Jump to content
Sign in to follow this  
wag

Exposure technique info please

Recommended Posts

Advertisement (gone after registration)

Maybe Guy can add this to our wish list. This would be a very big improvement. I too, would like to know where I'm at with the shutter speed without having to move the camera away from my eye.

 

That is where we oldies come in. Over the decades we have learnt to count the clicks....

Share this post


Link to post
Share on other sites
Is this a wind up?

Apologies...and welcome to the forum if it isnt...

Sounds like that old veiling flare again....

Share this post


Link to post
Share on other sites
I'm quite happy with the M8's exposure meter but I never allow any camera to decide exposure for me. Even in AE mode, I monitor and tweak what it is doing. The histogram eliminated the spot meter for me (probably permanently). In fact, because of the histogram I no longer use external meters at all.

 

But, again, it really helps to have the foundation and "The Negative" provides that very well. The other two books in the series, in case some are interested, are called "The Camera" and the "Print".

 

Cheers,

 

Sean

 

I'm afraid I have to strongly disagree here with the value of the histogram point being made (as I understand it). My reading of Ansel Adam's books referenced by Sean is that one tries to obtain a tonal range -- by specificially deciding which luminance values will be set for which specific areas of the image. For example, you might set some rock features to Zone V (which is the "perfect" 18% -- or 13% if you follow Michael Reichman -- exposure point). Everything else in the photo is either "under" or "over" exposed, in the sense that those items in the image fall below or above the luminance for the desired image feature -- rocks in my example. It is not enough, by any stretch, simply to have an image whose tonal values fall within the exposure capability of the film and, ultimately, the print. Rather, using Adam's technique, one makes an artistic choice for the specific tonal value for a specific item within an image. To achieve this degree of precision a 1 degree spot meter is used. All other items within the image fall below or above this luminance level.

 

The histogram is as blind as a center weighted reflective light meter in this regard. It only reports total luminance values for ALL elements in the image. You have no way of knowing where the feature within the image falls within the histogram, and hence, no way of knowing whether it is exposed at a level you wish (you might, for example, want to rocks in my example to reside in Zone IV).

 

Thus the histogram is nearly useless for purposes of achieving the tonal control in the image which Adams seeks to achieve. It will tell you if you have blown highlights or dropped shadow detail, but that's it. (If you can view the histogram in separate RGB channels it might also suggest color cast.)

 

One desserves Ansel Adams by relying solely upon a histogram. You might properly expose a cloud and miss the importance of the rock entirely.

 

Cordially,

 

Steve

Share this post


Link to post
Share on other sites
...

The histogram is as blind as a center weighted reflective light meter in this regard. It only reports total luminance values for ALL elements in the image. You have no way of knowing where the feature within the image falls within the histogram, and hence, no way of knowing whether it is exposed at a level you wish (you might, for example, want to rocks in my example to reside in Zone IV).

 

...

 

Steve, if you use the thumbwheel to zoom in a spot on the capture, you can get a very fine spot reading and histogram of just that spot. Spot the highs and lows and make the kind of zonal judgment Ansel would advocate if he were here today.

Share this post


Link to post
Share on other sites

Chris - I use the AP exposure mode. point the center of the frame towards the persons face, lock the exposure by pressing down the button half way, reframe and shoot.

I am always careful to expose the face well, but then will often have blown highlights in the backround.

How do you expose to avoid the blown highlights?

 

thanks,

 

alexander

 

 

Brad Wagstaff:

... I use it solely in Aperture Priority, with exposure compensation frequently at -1 stop [i hate blown highlights] and constant checking of the histogram...

................Chris

Share this post


Link to post
Share on other sites

Advertisement (gone after registration)

I'm afraid I have to strongly disagree here with the value of the histogram point being made (as I understand it). My reading of Ansel Adam's books referenced by Sean is that one tries to obtain a tonal range -- by specificially deciding which luminance values will be set for which specific areas of the image. For example, you might set some rock features to Zone V (which is the "perfect" 18% -- or 13% if you follow Michael Reichman -- exposure point). Everything else in the photo is either "under" or "over" exposed, in the sense that those items in the image fall below or above the luminance for the desired image feature -- rocks in my example. It is not enough, by any stretch, simply to have an image whose tonal values fall within the exposure capability of the film and, ultimately, the print. Rather, using Adam's technique, one makes an artistic choice for the specific tonal value for a specific item within an image. To achieve this degree of precision a 1 degree spot meter is used. All other items within the image fall below or above this luminance level.

