Zone VI modifications worth it?

**Paul Butzi** · 2-Sep-2004, 17:15

A little while back, Kirk Gittings posted a note retracting his
assertion that there's no real value to the Zone VI modifications to
the Pentax Digital Spotmeter.

I don't recall what exactly Kirk said in his retraction post, but
something in it didn't jibe with what I'd experienced and since I
actually own both a Zone VI modified meter and an unmodified one, I
set out and did a little testing to compare the two. I posted a
little note on my conclusions on Kirk's thread a few weeks back,
then had to take time off for other things.

I'm still interested in why some people seem to experience a
difference between the modified meter and the unmodified one. I
don't see much difference, although I did find that the unmodified
meter had better flare characteristics the the modified one.

I did metering in direct sunlight, shade, overcast, tungsten
light. I metered all the different colored patches of a Macbeth
color checker. I metered through filters as well as without filters.

My data as well as a description of how I got them, along with
some tentative conclusions, are on my web site at
 http://www.butzi.net/articles/zone%20VI%20worth%20it.htm

I'd be very interested in having folks take a look and make
suggestions on ways to improve the experiment or make comments on
the results.

**windpointphoto** · 2-Sep-2004, 17:40

If I remember correctly, Fred Picker said in his catalog, that you should meter and photograph different subjects with and with out filters. If you meter and expose all photos at zone five, proper proof and if all proofs were not zone five you needed a modified meter. I did the test and all were at zone five with my unmodified meter. I never have had any problems. A friend had an unmodified meter and his test came out at different tones. He had no end of problems until he got the meter modified. Test and then you'll know. Then go make pictures and just keep an eye on your proofs. If they're turning out as you think they should, no problem.

**j.e.simmons** · 3-Sep-2004, 08:23

IIRC, Fred's meter quest began when he noticed foliage was not reproducing at the Zone he anticipated. He learned it reflects far more infrared than he had anticipated and more than the meter had indicated. He said the film, however was sensitive to this "extra" infrared. He said that his modified meter matched the response of the film.

If all of the above is correct, I would think the subject matter photographed would account for the differences in reports. Some scenes may reflect light that's read correctly by an unmodified meter - others may not.

I owned a modified meter at one time (stolen) and now own an unmodified one. I never noticed any particular difference with the modified meter and don't see any real difference in those old negatives. But, I may not have been a sufficiently sophisticated photographer then. Or, maybe not as picky as Fred. john

**Paul Butzi** · 3-Sep-2004, 10:13

Several people have suggested that the Zone VI modifications change the IR response of the meter.

I've added an informal test of the IR response of both the modified and unmodified meters, details are on the web page cited before. It's not exhaustive but my tentative conclusion is that if there's a difference between the IR response of the modified and unmodified meters, the difference is small.

**Kirk Gittings** · 3-Sep-2004, 14:22

Paul, An impressive effort to say the least. It does confirm my experience with Sekonics which in my experience always read to high on the spot setting and lead to underexposure.

Since both of my meters are now modified, I can no longer compare different results. All I can say is that the ability to meter thru the filters and maintain a consistent Zone III placement for the shadows regardless of the subject is a reality with my modified meters. Before modification I would also have to apply a "factor" as developed by Gordon Hutchins to maintain shadow proper shadow detail. There was a distinct difference when I tested my meters before the second one was modified. I had a hard time believing it myself. There is now a 1/3 stop difference between my old and new modified meter that is consistent thru the entire range, but aside from that they agree with each other under all circumstances.

Is there any possibility that your meter, despite the label, was shipped without ever actually being modified?

This week I was in southern AZ on a commercial shoot and took some time to do some personal b&w work with filters metered as descibed above. I will check the results once again, but I am not expecting a problem.

