denisometers

[mark-461]

Well I am interested in doing a bit more experimentation, and reality
its probably a step I should have taken years ago.  I have always been
an it looks right kind of guy instead of a numbers kind of guy and just
really felt a need to put numbers to my black an white work.  Yes its
slowed the learning curve down at times.  Yet after a while a look at a
negative seemed to be just fine.

I am now curious about how my calibrated eyeball compares with the
numbers.  I wonder what a lower cost, decent denisometer would run and
what brands, makes, models ect I should look for an which ones I should
avoid.  As always help is greatly appreciated.

Mark

[karl shah-jenner]

Mark:

: Well I am interested in doing a bit more experimentation, and reality
: its probably a step I should have taken years ago.  I have always been
: an it looks right kind of guy instead of a numbers kind of guy and just
: really felt a need to put numbers to my black an white work.  Yes its
: slowed the learning curve down at times.  Yet after a while a look at a
: negative seemed to be just fine.
:
: I am now curious about how my calibrated eyeball compares with the
: numbers.  I wonder what a lower cost, decent denisometer would run and
: what brands, makes, models ect I should look for an which ones I should
: avoid.  As always help is greatly appreciated.


Just looked around and found this:

http://perso.wanadoo.es/terenciano/densitometro/densitometro.html
if you hve any electronice skills (or a friend who does ;) this would work
as well as any commercial densitometer

Personally I would use a voltage regulated power supply rather than the
simple one they use (none) and I'd also use a white light LED .. infinitely
better than an incandescent globe s the luminence does not vary anywhere
near as much as a heated filament globe :)

that way you could also use the LED in a swinging arm which trips the light
using a microswitch - much as a 'real' densitometer does

[ADavidhazy-2]

I seem to recall that in the book 101 Experiments in Photography by Todd
and Zakia they suggested using a light meter as the basis for building a
densitometer. I also seem to recall I made one of these at one time. In
fact, I have a picture of it somewhere but no details.

On the commercial side X-Rite used to sell small battery powered (or AC)
portable units but unfortunately I don't know where you can get these.

All in all this posting does not seem to be of much help. :(

Andy

[Don Roberts-2]

There are a number of densitometers, including X-Rites on eBay right now.  Many around $50 or so.  You should be able to find something there.
Don

ADavidhazy wrote:

I seem to recall that in the book 101 Experiments in Photography by Todd and Zakia they suggested using a light meter as the basis for building a densitometer. I also seem to recall I made one of these at one time. In fact, I have a picture of it somewhere but no details.

On the commercial side X-Rite used to sell small battery powered (or AC) portable units but unfortunately I don't know where you can get these.

All in all this posting does not seem to be of much help. :(

Andy

[mark-461]

I don't do ebay anymore and haven't for a long time, but knowing a brand name is a big help.  There is a local used photo place nearby I can check if I know of a something to look for.

Building one does sound interesting.  Frankly I usually end up learning something in the building process that I would have never learned had I just bought it.  That alone is usually worth something. 

First thing I noticed with the plans is a 220V for a light bulb.  My first reaction and I hope that this is just because this might have been a circuit with a European current in mind instead of the US 110V to run a 40 watt bulb. I can't see where 110 would be a problem to run a light bulb, but maybe I could be missing something.

Radio Shack should have most of the switches ect, but anyone have an idea for a source for the photo cell??

I'll have to look for 101 experiments in photography.  I think I have an old ambient light meter laying around.

-------- Original Message --------
Subject: Re: densitometers
From: Don Roberts <droberts@...>
Date: Sun, October 11, 2009 10:27 am
To: List for Photo/Imaging Educators - Professionals - Students
<photoforum@...>

There are a number of densitometers, including X-Rites on eBay right now.  Many around $50 or so.  You should be able to find something there.
Don

ADavidhazy wrote:

I seem to recall that in the book 101 Experiments in Photography by Todd and Zakia they suggested using a light meter as the basis for building a densitometer. I also seem to recall I made one of these at one time. In fact, I have a picture of it somewhere but no details.

On the commercial side X-Rite used to sell small battery powered (or AC) portable units but unfortunately I don't know where you can get these.

All in all this posting does not seem to be of much help. :(

Andy

[PhotoRoy6]

In the US to get 220 volts you just run two hot lines to the electrical outlet. Some clothes dryers and other machinery use to run on 220 volts in the US.

