DSLR vibration is a problem, but read this!

Charles Krebs · Post by **Charles Krebs** » Thu May 15, 2008 10:28 pm

From Canon's "White Paper" on the 40D, in the discussion about the "Live View" mode:

The EOS 40D's CMOS sensor has an electronic 1st-curtain shutter function, enabling shooting with the mechanical shutter completely open. With Live View Function image displayed, the 40D can shift seamlessly to slit exposures with the electronic 1st-curtain shutter, enabling silent shooting which is not possible with a mechanical 1st-curtain shutter. This electronic 1st-curtain shutter uses a unique high-speed scanning and electronic reset system that accurately mimics the EOS 40D's high-speed mechanical shutter operation. It synchronizes with the mechanical 2nd-curtain shutter to obtain a slit exposure. (Note that with CMOS, it is difficult to have an electronic 2nd-curtain shutter. Therefore, only the 1st-curtain shutter is electronic.)

With the CMOS sensor's electronic 1st-curtain shutter, shooting is possible while the image with Live View Function is displayed and the mechanical 1st curtain is open. The mechanical 1st curtain need not be closed in order to shoot.

This is not mentioned on the 40D instruction book. But it might be of great significance to people who want to use a DSLR on a microscope or on a bellows for very high magnifications. In these cases not only is the mirror mechanism a problem, but the shutter mechanism alone is sometimes enough to cause significant vibration problems. I don't have a 40D, but the way I read this is that when in "Live View" mode, with camera set to "Silent Mode" the following occurs:

The mirror is "up", and the mechanical shutter is open (since you are in "Live View"mode). When you "release" the "shutter" to take a picture, there is no need for the mechanical shutter to "close" before taking the picture. Canon has managed to incorporate an electronic 1st shutter curtain. The second shutter curtain (mechanical) is used to complete the exposure. It would seem like there would be only a very slight inertial "kick" when the second shutter curtain starts moving. The vast majority of any shutter vibration would likely occur when the 2nd curtain comes to an abrupt stop... but that's only when the exposure has already been completed. If this is so, it could certainly provide the lowest vibration DSLR operation I am aware of. Seems worth exploring a little more!

Planapo · Post by **Planapo** » Fri May 16, 2008 2:21 pm

Interesting detail of information, thanks Charlie for pointing this out!

With this complex and rapidly altering modern equipment (gosh, do I sound old now?!:) ) I find it difficult to keep an overview.
So it´s good to have someone who tells one what is really important among the loads functions.

--Betty

Graham Stabler · Post by **Graham Stabler** » Wed May 21, 2008 3:01 pm

A few weeks late for me

Charles Krebs · Post by **Charles Krebs** » Wed May 21, 2008 3:47 pm

Graham,

I just saw this recently myself. (And had I seen it a few weeks ago I might have made a couple of different equipment purchase decisions myself!)

The mechanical shutter will still eventually need to complete a cycle for each shot. If I understand your project, you are going to have so many shutter actuations that I think you will be better off not dealing with a mechanical shutter at all... if only in terms of durability and longevity.

It's sort of odd. Canon promotes this as a "silent shooting" technique, when in reality, I would think (if it operates as it seems) that the low vibration characteristics would be the big selling point here. It was in reading about the "silent shooting" options in the Canon 40D "White Paper" (where the actual operational steps were described) that it was obvious how nice this could be on a microscope or high magnification setup. I had seen some other references about using the 40D on a microscope, but I only recall those mentioning how nice it was to have "live view" in general. No mention of the "electronic" first shutter curtain, or possibility of very low vibration in silent mode.

I need to check to see if my understanding of it's operation is correct. It would also be nice to know the travel time for the mechanical second shutter curtain, so you could get an idea of the shutter speeds you could use where even any second shutter curtain vibration occurs for an insignificant amount of time relative to the total time the shutter is open.

puzzledpaul · Post by **puzzledpaul** » Wed May 21, 2008 4:43 pm

Charlie - am pretty sure Brian (LordV) has fairly recently bought a 40D - just wondered if contacting him might be (mutually) beneficial?

pp

rjlittlefield · Post by **rjlittlefield** » Wed May 21, 2008 4:55 pm

Charles Krebs wrote:It would also be nice to know the travel time for the mechanical second shutter curtain

Wouldn't that be just a hair less than the minimum shutter time that will work with electronic flash in normal sync mode?

--Rik

Charles Krebs · Post by **Charles Krebs** » Wed May 21, 2008 6:29 pm

Rik,
I suppose you could make a guess based on the fastest sync speed, which is 1/250 (4 msec). I imagine that even at the fastest sync speed the shutter curtains needs to remain "fully open" for a bare minimum of 1 msec, but maybe closer to 2 (or slightly more) msec in order to record the bulk of the flash "burn" time.

So (if the silent mode works like we're thinking here) then at shutter speeds of around 1/40 second and slower (conservatively) the second curtain would be in motion only at the end of the exposure, and for less than 10% of the total exposure time. Should be very safe for even the shakiest of set-ups.
(All suppositions and guesswork. Looks like a trip to Glazers tomorrow.

Paul,
I haven't seen Brian around here in a long time. Guess I could try a "private message.

Charles Krebs · Post by **Charles Krebs** » Wed May 21, 2008 9:14 pm

Just read the 40D instruction manual. The "silent mode" options within "live view" will not work with flash. And they can't be used with extension tubes. Oh well!

Graham Stabler · Post by **Graham Stabler** » Fri May 23, 2008 3:28 am

Does anyone know how approachable Canon are? Would it worth an email to express the kind of features we would love to see, for static work these cameras beat a great many of the expensive industrial types except for a few points.

Graham

Mike B in OKlahoma · Post by **Mike B in OKlahoma** » Fri May 23, 2008 4:16 pm

Graham Stabler wrote:Does anyone know how approachable Canon are? Would it worth an email to express the kind of features we would love to see, for static work these cameras beat a great many of the expensive industrial types except for a few points.

It certainly wouldn't do any harm, but I wouldn't count on any big results. Photographers doing the kind of work we discuss here are a very teeny minority....If Canon is going to be influenced by any group at all it will be either wedding/portrait photographers or news/sports journalism shooters, these are the only large markets other than affluent snapshooters (who are only influenced by bigger megapixel counts and little else if you accept what seems to be emphasized in the marketing...).

augusthouse · Post by **augusthouse** » Fri May 23, 2008 4:50 pm

I'm just wondering whether this is a hardware or firmware limitation? Probably a bit of both with the firmware protecting the hardware to some extent for general use; but can it be 'tweaked' for specialised applications within reasonable limits?

That is a question that might receive a relevant response from Canon or the Canon technical forums.

I suppose the question is whether the hardware has the desired capabilities and could it be safely persuaded to act in addition to the default firmware commands without adverse short-term or long-term consequences with regard to the mechanics and electronics.

Craig

Charles Krebs · Post by **Charles Krebs** » Mon May 26, 2008 11:29 pm

For an "update", and some pictures taken with the "silent mode/live view" see here:
http://www.photomacrography.net/forum/v ... php?t=5006

It will work with bellows and extension tubes (except apparently at very fast shutter speeds... 1/2000 and "faster"). Very effective for preventing vibration in high magnification shots at shutter speeds of 1/60 and slower. (Haven't been able to test what occurs at faster speeds).