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Author Topic: Too much contrast; how to tell from a test shot?  (Read 4095 times)
howard smith
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« on: May 20, 2004, 11:44:03 AM »
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[font color=\'#000000\']Lisa, thanks for that very clear explanation.

A question.  I shot film mostly, then scan it.  Assuming the film is exposed OK, can I use the histogram technique you described to make better scans?[/font]
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Lisa Nikodym
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« Reply #1 on: May 20, 2004, 04:51:26 PM »
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[font color=\'#000000\']Hi again, all -

Howard:  Yes, the same histogram logic applies to making film scans, if you (as you say) the film was properly exposed to begin with, and if you have some way to tweak the scanner exposure in software to move the histogram the direction you want.  (I've scanned film for some years now, and only got my first digital camera, a D70, two weeks ago!  Though I mostly used negative film because it's so much more forgiving of exposure, and I always seemed to be taking large-dynamic-range photos, in redwood forests and the like.)

Didger:  My camera doesn't have a clipping or histogram preview capability either, only after the shot, but (at least with my camera) it's quick & easy to take the shot, check the histogram and clipping screens, delete it if I don't like it, change the exposure and try again.  And no, no relation to the other rodent-avatar person whatsoever (except we apparently both have an affinity of some sort for small furry critters).  Though, if one wants to be precise, mine is not quite a rodent - it's a pika, which is a wild member of the rabbit family.
 

Lisa[/font]
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Lisa Nikodym
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« Reply #2 on: May 25, 2004, 09:57:57 AM »
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[font color=\'#000000\']Bob -
I particularly like your squirrel photo because your squirrel appears to be regarding the photographer, not just the other way around.  Different from the grey squirrels we have around here (California) too.

Yeah, I hear you.  I consider myself very lucky to be living in such a photogenic state and to be able to travel to yet more places often.  My photos really aren't the result of any real skill at all (I'm actually rather miserable when it comes to technique, though that's improving since I went digital a few weeks ago and now have a histogram and "post-view" to look at), but the result of going interesting places.  We joke that the only way to take a bad photo in Yosemite is to stand behind a bus.
 

Lisa[/font]
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didger
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« Reply #3 on: May 26, 2004, 05:42:15 AM »
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[font color=\'#000000\']
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Yeah, I regularly get that same look from my cat...
Your cat likes corn on the cob??? :laugh:[/font]
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didger
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« Reply #4 on: May 20, 2004, 09:52:46 AM »
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[font color=\'#000000\']Some time ago (somewhere) someone mentioned that if you're shooting a very high contrast scene where you may get dynamic range clipping even shooting raw, you can just do a test shot and look at the histogram to see if you need to do two shots (one over, one under-exposed) on a tripod and then merge them later.
Just what do you look for in the histogram that tells you for sure if dynamic range in the test shot has been clipped?[/font]
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didger
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« Reply #5 on: May 20, 2004, 11:22:57 AM »
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[font color=\'#000000\']Thanks, that's very helpful.  I haven't got my lenses for my new 1ds yet, but I gather you don't get any sort of digital display preview, you have to take a shot and then look at the result, so this feature of seeing clipped highlights wouldn't be possible.

Hey, are you any relation to our other rodent avatar member?[/font]
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didger
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« Reply #6 on: May 20, 2004, 01:14:02 PM »
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[font color=\'#000000\']Lisa may be able to tell you things about scanning that I don't know, but depending on what kind of film you use, by the time your picture goes into your scanner it may already be too late.  Slide film especially is poor in this regard.  The great thing with digital is that you can do test shots in the field and then either take two shots and blend later or take one shot that covers the contrast range as well as possible.[/font]
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Tim Gray
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« Reply #7 on: May 20, 2004, 03:45:44 PM »
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[font color=\'#000000\']so this feature of seeing clipped highlights wouldn't be possible.[/font]
[font color=\'#000000\']The 1Ds won't preview, but you will see the clipping in the review.  A spike at only one end can be accomodated by a + or - ev adjustment, but a spike at both ends requires a bracket.[/font]
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boku
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« Reply #8 on: May 20, 2004, 07:59:53 PM »
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[font color=\'#000000\']Hey, are you any relation to our other rodent avatar member?[/font]
[font color=\'#000000\']Not possible - she has far more photographic talent than I. I checked.

