BTZS Metering Technique

[mikxer]

I read in an article by Phil Davis that many who follow the techniques proposed by BTZS prefer to use an incident meter, rather than a spot meter. Why? What is the technique used to differentiat highlight and shadow?

[sanking]

With BTZS procedure two incident meter readings are taken, one in the shadows, the other in the highlights. This difference between the two is then added to 5 (which is the number of stops in a flat one-dimensional scene with no shadows) to give what is called the SBR, or subject brightness range. SBR 7 is considered a normal
contrast. SBR 5 is a very flat scene, and SBR 15 would be a very high contrast scene.

Exposure could based on either the shadow readings or on an average of shadow and highlight reading. The SBR value determines development time.


Sandy King





I read in an article by Phil Davis that many who follow the techniques proposed by BTZS prefer to use an incident meter, rather than a spot meter. Why? What is the technique used to differentiat highlight and shadow?

[Bruce Watson]

I read in an article by Phil Davis that many who follow the techniques proposed by BTZS prefer to use an incident meter, rather than a spot meter. Why?

This is the technique that Mr. Davis found that works best for him. It's not necessarily any better, or worse, than any other technique. Like all techniques, some people will swear by it, and some people will swear at it.

I personally find the use of a one degree spot meter to be highly intuitive. It works really well for me, letting me hit my exposures spot on, even when the shadow detail I'm trying to hit is the shadow detail on a rock in the middle of a fast flowing stream.

So I'm not tempted by the BTZS technique. That's just me, it doesn't mean you should or shouldn't be tempted because as we all know, YMMV.

[Michael Jones]

I read in an article by Phil Davis that many who follow the techniques proposed by BTZS prefer to use an incident meter, rather than a spot meter. Why? What is the technique used to differentiat highlight and shadow?

Objects of varying colors reflect light in varying proportions to the light striking it. Phil preferred to meter based upon the light striking the object rather than being concerned with the varying reflectance due to an object's color.

While Sandy's explanation is succinct, a one or two paragraph primer of a hundred plus page concept of metering and development is not going to be completely helpful or accurate. I suggest you review the book at a bookstore to get a feel for how Phil's concepts work.

Good luck.

Mike

[D. Bryant]

I read in an article by Phil Davis that many who follow the techniques proposed by BTZS prefer to use an incident meter, rather than a spot meter. Why? What is the technique used to differentiat highlight and shadow?
You may wish to visit:

http://btzs.org/

For more information.

Don Bryant

[sanking]

Most people who have used both Zone system and BTZS would agree that BTZS has better testing procedures. Better in that compared to Zone testing, BTZS takes less time, uses less film, and gives more precise results.

Also, while I gave a concise answer to the question of the OP, BTZS is not tied to incident metering. The Winplotter program, which Phil Davis developed originally for use on MAC+ computers, produces data for both incident and reflective reading, i.e. it gives both SBR values and N values. Davis discusses in his book the advantages and disadvantages of each type of metering system in his book.

These days, and especially in LF, many (perhaps most) people are exposing and developing to scan and print digitally rather than print directly with silver papers. In that case the precision of both Zone and BTZS is not required as one can simply expose for the shadows with one single incident reading, and develop to a fairly low CI.

Sandy King

[jeroldharter]

I have used spot meters for years and dabbled with various forms of zone system controls. Then I migrated to BTZS with spot metering. I do my own testing and use the WinPlotter and ExpoDev software. Certainly not for everybody but has been great for me.

Lately, I have been trying the incident metering method. I have not done it enough to be a convert yet and need to print more of the negatives to see what I think. But, it is significantly quicker and I think easier. I have a Luna Pro SBC meter for incident readings and the needle system which shows relative difference between readings in stops is much more intuitive and mentally quicker than using absolute EV values from the spot meter. So give it a try and see what you think. I am almost a convert to the incident metering.

[Eric Rose]

I use a hybrid of the two systems. An incident meter to find the SBR and a spot meter to measure and place my exposure. Works for me anyway. I guess I must be one of the few left actually printing on silver. Not because it's better (it's not) but because I enjoy it.

[Brian Ellis]

I read in an article by Phil Davis that many who follow the techniques proposed by BTZS prefer to use an incident meter, rather than a spot meter. Why? What is the technique used to differentiat highlight and shadow?

That was Phil's personal preference. I'm not sure it's the preference of a lot of users. I knew three or four peole who used the BTZS system and none of us used an incident meter. I attended two of Phil's workshops and I'd guess that about 75% of the people there were using reflected light meters. The system will work fine either way so to me it's just a matter of personal preference. Reflected light meters seem more familiar to a lot of people because that's what the meters in 35mm cameras are.

