What's Mirror Lockup?

[andretan]

What's Mirror Lock-up?

Can someone enlighten me? Thanks

[denizenx]

it's making the SLR mirror go up some time before the shutter opens... to reduce all possible reasons for vibrations

[Ian]

Quote: Originally posted by andretan What's Mirror Lock-up? Can someone enlighten me? Thanks

Mirror lockup is a camera feature that allows the photographer to selectively lock the reflex mirror (the mirror that sits in front of the shutter curtain) in the 'up' position to reduce vibration in the camera body to an absolute minimum. When mirror lockup is used the view from the viewfinder is blanked out

Mirror lockup used to be found on most better SLR bodies however in recent years it's been more and more pushed in to the realms of professional and advanced amateur level bodies.

It's particularly useful for critical photography where an absolute minimum of vibration is required, for example long exposure astrophotograpy, extreme macro photography and when using very long lenses.

If your camera doesn't have mirror lockup you can often get a similar effect by using the self timer function as most SLR's put the mirror in the 'up' position when the self timer is used.

[andretan]

Ok, thanks for the response guys

Appreciate that.

[Wai]

Quote: Originally posted by Ian It's particularly useful for critical photography where an absolute minimum of vibration is required, for example long exposure astrophotograpy, extreme macro photography and when using very long lenses.

hmm....so how long the exposure or how extreme the macro distance or how long the lenses will u recommend to use mirror lock up?

so when the mirror is up, are all the camera settings such as metering, focus, aperture, shutter speed all will be locked when u press the button first time?

[ninelives]

Quote: Originally posted by kamwai so when the mirror is up, are all the camera settings such as metering, focus, aperture, shutter speed all will be locked when u press the button first time?

yes.

Mirror lock-up will not affect your setting. It just lock the mirror(move up) for few sconds, then release the mirror(move down). For canon and minolta, mirror vibration damping is very bad, so mirror lockup is a good feature for these 2 systems.

[ckiang]

Quote: Originally posted by ninelives yes. Mirror lock-up will not affect your setting. It just lock the mirror(move up) for few sconds, then release the mirror(move down). For canon and minolta, mirror vibration damping is very bad, so mirror lockup is a good feature for these 2 systems.

Actually, in a "real" mirror lockup mechanism, you can explicitly lock the mirror up independent of the shutter release. Once it's up, you can separately release the shutter.

Most cameras nowadays implement it such that it goes up when you press the shutter, then either hold for a few seconds or wait for the next shutter trigger before opening the shutter, then flip back down. Not so elegant.

For the majority of people, it's probably not important, and from what I understand, is only critical in certain range of shutter speeds were vibration is greatest (read something like 1/8 - 1/15s or thereabouts).

Regards
CK

[Ian]

Quote: Originally posted by kamwai hmm....so how long the exposure or how extreme the macro distance or how long the lenses will u recommend to use mirror lock up? so when the mirror is up, are all the camera settings such as metering, focus, aperture, shutter speed all will be locked when u press the button first time?

I use mirror lockup when ever I feel it's needed.

As CK mentioned most cameras have a critical shutter speed range for vibration. The speeds most effected vary from camera to camera, but I've seen terrible vibration at speeds as high as 1/60th and as slow as 1/4 second on some of the less well damped bodies. Modern Japanese bodies (built in the last 20 years or so) are considerably better in this area than older bodies.

For macro I use mirror lockup once I get over 1:1 with still life objects (coins, jewels flowers etc) and if lighting conditions are poor in the field. I always use mirror lockup when using bellows and still objects.

To give you an idea, a Nikkor 55 Micro with 65mm of tube extension and 160mm of bellows means your less than 10mm from your subject with a magnification ratio of around 5.6:1 and when using my 105 Micro Nikkor with the same setup it's about 3.6:1 The problems get considerably worse when you start using 'long bellows' made up of two sets of bellows joined together.

With long lenses it depends on the subject. It's not practical to use mirror lockup on moving subjects however a bird at rest on a branch is an ideal candidate for mirror lockup, as are isolation shots (building detail, landscapes) etc. I'll use miror lockup with any long lens of 300mm plus.

Anytime I use mirror lockup I also use the viewfinder shutter to eliminate any sources of stray light.

Focusing and exposure values may or may not be locked, it depends on the camera. For example a if you use a 'manual' lens you can adjust aperture and focus after the mirror is locked up though why you'd want to do it is another question.