Ironic, isn't it?[/font]
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Bob Kulon

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didger
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« Reply #9 on: May 20, 2004, 09:16:14 PM »
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[font color=\'#000000\']
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Though, if one wants to be precise, mine is not quite a rodent - it's a pika
Good grief, how could I not have noticed, with all the High Sierra backpacking I've done.  Pikas are the cutest little critters in the mountains, even counting cute lady backpackers!![/font]
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boku
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« Reply #10 on: May 24, 2004, 05:48:59 PM »
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[font color=\'#000000\']Lisa,

I'm from NE Ohio.  With myself and close family members in failing health, my photo excursions are pretty limited.  I'd love to get to the grand vistas and significant geography that most of you on this site aspire to, but I have neither the time or the fortitude.

Nevertheless I make do. That "red squirrel" and his buddies spent the winter at our bird feeder on the back deck. I opened my package from B&H with the 70-200 L lens put it on the camera, looked up, and there he was, munching away. Hand held, wide open, 200mm, no IS, right through the dirty deck door glass, manual focus.

At the moment, it was a joke, but after the Photoshop work I couldn't believe the beautiful bokeh. At that moment, I was sold forever on owning quality lenses.

I'll stop rambling now. Funny, everyone liked the photo and all I was trying to do was test the lens.[/font]
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Bob Kulon

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Wayne Jacobsen
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« Reply #11 on: May 25, 2004, 10:20:49 AM »
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[font color=\'#000000\']For Howard:

I started off in digital by scanning film.  This site was very helpful in getting me started.  He has good information re the use of the histogram in scanning:
www.scantips.com

--Wayne[/font]
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Lisa Nikodym
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« Reply #12 on: May 25, 2004, 10:00:29 PM »
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[font color=\'#000000\']Bob -

Yeah, I regularly get that same look from my cat...   :cool:

Lisa[/font]
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Lisa Nikodym
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« Reply #13 on: May 26, 2004, 12:02:12 PM »
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[font color=\'#000000\']Well, she prefers avocado, but my mother once had a cat who insisted on having corn on the cob regularly!    

Lisa[/font]
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Lisa Nikodym
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« Reply #14 on: May 20, 2004, 10:55:22 AM »
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[font color=\'#000000\']If there's a big spike right at the end of the histogram, then you're clipping.  If you change the exposure in the correct direction and then look at the histogram again, you'll see the spike disappear, or at least reduce in height relative to the rest of the histogram.  (This is true not just of the bright end of the histogram, but also of the dark end, though digital camera sensors are much less forgiving at the bright end.)

Caveat:  If you have a significant amount of specular highlights (in laymans' terms, featureless bright reflections) in your photo, they will appear as a spike at the bright end too.  However, in this case, the spike is acceptable.

Some cameras can be set so that they show clipped highlights as blinking regions in the image on the camera's monitor.  That's very useful to see what parts of the picture are getting clipped, and judge whether they are featureless areas you don't care about anyway (such as specular highlights).

Lisa[/font]
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howard smith
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« Reply #15 on: May 20, 2004, 01:43:33 PM »
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[font color=\'#000000\']didger, well undertood.  That's why I added assuming the chrome is properly exposed.  The beauty of film is I get to exercise while in the field, bracket if I must, but live with the results.  Pain is a powerful teacher.[/font]
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Lisa Nikodym
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« Reply #16 on: May 24, 2004, 11:55:48 AM »
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[font color=\'#000000\']I live a few hours from Yosemite (just returned from a three-day weekend there), and have done tons of hiking in the Sierras, but only caught a brief glimpse of a pika *once*.  I seem to only see them in the Canadian Rockies, despite very limited time there.  Everyone else sees them in the Sierras, though, just not me!  (The guy in my picture was a Rockies pika.)

Thanks for the compliment, Bob.  Nice squirrel you have there, too.  But it looks like a different species from the ones I'm familiar with around here - where are you from?

Lisa[/font]
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boku
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« Reply #17 on: May 25, 2004, 05:50:40 PM »
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[font color=\'#000000\']
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Bob -
I particularly like your squirrel photo because your squirrel appears to be regarding the photographer, not just the other way around. Different from the grey squirrels we have around here (California) too.
Yes he was looking at me.

Looking with that "Hey you, I want more corn on the cob now and I MEAN NOW!" sort of stare.

I swear he resented me buying a lens instead of a bag of acorns.

He probably tripled his body weight last winter.

[/font]
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Bob Kulon

Oh, one more thing...
Play it Straight and Play it True, my Brother.
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