Macbeth TR924 question
Spam Free
operation seems to work perfect, but the reflection head I don't
understand. I don't have the low and high calibration patches that the
manual says to use to calibrate it. What density value are these? When I
arbitrarily use a Zone 0 patch to calibrate to an arbitrary density of say
0.10, the unit does its job. Then when I likewise arbitrarily calibrate to
a Zone X patch at say 1.90 density, the unit likewise seems to do its job.
The problem is when I try to read most of the in between zones, the unit
continuously autoscans and never settles on a reading? Does it need a new
bulb? Am I missing something? What is the little tiny button on the side
of the reflection head for?
Thanks for any help,
Troy
Gregory Blank
<notan...@spamfree.net> wrote:
Well the calibration values you chose seem pretty close. I am not sure
but each unit in being calibrated has a unique set of values.
Auto scanning is not good, you may have to have it refactory calibrated
and serviced.
I believe Eseco was charging about $300 for this service.....back when I checked
into it.
--
website{ members.bellatlantic.net/~gblank }
Gregory W. Blank Photography
"Aiki is the power of harmony, Of all beings, All things working together."
Cross-posters are idiots whatever system they use. Much more irritating than top-posters.
Jon Noxon
are 5 and 177 as determined by MacBeth, but due to age I would not be
surprised if the values have shifted a tad.
If you can locate another TR924 owner with a reflection standard, you can
"zero" the instrument to the white value (in my case 5) and the black value
(in my case 177) and then measure a couple of Formica samples, which you can
pick up at any Home Depot. As an example, I measured Formica 953-58 (Ice
White) at 9 and 909-58 (Black) at 163.
The down side is the Formica chips may deviate a little from true neutral
when using the Status A filters, but then so does the reflection standard,
but not as much as the Formica. At any rate, gluing a couple of these chips
to a board (about 2.5 inches apart edge to edge) will give you a reasonable
reflection standard on the cheap!
By the way, the little button is used to set the low value (not a true zero
value, as the reference, again in my case, is something like 5. You will
need to adjust the reflection "zero" (5 or whatever) to this value using the
potentiometer on the back of the MacBeth TR924 (while holding the reflection
unit down on the sample. Then set the high density WITHOUT USING THE BUTTON
while holding the unit on your high density sample.
Hope this isn't too confusing.
Good luck,
Jon
"Spam Free" <notan...@spamfree.net> wrote in message
news:3EA96253...@spamfree.net...
Tom Phillips
Jon Noxon wrote:
> I own a MacBeth TR924 and do have the reflection standard. The values on it
> are 5 and 177 as determined by MacBeth, but due to age I would not be
> surprised if the values have shifted a tad.
On my Macbeth Reflection Calibration Reference plate the zero adjust value
(white patch) is 0.05 (not 5) and the calibration value (black calibration
check patch) is 1.76. Perhaps you misplaced a decimal point or the values are
different for different machines? (one 924 vs. another 924.) The part number
for my reference is 29001402.
A recent post here by Craig Schroeder provided the current company for Macbeth
(http://www.gretagmacbeth.com/) and also a URL for the 900 series manual in PDF
form: by http://www.chibardun.net/~craigclu/900series.pdf
I have no idea if GretagMacbeth still supports the 900 series or if parts
(calibration references) are still available. Worth a shot though: 800-622-2384
> If you can locate another TR924 owner with a reflection standard, you can
> "zero" the instrument to the white value (in my case 5) and the black value
> (in my case 177) and then measure a couple of Formica samples, which you can
> pick up at any Home Depot. As an example, I measured Formica 953-58 (Ice
> White) at 9 and 909-58 (Black) at 163.
>
> The down side is the Formica chips may deviate a little from true neutral
> when using the Status A filters, but then so does the reflection standard,
> but not as much as the Formica. At any rate, gluing a couple of these chips
> to a board (about 2.5 inches apart edge to edge) will give you a reasonable
> reflection standard on the cheap!
>
> By the way, the little button is used to set the low value (not a true zero
> value, as the reference, again in my case, is something like 5. You will
> need to adjust the reflection "zero" (5 or whatever) to this value using the
> potentiometer on the back of the MacBeth TR924 (while holding the reflection
> unit down on the sample. Then set the high density WITHOUT USING THE BUTTON
> while holding the unit on your high density sample.
