Exposure Shift
 

Did I miss something? I've only just realized that the only exposure shift controls are in the menu(?!) and not on the camera. (I normally work under controlled lighting so this isn't something I've noticed until now)

Previously working outdoors I've used auto exposure on Sony FX1 to cope with changing light, but had the option to crank the exposure up or down with the exposure/iris wheel if the camera was doing something stupid.

Canon's blind commitment to using the same programme settings across their still cameras and video cameras is somewhat bemusing. Who the hell in their right mind is ever going to use Av on a video camera? You can't have the shutter speed ramping up and down in the middle of a shot!

Is there any way of compensating for camera auto exposure anomolies whilst still keeping it in auto?

are u saying there is NO manual overide if running auto anything?

Alex, I was irked with Canon's decision to put the AE shift in the menu as well. DUH!

The only thing I can suggest is getting used to using the Exposure Lock function on the occasion when you might need it.

Bill

This is the reason why there's a request to "move the AE Shift function from menu to iris ring" in our XH Firmware Upgrade Wishlist Poll.

Agreed. It's a holdover from their still camera line. I've always thought that Av mode was pretty much useless, except perhaps for some limited depth-of-field control.

Tv mode + Exp. Lock is the ideal operating mode for the camera. It's the best way to shoot, with shutter speed locked, and instant switching between manual and auto exposure using the Exposure Lock button.

Ah yes, indeed! I think at the time I didn't quite understand what that option was about - I had made the assumption that this was about changing the AE shift from the shutter wheel to the iris - however I can see the word "menu" is quite clearly written there, so I guess I should read things properly and not make assumptions! :-D

"This is the reason why there's a request to "move the AE Shift function from menu to iris ring" in our XH Firmware Upgrade Wishlist Poll"

- and that's one of the best ideas on the list. I hope Canon listens.

Uhh, excuse my visceral reaction to this statement but manual mode is the most ideal, lol.

:)

God yes! It seems to me that Canon were a little more interested in maintaining "corporate" consistancy than thinking "out of the box" (or even trying to design the best user experience) when it comes to the "UI design".

It's a fantastic camera, but there are one or two little things that are a bit like having a (metaphorical) finger cut off because you have to dip into the menu.

Of course it may be mostly because they used the H1 as their base.

Perhaps camera manufacturers should have open-source firmware?

Of course, but just like being able to hit the AF button whilst in manual focus, working in Tv with EXP LOCK gives you a sort of (back-to-front) AE button.

I realize the context of the statement but I just couldn't resist :)

curious... is there a way you can swap the shutter dial to become an iris wheel (ala DVX)? next to the exposure lock i mean...

that shooting mode wheel is such a waste of space IMO... so much more could have been put there, such as extra custom keys, custom preset dial...

Ha! Ha! You're such a trouble maker Steven ;-)

Yes. Commitment to corporate image over function...

Ha! But that's exactly what Tv + Exp. Lock is... manual mode!

It's the exact same functionality of M mode, with the advantage of having the ability to go to auto iris with the push of a button... something you can't do in M mode.

An experienced shooter like Steven would probably never choose to shoot in auto iris, but as the saying goes, different strokes for different folks... some people want and need that capability, so for them, Tv + Exp. Lock is a better way to shoot than Manual (because it's identical to Manual, with the advantage of AE if you need it).

We get a lot of new people coming through here who don't have much experience with video, so I make it a point to urge them to shoot in Auto settings at first. The camera does an adequate job in Auto. A new shooter should let the camera take care of those settings, and concentrate instead on the far more important aspects of framing and composition, and developing an eye. Then once they've accomplished that, graduate to the technical part of the photography.

The advantage of the power mode dial on the XL and XH cameras is that you can turn it on into whatever shooting mode you want.

And, of course, there are auto-iris buttons on the lenses of full size cameras. Back in the days of working in broadcast TV I was never shy about getting the camera to give me a hand with exposure when I thought it was appropriate.

I agree Peter. And regarding more custom keys, I had an ingenious idea (ok, not really) that was an afterthought that was too late for the firmware wishlist. Allowing the menu selector wheel as a "shift" function to add 2 more custom keys. Press inward & hold: custom key 1 = custom key 3, custom key 2 = custom key 4.

If OIS off is ever assigned to a custom key, I'll have to lose one. It's just silly. Two are not enough. Period. :)

Bill

Custom key 3 and 4 - very good idea Bill.

