Just got an EG&G Sensitometer

[ic-racer]

Tobias got back to me this morning..."The assembly is part number A1170 $410.00 2 week wait."

Quite unhelpful.

OK.

I have a question about it before making any suggestions. Is that assembly spring loaded to compress the film against the glass? I'm not totally understanding why the clear plastic you have on there is not working as well as the original glass.

 

[Bill Burk]

What if you make a smaller piece of glass, just to fit in the window (with some kind of tab to keep it from falling through), put the step wedge under glass, emulsion in contact with the film being tested. This could let the weight of the glass press the wedge against the film. And cost you nothing.

Also, if you find your tests come out overexposed, looks like you could put ND filters over the sensor to get longer exposures.

 

[Bill Burk]

Or you could increase the spacer, to fit a standard piece of glass in the original channel. Get the glass chamfered so the film will slide under it. Tape the wedge underneath. I don't think you need to be critical about contact with the step wedge, not like you care about the sharpness of the image.

 

[ic-racer]

Looking at that design I think it will work fine in its original configuration. There will be no bleed around the edges of the step wedge (so perfect contact is not needed). There is potential for a small amount of bleed between the steps, but I suspect it is insignificant.

 

[ic-racer]

As I wrote earlier about this machine: there is a sensor that measures the light inside

Good to see this project coming together.

Also, since you got your machine, I got ESECO sensitometer which also has sensors to to provide feedback on light intensity. The ESECO also firmly compresses the film right against the step wedge using a felt pad to produce sharp boundaries for the steps.

 

[Photo Engineer]

My old EGG died a while back and nothing I can check appears to be bad so it must be the lamp. I guess I have to spring for one somehow.

PE

 

[ic-racer]

My old EGG died a while back and nothing I can check appears to be bad so it must be the lamp. I guess I have to spring for one somehow.

PE

PE, did you ever get a new lamp? They are available, though they probably need to be soldered to the socket base of the original lamp.

http://www.xenonflashtubes.com/strobe-spiral.html

I probably don't need to tell you but just in case anyone out there is reading. Any time the capacitor is charged, the same voltage is always present at the lamp socket. There is no 'switch' or relay to control voltage to the lamp. And, even when the unit is turned off, there still can be voltage applied to the lamp socket for some period of time!

 

[Photo Engineer]

I never bothered with the older unit as I have 2. I gave my 3rd away. And I know about the voltage. That is also true of old tube TV sets which can carry a lethal voltage for a day or more.

Thanks.

PE

 

[RalphLambrecht]

I just got my EG&G sensitometer today. I currently have an older Wejex and would like to put together a buyers guide comparing the two. If I can pick up an X-rite green/blue sensitometer for cheap I would like to include that in the comparison.

Before plugging in the EG&G I took the cover off to inspect the capacitors and visually check the components for signs of damage.

Everything looked OK so I fired it up. The electronics seem to work OK except the three buttons for flash duration do not seem to work in the correct order. The 10-4 button gives the shortest flash but the 10-3 button gives the longest flash, with the 10-2 button falling somewhere inbetween. I'll have to take the cover off again to check this out. The cover had been off previously and the power cord had been replaced.

It looks like there is a diffusor screen missing from the exposure chamber. If someone out there has an EG&G I wish they could comment.

My light path is as follows: xenon bulb then a clear plate with black border over it. Next was a Wratten ND filter just placed over the clear plate. Next was the exposure chamber which is empty. Next is the rectangular clear glass on top of the exposure chamber and taped on that was a plastic step wedge.

It seems like I am missing a diffusor in the light chain.

ic racer,I have an x-rite dual-color sensitometermodel334 in good condition for sale for $150 plus shipping from Florida.if interested send email to rlambrec@ymail.com or call 352-633-7236

 

[ic-racer]

That original post is from 2007 and I have 4 sensitometers now (way too many ).

(there was a url link here which no longer exists), I suspect someone on APUG would want that at that price.

 

[RalphLambrecht]

That original post is from 2007 and I have 4 sensitometers now (way too many ).

(there was a url link here which no longer exists), I suspect someone on APUG would want that at that price.

still available

 

[Christopher Nisperos]

Hi,

Would any of you happen to have the instructions for an EG & G sensitometer? I can probably guess my way through it, but I'd sure appreciate having these on hand.

If you can help me, my email address is: chrisnisperos@yahoo.com

Kind thanks, in advance!

 

[Photo Engineer]

Chris, I have one here somewhere and if I can find it I will copy it and either e-mail it or send paper duplicates to you. It is about 5 pages long. Not much.

There was one on line and I read it a while back, but it is now gone. There are manuals for sale on EBay.

PE

 

[mr_coffee]

Hello everybody,
I've a question about the use of the eg&g mark VI sensitometer...

I would use it to test some films using the method suggested in the book "The way beyond monochrome".

On the sensitometer manual I read the following:
"The sensitometer is used for generating a characteristic curve for the particular film of interest.
This should be done using the manufacturer's recommended exposure and development schedule.
The exposure time (10-2, 10-3 or 10-4 second) used for the test strip should be in the range
recommended for the type of photographs that wil generally be made."

and then thre's also a table showing general filtration for different EI...

