Recent Posts

Another thing that gets me confused:

Which size is the Prontor professional 01s: size 0 or size 1?

Prontor 01 is a Copal 0

Digital is linear and any shadow luminance will be recorded but any image detail may be lost in noise. The digital sensor response is linear without any shoulder and highlights will be clipped abruptly when the sensor saturates. Some highlight recovery may be possible with Bayer CFA sensors, since the red and blue channels may still have some detail, but the color information in the green channel that clips first (with daylight and most artificial illumination) will be lost.

[snip]

The concepts have not changed: one exposes to get optimal image quality, taking into account the characteristics of the medium.

Well said, Bill -- as usual. Thanks.

There's something else that hasn't changed. Photographers can use knowledge of how their tools work to make better images, as you are proposing. They can also become fixated on technical minutia to a degree that it interferes with, or even prevents, making better images.

Jim

I pay virtually no attention to anything Janes writes.  And yes, 'implicit'.  As in implied.  Which is what I said originally when I noted 'Emil hints at it'.  All I doing was trying to make it clearer. 

I usually ignore your posts too, since any reasonable discussion with you is fruitless. You should brush up on basic definitions. Exposure is measured in lux seconds and is independent of the ISO. ISO (film speed on see Wikipedia) does affect our exposure decisions, since it describes how the sensor responds to exposure in terms of saturation.

Regards

What's it doing to reduce the noise?

Good to know that at least some are agreeing that this process isn't increasing the photon count, I've been scratching my head trying to understand what the ISO on the Canon is doing to reduce the noise. Not implementing ETTR and setting the Canon to ISO 100 certainly doesn't produce the lowest noise in a capture. Why?

I can understand the argument that exposure is Aperture + Shutter but then ISO, at least in this case, plays a role. Do we need a separate acronym for Canon cameras whereby we increase ISO, don't adjust 'exposure' based on the increase and end up with less noise?

The answer for your Canon camera is discussed by Emil here in Figure 12a and the accompaning text:

"There are several ways to interpret this graph that are useful to keep in mind for making exposure choices. If one has the option to lower the ISO and the shutter speed (or widen the aperture), the highest S/N for the image is obtained by increasing the exposure, pushing the right end of the histogram right up to the upper edge of the range of exposure on the horizontal axis. This is the usual ETTR philosophy. Lowering the ISO one stop pushes the upper end of the dynamic range one stop to the right in absolute exposure, and pushing the histogram to the right climbs the rising S/N curve to better overall image quality.

If on the other hand, one is limited by the subject matter (freezing motion, depth of field requirements, etc) to a given maximum EV, then it makes sense to raise the ISO to pull the top end of the camera's dynamic range down to the top end of the histogram; this has little benefit at that upper end, since all the curves are on top of one another in that regime. Nevertheless it improves image quality by raising the S/N ratio on the shadow end of the curves."

In the latter case when one is limited by the subject matter, one gives the required exposure in terms of f/stop and shutter speed, and raises the ISO. In this case exposure (measured in lux-seconds) is fixed at the required level.

Bill

OK...didn't read that in your comment, as I thought it was implicit in the original statement, "For a photographer, the exposure net result includes the consideration of ISO", as well as Bill Janes post.

I pay virtually no attention to anything Janes writes.  And yes, 'implicit'.  As in implied.  Which is what I said originally when I noted 'Emil hints at it'.  All I doing was trying to make it clearer. 

+1 for those who have mentioned the AF Zoom Micro-Nikkor 70-180 mm f/4.5-5.6 ED. It was only made for about 5 years, Nikon ending production in about 2005. It never really got popular until they stopped making it. I found a really clean copy for $2,000 on eBay several years ago and have never regretted the purchase. Of the current lenses, my favorite is the 105VR. While I haven't really done it seriously, don't forget focus stacking is all the rage now. I find the D800 is not all that good for depth of field as it is necessary to limit the minimum aperture to around f8 or so due to diffraction. That sharp sensor doesn't come without issues!