It could be done with Custom Keys alone also: press and hold 1 and then press 2 = Custom Key 3. Press and hold 2 and then press 1 = Custom Key 4.

So, with all these great ideas people post on DVInfo.net, all we need is just Canon's cooperation :-)

Exactly. Or maybe a long push on a single button.

But come to think of it, designating the menu select wheel as THE shift function (since depressing it does nothing unless in the menu anyway) all one would have to do is use their thumb to depress it while selecting CK1 or CK2 buttons. It sems to me anyway that it would be easier, but that's just me :)

Bill

Thanks so much.
I've read this thread twice now, and I still don't understand the "exp lock". And yes, I've read the manual... didn't really get it there either. (Disclosure: I haven't bought the A1 yet - that's why I'm reading everything here and I'm trying to understand as much as possible without actually having played with the camera).
I guess I go back to the manual tonight and study this section once again. Coming from still photography, Alex's first post in this thread was initially a shock to me. Only then did I realize that AV really doesn't seem that useful on a camcorder (as compared to a still SLR camera).

Dino

Chris...are you saying you can put it in TV mode with Exposure Lock ON, and it 's the same as manual, but you can push a button for auto iris? Which button? (Sorry I don't have the camera with me at the moment.)

This would be handy, because sometimes even with the DSR500 I'll use the auto iris button to let the camera get close, then I'll open up or stop down as needed.

Bill, while in Tv mode & Exposure Lock on, it's the same as Manual. Push the Exposure Lock again to turn it off, then you're in Tv mode again, which is "auto iris" mode.

Bill

Really great would be a push exposure in the manual mode, the same action as push focus. As long as you push, it is auto as soon as you release it is manual again. Not this 'push twice act as a button'. But next to manual... TV mode is the only programme I use.

If you use TV mode, a digital shutter prevents 'overloading the chip' in exceptional cases, not the same as manual. All others can be diminished, like theater and auto and AV.

Don't forget about diffraction.
 

There's another reason to use Av: diffraction. My tooling about with the Cambridge In Color diffraction limit calculator (http://www.cambridgeincolour.com/tut...hotography.htm) indicates that the 1.5 megapixels squeezed into Canon's 1/3" sensor will reach the diffraction limit at just f/4.0. By f/9.5, the softening effect is pronounced.

Because of that, I would rather the camera go from 1/250 to 1/15000 than f/1.6 to f/9.5. For my subjects, 1/250 is just as good as 1/15000. Acceptable changes in motion blur will depend on the audience, subject, and post. 1/250 to 1/48 would be pretty jarring for a scene with a lot of action.

Wow it sure is soft. I shot a test in bright sun at around F9 and it looked way out of wack!

The manual even mentions it on page 37.

In some situations, the shutter ramp (aperture priority) is no problem, but I prefer to work with (extra) ND to reach the diffraction limit / resolution max with the motion blur and cadense we like from film.

That's an excellent point, Daniel. The explanation in your post there provides a good case for Av mode. Thanks a bunch for sharing that!

Hmm... Is that true of any 1/3in CCD camera with similar pixel count?

I certainly notice softening by the time it gets beyond about f5.6.

Here is a clip that shows how diffraction can reduce sharpness on the Sony V1; engaging ND filter and opening iris more makes the picture a lot sharper!

http://rapidshare.com/files/18138889...rpness3_ND.m2v

Yes. The only things that matter are focal ratio and pixel size. If the output medium will have larger pixels than the capture medium (e.g. HDV to SD DVD), then the larger of the two is what sets the diffraction limit (assuming the use of a really good resize algorithm.)

For example, Super35 film has very large "pixels". On a work print, f/8 shows no diffraction at all, and even f/11 and f/16 are very sharp. But if it's resized to 480p, it's likely that even f/22 will not show softness.

Thanks for that explanation guys (and the clip Piotr). I had never really understood why softness from diffraction happened at different f-stops on different cameras. And now I do! Hooray!

And at the same time - woah! That's a fairly limited usable range we have!

Yeah, I think we could have done with a 3rd ND filter in the camera. Having said that I have noticed major softening was at F9.5. I shoot with the sharpness turned down to -2 anyway so that might have masked some softening at lower F stops. I usually aim to stay above f5.6 if at all possible but on a bright sunny day that can be a challenge without additional NDs.

Hopefully someone will develop a matte box that does not impinge on the IAF so adding additional NDs will be a cinch. I am not a fan of filter stacking screw-ons.

