OT: HDR images and Film

I've seen several mentions lately of HDR (high dynamic range) images on photo

forums and even an article about the technique in The New York Times.

The concept, as I understand it, is to take several exposures with a digital

camera on a tripod and then combine the files for printing, so that there will

be detail in both the shadows and the highlights -- over a greater range, in

fact, than film would be able to provide.

But wait! Couldn't we achieve a similar result by shooting a film like TMX,

whose characteristic curve has a very long straight line segment, scan it at

different "exposures" (if that's the correct term) and thereby achieve in one

click of the shutter, even with a moving subject, what digital photographers

are doing with their multiple exposures for stationary subjects only?

Leica content: Sometimes I shoot TMX in my MP.

Might not this multiple-scanning technique be superior to both dodging and

burning and their analagous digital techniques?

By the way, if this is something that everyone's been doing already and I'm

just late to the party, please cut me some slack. Thanks.

Peter, I think I understand what you're saying...

...but my point (to which, I admit, you may be directly responding and I'm just not getting it) was that a single exposure of a long-straight-line film would allow HDR-type multiple scans of a single exposure, thus allowing shots of moving subjects without the need for any masking.

Probably wouldn't work with TX or the chromogenics, whose curves make them easier to print, usually, but which have a less linear density/exposure function. That's why I had TMX in mind.

To use the HDR function, the shots have to be pretty far apart (like 4 stops?).

There is a technique called MDR which is more like what you are talking about. Taking

two versions of the same RAW File and combining them.

jmp

Thanks, Peter. Now I see that you see what I was getting at:

With an extremely fine-grained straight-line film, generous exposure, slightly extended development and a high-quality scanner, I wonder if gaining a stop or two from multiple scans at different exposures might, in rare instances, be worth the effort.

Not suggesting it as a general practice...but it might be interesting to do some experiments.

As far as I know the dynamic range of current B/W emulsions is far beyond what you get on paper, even with toning.

C41 isn't as good as B/W but should be better than most prints as well.

Monitors are limited, too.

It may make sense with slides you want to scan and print.

HDR gives the photographer the opportunity to create images with more lattitude than the human eye can manage in the same scene. That makes HDR (performed towards the extreme) an exceptional technique. The lattitude of film remains well within the boundaries of human perception. HDR goes beyond. (It doesn't have to, but... read on.)

Further, HDR attempts to give texture and detail in what would be blocked areas in conventional film techniques. That is, it would give shadow and highlight contrast and detail at extreme extents, something not within the capabilities of straight film work.

Of course, the same could be done with an enormous effort with conventional means of masking and multiple exposures, but by convention HDR is an expression of the digital domain.

HDR has great aspirations. It 'wants' to do more than just make up for film exposure management. Therein is the challenge. Take Adobe's Photoshop HDR. It "likes" (meaning the programmer prefers) to use frames of great ranges. You can see this by supplying Photoshop (CS2) images without EXIF information. It brings up a dialog asking you to input F-Stop values. If you do not give a range sufficient to the algorithm (extremes), it states that the images are not susceptible to HDR (or to that effet) and does not perform the HDR.

HDR algorithms have been a huge challenge and the effort yielded lots of research and papers. I've been watching it for many years, and had the honor of corresponding with at least one brilliant mathematician in Poland. (I can post a URL of an early outcome evincing some interesting problems, but remarkable nonetheless).

So... there you go. While HDR could produce modest ranges to help overcome some shortcoming in anyone's technique to produce typical film ranges, the intent is really to produce outcomes of the extreme.

I hope this helps,

I would be interested in seeing the results of your theory- give it a go,

Personally, I use HDR for product shots. I understand combining multiple exposures for this purpose has been used by film cameras/scanning for quite some time.

However, most of the posted HDR shots I have seen begin with snapshots I would delete. Right now HDR seems to be experimental and unrefined. I welcome it when used with strong compostions and subject matter.<div></div>

You can get surrealist photos like this too with HDR.

<img src=http://lh6.ggpht.com/saviourag/SPoMkumBQBI/AAAAAAAACQM/KFcBVCpxQ24/s576/IMG_2434HDRe.resized.jpg>