Discussions: 45,011 | Messages: 606,870 | Members: 29,743 | Online: 356 | Chatroom: 0
User Name:  Password:
 

"That is called grain. It is supposed to be there." -Flotsam


 
APUG search    RSS MOBILE
Customize Sidebar

#9 Ash

by Wolfgang Moersch
Enter the Gallery
Gum-Silver Process
Author: Dwane
873 view(s)
aj 12 + various things
Author: jnanian
398 view(s)
Kodak D-19
Author: Tom Hoskinson
819 view(s)
Go Back   APUG > APUG English Forums > General Discussion > Exposure Discussion > Can DOF affect Exposure?

Reply
 
Thread Tools Display Modes
Old 06-20-2003, 04:01 PM   #1 (permalink)
 
Bruce Osgood's Avatar
 
Join Date: Sep 2002
Location: Brooklyn, N.Y. USA
Posts: 1,924
Default

I was shooting a group of roses - deep red - with lush green leaves around and behind the main subject. It was a low light/low contrast morning and had rained earlier, the flowers and leaves were showing rain drops. I metered on the green leaves and placed them on Z-V, the flowers fell about Z V-1/2. I wanted to use a red filter (#90, factor of 5) and opened up 2-1/2 stops. It was a close up shot and I wanted to use a shallow DOF to capture the Bokah in mid tones and the subject roses sharp and with *etched* detail. The exposure after filter factoring was 1/4sec @ f-4.5

The lens was Zeiss VS 80-200 at about 85mm.

The film was 35mm Pan F+ rated at EI 40.

The development was: small tank (one roll); DD-X 1:4; 22-c @ 5:30.

The results are: Blownout midtones - unprintable even burning at 2X base exposure. The subject roses look good and are quite interesting to me. They are in the area of my intent.

My questions come down to:
1) While trying to capture Bokah with a shallow DOF would/could luminosity be scattered to a point different than indicated by a spot meter (Pentax V)?
2) Did I simply process the film incorrectly?
3) Did I incorrectly apply the filter factor (factor of 5 = 2-1/2 stops)?
4) Given the subject to film plain distance of less than 1 meter should I have compensated for that in exposure also?

The weather conditions for today and tomorrow are the same as they were a couple of days ago (and weeks before that) when I took the picture and I would like to try it again.
__________________
Bruce Osgood
http://camclicker.com/Openingx.html revised April 08
Bruce Osgood is offline   Reply With Quote Ignore this user Ignore this thread Ignore this forum
Old 06-20-2003, 04:10 PM   #2 (permalink)
 
David A. Goldfarb's Avatar
 
Join Date: Sep 2002
Location: New York, New York
Posts: 12,479
Default

I think (4) is a possibility, if you were using an external meter. At 1m, magnification with an 85mm lens is about 1:10, so you need to add 1/3 stop, and if you were closer, you would need to add more. Of course, if you were using the camera's internal meter, it would compensate automatically.
__________________
Photography-- http://www.echonyc.com/~goldfarb/photo
Academic (Slavic and Comparative Literature)-- http://www.echonyc.com/~goldfarb
David A. Goldfarb is offline   Reply With Quote Ignore this user Ignore this thread Ignore this forum
Old 06-20-2003, 04:34 PM   #3 (permalink)
Ole
 
Ole's Avatar
 
Join Date: Sep 2002
Location: Bergen, Norway
Posts: 8,624
Blog Entries: 1
Default

Quote:
Originally Posted by Bruce (Camclicker)
My questions come down to:
1) While trying to capture Bokah with a shallow DOF would/could luminosity be scattered to a point different than indicated by a spot meter (Pentax V)?
2) Did I simply process the film incorrectly?
3) Did I incorrectly apply the filter factor (factor of 5 = 2-1/2 stops)?
4) Given the subject to film plain distance of less than 1 meter should I have compensated for that in exposure also?
1) No, but... The spotmeter doesn't focus close. It will be influenced by the surroundings.

2) Seems a bit too bad to be mere processing?

3) That sounds about right to me.

4) Yes, but failing that would lead to underexposure.

I have tested the bokeh of an old (1934) Heliar 150mm by shooting the same scene at f:4.5, f:16, and f:45 adjusting the shutter time accordingly. The exposures were identical - incidentally proving that the shutter is still reasonably accurate.

Wrong exposure is the likely culprit - check your meter. And also have a look at how it behaves close up...
__________________
-- Ole Tjugen, Luddite Elitist
Norway
Ole is offline   Reply With Quote Ignore this user Ignore this thread Ignore this forum
Old 06-20-2003, 05:19 PM   #4 (permalink)
 
Join Date: May 2003
Location: near Amsterdam, Holland
Posts: 745
Default

My Minolta Spotmeter F does not work properly within 1m30cm. I guess your Pentax V might have the same problem.