TT

contrast focus range?
 

i guess i need help understanding the diffraction issue. i am new at using an xh a1 and just returned from vancouver island shooting nature, eagles, seals etc along the coast...juan de fuca trail. having come from a well published still photo background...i understand pin hole diffraction at higher f stops of f16 or 22. but why is that point so low on f stops in the canon lens on the xh a1? does that really mean shoot at aperature priority 5.6 for all scenics and wildlife, and use a neutral density filter to decrease light on a bright day? i could not open up the example sent. so i need a simple explantation.

thanks ahead, this is a great forum. bill

Hi William. As you say, the same effect is seen on still cameras too. The reason it happens at much wider apertures on video cameras is that the sensor is much smaller than on any still camera. And because the A1 is fairly high definition, the individual sensor dots on the CCD are physically much closer together, therefore it does not take much bending of the light to cause a softer image.

Personally, I wouldn't shoot at aperture priority though. I tend to use Tv mode plus exposure lock. When you press exposure lock you get a readout of the aperture so will know when to add ND (or use faster shutter if absolutely necessary).

Richard

Exactly.

My MTF50 resolution measurements using the Imatest software support the finding of F4.0 being the boundary for diffraction. At the center, F3.7 is the measured peak, but corner sharpness improves at F4.0 and beyond. F4.8 is where the softening first becomes noticeable if only very slightly.

The problem with aperture priority for video cams is not the effect upon the change of subject blur, but rather that it introduces flicker when the shutter speed changes. Better to put it in manual, or Tv mode. As the poster mentioned, if you press the exposure lock you can read out the aperture. Use the ND to get the exposure.

okay, now how to use exposure lock and nd
 

thanks for the replies. i comprehend the small sensor size, but then i would think aperature priority would be the way to go, unless you are panning or zooming and there is a light change and the shutter may flicker?

however i tried Tv just a few minutes ago, and panned around in the kitchen, and no matter where i landed, it showed with exposure lock f1.6...even in the darker areas at 1/60. the manual states exposure lock is in a plus or minus 2 stops range, which really seems to be a lot of variation. if f 4 seems to be the highest corner focus strength, and f3.7 the sharpest in the center...how do i keep the aperature in that range having to deal with the great plus or minus 2 in the aperature range? thanks again. bill

Forget about the kitchen.
Get some daylight. Set the camera to aperture priority f3.7, compose your scene, press the exposure lock and read what the shutter speed is. Unlock it and repeat after switching the ND. Use ND to lower the shutter speed where you want it to be, perhaps 1/125 or 1/60. Now switch modes to shutter priority and set it for 1/125 or 1/60. Although you can't lock the aperture or even know exactly where it is, you know it's going to be centered at f3.7, going up or down a little as you pan the scene.

So what you've done is use aperture priority and exposure lock to read out the shutter speed, that you're going to switch over to with the expectation that the iris will be centered at the point where you read the shutter speed.

The other way of doing it is to switch to manual. Set your aperture, then move the jog wheel to adjust the shutter speed until the arrow goes to the center of the scale on the light meter display. Once the arrow is at the center of the scale, read the shutter speed and switch to shutter priority mode and set it to the number you just read while in manual. As you pan the scene, the iris will open and close above and below but always close to your intended aperture center point. Although when shooting you won't know exactly where it is, the iris can open or close above or below the center point to maintain proper exposure without introducing the flicker. And it will be always close to where you would have locked it to in Aperture priority mode. If using the above methods the aperture deviates from f3.2 to f4.8, you will be within the sweet spot where the lens gives its best performance. It isn't necessary to lock the aperture rigidly to exactly f3.7.

Re-reading your post, I understand what you mean about the 2-stop +/- range using exposure lock.

You get around that problem using the second method I outlined. Switch to manual. Set your aperture at f3.7. Then move the jog wheel for the shutter speed until the light meter goes to the center of the scale. You will note that the resolution of the shutter speed offerings in manual has more discrete values, 1/60, 1/75, 1/100, 1/125, 1/200, 1/250, 1/300 etc...

...whereas in exposure lock, they basically double, 1/60, 1/120, 1/250, 1/500 etc.

thanks tom for the information. that really helped. i was hoping i could read the f stop on the camera at all times...not quite sure that is an option on the display mode in either automatic of Tv. will research it. The clear footage this camera takes is amazing...bill

Yes it is, sort of. When in A or Tv mode, press the Exp. Lock button to display the current f/stop setting. Press again to return to automatic exposure.