 

The histogram is as blind as a center weighted reflective light meter in this regard. It only reports total luminance values for ALL elements in the image. You have no way of knowing where the feature within the image falls within the histogram, and hence, no way of knowing whether it is exposed at a level you wish (you might, for example, want to rocks in my example to reside in Zone IV).

 

Thus the histogram is nearly useless for purposes of achieving the tonal control in the image which Adams seeks to achieve. It will tell you if you have blown highlights or dropped shadow detail, but that's it. (If you can view the histogram in separate RGB channels it might also suggest color cast.)

 

One desserves Ansel Adams by relying solely upon a histogram. You might properly expose a cloud and miss the importance of the rock entirely.

 

Cordially,

 

Steve

 

To each his own. I rely entirely upon the histogram and my own understanding of how the light in the subject will be transformed in a digital file. This comes from two decades + work as a professional photographer and several years of work as a B&W exhibition printer. With digital capture, I don't need spot meters at all anymore.

 

I spent many years developing each sheet of film independently so as to set its contrast. It's important to understand that film + development is very different from RAW file plus conversion. They're different mediums and they respond differently to exposure and processing. One can pull highlights in a negative during development but one cannot recover (desired) highlight detail beyond what is in the RAW file. In short, digital is a related, but very different, ball game. With negative film (sheet film ideally) one often exposes for desired shadow values and develops for desired highlight values. With digital capture, the opposite is often the case.

 

If one understands a histogram in the context of exposure, broadly conceived, its a very rich source of information. The essential task, as I approach exposure for digital capture, is to define which highlight details one wants to preserve (maybe an area of a dress but not the sky behind it) and then exposing accordingly. The histogram, combined with a good knowledge of exposure and contrast (again, broadly conceived) can be all one needs to do this.

 

Responding completely to your points would, unfortunately, take more time than I have free right now but I think you may be misunderstanding the relationship of Zone System - development - metering - histogram - RAW development - lens contrast -dynamic range in digital - etc. Remember that the highlight density in a negative is not set until the film moves into the stop bath. In digital, the highlights limits are set when the shutter is pressed.

 

When I have enough time free to give this a more thorough response I will.

 

Cheers,

 

Sean

Share this post


Link to post
Share on other sites
Chris - I use the AP exposure mode. point the center of the frame towards the persons face, lock the exposure by pressing down the button half way, reframe and shoot.

I am always careful to expose the face well, but then will often have blown highlights in the backround.

How do you expose to avoid the blown highlights?

 

thanks,

 

alexander

 

By exposing for the highlights, so that these are not blown and recovering the shadows if needed in post-processing.

Share this post


Link to post
Share on other sites
Chris - I use the AP exposure mode.....reframe and shoot......I am always careful to expose the face well, but then will often have blown highlights...............How do you expose to avoid the blown highlights?

 

Alexander - In the example you cite you are over exposing, the highlight detail in the background would be vital for the the integrity of the image if I was making it. Whilst small images with blown highlights might be acceptible to some, the larger one goes in print, the more ghastly that white paper becomes, this was always true for B&W darkroom printing too.

 

Jaap got the answer in ahead of me. I expose all subjects the same way and hardly ever use the 'expose, reframe, and shoot' technique. For the first image in a group of images to be made under it's lighting conditions I take one or more test shots, being sure to include the hottest highlights likely to be in one of those images, study the highlight corner to make sure the highlights are not blowing out, and adjust the exposure compensation as needed using the principle of 'expose to the right'. That setting will be safe for all images made in that circumstance. It's exactly as Jaap said; expose for the highlights and let the mid-tones and shadows take care of themselves [this is assuming, of course that the lighting/subject circumstances are not so extreme as to need multiple exposures for HDR sandwiching].

