taking a High dynamic range picture
I've made some HDR pictures before with a digital camera and photoshop (don't shoot me), but I think this can also be done with analogue camera's.
My guess is that I use double exposure and divide the shutter time. For instance, let's say a single shot would have to have a 1/60 shutter time. I would divide this into 1/20 and 1/40. Making it a total exposure time of 1/60.
Is that right or doesn't it work that way?
No. that would be over-exposed. to make up 1/60 you would need two exposures of 1/125 or four of 1/250 (or any other combination which keeps the shutter open for an equally long time).
Originally Posted by Steven L
It won't alter the dynamic range though.
Darn you're quick Steve
I see the logic in 2 exposures of 1/125 or 4 of 1/250. I see what I did wrong. 1/20 + 1/40 isn't 1/60, it's about 1/13th of a second. 2x 1/125 = 1/62,5 (calculated a bit over exposed)
What if I shoot ones 1/125 and twice 1/250? Same result as 1/60?
Is it possible to make an uneven division of the two exposures to create a HDR picture? Or can HDR only be created after taking two seperate pictures?
HDR can't be done in camera on one piece of film as you suggest. HDR selectively chooses pixels from multiple images and recombined them into one composite image. All you are doing with your suggestion is adding more exposure to all grains of the film. Additional exposure is not selective, so it won't achieve the effect you intend.
Essentially what you want to do is compression or expansion so that the image you capture on film can be printed well. This has been done for years using the zone system. You can think of the zone system plus dodging, burning, bleaching, etc. As the analog version of HDR.
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So basically what I can do with double exposure directly on film is something like this.
With the technique Steve Smith has mentioned.
I guess I just have to give it a try some time and experiment. Right now I only have a 35mm SLR without the ability to develope or print. All I do is bring the film to a photographer and have it developed and printed.
I wonder what would be the outcome of a double exposure of the same scene, where one object is close and another object is far away. 2 exposures, 1 focussed on the close object, 1 focussed on the further object. I'm going to give that a try some time.
Thank you all for your information. Any fun experiments with double exposure is welcome.
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Something else which is fun to experiment with is a double exposure at two different apertures. One wide open and one closed down to give a large and narrow depth of field of the same image. It's a bit more complex though as you need to work out the correct shutter speed for each aperture value then use the next highest speed to give half the exposure for each.
e.g. if your normal exposure is going to be f8 at 1/60 and you chose to make an exposure at f2.8 and f16, your shutter speeds would need to be 1/500 and 1/15 respectively.
Last edited by Steve Smith; 02-17-2012 at 07:56 AM. Click to view previous post history.
Well with film you need to think a bit differently.
Double exposure is only important if you want two sets of content.
Adding more exposure adds more shadow detail, extends the range down. This is known as placing the shadows and relates directly to choosing exposure.
The upper limit is a function of the film and/or development you choose. With negative films the scene brightness range you can get on film is naturally quite long, some films considerably longer than others.
Even with normal exposure the scene brightness range on the negative may, and in fact probably, already be considerably longer than a strait print can show. To get at that info in the analogue world we do things like burn and dodge in an enlarger to get it onto the paper.
The paper and screens are the limiting factors much more than the film. Paper and screens have short brightness ranges.
Scans can get that info too and and PS type programs can be used to get that info into the printable range. Discussing those techniques here though is off topic.
Mark Barendt, Ignacio, CO
"We do not see things the way they are. We see things the way we are." Anaïs Nin
Choose the right negative film and development, and you do not need HDR, you get it all in 1 exposure. Of course dark areas are darker than the bright areas, thus each local area is lower contrast, unless you mask it, to raise contrast in each area.
Originally Posted by Steven L
You can also try graduated ND filters.
With the prints I get from the photograph, I aslo get the negatives. I could try to do the "unmentionable"
(I know Mark Barendt, x-nay on the igital-day)
I mentioned HDR because I like the way it looks like a drawing or painting. It seems to be unreal and over-colorfull.
I re-discovered analogue photography recently with my wife's old SLR. I've shot a 36 roll to get used to the manual setting. (written down every setting of every picture, for future refrence) I'm going to have this one developed and printed next week. The next roll will be an experimental one. Double exposure, out of focus, over exposure, under exposure. This thread gave me some idea's of what to do.