>
> Hope this isn't too confusing
I would just caution him to not set the CAL Zero density to a sample other than
the actual Reflection Reference or it will not provide him with the true value
and will be off. He could choose another sample, I suppose as the formica noted
above, measured and noted *after* zeroing with a correct Reflection Reference
and use that for a new CAL Zero, but once zeroed with the Calibrated Reflection
Reference patch it's rare you need to recalibrate (as long as you don't
mistakingly press the zero button when reading reflection densities...)
Tom Phillips
Tom Phillips wrote:
> I would just caution him to not set the CAL Zero density to a sample other than
> the actual Reflection Reference or it will not provide him with the true value
> and will be off. He could choose another sample, I suppose as the formica noted
> above, measured and noted *after* zeroing with a correct Reflection Reference
> and use that for a new CAL Zero, but once zeroed with the Calibrated Reflection
> Reference patch it's rare you need to recalibrate (as long as you don't
> mistakingly press the zero button when reading reflection densities...)
Sorry. Not quite clear. You do need to zero (white patch) for each use. You just
don't have to check (recalibrate) the calibration value (black patch) very often,
if ever in my experience.
Jon Noxon
You are certainly correct that the value is .05, but usually I just write
down the value without regard to the decimal. The point I was trying to make
is the standard is only standard because the values have somehow been
"calibrated" and are used to transfer these "standard" values to the
machine. I have a Kodak standard as well (enameled metal) and the values on
it are different, and include color patches for checking the stability of
the Status Filters along with the electronics in the whole. The low density
on that one is .08 and the high density is 2.00.
The only thing magic about the MacBeth standard is that it has a low density
and high density patch with "known" values which can be transferred to the
densitometer.
I'm sure new replacement plaques are available, but have no idea of the
cost.
Jon
"Tom Phillips" <nosp...@aol.com> wrote in message
news:3EA9D5A8...@aol.com...
Tom Phillips
Jon Noxon wrote:
> Tom,
>
> You are certainly correct that the value is .05, but usually I just write
> down the value without regard to the decimal. The point I was trying to make
> is the standard is only standard because the values have somehow been
> "calibrated" and are used to transfer these "standard" values to the
> machine.
I assumed they were all calibrated to a known value but never gave much thought
to how or why. I'm not aware of the Kodak patches, however. Depending on where
you live (humidity, etc.) checking the filters would certainly be a plus. Know
(Jon, anyone) if this is available or if Macbeth made one?
Spam Free
got the formica chips. The unit will calibrate reasonably well to either
the low or high values and will read my Zone patches (made on Ilford MG IV
RC glossy) in the vicinity of the calibration values (Zones 0,I,II and Zones
VIII,IX, and X) but it will not settle on a reading for the in-between
zones, or any values between approximately 0.14 and 1.60. Oddly, it wants
to read Zone V as about 4.40 or so, but it otherwise endlessly auto scans
and never settles on a reading for values between about 0.14 and 1.60. So,
it appears to be an internal electronic problem and not a simple problem of
calibration. Fortunately, the transmission mode of the unit works perfect,
no problems.
It does look like the Kodak patches would be good to have, assuming I can
ever get the reflection mode to work. Where can they (it) be obtained?
Thanks again for all the help.
Troy
Craig Schroeder
you don't have the directions.
I've also posted the entire document at:
http://www.chibardun.net/~craigclu/900series.pdf
I wasn't sure if you were winging it or had the book.
Page 3
Reflection Calibration Procedure
This procedure is intended for use with the following instruments:
TR924
Before beginning the calibration procedure, make certain you have the
instrument calibration reference. For Model TR-927 and RD-
917, the calibration reference states on the reverse side that the
Green filter should be used. All others state that the Visual filter
should
be used. Also, note the assigned values for Zero (White) and
Calibration (Black).
Note: Steps 1 through 7 must be performed each time the instrument has
power applied to it.
1. Power ON the instrument using the back panel ON/OFF button. The
light in the Density button illuminates.
2. Make certain that the instrument calibration reference is clean and
dust-free.
3. Place the filter wheel in the Green position (Model TR-927 and
RD-917) or the Visual position (Models TR-927J and TR-
924).
