Mirror Lock....or not?

A few months ago, EOS Magazine published an article which leads one to question the use of mirror lock's value on very fast or long shutter speeds.

EOS Magazine is a UK publication, which I though many in other geographies might not have access to. I requested the ability to copy and post this article and yesterday received the following reply:

Hi John

Further to your e-mail, we intend to put the Mirror Lock article on our site, but in the meantime here is a pdf version for you to use. Please credit EOS magazine and our website.

Kind regards


Angela August
Editor



The EOS magazine web site is: http://www.eos-magazine.com/ They also have a forum at: http://www.eos-forums.com/

I have placed the article on 'Free File Hosting'. This is my first use of FFH, so I hpope it works OK.

http://www.freefilehos​ting.org …c/46051/Mirror%​20lock.pdf

Thanks for a very interesting article.

I'll probably continue to use mirror lock---until they use me as their test photographer. Hard for me to believe that my fat fingers on the shutter won't trigger any additional vibration.

Now with the 40D (and 1DMk3?) we finally have a fast MLU button plus the added bonus of not losing visual contact with the subject. No reason not to use it a lot more even without a tripod.

dovbaer wrote in post #4116188
I'll probably continue to use mirror lock---until they use me as their test photographer. Hard for me to believe that my fat fingers on the shutter won't trigger any additional vibration.

That is what wired or wireless shutter triggers are for....or even the timer. Not MLU.

Very true but I can still see how MLU has very valuable merit if someone is taking macro photography and interested in using natural light. MLU can be a valuable work-around for the in-between time waiting for the funds to get other accessories!

tsalman, why would you use the mirror lock-up without the camera being on a tripod?

Dale

Having shot a number of images of Jupiter and the Moon through a 1200mm telescope (as well as with much higher effective focal lengths using "eyepiece projection"), I'd say that MLU is absolutely necessary for very long focal lengths. Virbations from mirror slap will appear to last much longer much to the higher magnifications. Lenses and telescopes in this focal length range are also heavier which will aggravate matters.

dale65bama wrote in post #4119397
tsalman, why would you use the mirror lock-up without the camera being on a tripod?

Dale

you wouldn't

dale65bama wrote in post #4119397
tsalman, why would you use the mirror lock-up without the camera being on a tripod?

Dale

When using a wide-lens (10 - 30 mm.) you could have speeds that although theoretically hand-holdable (in the range 1/15 - 1/60) could still benefit from MLU and the 2 second timer. Obviously using a tripod would be preferable, but not always possible. Before Live Preview you wouldn't do so because of the possibility of losing your framing, but new technology allows new ways of thinking.

MLU is hugely helpful on long telephoto shots.. I don;t care what the article says the proof is in the shots.

CyberDyneSystems wrote in post #4121014
MLU is hugely helpful on long telephoto shots.. I don;t care what the article says the proof is in the shots.

Is that "long lens" of "long time"?

The first premis is if the article is correct, which it seems to be, that the mirror slap viabration is damped within ~1/60 sec. due to mass of camera, lens, and tripod.

Then....if you have a 5 second exposure, it would seem logical that any viabration occuring in the 1/60 would have no chance of being recorded vs. the other 299/60ths.

The key here is that the article documents the premis they make. I have not seen and documention of long exposures where using MLU did make a difference....usually it is "hearsay"....or "I don't care....I'm gonna do what I do" ( not your words...mine).

The important point is that the image quality-degrading effects of mirror-induced vibration are typically minimized by both faster and longer exposures. Though, other factors such as lens and fl used, mass of equipment, etc. will influence.

The point is some never use MLU, some blindly use it because they were told they should.

It would help us all to better understand where it is best used and where the extra effort is not worthwhile. One factor which has not been discussed is the effect of long MLU prior to the actual shot has on exposing the sensor to light, heating it up, and this contribution to increased sensor noise.

Long lens, and for what I'm shooting my exposures are not so long that mirror slap would have no effect.
Canon has even gone so far as to design the IS in the super teles to go into a tripod mode that helps reduce mirror slap vibrations...

Apologies for sounding so gruff in my last post.
Should have glanced at the article, but what it says is nothing new to me. My use of MLU is pretty much exactly when it's needed.
I agree that MLU is not a cure all, but it does habve it's appications.

Remember that longer lenses will magnify the minimal effect of slap exponentially, thus for long lens shooters it is really a very important tool to use when we are not shooting at "fast action" shutter speeds.

Where MLU makes most difference is when the lens not the camera is attached to the tripod, and the longer the lens the more important MLU becomes. In this case the mirror vibration is happening someway from the tripod attachment point and the whole assembly will vibrate for much longer than 1/60 second.

I wouldn't expect MLU to make much difference when the camera body is securely mounted on a heavy tripod.

Madweasel wrote in post #4121213
Where MLU makes most difference is when the lens not the camera is attached to the tripod, and the longer the lens the more important MLU becomes. In this case the mirror vibration is happening someway from the tripod attachment point and the whole assembly will vibrate for much longer than 1/60 second.

I wouldn't expect MLU to make much difference when the camera body is securely mounted on a heavy tripod.

It is the longer focal length lenses that are are typically attached to the tripod via lens mount. These lenses are heavier making tripod stability all the more critical. More importantly, longer focal lengths are more sensitive to vibration because, in effect, they magnify the visual effect of vibrations. Vibrations that appear to have damped out by 1/60 sec at 100mm will still be apparent at longer focal lengths. The idea is similar to the link between camera shake and focal length for blur free images.