canon 70-200 4/L, no difference when mirror lockup enabled?

[carmen_m]

Hello,

<br /><br />

I own a 350D and have just bought a Canon 70-200 4/L (could not afford the IS

version) which I have done some tests with. All tests have been done with tripod

(Manfrotto 190xprob, head plate attached to Canon tripod ring) and wireless

remote release.

<br /><br />

 

I have taken some photos at dusk at 200mm @ 0.6 seconds, ISO 100. I figured this

combination would be ideal to test mirror lockup effects on image quality. To my

surprise, I see absolutely no difference when mirror lockup is enabled or

disabled.... maybe it's my eyes?

<br /><br />

Both pictures seem just as sharp (see below). I was under the impression that

mirror lockup would remove vibrations which affect image quality especially at

telephoto end. Does this mean my tripod is particularly sturdy? Needless to say

I don't mind in the least, I was just curious why this happens.

<br /><br />

<img src="http://www.mardiros.net/mirror.jpg">

 

<br /><br />

One other thing, I originally set the lens on MF @ infinity and all the pictures

turned out blurred. They all turned out sharp when I use AF mode. The fact that

the infinity indicator is not precise worries me, how can I make sure I get

sharp pics when lens is manually set @ infinity?

<br /><br />

Thanks

[m_barbu1]

Have you tried this test photographing text on paper, where the paper is parallel to the plane of your camera?

[bongeiste]

Your results may simply indicate that mirror lockup has no significant benefit over the mirror's regular operation in the situation you tested or at the magnification at which you view your pictures. I've found that for my uses, mirror lockup is usually unnecessary.

[apetty]

Mirror lock up is very useful in macro photography.

[carmen_m]

That's a 100% crop, I should have probably mentioned that.

 

I have tried the newspaper on the wall test but with mirror lockup disabled. Image was not as sharp at 200mm as it was at 70mm. Plus, as careful as I was, I cannot be 100% sure that the paper was parallel with the camera. Same with the dreaded 45 degrees test...

[carmen_m]

So for landscape photography mirror lockup might be unecessary? What about at dawn/dusk or at night?

[photo_dark]

To my understanding... infinity varies on focal length, temperature, air pressure etc.

 

So according to any average lens, 'infinity' distance is variable.

[mendel_leisk]

I'm not sure, but maybe: 0.6 second exposure time negates much of the benefits of Mirror Lock Up. It seems to me, the longer the exposure, the less MLU matters.

[PuppyDigs]

Yep, MLU makes little or no diff most of the time. The sweet spot for MLU making a diff

seems to be around 1/15 for many bodies. Longer exposures--5 sec--you can even get

away with pressing the shutter with your finger...

[dave chew]

In regards to your infinity comment, the lenses are designed to focus past infinity on purpose. Supposedly to account for temperature changes. It also helps with an extension tube, because you have a little more leaway to focus farther out.

[colinsouthern]

April 01, 2008

 

The writing looks slightly sharper on the MLU enabled shot.

[mark u]

Puppy Face has the right answer... MLU is most effective for shutter speeds between 1/30th and 1/4. With longer exposures, vibrations die down so as not to be noticeable.

[jcolwell]

Most manual focus lenses do not focus past infinity; they stop at infinity. Most autofocus lenses focus past infinity to allow the camera's AF control to determine where it's at sharpest focus - in order to find this for a subject at "infinity", the lens has to go past it, so the camera can detect the fall off in sharpness (or contrast, or phase, whatever is measured).

[bryan_lardizabal]

I rarely use MLU on short focal length lenses. The primary benefit is for longer lenses such as 400mm+ when shoot longer than 1 sec. such as this eclipse shot.<div></div>

[bobatkins]

MLU is only really useful for longer lenses and exposures between about 1s and 1/30s. I wrote this small article which explains why - http://www.bobatkins.com/photography/tutorials/mlu.html

 

If you have a good tripod on firm ground, you won't see much difference with a 200mm lens.

 

Try it with a 600mm lens on a flimsy tripod and you'll see a difference!