PDA

View Full Version : Checking Zone VI Modified Meters



neil poulsen
1-Nov-2014, 21:40
Is anyone familiar with a reliable check to determine whether or not a Pentax or Soligor spot meter has actually been converted to a modified Zone VI meter?

I have a Pentax V modified meter that I sent to Calumet for the Zone VI modification. I also have, what I believe to be, a non-modified Pentax digital meter. Making some comparison readings, they were in relatively close agreement. But then, I didn't include any filtration when taking the readings.

I ask, because I have it in mind to sell the digital meter that I have for a modified digital. But given that they sell for a premium, I can imagine that some sellers would list a non-modified meter as modified. Who knows, I may already have a modified digital meter?

Peter De Smidt
1-Nov-2014, 21:46
Richard Ritter would know.

Arne Croell
2-Nov-2014, 01:14
Is anyone familiar with a reliable check to determine whether or not a Pentax or Soligor spot meter has actually been converted to a modified Zone VI meter?

I have a Pentax V modified meter that I sent to Calumet for the Zone VI modification. I also have, what I believe to be, a non-modified Pentax digital meter. Making some comparison readings, they were in relatively close agreement. But then, I didn't include any filtration when taking the readings.

I ask, because I have it in mind to sell the digital meter that I have for a modified digital. But given that they sell for a premium, I can imagine that some sellers would list a non-modified meter as modified. Who knows, I may already have a modified digital meter?

I have both the modified and an unmodified Pentax digital. In my experience, one can "modify" the original Pentax by adding a UV/IR filter (aka "digital filter") like these:

http://www.bhphotovideo.com/c/search?atclk=Circular+Sizes_40.5mm&ci=16886&N=4026728330+4291599900+4294955308
http://www.bhphotovideo.com/c/product/156795-REG/Heliopan_740586_40_5mm_Digital_Glass_Filter.html

+ a good hood on top of it like this one: http://www.bhphotovideo.com/c/product/800634-REG/Heliopan_72540H_40_5_mm_Metal_Lens.html. Those hoods can also be stacked for added shielding, and improve even the flare control of the Zone VI modified version.

Payral
2-Nov-2014, 02:22
Here is a complete modification list according to 1995-96 Zone VI catalog
124428

Payral
2-Nov-2014, 02:27
and a Zone VI modified meter has a special label on it:
124429

Doremus Scudder
2-Nov-2014, 04:02
The Zone VI modified meter will have a label on it indicating that it is a Zone VI product (as pictured above).

FWIW, I own two Zone VI modified meters and two unmodified Pentax digital spot meters. I use them interchangeably and see no appreciable difference. The idea of using a filter pack to adjust the meter's sensitivity to that of the film is a good one, I'm just not sure that it works much better than the OEM in this case.

See Paul Butzi's discussion of this topic here: http://www.butzi.net/articles/zone%20VI%20reprise.htm

Best,

Doremus

Arne Croell
2-Nov-2014, 05:14
The Zone VI modified meter will have a label on it indicating that it is a Zone VI product (as pictured above).

FWIW, I own two Zone VI modified meters and two unmodified Pentax digital spot meters. I use them interchangeably and see no appreciable difference. The idea of using a filter pack to adjust the meter's sensitivity to that of the film is a good one, I'm just not sure that it works much better than the OEM in this case.

See Paul Butzi's discussion of this topic here: http://www.butzi.net/articles/zone%20VI%20reprise.htm

Best,

Doremus
I know Paul's article, but I also have a Zone VI version of the Pentax digital and a regular one, and I did my own comparison as well. He is right about the fact that there is no measurable flare improvement, e.g. when measuring a dark background with a light source in front, slowly moving the meter spot closer to the light and checking when the measurement of the background goes up. A good hood like the ones I mentioned in my earlier post helps with that. However, I did see an improvement with respect to the IR sensitivity of the meter. When measuring green grass in sunlight, the unmodified meter gave a 1/3rd EV higher value, but not when measuring a gray card in sunlight. Likewise, when measuring a sunlit white wall through an orange and a dark red filter, I got 1/3rd and 2/3rd EV higher readings with the unmodified meter, respectively. Using the UV/IR filter mentioned above on the unmodified meter , I got identical readings from both meters (the UV/IR filter had no effect on the readings of the Zone VI modified meter).

Bruce Barlow
2-Nov-2014, 05:26
Fred used to always say that the rendering of foliage was the biggest difference, along with accurate metering through filters. He has a rant somewhere about filter factors.

The links to the filters are, to say the least, very interesting...especially since the modifications are no longer available.

RichardRitter
2-Nov-2014, 06:11
Paul said that if we took all the flare problem out of the meter it would not behave like taking lenses. We did make one with no flare problem and it was not good for photography as most photographers work. If you think you need better flare protection a toilet paper roll tube painted flat black works.

One thing that is not talked about in the newsletter is that we found that all meters have a color problem and that was partly why you could not meter through filters. Part of the mortification was a color correction filter.

As to the main filter in the meter a similar type of filter is used in digital cameras.

One note some photographers think the modification was a waste of money and came up with test to prove Fred wrong. The meter is highly sought after in the movie industry.

Arne Croell
2-Nov-2014, 07:05
Paul said that if we took all the flare problem out of the meter it would not behave like taking lenses. We did make one with no flare problem and it was not good for photography as most photographers work. If you think you need better flare protection a toilet paper roll tube painted flat black works.

Yes, and much cheaper than the cylindrical metal lens hoods. The mechanical stability of toilet paper rolls, when thrown into a backpack/camera case, is questionable, though..... ;-)


As to the main filter in the meter a similar type of filter is used in digital cameras.
Similar, yes, but not the same. I seem to remember that the Zone VI modification involved interference filters, which is also the case with the UV/IR filters I mentioned above. The IR filters in front of the CCD or CMOS sensors in digital cameras ar usually absorption filters made from a glass such as Schott BG39, which not only cuts off IR, but also has a blue-green tint (BG stands for blue-green). Therefore they do reduce the amount of visible light going through.

Eric Woodbury
2-Nov-2014, 11:25
Meter a grey card in neutral light through strong filters such as the 25, 58, and 47 (red, green, blue). You should see differences. Uncorrected meters see red too much and blue not enough. This is the nature of the silicon diode (photo sensor) spectral responsivitiy. If you don't have these filters, meter the sky and deep green foliage and red apples. You'll need strong, deep colors.

Corran
5-Nov-2014, 14:19
Fascinating article (Butzi). I've always felt that if the meter needed a massive modification to operate correctly...why are the Pentax meters even trusted to begin with? Anyway, I bought a Pentax Spotmeter (analog) two or so years ago and been really happy with it, save for the size. Just yesterday I bought a digital one on eBay for about what the analog ones sell for, so I'm fascinated to see if they are even close to measuring the same. This has little to do with the "modified" meters but honestly having used the old warhorse analog model and gotten great exposures (assuming I didn't screw up) I really doubt I'll be looking for a modded one. Anyway, back to the topic at hand...