 

When shooting film, I was always tracking mid-tones with my light-meter, having confidence that my technique would ensure the shadows and highlights would be safe. Then, post production was darkroom technique. Now, I track highlights instead.

 

My suggestion to you is make sure you retain all highlight detail that you can, and if specific parts of the image need altering; that's the role of post production. Sorry this post has become horribly long winded.

 

..................Chris

Share this post


Link to post
Share on other sites

The only caveat to what Sean has said, IMO, is that for super-critical work, when you're shooting RAW, the histo is not reporting the RAW tonality, but the embedded (or created?) JPEG.

 

So as a rule of thumb you generally have at least a half stop more in the highlights (and on some cameras up to a full stop or more) than the histogram shows you when shooting RAW.

 

You need to check this on a camera model basis, in my experience; RAW converter also makes a difference here too.

Share this post


Link to post
Share on other sites

As an addendum to that: In the play mode, when you push the info button, the camera will display the RAW blown out highlights for an instant, before "jumping" to the Jpeg situation.

Share this post


Link to post
Share on other sites
.... In the play mode, when you push the info button, the camera will display the RAW blown out highlights for an instant, before "jumping" to the Jpeg situation.

 

Jaap - You must have a special edition, mine refuses to jump.

 

.............Chris

Share this post


Link to post
Share on other sites

Both of them do it; when I "info" a shot the red highlight marking expands after a brief instant, at the same time the corrected colour comes in. It only works, though, if you push the play button ( or browse to the shot ) and then immediately press the info button, before the camera has a chance to apply the Jpeg corrections.

Share this post


Link to post
Share on other sites
The only caveat to what Sean has said, IMO, is that for super-critical work, when you're shooting RAW, the histo is not reporting the RAW tonality, but the embedded (or created?) JPEG.

 

So as a rule of thumb you generally have at least a half stop more in the highlights (and on some cameras up to a full stop or more) than the histogram shows you when shooting RAW.

 

You need to check this on a camera model basis, in my experience; RAW converter also makes a difference here too.

 

That's true. I like to think of it as a bit of a safety net for highlight or shadow recovery.

 

Cheers,

 

Sean

Share this post


Link to post
Share on other sites
The only caveat to what Sean has said, IMO, is that for super-critical work, when you're shooting RAW, the histo is not reporting the RAW tonality, but the embedded (or created?) JPEG.

 

So as a rule of thumb you generally have at least a half stop more in the highlights (and on some cameras up to a full stop or more) than the histogram shows you when shooting RAW.

 

You need to check this on a camera model basis, in my experience; RAW converter also makes a difference here too.

 

Jamie, are you saying that if you shoot in RAW only, the camera is making a JPEG for the purposes of creating a histo? I don't think so. On the other hand, is there tonality in a RAW file? Again, I don't think so. The tonality does not arrive until the RAW file is processed into an image, IMHO. Certainly, the camera makes an image converted from the RAW file to show on the LCD and, obviously, some compression is going on just to get all that data represented on this little screen, but that isn't a file, JPEG or otherwise.

 

My understanding is that the histo is only a representation of the light values on the selected area of the RAW mosaic; zoomed in to a few or out to all. I will be happy to be educated on this, however, if to the contrary. I don't see how camera model is relevant.

 

Finally, where do you get f-stops from in-camera histograms? Sticking to the camera that is the subject of the Forum (the M8) and some of this thread's discussion of chimping RAW files histogram information, I do not see any calibration indicators for the displayed histo. It wouldn't be a bad product enhancement to have that, but I don't see it here yet.

Share this post


Link to post
Share on other sites

Finally, where do you get f-stops from in-camera histograms? Sticking to the camera that is the subject of the Forum (the M8) and some of this thread's discussion of chimping RAW files histogram information, I do not see any calibration indicators for the displayed histo. It wouldn't be a bad product enhancement to have that, but I don't see it here yet.

 

That's an interesting idea. For now, though, I do it largely by "feel". As I get to know a camera, I can see how much the histogram would shift with a 1-stop increase in exposure, etc.