• RD-917
• RD-918
• RD-919
• RD-921
• TR-927
• TR-927J
• TR-924
4. Position the reflection measurement head target aperture over the
white patch on the calibration reference. Hold the
measurement head in the down position.
5. Press and hold the ZERO button. A density value appears on the
display. Continue to hold the measurement head in the down
position.
• If the density value in the display is equal to the assigned value
for the Zero (White) step. Go to step 7.
• If the density value is not equal, continue to hold the ZERO button
and the measurement head in the down position. Go to
step 6.
6. While holding in the ZERO button, adjust the ZERO potentiometer
until the displayed value is equal to the value assigned to
the calibration reference. After these values are equal, release the
ZERO button. Continue to hold the measurement head in the
down position.
7. Rotate the filter wheel to the next filter position and press the
ZERO button. Continue this procedure until all filter positions
have been “zeroed”.
Note: Steps 8-10 need only be performed periodically, but it is best
to perform daily calibration for accuracy.
8. Place the filter wheel in the Green position (Model TR-927 and
RD-917) or the Visual position (all other instruments).
9. Position the reflection measurement head target aperture over the
black patch on the calibration reference. Hold the
measurement head in the down position. DO NOT PRESS THE ZERO BUTTON.
10. While holding the measurement head in the down position, verify
that the value shown in the display is equal to the value for
the calibration reference. If it is not equal, adjust the CAL
potentiometer until the values are equal. Raise the measurement
head. The densitometer is now calibrated.On Fri, 25 Apr 2003 16:28:21
Mike King
point and then my lab manger pointed out that over a thousand controls
strips that would be ten thousand periods--being lazy I dropped writing in
the decimal since a density above 4.00 will never be achieved with normal
contrast materials I can usually figure our where to put the decimal when I
actually plot out the curve.
--
darkroommike
----------
"Tom Phillips" <nosp...@aol.com> wrote in message
news:3EA9D5A8...@aol.com...
>
>
Tom Phillips
Mike King wrote:
> Note that when I started using a densitometer I always put in the decimal
> point and then my lab manger pointed out that over a thousand controls
> strips that would be ten thousand periods--being lazy I dropped writing in
> the decimal since a density above 4.00 will never be achieved with normal
> contrast materials I can usually figure our where to put the decimal when I
> actually plot out the curve.
Does that mean "5" would indicate .5 or .05? Could be either in your short
hand. Technically, then, it should be 05 or 005, or 105, or 115 for readable
short hand minus the decimal. Course I might have mistaken 005 for one of her
majesty's double 0 agent designations.
Mike King
slipping his reply below my post but above every other comment in this
thread--I thought it would be better to add my reply to the bottom of his
query and just chop the rest. Please read down through all the stuff you
have already read a dozen times to see my current pearl of wisdom at the
bottom of this message. (OK, am now extracting my tongue from cheek.)
----------
"Tom Phillips" <nosp...@aol.com> wrote in message
news:3EAB5D2C...@aol.com...
>
>
> Mike King wrote:
>
> > Note that when I started using a densitometer I always put in the
decimal
> > point and then my lab manger pointed out that over a thousand controls
> > strips that would be ten thousand periods--being lazy I dropped writing
in
> > the decimal since a density above 4.00 will never be achieved with
normal
> > contrast materials I can usually figure our where to put the decimal
when I
> > actually plot out the curve.
>
> Does that mean "5" would indicate .5 or .05? Could be either in your short
> hand. Technically, then, it should be 05 or 005, or 105, or 115 for
readable
> short hand minus the decimal. Course I might have mistaken 005 for one of
her
> majesty's double 0 agent designations.
>
Darkroommike replies:
5 is .05 or 0.05 (the most correct way to write it in standard lab notation)
50 is .50 or 0.50
500 is 5.00
You'll find a lot of old hands that do it this way. I'm more likely to
misread 0.05 and 0.50 (and I suspect that dyslexics would have even more
difficulty) when plotting, than 5, 50, 500, and I always use a work sheet
similar to what's in the Kodak Z-manuals when recording readings, so then I
can double check my notoation by where the number is placed on my worksheet,
when I get ready to transfer my readings to a chart.
