the effect of the mirror slap, thus making it easier to see. As I attempted to indicated, this is not good practice and, like you, is one thing I will do just about anything to avoid.

pathfinder

No tarnish intended, Scott, I knew you had stated the deliberate extension of the tripod head.

We have all learned a bit here I think.