Does Mirror Lock-Up Actually Improve Sharpness?

This article is a separate explanation for my testing of how UV filters negatively impact image quality, and is referenced in my article “13 Photography Myths Every Photographer Should Know.”

What is mirror lock-up?

mirror lock-up

Mirror lock-up is a feature on almost all DSLRs that allows the photographer to flip up the mirror in the camera and then wait for any vibration from the mirror flipping to dissipate before tripping the shutter.  The purpose of mirror lock-up is to control vibration in the camera so that camera shake does not negatively impact the photo.

Who uses mirror lock-up?

Mirror lock-up is never used by portrait photographers because it is too cumbersome and the shutter speeds most commonly used by portrait photographers are so fast that it would provide no benefit.

Landscape and night photographers, however, frequently use mirror lock-up because they utilize long shutter speeds on almost every shoot.  The idea is that it will add just a tad bit of sharpness to the photo because there is no vibration caused by the mirror.

How I tested mirror lock-up

In my opinion, the best way to test sharpness of anything is to take a picture of a newspaper.  This works perfectly because the subject is perfectly still and you can zoom in on the letters to easily see if the sharpness is improved.

In this particular test, I used a 200mm lens so that any vibration would be magnified and I could see the reduction in sharpness caused by the vibration of the mirror.

I took many test shots using mirror lock-up and no mirror lock-up with the camera mounted to a sturdy tripod.

Mirror lock-up sharpness test
Mirror lock-up sharpness test

So did mirror lock-up show ANY increase in sharpness?

Nope.  Not a bit.  The photos with no mirror lock-up produced precisely the same quality of photos as the photos with mirror lock-up engaged.  I tried EVERYTHING to see if I could tell a difference.  Firing multiple shots in a row with long shutter speeds didn't even affect the regular photo.

Basically, the conclusion that I draw from this test is that mirror lock-up is a great THEORETICAL way to prevent vibration from affecting the image, but when it comes right down to it… it doesn't seem to make even the tiniest bit of difference.

I suppose if you have a cheap tripod that is not sturdy, mirror lock-up could possibly help things slightly.  With my sturdy tripod however, I couldn't see any tiny bit of difference between the shots even when I was trying to make the regular shot show vibration from mirror flap.

17 thoughts on “Does Mirror Lock-Up Actually Improve Sharpness?”

  1. probably depends a lot on the camera and the resulting weight of the mirror. Also depends a lot on shutter speed – it isn’t long shutter speeds that are a problem – but ‘medium’ shutter speeds, were the period of vibration is a significant amount of the time the shutter is open – 1/8th to 1 second for example.

    It is pretty apparent with a long lens (e.g., a big, pro 300mm or longer prime and heavy mirror (e.g., a 1 series canon lens))

    You don’t mention much/anything about the camera you used, lens size (not focal length) you used or the actual shutter speeds you looked at.

  2. I’ve never really cared much about mirror lockup. when I shoot landscape and macro, and have time to compose the shot, I use liveview on the camera anyhow. That “engages” the mirror lock to see the image on the LCD sensor on the back.

  3. I find the mirror helps with using a telephoto lens to photograph the moon. Maybe I did something else wrong but I may have found a more sensitive circumstance than the test was.

    1. @Daniel – Interesting. Note that the sample I used here was using a 200mm lens on a crop sensor camera and zoomed in to 100%. I can’t imagine a more sensitive situation….

  4. @Shadows44 – I’m shooting with a 200mm lens on a crop sensor camera zoomed in so close that it shows only a few words on a newspaper clear across the room. I think that qualifies as macro…

  5. (1) To the comment that “Mirror lock-up is never used by portrait photographers because it is too cumbersome and the shutter speeds most commonly used by portrait photographers are so fast that it would provide no benefit.”

    FALSE. Indeed, in low light situations, I perhaps use mirror-lock up mode more for my people pictures than I do for any landscape images I make.

    (2) The benefit of mirror lock-up not isn’t going to be so noticed on a camera that’s locked rock tight to a tripod, but rather in circumstances where one is hand-holding a camera. And most particular for any shot which is done with a shutter speed of 1/30 second or less. But to run this test with a camera that’s locked rock solid to a tripod is simply misleading as to where mirror lock-up mode is use best and most effectively.


  6. Okay Jim, I’ll re shoot the moon in the same conditions, list all my gear and put both on my blog. Maybe I can confirm one way or the other. I shoot a 7D on a good but consumer grade tripod. You can see what I got with the mirror locked up Halloween night. My mind is open on this, let’s see. Jim, I can get ya the RAWS if you want them.

  7. In many cases you are right but there are definitely situations where you want mirror lockup. One is on a tripod when your gear is just too heavy for the tripod. Here it’s trivial to see — you can see the shake on a big long lens from anything — touching the camera even. You need a cable release too here.

  8. It’s been mentioned before; it depends on the mirror size, the duration of the exposure, the length of the lens, and i would venture a guess on how well they “pad” where the mirror lands.

    i don’t know what camera you’re using, or the length of exposure you’re using.

    so i have no way to test your method/verify what you did on my end.

    i would suppose an ideal test target would be a resolution chart; newspaper print, from what i know, has a lot of bleed.

  9. Lots of people have commented “it depends on this or that” or “that’s not necessarily true”, etc. HOWEVER, I still haven’t seen anyone prove to me that mirror lock-up improves sharpness. Go do a test of your own and I’d love to see what you come up with, but otherwise… your comments are merely theories.

  10. I learned on my D80 shooting at 500mm. the subject were two beavers in a low light situation. My exposure was around 1/15 of a second. Shot using a solid tripod. Several shots made, but none really very sharp. I then went to the shutter delay mode (no mirror lockup on the D80). BIG improvement. I have since learned that there is a “critical window” where mirror slap can be a problem with most cameras. I would say that with the D80, it was most notable from around ½ sec. to maybe 1/30th of a second. At higher shutter speeds or longer shutter speeds the mirror slap to exposer ratio is wide enough to overcome the problem.

  11. Although the description of test condition is vague, the results didn’t surprise. Several years ago I have performed some vibration tests. MLU improves the vibration levels about ten times (tested on Nikon FM2n). However, the results with FM2n without using MLU were still very acceptable.
    The whole article isn’t in English, sorry: http://www.mry.cz/articles/camera_shake/shake1.htm

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  13. Did you test this on short distance photos only, like the example, or did you test it on landscapes as well?

    I haven’t done any test on mirror lock-up, but I have a feeling camera shake from the mirror might be visible in a landscape picture, where the distance from your camera to your subject might be miles. This is because the tiniest shake on your camera is multiplied when the distance is increased.

    Example. If you try to zoom in on a subject from far away with a 200-300mm lens, it’s virtually impossible hold the camera steady enough. The tiniest shake is critical, and you need some kind of support. But if you go closer, and use say a 50mm lens, it is no problem to shoot hand held.

    I would test this my self, if I had a long tele lens, but I don’t…

  14. Great article and test. I have read many times of mirror lock-up for improved images, and wandered if any significant difference could be gained.
    Thank you for doing these tests and sharing them.
    Best regards,

  15. Greetings, normally i use heavy tripod for my Nikon D750, average shutter for daylight 1/8″-1/60″, MLU, 2second delay. But wanting to build lighter system, D750 two lenses 20mm & 60mm macro. Using MLU and 2 second delay, can I use much smaller tripod?

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