Mirror Lock-Up Question

[Lisa Nikodym]

I finally received my new Nikon D200, and a technical question has occurred to me that I hope someone here knows the answer to.  I'm using it with a VR lens (Vibration Reduction, the Nikon equivalent of Canon's IS).  With VR at wide angle, I can imagine decreasing the shutter speed to the point where it's starting to get into the range where MLU is usually considered a good idea.  The question is, does VR or IS negate the need for MLU, or should one use MLU anyway under those conditions?

Lisa

[Jack Flesher]

Hi Lisa:

Congrats on the new camera!  (Hope to see it at our next Palo Alto coffee  get-together!)

My take on VR/IS is from the Canon IS perspective, so I am not sure how much is relevant to Nikon's VR, but here goes.

IS is controlled by micro-motors and micro-gyros.  As such, when they are spinning (on) they can impart some high-frequency vibrations to the camera.  These are especially noticeable if the camera/lens is solidly mounted, like on a tripod, and Canon recomended with its early designs to turn IS off if you were using a tripod.  Canon has alleviated this problem in its recent IS designs, allowing the system to sense it is on a tripod and turning itself off, but I don't know how Nikon handles that.

Thus, my IS/VR advice would be that if your lens is on a tripod and you are using relatively slow speeds, turn IS off.  Though truth be told, I never bother since my IS lenses are the newer designs  

Now for mirror lock-up.  When I used to shoot Nikon (film cameras only) I noted that the mirror slap was most notable at 1/8th or 1/15th second, depending on the body.  The negative effects of mirror slap tapered off as you went higher or lower, being essentially gone after 1/30th on the top end and gone by 1/2 sec at the low end.  Interestingly, when I switched to Canon these parameters held, though now it seems the safe range is a little narrower being more like 1/30th and over and 1/4 or longer.  You can easily test this with a moderate tele and your camera on your tripod.  

So as a rule of thumb, I avoid 1/8th and 1/15th like the plague unless I use MLU.  And typically, if I am on the pod and those speeds are even a possibility -- which often they are -- I'll use MLU as a matter of course.

Hope this helps,

[Lisa Nikodym]

Hi Jack -

Thanks for your answer.  I did one small experiment with the VR lens when I got it, which serves only to confuse things.    With my MLU-less D70 on a tripod, I took the same picture with both my old lens (non-VR) and the new lens (with VR on) at two shutter speeds, one pretty high (something like 1/200 sec) and one slow (about 1/4 sec, where one would wish MLU).  The fast photos produced by the two lenses were very similar in terms of sharpness, but, in the slow pair of photos, the lens with VR was *considerably* sharper than the one without.  I haven't checked if the experiment is reproducible, but, if I did it right, that suggests that VR *does* help reduce mirror slap when it's on a tripod.

Perhaps after I get the cable release for the D200 (arriving any day now) I'll retry the experiment with and without MLU and see what happens.  There's nothing like empirical data...   I'm surprised noone else here has produced any answers on the subject.  I"ll have to report back on the results.

Lisa

P.S.  Speaking about group coffeehouse get-togethers, is it about time to organize another one soon?  (You can send me an email offline.)

[Lisa Nikodym]

I'll retry the experiment with and without MLU and see what happens.

OK, experiment done.  I tried four combinations:
(1) without either MLU or VR
(2) without MLU, with VR
(3) with both MLU and VR
(4) with MLU, without VR

(1) was, as expected, much worse than the others.  The other three were very similar, with version (2) being very slightly the best of them.  My conclusion is that you need either MLU or VR when tripod-mounted at mirror-slap shutter speeds, but either (or both) will do.  Makes sense, I guess.  (Expect that turning on MLU when you already have VR made it slightly worse - but the difference was so small that if one had been taken when there was a slight gust of wind it could have produced the difference.)

Lisa

[Jack Flesher]

Lisa:  

Just curious -- was your lens mounted to the tripod or was it the camera body?

[Lisa Nikodym]

The camera body was mounted to the tripod.  The 18-200 DX VR lens is very short for its zoom range (less than 4"), and doesn't have a mounting collar since it doesn't need one.  Are you thinking that maybe the VR was compensating for vibrations caused by the moment arm between the tripod and the lens?

Lisa

[Jack Flesher]

Are you thinking that maybe the VR was compensating for vibrations caused by the moment arm between the tripod and the lens?

Lisa
[a href=\"index.php?act=findpost&pid=58708\"][{POST_SNAPBACK}][/a]

Yes I was

With Canon IS, the lens itself has to move before the micro-gyros can compensate and I assume it is the same with Nikon's VR.   If the lens is mounted to the tripod directly below the center of the gyros there is less motion at the gyro to sense.  The motion is also in a different direction, being almost parallel to the lens as opposed to perpedicular...

Not sure how relevant any of this is since you are testing empirically in the configuration you will be using your camera.  But it may explain why we get different results with our respective camera systems  

Cheers,