--
darkroommike
Big snip
Tom Phillips
Mike King wrote:
> Note I have abandoned my usual top post practice here since Tom insisted on
> slipping his reply below my post but above every other comment in this
> thread--I thought it would be better to add my reply to the bottom of his
> query and just chop
<snip...>
> 5 is .05 or 0.05 (the most correct way to write it in standard lab notation)
> 50 is .50 or 0.50
> 500 is 5.00
>
> You'll find a lot of old hands that do it this way.
snip again....
5 is "5" (sort of like a "wash" is a wash, right? Come now, let's be
*consistently* anal...) and 0.05 is .05 or 0.05.
A lot of "old hands" must be lazy as you noted. Meaning when someone else sees
"5" they may only assume you mean 0.05. I guess that's the reason we actually
have and use decimals.
Tell me, what is it that draws you to piss your acid wit on *my* posts?
Mike King
actually use MY notation is on my worksheets, from which I transfer my
values to my final plots I guess I don't really care how YOU want us all to
write down OUR readings. I was just pointing out that a lot of people have
more important things to do than listen to you stink up the place. In
addition, all those extra periods and zeroes just waste time and ink.
--
darkroommike
----------
"Tom Phillips" <nosp...@aol.com> wrote in message
news:3EACC8DE...@aol.com...
Tom Phillips
Mike King wrote:
> I don't think I started the pissing contest, and since the only place I
> actually use MY notation is on my worksheets, from which I transfer my
> values to my final plots I guess I don't really care how YOU want us all to
> write down OUR readings. I was just pointing out
Actually, it was you who felt the need to interject your mildly sarcasm humor
about how to write down readings. No one else had any issue with this. What
escapes your genius (and why I even made mention of it) is that most people
reading this would not automatically know that "5" is otherwise meant to
indicate 0.05. How you or anyone else jots down personal notations is
irrelevant.
> that a lot of people have
> more important things to do than listen to you stink up the place. In
> addition, all those extra periods and zeroes just waste time and ink.
Oh I agree. Lot's of people have more important things to do than create an
issue out of making proper use of a decimal point. Except you, apparently.
Donald
Dmin and Dmax (usually in the .10 and 1.90 region).
The "autoscanning" problem is harder to explain. The reading that you see on
the display is the amount of light that the PMT (photo multiplier tube) is
reading from the reflected light. The first thing to check is that the lamp
does not flicker or change intensity. Do this by closing the aperture jaws
while holding the head upside down and watch the lamp for changes in
intensity. There is a switch that is made when the head is lowered that
"tells the unit to take a reading, if this is not made or is flaky it will
not lock a reading in. What surprises me is that you have no problems while
calibrating or reading the Dmin or Dmax patches, there is no difference
between these and any other reading. You do get repeatable readings on the
Dmin and Dmax patches if you read them multiple times? The possible causes
of miss readings are a bad PMT, a broken wire in the cable or a bad auto
zero board in the unit, also the bad switch that I spoke of earlier.
Make sure that you follow the calibration procedure carefully and that the
bulb is bright and does not change intensity. These units are not supported
by any one any more. There might be someone who still repairs these units,
but I'm not aware of anyone (I was factory trained by MacBeth for the
company I worked for, but have not worked on any in many years). Let me know
if the calibration patches show repeatable readings and I will try to help.
Spam Free
Thanks for the very generous offer of help, Donald. I'm always amazed at
the quality of help that is often offered on the newsgroups. There was
generally no flickering, but I did notice that I need to hold the read head
down more firmly for a good reading.
I think I lucked out on this one. I removed the cover from the unit, lifted
out the microprocessor board, and saw that all the ICs were socket mounted,
so I carefully removed and reinserted each one, knowing that time can
corrode the contacts. Lo and behold, the autoscanning went away! Now the
reflection mode is quite stable (as stable as the transmission mode), no
endless autoscanning, and seems to give accurate readings, though I need to
get some calibrated patches to be absolutely sure.
I am using the Formica ice white and black patches in the meantime to
calibrate at .09 and 1.63. My 18% gray card gives a reading of .74, so I
figure it must be doing pretty good. Calibrated to the Formica chips, my
Ilford MG RC glossy paper gives a Dmin reading of .05 and a Dmax of 1.98,
and these readings do not vary significantly with different readings at
different times (no more than .01 or .02).
Thanks again for your offer of help. I may have need to ask again if
something doens't hold up well.
Troy