mirror lock-up - what does it mean? What is it for?

I have jumped in at the deep end and bought my VERY first Medium

format camera - a Bronica SQ-Ai 6x6. It has a mirror lock-up switch

and I can't seem to find out what it's for and what it does - can

anyone PLEASE help and advise me?

Mirror Lock Up- some 35mm cameras have it. It means that the mirror prefires. You can then fire the shutter and, since the mirror is already locked up, there are very little vibrations from the camera. MLU is recommended for shots when you have to reduce camera vibration, such as night shots, or macro shots.

 

I don't know about your specific camera, but this is basically what MLU is.

 

*daniel

It locks the mirror up ahead of time to minimise any vibrations to the camera during exposure. Anything that moves on the camera can degrade the image and medium format mirrors are relatively heavy so they can cause more problems then in 35mm. MLU on 35mm is a good idea also but not many have it anymore.

It can also be utilized for very long lenses, again to minimize vibration. On 35mm cameras it is also utilized for extremely short focal length lenses such as certain Fisheye models where the rear element actually protrudes back into the mirror chamber.

In otherwords... If you're on a tripod and shooting a static subject, USE IT. You will be maximizing the sharpness of your lens and film.

 

I know people that use MLU when hand holding!! They say they can definitely see a difference. I don't think I'd be willing to go that far, but on a tripod it is definitely worth it.

The need for MLU shows up at about 1/15 to 1/2 sec. shutter speeds. Faster shutter speeds won't be (much) affected by the mirror's vibration, and with longer shutter speeds the mirror's vibration lasts too short to be registered on the film. Quite a few folks, though, can't tell the difference between shots in which mirror lockup was or wasn't used, period. But using "maximum sharpness technique" can make the photographer feel better.

Wow! Using mirror lock when hand-holding!?! I wish I could do

this with my Hassie, but then I couldn't see the image in the

view-finder! I don't know about how other MF SLR's work, but I

wouldn't think that you could effectively hand hold with mirror

lock-up, since you run the risk of screwing up your composition.

The previous post about not being able to see the image through the viewfinder is dead-on...if you have the same type of mirror lock-up that I have on my 35mm (Nikon F3). For tripod-based work, this doesn't present a problem, because you take a while to set up the shot, and flip the switch just before making the exposure. But for hand-held shooting, it would result in tilted and/or cut-off images.

 

HOWEVER, I used to use a Canon Eos Elan, whose programmed mirror lock-up mode was user-transparent. That is, with the function set, I could still see the image through the viewfinder long enough to shoot hand-held, and I didn't have to manually unset the lock as I have to do with my F3. (I didn't actually use it while hand-holding, though -- no point in doing so.)

 

How much of a sharpness difference between using and not using lock-up might depend on the camera itself. On mine, there definitely is a difference. I found that out accidentally; several times I forgot to set the lock and, upon realizing my error, immediately took another photo of the same subject with the lock on. The slide with the lock on always looks sharper. This was with slow shutter speeds (1/30 to 1/2 sec) and a tripod.

With great trepidation I will hereby publicly admit that sometimes, but not all that often, I will take a hand-held shot using the mirror lock-up on my Pentax 67 or 67II cameras. While I use a tripod whenever possible for my landscapes and the like, I have found myself in situations in which I could not get the camera in the position I wanted using the tripod. It was just impossible, even though I have a very flexible tripod. In those situations, I have positioned myself against something for greater stability when I can, like a tree trunk, got everything on the camera set very carefully, and, while holding the camera as still as possible, locked up the mirror and after a second took the photograph.

 

It is even more challenging since I typically bracket everything, so I have to note and remember the borders of the first photograph to duplicate the first shot. While there is not doubt that it is impossible to make each of the hand-held photographs exactly alike, they can obviously be quite close. When they are not exactly the same, the fact that I get approximately 10% more area in my photographs than what I see in the viewfinder allows me some cropping room if needed. I have also found my monopod helpful in taking such shots.

 

I would not try it for shots with a lengthy shutter speed but this would be, of course, subject to differences of opinion. I would do so for shutter speeds in the range of 1/8th to 1/30th or maybe even a 1/60th, depending upon what lens I am using. I might even try it at 1/4th of a second with my 45mm lens, if it were my only option. I believe it helps provide a sharper image, but I want to reiterate that I always use my tripod when that is an option.