**Paul Butzi** · 3-Sep-2004, 16:46

Kirk, I suppose it's possible that my Zone VI modified meter, which I bought directly from Zone VI, was modified only to the extent that the stickers were put on the outside. Your suggestion that my meter was shipped without being modified certainly raises the question that, perhaps, large numbers of meters were shipped with the only modification being the stickers applied to the outside. Since the modified meter sells at a $140 premium over the unmodified one, I can see a substantial motivation for that, although I don't believe for a second that's what has happened.

Another possiblity is that when the modifications were originally designed, the sensor in the Pentax was not the same as what was shipped in more modern meters, and that now the modifications are being done but are having essentially no effect.

I'd be very interested in what Richard Ritter has to say about it. I admit I am stumped, I expected to see substantial differences between the meters.

If anyone else has access to both modified and unmodified meters, it would be darn interesting to see them compared head to head in this way.

**RichardRitter** · 4-Sep-2004, 09:01

Since I do not work for Calumet and receive no money to do marketing for their meter. I am going to stay out of this debate. I would like to point out the meter has been around for 20 years and over 10,000 have been modified. If there was a problem with then we would of known about it years ago. You also need to know that the meter was sent to AA for testing and most of his assessments have the meter. All we got from then was praises. Paul you did prove one thing in your test that no two meters agree. Which one is right?

Kirk as to the 1/3 reading difference as you said they read the same over the whole range, set the ASA so the readings agree and mark the meter that is off. Through the years there has been a lot of nay sayer about the meter, once they worked with the meter they have changed their minds about the meter. Also ask your self how many meters can you meter through filters and get consistent results?

**Paul Butzi** · 4-Sep-2004, 12:40

> Since I do not work for Calumet and
receive no money to do marketing for their meter.

> I am going to stay out of this
debate. I would like to point out the meter has been around

> for 20 years and over 10,000 have
been modified. If there was a problem with then we

> would of known about it years ago.

 

It's interesting to hear that 10,000
meters have been modified.  That's a lot of meters!  But if the
assertion is that 10,000 meters sold somehow proves the superiority of the
modified meter, I'd have to disagree.  In the vast majority of the cases,
the people buying the meter will never have the chance to compare multiple
meters head-to-head as I have done.  While I'd claim that my tests suggest
that the modifications in fact make no difference, I'd also claim that they
quite clearly show that the modifications do no harm - and as long as people get
decent results from the modified meter, they will be satisfied.  They may
well have been satisfied with the unmodified meter as well.  Who knows?

 

After all, I bought my modified meter
in 1994, and I've been happily using it for ten years now.  I bought an
unmodified meter this past summer when I had a great deal come my way, just so
I'd have a backup meter.  A little informal testing suggested that there
was little or no difference between the modified and unmodified meter. 
That prompted me to do more formal testing, which is what is on the web page. 
That testing also seems to indicate that there is essentially no difference
between the results with the modified and unmodified meter, in four different
kinds of illumination, metering targets of 24 different colors, and metering
both without filters and through 3 different filters.

> You also need to know that the meter was sent to AA for testing and most of
his assessments have the meter. All we got from then was praises.

That is interesting.  How many of them tested the meter head to head
against an unmodified meter?  And can you point me to a place where I can
read their results and a description of their testing process?  I'd be
happy to discover that my testing is wrong in some way - the result would be
that I'd just send my unmodified meter to you to be modified.

> Paul you did prove one thing in your test that no two meters agree.

I disagree.  I would interpret the results as saying that the unmodified
Pentax Digital Spot and the Zone VI modified Pentax Digital Spot agree.  I
metered the 24 patches of the Macbeth color checker with the two meters in six
different sources of illumination.  That's a total of 144 different
metering situations.  In 65 of those situations, the two meters produced
exactly the same reading.  In 142 of those 144 situations, the readings
from the two meters differed by 1/3rd stop or less.  In two of those 144
situations, the meter readings differed by 2/3rd of a stop.

> Which one is right?

