Spot Meter by Zone VI

[ColColt]

I ran across a super nice Pentax Digital Spotmeter with case and manual. What was puzzling was there was a letter shown with it from Zone VI Studios and that they had modified the meter? Apparently the original owner had purchased it from them. Any ideas if this means Zone V won't be Zone V?

 

[Ken Nadvornick]

My long ago understanding is that the meter has been modified with custom filtration, and possibly additional internal flare baffling features, to make it a closer match to the spectral response characteristics of black-and-white film. How effective those filtration changes are for today's films I do not know.

There are occasionally active members here on APUG who once worked at Zone VI Studios and are far more knowledgeable regarding the details than I am. Perhaps they will see your thread and respond?

Ken

 

[Bill Burk]

Hi ColColt,

Don't let the name Zone VI Modified make you think it can't read Zone V. The meter takes readings as Zone V.

Zone VI Studios is the name of the business that Fred Picker ran in Newfane Vermont after he moved from White Plains New York.

Fred Picker wrote quarterly newsletters that are as much fun to read today as many threads here on APUG. It's like reading the Farmer's Almanac of Photography.

When you see "Zone VI" meters there's a couple possibilities. There were some stickers that showed the brand name Zone VI and showed gray Zones that people could stick on their own meters. That was cheap and didn't make the meter any better.

Then there were the "Zone VI Modified" Soligor and Pentax, analog and digital spotmeters. Ken Nadvornick remembers them right. They had baffles to reduce flare, an infrared cutoff filter, a small degree of color correction filtration, but not a UV cutoff filter. You are expected to use UV filter on the camera.

The modifications were designed to match the spectral response of Kodak Tri-X film. And the idea is that if you choose a variety of different color subjects, spot meter the subject and expose for Zone V as the meter recommends, the results would be prints with the subject on Zone V. This was claimed to be superior to an unmodified meter. Fred Picker claimed if you performed a similar test using an unmodified meter, exposure errors would be the norm. He showed a graph of the exposure errors of an unmodified meter versus the exposure consistency of the Zone VI Modified meter.

There is a fairly well known analysis that disputes how effective the meter modifications were, and how necessary it was to modify a meter.

http://www.butzi.net/articles/zone%20VI%20reprise.htm

My only complaint against that write-up is that (aside from Fred not being here to defend himself) the author of the article used a Macbeth Color Checker. A significant issue the meter was intended to resolve is excess infrared from foliage throwing off the meter reading. I don't think it was fair to use a green patch of ink in place of a real green leaf.

Since the meter you ran across had the printout, it is likely the real McCoy. I would think the analog Pentax Spotmeter version would be the most fun to own of the bunch. By the time Pentax went to digital, it might fairly be argued that the sensor changed to one that was less sensitive to infrared.

 

[Ken Nadvornick]

Bill, do you have knowledge or recall regarding if the meter modification was another effort by Dr. Horowitz?

I seem to also remember (maybe from the newsletters? I have the complete set) Mr. Picker stating that the full system was supposed to be the modified (spectrally matched) meter for exposing the negative, the modified (compensating by temperature) processing timer for developing the negative, and the modified (compensating by light intensity) exposure timer for printing the negative. The three were supposed to be a complementary set.

I still have the latter two and continue using them to this day. They still work perfectly, although I did have to do a sensor rework to get the exposure timer to work correctly with my Aristo VCL4500 head.

But I never did acquire the meter.

Ken

 

[juan]

Richard Ritter sometimes posts here. I believe he did the meter modifications.

 

[RalphLambrecht]

My long ago understanding is that the meter has been modified with custom filtration, and possibly additional internal flare baffling features, to make it a closer match to the spectral response characteristics of black-and-white film. How effective those filtration changes are for today's films I do not know.

There are occasionally active members here on APUG who once worked at Zone VI Studios and are far more knowledgeable regarding the details than I am. Perhaps they will see your thread and respond?

Ken

Thst's my understanding too. I had both,unmodified and modified and preferred the unmodified,which gave me better results when using filters.

 

[Bill Burk]

...Then there were the "Zone VI Modified" Soligor and Pentax, analog and digital spotmeters. Ken Nadvornick remembers them right. They had baffles to reduce flare, an infrared cutoff filter, a small degree of color correction filtration, but not a UV cutoff filter. You are expected to use UV filter on the camera..

I pulled out Zone VI Newsletter Number 37, November, 1983 Paul Horowitz provided the theory and design and worked out the modification procedure with Richard Ritter.