 

Cheers,

 

Sean

Share this post


Link to post
Share on other sites

@ Philip--I'm with Sean on this; I only know about how much more the actual RAW file gives me vs the histo from having shot them and processed them. On the M8, it's just under a stop's worth of information. It's much more on the shadow side.

 

If I understand correctly (and I may not

) the histogram is taken, when shooting RAW only, from the in-RAW JPEG thumbnail that gets created in each Leica DNG.

 

In fact, and as an aside, though it takes longer to write to the card, if you shoot RAW + JPEG you can have a significantly better preview, especially for checking focus zoomed in, because the camera will use the created JPEG instead (evidently, anyway).

 

@ Sean, yes--a true EV indicator would help with the zone system stuff, as would a true "you've really gone and clipped it, man" indicator too, Wouldn't be a histogram, because the RAW data doesn't even have gamma applied and is linear, but you could still program something to indicate pixels past the high (or low) RAW levels...

Share this post


Link to post
Share on other sites

Jamie--

I'm not sure where the M8 gets its preview images from, but the author of the article in LFI 5/2007 on shooting with IR-pass filter in Andalusia recommends using DNG mode for determining IR focus adjustment. "In DNG + JPG mode, the camera shows the JPG in the display, making determination of plane of sharpness much less exact." (p 47, my rough translation from the German edition)

 

In other words, Bültert suggests setting the camera to DNG-only to avoid viewing the JPG image.

 

Perhaps the M8 shows a DNG-contained JPG in DNG-only review, but if so, Bültert feels that it's a 'better' JPG than the one generated by setting the camera to generate JPGs.

 

To me it sounds as if the M8 may be generating DNG review images on the fly, and only when there isn't a JPG to use instead.

 

So I'm confused and would be delighted by any clarification on the matter.

 

--HC

Share this post


Link to post
Share on other sites

I think the M8 meter is a right tool, and I appreciate it more and more while I am learning the way of operating with M8 (2 months of experience with less then 300 shots). I think it depends a lot on your past experience: for example, I NEVER had really used TTL metering (my old Contarex meter is always battery-drained... the only defect), and I was accustomed to use an external meter, no spot, but pointing it a little round to have an idea of light balance...and was accustomed to this: so, it took a certain time to get accustomed to M8 meter, expecially for making use of the "half pressed button" that give you time in AP mode: but now i have arrived to the conclusion that the combination of this way of working, together with the "spot metering" intrinsic of M8 is REALLY WELL USEFUL : I have learned to point quickly to 2 to 4 points, see the computed times, make my evaluation, and if the case set the time manually: 1/2 stop precision is sufficient imho; as I said, that is MY experience, and anyone has to find his way... for instance, I had never used digital cameras, so still don't make use of the exposure curves displayed in LCD... not at all accustomed to make USE of that information... maybe one day I'll get.. on the contrary, I don't find difficult to operate the shutter times knob... had years of attitude on doing it on my M4.

Share this post


Link to post
Share on other sites
Jamie--

I'm not sure where the M8 gets its preview images from, but the author of the article in LFI 5/2007 on shooting with IR-pass filter in Andalusia recommends using DNG mode for determining IR focus adjustment. "In DNG + JPG mode, the camera shows the JPG in the display, making determination of plane of sharpness much less exact." (p 47, my rough translation from the German edition)

 

In other words, Bültert suggests setting the camera to DNG-only to avoid viewing the JPG image.

 

Perhaps the M8 shows a DNG-contained JPG in DNG-only review, but if so, Bültert feels that it's a 'better' JPG than the one generated by setting the camera to generate JPGs.

 

To me it sounds as if the M8 may be generating DNG review images on the fly, and only when there isn't a JPG to use instead.

 

So I'm confused and would be delighted by any clarification on the matter.

 

--HC

 

As far as I know the M8 generates a small Jpeg, using the standard Jpeg parameters, to display on the LCD, when in DNG mode. I think this remark of Bultert is a mistake. The LCD cannot display undeveloped RAW.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue., Read more about our Privacy Policy