Roy 

 

 

 

In a message dated 10/11/2009 8:47:30 P.M. Eastern Daylight Time, mark@... writes:

My first reaction and I hope that this is just because this might have been a circuit with a European current in mind

 

[ADavidhazy-2]

I'd say in the build it yourself scheme ... avoid 110 or 220 like the
plague - you can get an unpleasant shock! . Use high intensity LEDs if
at all possible. These can be run from batteries. I don't know about
their output vs. drop in voltage but they consume little power and
should provide a fairly steady output. You can get them at Radio Shack.
You can also get a CdS photocell there.

BTW, the calibrated Stouffer wedge may be expensive. I have not checked
price myself though.

cheers,
andy


PhotoRoy6@... wrote:
>  
> In the US to get 220 volts you just run two hot lines to the electrical  
> outlet. Some clothes dryers and other machinery use to run on 220 volts in the
>  US.
> Roy

[mark-461]

Yea there is a dryer hook up, but it would be VERY limiting and I am guess probably not necessary

-------- Original Message --------
Subject: Re: densitometers
From: PhotoRoy6@...
Date: Sun, October 11, 2009 8:07 pm
To: List for Photo/Imaging Educators - Professionals - Students
<photoforum@...>

In the US to get 220 volts you just run two hot lines to the electrical outlet. Some clothes dryers and other machinery use to run on 220 volts in the US.

Roy 

 

 

 

In a message dated 10/11/2009 8:47:30 P.M. Eastern Daylight Time, mark@... writes:

My first reaction and I hope that this is just because this might have been a circuit with a European current in mind

 

[Roger Eichhorn]

If you do this, you'd better know what you're doing!  There's no  
ground to the circuit, unless you have the third (neutral) wire.

Roger

On 11 Oct 2009, at 6:07 PM, PhotoRoy6@... wrote:

> In the US to get 220 volts you just run two hot lines to the  
> electrical outlet.

[Roger Eichhorn]

How do you calibrate it once you have it built?

A few years ago I ran into an EE friend who was returning to the  
college from a purchasing expedition.  He said that he was picking up  
a "constant voltage source" -- alkaline batteries.  It used to require  
mercury cells, probably no longer available.

Roger

On 11 Oct 2009, at 6:18 PM, ADavidhazy wrote:

> I'd say in the build it yourself scheme ... avoid 110 or 220 like  
> the plague - you can get an unpleasant shock! . Use high intensity  
> LEDs if at all possible. These can be run from batteries. I don't  
> know about their output vs. drop in voltage but they consume little  
> power and should provide a fairly steady output. You can get them at  
> Radio Shack. You can also get a CdS photocell there.
>
> BTW, the calibrated Stouffer wedge may be expensive. I have not  
> checked price myself though.
>
> cheers,
> andy
>
>
> PhotoRoy6@... wrote:
>> In the US to get 220 volts you just run two hot lines to the  
>> electrical  outlet. Some clothes dryers and other machinery use to  
>> run on 220 volts in the  US.
>> Roy
>

[ADavidhazy-2]

It is calibrated against a calibrated step wedge sold by Stauffer (sp?)

andy

Roger Eichhorn wrote:

> How do you calibrate it once you have it built?
>
> A few years ago I ran into an EE friend who was returning to the  
> college from a purchasing expedition.  He said that he was picking up  a
> "constant voltage source" -- alkaline batteries.  It used to require  
> mercury cells, probably no longer available.
>
> Roger

[Roger Eichhorn]

if i recall correctly, PhotoShop allows one to set up and measure the  
density of a step wedge that can then be printed out on transparency  
film.  Will that do to calibrate?  Or, why can't one just scan the b&w  
negative and use the photoshop densitometer to make the measurements  
and avoid building or buying anything else at all?