I was a bit wrong about UV. There is a UV filter in the meter. I was right that you are expected to use UV filter on the camera. A few paragraphs dedicated to the topic Ultraviolet is Also a Problem explain why. Basically film is sensitive to UV and meters aren't so the solution is to block UV from both.

 

[bdial]

Richard calibrated my (non-modified) Pentax digital. When he gave it back to me he told me that using a B+W UV-IR cutoff filter on it would be roughly equivalent to the Zone VI internal filtration mod.
The filter is B+W MRC 486
http://www.bhphotovideo.com/c/product/718409-REG/B_W_66_036722_66_036722_40_5mm_UV_IR_Cut.html

 

[ColColt]

Very knowledgeable folks responding to this question-thanks a bunch. My only question is now that Tri-X and most other film today, isn't what it was back in the day of Zone VI mods and cold light enlargers I'm wondering if I should bypass this modified meter.

 

[Alan9940]

I use a Zone VI modified Pentax Digital spot meter with a fairly wide range of modern films and I've never experienced any exposure problems or errors; except the ones the idiot behind the meter makes!

 

[Richard T Ritter]

When the testing was done back in the 80's most films both color and black and white had a cut off that average out to be around 645nm. That was the cut off for Tri X Fred's film of choice. Most films made to day still behave the same way. One thing that was never talked about by Fred but Paul and myself decided was a good idea and told Fred it was to make the meter better for metering through filter, was to color corrected the meter. All the meter we tested back in the 80's had problems with color and should have been color corrected. At most it as around a 1/3 to a 1/2 stop differences depending on the color of the light and the color being metered. To day that is not a big issue most who work with color use digital cameras and the meters we tested are no longer made.

The Pentax digital meter is used by a lot of lighting people in Hollywood in setting light ratios.

 

[ColColt]

My biggest use would be with B&W film and little to no color. Perhaps the modified version wouldn't be an issue.

 

[Bill Burk]

When the testing was done back in the 80's most films both color and black and white had a cut off that average out to be around 645nm. That was the cut off for Tri X Fred's film of choice. Most films made to day still behave the same way. One thing that was never talked about by Fred but Paul and myself decided was a good idea and told Fred it was to make the meter better for metering through filter, was to color correct the meter.

Thanks for filling in the background with your first-hand story!

 

[RalphLambrecht]

I bought my modified meter from Calumet in the 1990s.It was so much off the advertising claim that Calumet agreed to take it back and I bought the unmodified meter,which I'm still using today.

 

[Richard T Ritter]

I bought my modified meter from Calumet in the 1990s.It was so much off the advertising claim that Calumet agreed to take it back and I bought the unmodified meter,which I'm still using today.

Yep They not Fred decided that the standard that the meters were being calibrated to was wrong and change to a different settings. I am still getting meters that were calibrated to the wrong standard. Also the people working for Calumet did not care and were not photographers.

 

[Ken Nadvornick]

Yep They not Fred decided that the standard that the meters were being calibrated to was wrong and change to a different settings. I am still getting meters that were calibrated to the wrong standard. Also the people working for Calumet did not care and were not photographers.

Over the years I've noticed a seeming bipolar distribution of opinions regarding the meter modifications. People seemed to either love them or hate them, with little middle ground. For a long while I assumed it was just a case of broad sample variation, perhaps due to quality control issues. That distribution of opinions was one reason I never seriously considered a purchase.

What you say here could explain a lot. It could also make the provenance of used modified meters offered for sale a relevant purchasing criterion.

Ken

 

[ColColt]

Are there different types of cells in the modified versions? Maybe I missed that somewhere. With the age of the standard Spotmeter V and the Digital meter I have to wonder if they ever need repair or calibration who would do it. Then I recalled the great job George did at Quality Light Meter on my Luna Pro SBC and worries were put asunder.

 

[Alan9940]

AFAIK the actual meter cells were not changed and/or modified. I believe Richard works on these meters, too.

 

[Richard T Ritter]

ON the modified meters the cell were change to a photo cell that had better and known response to visible light. The early Pentax meters the cell were the best that were around at the time not very good in some areas of visible light. Same goes for the Soligar.

Before Fred past away he was working on a new meter it had a different type of cell in it that had very good visible light response. When the cell came available we tried to fit it into the Pentax. It was too big and the area in the Pentax too small. did not work. Calumet would not let us work on the new meter so Fred took it on himself I did work with and ran some of the test with the prototype meter. Shame is one knows what happen to the meter or the drawings.

I still repair the meters I can not modify then some of the parts are no longer available.

 

[ColColt]

The modified cells, were they of the SBC variety as in the Luna Pro SBC rather than Cds cells?