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13th April 2008, 12:02 AM
Can I Use HDR with Scanned Film?
As a film user, many digital photos I have seen lately confirmed what someone said, that long and night exposures don't suffer from the reciprocity shifts with film, and retain normal color. How right they were. There's a whole new world out there!
I was reading this site's tutorials on high dynamic range (HDR), and I gather from what you said that the HDR processor only works for digital images, and will not work on digital files from scanned film, because photoshop uses metadata to help it decide how to sort out values. Do I understand this correctly?
Last edited by McQ; 20th October 2009 at 12:30 AM.
13th April 2008, 12:10 AM
HDR could conceivably be applied to film scans if you were to enter the exposure information manually.
Therein lies the difficulty though; you will need to have recorded each photo's exposure info, they will all need to have been taken using the same film, and the darkroom developing will need to be identical between each shot--not to mention all the usual requirements that also apply to digital, such as using a tripod, etc. Further, if this is for very long exposures, the exposure information you manually provide to the software will need to be corrected for to account for reciprocity. Overall, it can be done, but much better--and easier--results will be achieved with a digital camera.
Another option would be to scan a single negative using a film scanner with a high Dmax (see http://www.cambridgeincolour.com/tut...amic-range.htm). You could then capture the full dynamic range using the scanner's RAW file format (or whatever the high bit depth equivalent is called for the particular scanner), and then "develop" this RAW file at several different exposures. These could then be combined using Photoshop CS2/CS3's HDR technique as if they had all been taken as separate photos.
14th September 2008, 02:07 AM
Re: Can I Use HDR with Scanned Film?
you dont even need to scan the film.
There is a far easier way for film users to get a hdr image, just my doing multiple exposures.
Theres no need for photoshop, or even to scan the negs, just shoot three different exposures on the same neg, simply by shooting it 1 stop over, 1 under, and 1 at the correct exposure, and by doing this it = the correct exposure, so theres no need to mess arround with it.
I do this using my twin lens mamiya c220 and it works a treat.
Hope this can be of some help to you.
14th September 2008, 07:53 AM
Re: Can I Use HDR with Scanned Film?
Regarding the last post in this thread; while I am no expert in this field, I believe the basic principles will still apply: if on the first exposure, an area of film emulsion equivalent to a pixel is fully exposed, further exposure of that area will have no effect, so '+1 stop over' won't add to it and niether will '-1 stop under' take away from it. The top end of the tone curve is fixed by the emulsion/developing combination (effectively fixing the emulsion's speed, or ISO rating). So an area that was almost fully exposed initially will be pushed into saturation by the subsequent exposures, 'blowing' the highlights.
I can see how it will appear to work though; because the darker areas of the picture will gain from the additive effects of subsequent exposures. One expects highlights to be 'blown' out, so the eye only sees the positive benefits (gain) in the darker areas.
Far more likely is that what the meter is telling you, results in under exposure by 2 stops and actually all you are doing is correcting that under exposure.
However, I do think one long exposure (of the 3 combined shutter durations) would achieve exactly the same effect. Maybe something to try?
Hope this helps simplify* the picture taking, Dave
* 2/3 less chance of the camera moving as you touch it to expose, etc.
NB This is only my suggestion and if you have a method that works for you, go for it.
Any chance we could see an example f.stop.photec?
Last edited by Dave Humphries; 14th September 2008 at 08:11 AM.
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