Mirror Lockup - what is it used for?

[smudwhisk]

OK, I'm showing my ignorance here but my Bronica SQA has mirror lockup facility. What would I use it for?

 

[roteague]

It is particulary useful when using a slow shutter speed. It keeps the movement of the mirror from being transmitted to the lens during an exposure.

 

[jeroldharter]

When you press the shutter, the mirror flips up out of the way of the film plane. That creates some vibration which can degrade sharpness.

If you are using a tripod:

you compose the picture, activate the mirror lock-up (at which point you can no longer see anything through the viewfinder), give it a couple seconds to equilibrate, and then trip the shutter. I think it is a good practice to get into, especially with macro photography when possible.

 

[David A. Goldfarb]

MLU is most useful in the range of about 1/60 sec to 1/2 sec, when vibration due to mirror slap could occur over a significant portion of the exposure. For very long exposures, it won't matter much.

 

[Kevin Caulfield]

Even on hand-held shots I often use it. Obviously not being able to see the subject through the finder then makes it a bit hit and miss, but it's great for taking photos of our baby in low light.

 

[jovo]

Mirror lockup is also used to punish mirrors that have been naughty.

 

[narsuitus]

Some extreme wide-angle lenses extend so deep into the camera body that the mirror must be locked up to accommodate the lens. I do not know if Bronica makes such lenses but if they do, the mirror lock up is necessary.

 

[Soeren]

Do you have a laser pointer ? put it on your camera or lens (on tripod) and use a mirror to make a fairly long path, mine is 20m form camera to mirror and back to the wall behind me. Trip the shutter with and without MLU, watch the dot on the wall and you will know what its for, whether your tripod is stable enough and if your tripod shooting technique is good enough. I found severe mirror slack on my Pentax 6X7 (which was expected) and also shutter induced wibration (which also has been reported). Whether it (shutter induced..) is enough to affect image quality I don't know yet but I found that there was no difference in using mannfrotto 055 (2,6kg?) or the heavier 058 (app 6kg) with the mannfrotto 141 head. The novoflex mini magic ball did a bit worce, but only a bit bit. My conclusion is that the way the camera is attached to the tripod head is of great importance as is the way the tripod is used (offcource). BTW the little plastic thing to use instead of the centerpole has now been thrown far away and the centerpole will be cut to allow low wievpoint shots.
Regards Søren

 

[Dan Henderson]

As illustrated in the last post, there is almost always camera movement induced by the mirror. Some people (including Barry Thornton in "Edge of Darkness") recommend using MLU all of the time, regardless of shutter speed being used.

 

[mmcclellan]

When shooting a reflex camera on a tripod, especially below about 1/30 second, I always use mirror lock-up, just to give that extra stability and to minimize vibrations. If you're using a tripod, anyway, the subject isn't going anywhere so you might as well take the extra second or two or raise the mirror. It can help!

 

[smudwhisk]

Thanks guys, I'm duly enlightened. Will have to try it sometime. Thanks.