SBR & Development Adjustment

[Bruce Osgood]

When considering an adjustment to development of negatives, one thing we seem to consider is the Shadow to Brightness Range. I thought this was like a spot metered Shadow EV of 6 subtracted from a Bright EV of 13 giving a SBR of 7 stops. From that 7 we would make a personal discission whether or not to adjust our development time and by how much. Perhaps the 7 is a lot, perhaps a little or perhaps no adjustment is needed.

It dawned on me that this may be the wrong way to approach the question of +/- development. If we believe in the tenant of "Exposure places the shadows and development places the highlights", then shouldn't we consider adjustment to the highlight portion of the spectrum because the shadow portion is not going to be altered regardless? In the example of EV's 6 and 13 suppose the mid-gray were 11 EV, wouldn't a better conclusion be that you had 2 stops to consider?

I think this would be important in low key photos where you have an image of long toe and short straight line.

Perhaps you see no merit in the question but these kind of things bug the heck out of me.

 

[Claire Senft]

BTZS

If you get a copy of Phil Davi's BTZS it will tell you how to test both your paper and film.

 

[mikepry]

Also, I might add, that BTZS.org is much better suited for these types of questions and learning the BTZS approach. Try this link.............

btzs.org

 

[wm blunt]

Bruce,
The shadow ev 6 subtracted from the highlight ev 13 gives you 7 which is added to 5. So the SBR is 12. A SBR of 7 is considered normal.

 

[Bruce Osgood]

Thank you

Claire
mikepry
wn blunt

Your replies are useful and I will dig further.

 

[noseoil]

High SBR

Bruce, this is one of the first shots with a high contrast range (shot was 7 2/3 on the bottom and 15 2/3 on the top) I attempted as a sort of test of BTZS concepts. I exposed at ev 9 to make sure shadows had enough density and then backed down development to bring in highlights. As Mike and others have mentioned, BTZS was the only way I could understand this extreme range of values and translate it into a print which worked. While not a great image, it does give an idea of how BTZS values are applied in terms of a real shot.

While Phil Davis's book gets a bit long on numbers, the concepts expressed in his work are the only way I can see to relate paper, film, exposure, development and printing in this type of extreme situation. All the other systems fall apart in a scene with this type of exposure and development issues. Try it, you'll like it. tim

 

[mikepry]

Tim...are you showing off?????? Seriously, that is unbelievable what you have attained with that image. We are expecting to see some nice cactus blooms in the very near future with all the good rain you have had out there.

 

[Zathras]

Bruce,
The shadow ev 6 subtracted from the highlight ev 13 gives you 7 which is added to 5. So the SBR is 12. A SBR of 7 is considered normal.

Wouldn't that depend on how Bruce is metering? If he's using the Incident Method, this would be correct. If he is metering with reflected light, and if my understanding of BTZS is correct, subtracting 6 from 13 would make for a 7 stop SBR. I am just starting down the slippery slope of BTZS myself, so I realise that I may be wrong. It wouldn't be the first time... :rolleyes:

Mike Sullivan

 

[wm blunt]

Mike,
You can use a spot meter with the BTZS system instead of incident meter and it works just fine. I use both but when possible I use the incident.

 

[Bruce Osgood]

My origional Post:
"I thought this was like a spot metered Shadow EV of 6 subtracted from a Bright EV of 13 giving a SBR of 7 stops. From that 7 we would make a personal discission whether or not to adjust our development time and by how much. "

Wouldn't that depend on how Bruce is metering? If he's using the Incident Method, this would be correct. If he is metering with reflected light, and if my understanding of BTZS is correct, subtracting 6 from 13 would make for a 7 stop SBR. I am just starting down the slippery slope of BTZS myself, so I realise that I may be wrong. It wouldn't be the first time... :rolleyes:

Mike Sullivan

 

[wm blunt]

I would recommend to anyone wanting a shortcut to the BTZS method to contact one of our sponsors, The View Camera Store, and purchase BTZS LITE and a Power Dial. I've never read the BTZS book but use the system or parts of the system and they seem to be working for me. I use the system to make long scale negatives for palladium.

 

[Zathras]

Mike,
You can use a spot meter with the BTZS system instead of incident meter and it works just fine. I use both but when possible I use the incident.

I will be using the incident method myself after I go through the calibration testing. I did a quick and dirty experiment with this system without making any attempt at calibration, and the results I obtained have convinced me that it shows great promise, once I get the all my variables under control for the film and paper that I want to use.

I'm glad that I stuck it out when I was reading the book. It took a while before my feeble little brain figured what the concept is all about. It also helps quite a bit that I managed to get my hands on an ancient Mac that had the Plotter/Matcher program installed. This means no plotting curves by hand. Yeeehawwww!

Mike

 

[fhovie]

I have always done pretty well with the long scales and toning them down. I recently got bit by ignoring the flat scenes. I shot some of some desert dunes recently at mid-day. It was all pretty bright but I failed to consider that the sand was EV15 and I placed it at zone 8 - the lowest EV was 13 and I have this really flat and thin negative. A painful lesson for me because I think I would know better. I will have an opportunity to do it again in the next 2 weeks and will rate my film (TRI-X) at 400 instead of 200 and will go for 19 minutes in PyrocatHD 1:1:100 instead of the 12 minutes I did before. I am believing that will streach my dismal 2 stop range to a modest 4 stop range and make the scene more interesting. It is enough to make you wonder if the developer is getting shelf worn or if I just goofed when I mixed it. Oh well ...

 

[Zathras]

My origional Post:
"I thought this was like a spot metered Shadow EV of 6 subtracted from a Bright EV of 13 giving a SBR of 7 stops. From that 7 we would make a personal discission whether or not to adjust our development time and by how much. "

No argument here. Using a spot meter, you'll get a 7 stop SBR with the readings you mentioned . If you use the BTZS Incident System, which involves multiple incident readings as well as film speed manipulation, than you would determine the SBR as explained by Mr. Blunt.

For a more detailed explanation, see "Beyond The Zone System" by Phil Davis, specfically the the section on the Incident System. If I attempt to explain this, I'll just end up confusing myself

Mike

 

[noseoil]

fhovie, you might want to consider a film with better expansion characteristics than Tri-x. Efke 100 or Efke 25 would both be better choices for a flat scene, as they can be squeezed further than tri-x. Tri-x is great for snappy contrast scenes and light, but I prefer something with more latitude with the flat light you will be working in. Both do well in pyrocat.

 

[fhovie]

Thanks for the thought nosoil, that is something I had not really considered - I used to shoot a lot of FP4 in LF and kind of got away form it because my exposure times often became too long for the scene.(movement) When I shot the dunes the other day, with tri-x at 200, I was still shooting at 1/4 second due to the red filter (-2) and an unwillingness to open further than f32 (for the movements) - I still have a full box of FP4 in the freezer and also some TMAX 100 - which I hear is really contrasty - - I will try both of them out here at home and see how the work for expansion. - With landscapes it seems contraction is always the important skill and so here I am again on the learning curve.

Which is why I stick with photography as a hobby. I don't think one can really learn all of it in one lifetime. - Always something new to do with it.

 

[mikepry]

FP4 is gustier than avererage and TMax is as well. You'll get great results with both.