One colour abstract begets another

[Mike Buckley]

I blew the highlights quite badly, as I forgot that the camera can't meter with the mirror up.

I'm confused by that, Janis. I don't understand why raising the mirror had anything to do with blown highlights.

According to my camera manual, my camera also doesn't meter while the mirror is up. However, if I meter the scene before lifting the mirror, then raise the mirror and then release the shutter, the image is exposed at the values that were metered before raising the mirror.

That's true when I use Aperture priority. If I were concerned about it not working effectively for whatever reason (I'm not concerned), I could use manual metering to lock in the exposure.

I would not know until capturing the image whether there were any clipped highlights but that is true whether or not shooting with the mirror up.

I actually wonder if the camera manuals are written improperly. I imagine that the camera actually does meter while the mirror is up and it's only that the camera doesn't display the metering results in that situation. Indeed, if the camera does not meter while the mirror is up, I would expect all of the camera manuals to recommend using manual metering before raising the mirror and none of the manuals I have reviewed make that recommendation.

By the way, the same camera manuals explain that the camera will not auto focus while the mirror is raised. Yet I can use auto focus while using mirror-up mode and the camera focuses properly. Again, I believe that's because the camera actually is focusing while the mirror is up even though it is not displaying whether focus has been achieved.

[purplehaze]

Mike, I think what happened was that, in searching for a composition, I took an accidental exposure of a frame that was less directly lit, and it was only after that that it occurred to me to try the MUp setting. But I am curious to experiment with different exposures and perhaps an added diffuser between the lights and the glass. The glass has enough texture that, at this magnification, there is quite a lot of potential for creating different compositions.

[Mike Buckley]

Mike, I think what happened was that, in searching for a composition, I took an accidental exposure of a frame that was less directly lit, and it was only after that that it occurred to me to try the MUp setting.

That would explain it if you were using manual exposure settings, not if you weren't. Even so, that undesired exposure would also have happened if you hadn't switched to Mirror-Up mode.

[vaez]

beautiful image how you did it ?

[purplehaze]

Thanks, Vaez. All is revealed in post #20 of this thread.

[purplehaze]

I actually wonder if the camera manuals are written improperly. I imagine that the camera actually does meter while the mirror is up and it's only that the camera doesn't display the metering results in that situation. Indeed, if the camera does not meter while the mirror is up, I would expect all of the camera manuals to recommend using manual metering before raising the mirror and none of the manuals I have reviewed make that recommendation.

I think I follow your logic, Mike, but it seems that the meter cells for through-the-lens metering are in most DSLRs up in the pentaprism, so locking up the mirror would presumably block light coming through the lens from reaching them. Or am I missing something?

I gather that if you have Live View on, a meter reading is taken off the sensor, so no problem (maybe; see below). But I didn't have Live View on, just focused manually through the viewfinder, and then turned the dial to the MUP setting without thinking that I maybe needed to meter manually. I was on Aperture priority, so I think the camera just used my previous settings.

By the way, the same camera manuals explain that the camera will not auto focus while the mirror is raised. Yet I can use auto focus while using mirror-up mode and the camera focuses properly. Again, I believe that's because the camera actually is focusing while the mirror is up even though it is not displaying whether focus has been achieved.

Again, could you be talking about how the camera operates with Live View on? As Live View also uses a different focusing system, that would explain that.

Forgive me if I am trying your patience, but I am struggling to understand. I have been searching in vain for a clear picture of how the camera's internal metering works; all I could find out is that, with most DSLRs, it has something to do with pinholes.

And I read on DPReview that there can be a difference between the exposure reading provided by the viewfinder system and that provided by Live View. Something for me to keep an eye on.

Edit: I'm thinking now you and the manuals are both right. There's no focusing or metering while the mirror is up (and Live View is off), but the focusing and metering are done in the moment before the mirror is raised. Does that make sense? Doesn't explain my overexposure, but it explains something.

[rpcrowe]

Amazing and lovely image...

[Stagecoach]

Edit: I'm thinking now you and the manuals are both right. There's no focusing or metering while the mirror is up (and Live View is off), but the focusing and metering are done in the moment before the mirror is raised. Does that make sense? Doesn't explain my overexposure, but it explains something.

Absolutely correct Janis for Non Live-view shooting.

If you want to confirm/prove it to yourself put the camera in 'MuP' mode, in Aperture Priority, point at the sky, 1/2 press the shutter, note the exposure (eg f/11 - 1/200th), fully press the shutter (this lifts the mirror), move to aim the camera at a dark place, fully press the shutter again. If you now check the exposure reading they will still be as those noted.

The light meter RGB CCD sensor on modern Nikon DSLRs is in the pentaprism area, the AF sensor at the bottom.

Some good general info on how the Live View systems work can be found here;
http://www.nikonusa.com/en/Learn-And...ing-modes.html

and some general Nikon metering info here;
http://dpanswers.com/content/nikon_exposure.php

There seems to be a lack of good images that show the location details other than for Canon

Grahame

[purplehaze]

Thanks for the comments, Richard, and thank you, Grahame, for the links. I'm finding the second one in particular very informative; now I know what the "i" in "i-TTL" means.