Well, I don't know.  I don't attempt to determine which of the three
meters I tested is 'right'.  I'm just trying to figure out if the meters
are different. 

If the meters are all the same, we can make our meter purchase decisions
based on issues other than accuracy. Only if the meters produce different
results can one meter be 'right' and the other 'wrong'.  That's exactly my
problem - the modified and unmodified meters agree within 1/3rd of a stop 99% of
the time and within 2/3rd of a stop 100% of the time - a performance that, given
what I think is likely to be my experimental error, I would interpret as reading
the same in essentially all of the controlled tests I performed.

> Through the years there has been a lot of nay sayer about the meter, once
they worked with the meter they have changed their minds about the meter.

That's interesting, I agree.  Kirk, in fact, is one of the converted
former naysayers. Kirk is well known, appears to be a careful worker, and the
fact that his experience doesn't match my testing makes me wonder if my tests
are wrong for some subtle reason.  But I am still left with an extensive,
controlled test that failed to find any significant difference in results
between the modified and unmodified meter, and no one so far has suggested what
I might be doing wrong.

> Also ask your self how many meters can you meter through filters and get
consistent results?

Well, assuming that the Zone VI modified meter allows me to meter through
filters and get consistent results, this test seems to show that I can do the
same thing with the unmodified meter.  So, my answer would have to be
"Two."  Most interestingly, one of the two is $140 cheaper, and appears to
be identical in every respect except it does not have the handy zone label on
the barrel and doesn't have the 'modified by Zone VI studios' sticker on the
side.

**Struan Gray** · 4-Sep-2004, 15:08

Paul, the only thing that occurs to me is that your tests haven't really gone into the IR thing deeply enough. A Macbeth chart will reflect IR differently from, say, leaves or the standard impossible-to-photograph blue flowers. Also, remotes may simply operate so far from the visible that the Zone VI filter doesn't actually filter anything - it may just concentrate on the sort of near-IR that mucks up flower colours and makes deep reds look odd.

Do you have access to a standard bluebell?

**Paul Butzi** · 4-Sep-2004, 16:06

Struan, I agree that the IR thing needs to explored more completely, as well as sensitivity to UV (which is, I believe, what makes blue flowers so darn hard - the UV messes up the color rendition).

Browsing the catalogs of IR emitters/receivers for remote control use, the most common center wavelength seems to be about 880nm - way, way up above the IR sensitivity of most films. Tri-X, for instance, cuts off quite sharply at 650nm, Tmax-100 at about 680nm). The substantial sensitivity of ALL the meters to the IR coming out of IR remote controls is fairly suprising. Browsing the web, most of the dichroic IR cutoff filters I've found seem to cut off dramatically at about 700nm. I would expect that if such a filter were installed in either meter it would pretty effectively block the IR from the remote.

If the Macbeth Color Checker was completely non-reflective in the IR range, that would certainly call the results into question. I expect, though, that in IR light, it's not uniformly black. An easy way to find out would be for someone who has an IR sensitive camera to photograph a color checker through an visible opaque, IR transparent filter like a Wratten 89b) and see if there is any variation in the reflectivity of the patches.

I would think, though, the patches vary in IR reflectance and that the IR component of the light striking the target in the varied situations I set up (direct sun, open shade, overcast, tungsten) would vary enough that if it were IR senstivity that was the real difference, I would have detected it.

Over the past few days I've wandered about with the two meters and a few filters in direct sun, open shade, and overcast, metering various bits of foliage (both deciduous and conifer), and so far I haven't been able to make the meters read differently. It's difficult to write those results up in an objective way, because there's no reproducible standard involved, as you point out with your pointed comment about the standard blue bell.

I am not yet completely convinced but I have to say that if the difference between the modified and unmodified meters were as dramatic as all the marketing claims would make it appear, it should not be this difficult to construct a situation where the meters produce different readings.

I am just shy of opening the two meters up to see if there's really any internal difference between them.

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