Try measuring the roses from farther away. If the Pentax is a 1° meter, this will work OK.
Annemarieke is offline   Reply With Quote Ignore this user Ignore this thread Ignore this forum
Old 06-20-2003, 05:34 PM   #5 (permalink)
 
Aggie's Avatar
 
Join Date: Jan 2003
Location: So. Utah
Posts: 4,925
Default

..
Aggie is offline   Reply With Quote Ignore this user Ignore this thread Ignore this forum
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)

Old 06-20-2003, 06:05 PM   #6 (permalink)
 
Eric Rose's Avatar
 
Join Date: Nov 2002
Location: Calgary AB, Canada
Posts: 3,157
Default

Your meter does not read deep red very well. Most meters don't. I usually put a grey card in the scene and meter off that if possible. The same problem happens if you put a red filter in front of the lense on the spot meter. For some reason they are not linear in their response to color.
__________________
Everyone gets everything he wants. I wanted a mission, and for my sins
they gave me one. Brought it up to me like room service. - Willard

www.ericrose.com
Eric Rose is offline   Reply With Quote Ignore this user Ignore this thread Ignore this forum
Old 06-20-2003, 06:05 PM   #7 (permalink)
 
Join Date: Dec 2002
Posts: 6,242
Default

The one thing which you reported that I tend to question is:

Quote:
The results are: Blownout midtones - unprintable even burning at 2X base exposure. The subject roses look good and are quite interesting to me. They are in the area of my intent
.

The reason that I question that statement is that I have heard of blown out /blocked highlights and I have heard of underexposed shadows but I have never heard of blownout midtones in my life.

If the shadow detail is there and the highlight highlight detail is there then the midtones need to be there as well. Perhaps if one knew which end of the spectrum you feel is missing then a direction might be more readily addressed. The matter of metering this scene is the same as always. Expose for the shadows and develop for the highlights.

Additionally you failed to account for the effects of the red filter on the green foliage. It darkens it as it is the opposite of green. Filters lighten like colors and darken dissimilar (opposite) colors in a print.

Quote:
The subject roses look good and are quite interesting to me. They are in the area of my intent.
.

The red filter lightens the color of the red roses and that is why you got some exposure on the blossoms (I am assuming here) but no printable exposure on the green foliage.
[/code[/i]
__________________
Art is a step from what is obvious and well-known toward what is arcane and concealed.

Visit my website at http://www.donaldmillerphotography.com
Donald Miller is offline   Reply With Quote Ignore this user Ignore this thread Ignore this forum
Old 06-20-2003, 06:36 PM   #8 (permalink)
 
David A. Goldfarb's Avatar
 
Join Date: Sep 2002
Location: New York, New York
Posts: 12,479
Default

Here's another thought:

An overcast morning at EI 40 should give you about f:5.6 at 1/40 sec., so make it 1/30 sec. to account for the magnification factor, and adding 2.5 stops for filter factor gives you f:4.5 at 1/8 sec., so you should have been in the ballpark, exposure-wise.

Could you post a scan? Like Donald, I'm a bit unsure about what you mean by "blown out midtones."
__________________
Photography-- http://www.echonyc.com/~goldfarb/photo
Academic (Slavic and Comparative Literature)-- http://www.echonyc.com/~goldfarb
David A. Goldfarb is offline   Reply With Quote Ignore this user Ignore this thread Ignore this forum
Old 06-20-2003, 07:12 PM   #9 (permalink)
 
Bruce Osgood's Avatar
 
Join Date: Sep 2002
Location: Brooklyn, N.Y. USA
Posts: 1,924
Default

Quote:
Originally Posted by David A. Goldfarb
Here's another thought:

Could you post a scan? Like Donald, I'm a bit unsure about what you mean by "blown out midtones."

See Chritique Gallery
__________________
Bruce Osgood
http://camclicker.com/Openingx.html revised April 08
Bruce Osgood is offline   Reply With Quote Ignore this user Ignore this thread Ignore this forum
Old 06-20-2003, 07:31 PM   #10 (permalink)
 
David A. Goldfarb's Avatar
 
Join Date: Sep 2002
Location: New York, New York
Posts: 12,479
Default

Looks like the dark red filter lightened the roses substantially, and now they're hard to print. The green leaves should look virtually black with that filter. My strategy would be to increase the overall exposure to get detail in the highlights, if that is possible, and dodge to get the shadows, maybe using a lower contrast grade.

This might also be a neg to try some pre-flashing on to get the highlight detail, but there are others here more experienced in that technique than I am.

Next time, try a lighter red filter.
__________________
Photography-- http://www.echonyc.com/~goldfarb/photo
Academic (Slavic and Comparative Literature)-- http://www.echonyc.com/~goldfarb
David A. Goldfarb is offline   Reply With Quote Ignore this user Ignore this thread Ignore this forum

APUG.ORG Block Ads. (APUG Subscribers have the option of closing this block)
 


  Contact Us - Advertise on APUG - Archive - Top - Site Terms - Forum Rules  
    

All times are GMT -5. The time now is 09:22 AM.
  
All Content Copyright © 2002-2008 Photocentric Ltd.   Search Engine Optimization by vBSEO APUG.ORG is a division of Photocentric Ltd.
This site is best viewed with a resolution of 1280x1024 (or higher), we recommend using