Roger

On 11 Oct 2009, at 7:06 PM, ADavidhazy wrote:

> It is calibrated against a calibrated step wedge sold by Stauffer  
> (sp?)
>
> andy
>
> Roger Eichhorn wrote:
>
>> How do you calibrate it once you have it built?
>> A few years ago I ran into an EE friend who was returning to the  
>> college from a purchasing expedition.  He said that he was picking  
>> up  a "constant voltage source" -- alkaline batteries.  It used to  
>> require  mercury cells, probably no longer available.
>> Roger
>

[ADavidhazy-2]

Roger, I am no color measurement expert but my gut feeling is that you
are not only correct but that others have already done this. ImageJ is
another program that does this. I am not sure that Photoshop or ImageJ
for that matter read out in density "units" ... like log values. I am
used to reading density as logs. In CMYK is the K value not a "variant"
of density? I've used the K value - guess in my case it was %
transmission (?) as an indicator of "tonal value" since I did not need
actual density values but simply matching "darkness" levels. Anyway, I
better stop 'cause I am feeling like a fish out of water!!  ;)

andy


Roger Eichhorn wrote:

> if i recall correctly, PhotoShop allows one to set up and measure the  
> density of a step wedge that can then be printed out on transparency  
> film.  Will that do to calibrate?  Or, why can't one just scan the b&w  
> negative and use the photoshop densitometer to make the measurements  
> and avoid building or buying anything else at all?
>
> Roger

[mark-461]

Well that is an option only I just hate to take the time scanning.  I am still running CS2 so I will have to check and see if it has that feature in it.  Its one I didn't know about

-------- Original Message --------
Subject: Re: densitometers
From: Roger Eichhorn <eichhorn@...>
Date: Sun, October 11, 2009 9:20 pm
To: List for Photo/Imaging Educators - Professionals - Students
<photoforum@...>

if i recall correctly, PhotoShop allows one to set up and measure the
density of a step wedge that can then be printed out on transparency
film. Will that do to calibrate? Or, why can't one just scan the b&w
negative and use the photoshop densitometer to make the measurements
and avoid building or buying anything else at all?

Roger

On 11 Oct 2009, at 7:06 PM, ADavidhazy wrote:

> It is calibrated against a calibrated step wedge sold by Stauffer
> (sp?)
>
> andy
>
> Roger Eichhorn wrote:
>
>> How do you calibrate it once you have it built?
>> A few years ago I ran into an EE friend who was returning to the
>> college from a purchasing expedition. He said that he was picking
>> up a "constant voltage source" -- alkaline batteries. It used to
>> require mercury cells, probably no longer available.
>> Roger
>

[karl shah-jenner]

Andy:

: I'd say in the build it yourself scheme ... avoid 110 or 220 like the
: plague - you can get an unpleasant shock! . Use high intensity LEDs if
: at all possible. These can be run from batteries. I don't know about
: their output vs. drop in voltage but they consume little power and
: should provide a fairly steady output. You can get them at Radio Shack.
: You can also get a CdS photocell there.

agree with Andy 100%, mains powered is unnecessary (so maybe my link was a
bad choice!)

You could cobble this together cheaply, easily and with greater safety
using 1 9V battery .

A voltage regulator circuit stabilizes the voltage so the power consumption
is fixed and then the light output will remain to all intents and
purposes - constant.

let's see..  (heads to US radioshack website)  whoah!  hmm.. Radio shack
prices are as ridiculous there as they are in Australia I see, but pushing
on..

bits needed:
http://www.radioshack.com/product/index.jsp?productId=2062599
1x 7805 voltage regulator IC

http://www.radioshack.com/product/index.jsp?productId=3060980
1x 5mm white LED 25mA 3.3V

http://www.radioshack.com/product/index.jsp?productId=2062590
1x CDs photoresistor  (not used in this part of the circuit)

http://www.radioshack.com/product/index.jsp?productId=2062314
1x 68 ohm (dropping) resistor

http://www.radioshack.com/product/index.jsp?productId=2102510
1x 100µF 35V Electrolytic Capacitor

http://www.radioshack.com/product/index.jsp?productId=2062365
0.1µF Ceramic Disc Capacitor


this is your light source circuit, nice and safe and very stable :)

       switch           ___      68 ohm r
        \              |   |
+9VDC--  \-------------| A |------/\/\--
           |           |___|    |      |
           |             |      |     _|_
           |             |      |     \ / LED
          _|_            |     _|_   __V__
 100uF    ---            |     ---     |
           |             | 0.1uF|      |
           |             |      |      |
___________|_____________|______|______|

A= 7805 voltage regulator



hope this helps




: BTW, the calibrated Stouffer wedge may be expensive. I have not checked
: price myself though.

you could always ask around any of the local graphic degign places and see
if they have one lying about - also remember that densitometers need to be
calibrated each time they're used, though you'll find an LED model to be a
lot more stable than an incandescent light source model




karl

[Roger Eichhorn]

Something happened in the transmission, or receipt!