[Brian Ellis]

This is the technique that Mr. Davis found that works best for him. It's not necessarily any better, or worse, than any other technique. Like all techniques, some people will swear by it, and some people will swear at it.

I personally find the use of a one degree spot meter to be highly intuitive. It works really well for me, letting me hit my exposures spot on, even when the shadow detail I'm trying to hit is the shadow detail on a rock in the middle of a fast flowing stream.

So I'm not tempted by the BTZS technique. That's just me, it doesn't mean you should or shouldn't be tempted because as we all know, YMMV.

Bruce - It sounds like you perhaps don't understand the "BTZS technique." It's as usable with a spot meter as with an incident meter. Phil Davis happened to prefer an incident meter but you could use the system with your spot meter equally well if you were so inclined.

[Bruce Watson]

Bruce - It sounds like you perhaps don't understand the "BTZS technique." It's as usable with a spot meter as with an incident meter. Phil Davis happened to prefer an incident meter but you could use the system with your spot meter equally well if you were so inclined.

You miss my point. All these processes all boil down to "expose for the shadows and develop for the highlights." There are many paths to the waterfall as they say. And many tools to use on the way, be they incident meters or spot meters or sunny-16 rules, whatever.

My point is that one should use the tools and processes with which one is comfortable. There is no right way or wrong way.

The OP asked why Mr. Davis uses an incident light meter. My theory is that this is what makes Mr. Davis comfortable. But just because Mr. Davis is comfortable with it doesn't mean that everyone is. Just because he has a better way for himself and others who like his tools and methods doesn't mean they'll be right for everyone. That was the point I was trying to make anyway.

[mikxer]

Thanks to everyone for these replies.

I'm getting the sense that everyone has their own preferred methods and even amongst BTZS users that their technique for metering is unique to them. Which makes sense.

That said, it does seem from reading other threads that not everyone exposes for the shadows. Some prefer Fred Picker's expose for ZVIII or ZVI.

[Bruce Watson]

Thanks to everyone for these replies.

I'm getting the sense that everyone has their own preferred methods and even amongst BTZS users that their technique for metering is unique to them. Which makes sense.

That said, it does seem from reading other threads that not everyone exposes for the shadows. Some prefer Fred Picker's expose for ZVIII or ZVI.

Mr. Picker was a special case. My take after reading vast quantities of his writings (and his excellent Zone VI Workshop book) is that he was only interested in the highlights. He wanted highlights that "sang" for him. So he created a workflow that worked for him, which was expose for the highlights and let the shadows fall where they may. Worked well for him apparently. So who's to say it's wrong?

My own variant, which I don't actually advise anyone else to use, is the exact opposite of Mr. Picker's. I expose for the shadows and let the highlights fall where they may. This works for me because my workflow is fully optimized for drum scanning. I'd hate to try to print these negatives in the darkroom. That wouldn't be at all pretty.

[Andrew O'Neill]

I read the article about 10 years ago, whipped out my incident metre and tried his technique. Didn't work for me. I found it to be inconsistent. I prefer metering the subject to evaluate the light coming off of it...you have to be in the subject when using his method and you can't always be in it. I only use my incident meter as a backup.

[Don Hutton]

I read the article about 10 years ago, whipped out my incident metre and tried his technique. Didn't work for me. I found it to be inconsistent. I prefer metering the subject to evaluate the light coming off of it...you have to be in the subject when using his method and you can't always be in it. I only use my incident meter as a backup.
It works perfectly even if you can't get into the "subject" - but it needs a decent understanding of the system...

[Chuck P.]

[QUOTE=sanking;439227]Better in that compared to Zone testing............ gives more precise results. /QUOTE]

How so? Can you expand on this?

[sanking]

You can assume that if there is full sunlight falling on the subject it will be the same as full sunlight falling on you. For the shadow values you take the reading in your body shadow, or perhaps under a tree. In practice this works very well and gives the same values you would get if you were in the subject.

Sandy King




[QUOTE=sanking;439227]Better in that compared to Zone testing............ gives more precise results. /QUOTE]

How so? Can you expand on this?

[Shen45]

It is always interesting to see the level of shared knowledge from so many that know so little about BTZS.

The system works equally well with incident or spot metering. My preference is for incident.

Although not very active you can get excellent information on the system at

www.btzs.org.

Sandy's description of the metering method should give a starting point to any who are after a good understanding.

Please remember this is not the Zone System --- it is similar but not the same. It is a complete testing, exposure and development system. The system relies on accurate data otherwise -- gigo.