My first order to Omega was for around $2,000.  The only numbers discussed were my credit card number, shipping address, and telephone number.

Pretty much the only surviving store-front-only holdouts are Larson-Juhl and Roma.   For most of the others, money talks and an account is only a short phone call away.

Herein I will disclose the REAL reason for wanting to use a framer.  You heard it here first.  An increasingly large percentage of the moulding you will receive will be twisted, warped, damaged, unmatching, and generally unusable poop.  Let your poor framer fight with the distributor and save your venom for other battles.  And be understanding if it takes a few extra days.  That's why framah is the way he is.  End of story.

["...Therefore, in the absence of compelling reason to give the additional one stop of exposure, use the Zone III placement of the shadow area; the resulting negative will have less grain and higher acutance since there is no 'wasted' density, and will still have full detail in the important areas."]

This entire ETTR, exposure, ISO, testing takes me back to the mid 1980's while at photo school. I think 2nd trimester, we had one of our first assignments shooting color (first trimester we only shot 4x5 B&W film, it could not be burned or dodged in the darkroom for any assignment). This new color assignment was to shoot 4x5 color neg, I think it was Kodak VPS II or something. Stated ISO 160 on the box. The subject had to be stationary and have an 18% gray card in the center filling up at least 20%. We were to shoot at the recommended ISO, then 1, 2 and 3 stops under and over. We processed all the film together. Then in the darkroom, we had to make prints whereby the gray card on the print matched the actual gray card. Once all 7 prints were mounted and viewed, the results were very surprising! The plus 1 and 2 stops were easily printable and both produced a better print quality than the "normal" ISO 160 image. The under exposed prints all suffered compared to the 'normal' exposure.

ISO 160 for VPS worked just fine! But rating it at ISO 80 (or 40) and treating the rest of the process the same produced a very visible and beneficial result! No Histograms. But we did expose to the right if you will.

Historical perspective is always helpful and many concepts learned earlier can be carried over into digital photography. However, the response of negative film and the digital sensor are quite different. Negative film has a toe on the H&D curve and exposures that do not place shadows above start of the toe will result in blank film base and all shadow detail will be lost. From my film days when using negative film, I had a sinking feeling when the shadows recorded as base density on an important shot that could not be recovered. Digital is linear and any shadow luminance will be recorded but any image detail may be lost in noise. The digital sensor response is linear without any shoulder and highlights will be clipped abruptly when the sensor saturates. Some highlight recovery may be possible with Bayer CFA sensors, since the red and blue channels may still have some detail, but the color information in the green channel that clips first (with daylight and most artificial illumination) will be lost.

The H&D curve has a shoulder that rolls off gradually and negative film is resistant to overexposure for this reason. With ETTR, one exposes for the highlights, placing then just short of clipping, and overall tonality can be brought back in post processing. What about negative film: the usual advice is to expose for the shadows and develop for the highlights, the exact opposite of digital.

Going back to your experiment with VPS the effect of exposure will depend on what you have surrounding your gray card. This is discussed in Ansel's The Negative, page 67 in my 1981 edition. For what he describes as a short-scale subject, one can place the important shadows on Zone III and the highlights will fall on Zone VI and less than the full range of tones will be exposed. This gives the option of placing the shadows higher and getting better shadow definition. Ansel states: "...Therefore, in the absence of compelling reason to give the additional one stop of exposure, use the Zone III placement of the shadow area; the resulting negative will have less grain and higher acutance since there is no 'wasted' density, and will still have full detail in the important areas." He then proceeds to talk about development and printing procedures to give the desired tonalities in the print and the handling of full scale subjects where there is less "exposure latitude".

This is the exact opposite of your findings with VPS, and we would call Ansel's exposure in this case as to the "Left". In his exposure scales, he placed Zone I to the left just as we do with histograms in the digital era. The concepts have not changed: one exposes to get optimal image quality, taking into account the characteristics of the medium.

Regards,

Bill

You are all so amusing even the crocodile thinks you are funny. 

And your croc is a real stand-up comic.

Love it!