Roger

On 11 Oct 2009, at 7:39 PM, karl shah-jenner wrote:

> this is your light source circuit, nice and safe and very stable :)
>
>       switch           ___      68 ohm r
>        \              |   |
> +9VDC--  \-------------| A |------/\/\--
>           |           |___|    |      |
>           |             |      |     _|_
>           |             |      |     \ / LED
>          _|_            |     _|_   __V__
> 100uF    ---            |     ---     |
>           |             | 0.1uF|      |
>           |             |      |      |
> ___________|_____________|______|______|
>
> A= 7805 voltage regulator
>

[karl shah-jenner]

Roger Eichhorn
: Something happened in the transmission, or receipt!


hmm, doesn't look *quite* right, though the original came through fine for
me

still better than some i've sent in the past that just muddled up
comletely!


if I look at the message source (control+f3 on a windows machine) I see the
posted message looks OK - it can be copied and pasted out of that into a
text editor for a clearer view

k

[lookaround360]

Look here and you may find instructions for making a good densitometer
from a light meter.

http://www.markerink.org/WJM/HTML/mainpage.htm

 Google "Zone System". The late Phill Davis, U of Michigan prof., and
author of several Zone System texts had a good design for an old
Honeywell spot meter.

AZ


LOOKAROUND - Since 1978
Build a 120/35mm Lookaround!
The Lookaround E-Book 5ed.
http://www.panoramacamera.us

> -------- Original Message --------
> Subject: [SPAM] Re: densitometers
> From: karl shah-jenner <shahjen@...>
> Date: Sun, October 11, 2009 11:15 pm
> To: List for Photo/Imaging Educators - Professionals - Students
> <photoforum@...>
> Roger Eichhorn
> : Something happened in the transmission, or receipt!
> hmm, doesn't look *quite* right, though the original came through fine for
> me
> still better than some i've sent in the past that just muddled up
> comletely!
> if I look at the message source (control+f3 on a windows machine) I see the
> posted message looks OK - it can be copied and pasted out of that into a
> text editor for a clearer view
> k

[mark-461]

The LED method looks fairly easy, and the parts don't appear that expensive.  I know how to solder.  What I am not as familiar with is all the symbols used in circuits.  Some like the switches are not that hard to figure out.  Others are more difficult, but it basically is just a plan for the path of electrons.  I just need a reference on how to read the plan.  grin.

-------- Original Message --------
Subject: Re: densitometers
From: lookaround360@...
Date: Mon, October 12, 2009 7:26 am
To: List for Photo/Imaging Educators - Professionals - Students
<photoforum@...>


Look here and you may find instructions for making a good densitometer
from a light meter.

http://www.markerink.org/WJM/HTML/mainpage.htm

Google "Zone System". The late Phill Davis, U of Michigan prof., and
author of several Zone System texts had a good design for an old
Honeywell spot meter.

AZ


LOOKAROUND - Since 1978
Build a 120/35mm Lookaround!
The Lookaround E-Book 5ed.
http://www.panoramacamera.us



> -------- Original Message --------
> Subject: [SPAM] Re: densitometers
> From: karl shah-jenner <shahjen@...>
> Date: Sun, October 11, 2009 11:15 pm
> To: List for Photo/Imaging Educators - Professionals - Students
> <photoforum@...>
> Roger Eichhorn
> : Something happened in the transmission, or receipt!
> hmm, doesn't look *quite* right, though the original came through fine for
> me
> still better than some i've sent in the past that just muddled up
> comletely!
> if I look at the message source (control+f3 on a windows machine) I see the
> posted message looks OK - it can be copied and pasted out of that into a
> text editor for a clearer view
> k

[Bob W8IMO]

Try this URL   http://en.wikibooks.org/wiki/Electronics/Symbols

Bob

mark@... wrote:

The LED method looks fairly easy, and the parts don't appear that expensive.  I know how to solder.  What I am not as familiar with is all the symbols used in circuits.  Some like the switches are not that hard to figure out.  Others are more difficult, but it basically is just a plan for the path of electrons.  I just need a reference on how to read the plan.  grin.