How practically I can know the correct combination of time and filtration to use for example with a
Kodak T-MAX 100, just doing trials or there's a scientific way?
...maybe I didn't get what the table on the manual says:
- EI 100 - Speed value 5 - ND Filter 2.0 ...ok but what exposure time? 10-2, 10-3 or 10-4?

...and also... I think that the purpouse is to have a step wedge corrected exposed from step 1 to 21,
is that right?
I think I can obtain a step wedge corrected exposed using different combination of time and
filtration but reading "the exposure should be in the range for the type of photographs that will be made"
let me to think that different combination of time and filtration will return different informations and I should
be use the correct combination for the type of photographs I'm interesting to make...(?)

Thank you in advance for any reply,

MB

 

[ic-racer]

To generate a control strip, any exposure and filtration that places the toe far to the left is fine. If you are speed testing, you need to choose the same exposure time as your camera.

 

[mr_coffee]

To generate a control strip, any exposure and filtration that places the toe far to the left is fine. If you are speed testing, you need to choose the same exposure time as your camera.

Thanks for your reply...

I'm sorry but I'm getting confused maybe because the gap of the language ...what do you mean for "speed testing"?

The purpouse of my test is to know the influence of different developing diluition and time against a film to draw my own curves
and to know how to correct expose and then develope that particular film ...should I use a particular time/filtration exposing the
film with the sensitometer to reach this goal? ...I think this is the "speed testing" of a film (?)
...so in this case, how could I convert that 10-2, 10-3, 10-4 values to my camera exposure time?
and also, do you mean I will have to shoot films using always the same exposure time to be congruent with the test?

Thanks again...

 

[ic-racer]

Control strip gives slope or gamma = film+development quantification.
Speed test gives toe densities = film+light quantification.

10^-2 = 0.01 sec = 1/100

 

[ic-racer]

In camera exposuer index test is practical.
Sensitometer speed test can be difficult to apply practically. More useful to compare known film to unknown; like compare Delta100 to Arista100.

 

[mr_coffee]

Control strip gives slope or gamma = film+development quantification.
Speed test gives toe densities = film+light quantification.

10^-2 = 0.01 sec = 1/100

Thank you... so if I understood it right I’m going
to expose a strip using any kind of exposure time and filtration combination (except to not fall into the reciprocity failure) and then I will use that strip to draw my curves and determine the contrast variation against development times and diluition...

To determine the film speed I should then use
the time you say is “the same speed of camera”

Am I right?

Actually I don’t really have a known film, is maybe
there some standard parameter to expose and develope the Delta 100 to have then a known
film to use to compare others?

Thank you so much for your patience

MB

 

[Bill Burk]

There are a few different buttons on the EG&G.

These are the flash exposure times. The exponent -2 -3 -4 are 1/100th of a second, 1/1000th of a second and 1/10,000th of a second respectively.

1/100th second (the 10-2 setting) is the one designed for regular film tests. It's pretty bright so you need a neutral density or a physical filter. You can block the light with a piece of foil with stripes cut out of it... that's a physical filter. It would make sense to cut a piece of acrylic and glue foil to it and cut it to block the right amount of light (so it won't change much over time)...

But I use a piece of neutral density gelatin filter in the bottom of the well, I just checked it's about 1.84 density. This is good for a 100 ASA film. for a 400 ASA film I add another ND filter giving 0.6 density (2 stops) more blocking power.

As I said, the 10 -2 button gives you a flash of 1/100th second. I always use this for film because 1/100th is a good shutter speed.

One of the others is super bright and even though it's a short exposure time it can expose paper for a paper test... you just "ignore" the reciprocity for that situation.

Otherwise the other two buttons 10 -3 and 10 -4 are for "reciprocity studies" - unless you really want to study reciprocity you probably won't use them for that purpose.

 

[Bill Burk]

Actually I don’t really have a known film, is maybe
there some standard parameter to expose and develop the Delta 100 to have then a known
film to use to compare others?

Sure. I use 400TMAX as a known film and compare others to it.

Develop until your graphs reach 0.62 (until you meet the ASA parameter for contrast) and then draw a line where the film crosses 0.1 above Base + Fog... From that you can determine the light which the EG&G hit your film with... by backwards calculating from the definition of a known film's ASA speed.

 

[ic-racer]

Bill did some work on 'speed sensitometry,' and as I recall there is a lot of good info in those threads. Most of my work is with control stirps and relative speed (film a vs film b) testing.

This thread is a real blast from the past; I think it is one of the first threads I started, 8,000 posts ago.

 

[mr_coffee]

There are a few different buttons on the EG&G.

These are the flash exposure times. The exponent -2 -3 -4 are 1/100th of a second, 1/1000th of a second and 1/10,000th of a second respectively.

1/100th second (the 10-2 setting) is the one designed for regular film tests. It's pretty bright so you need a neutral density or a physical filter. You can block the light with a piece of foil with stripes cut out of it... that's a physical filter. It would make sense to cut a piece of acrylic and glue foil to it and cut it to block the right amount of light (so it won't change much over time)...

But I use a piece of neutral density gelatin filter in the bottom of the well, I just checked it's about 1.84 density. This is good for a 100 ASA film. for a 400 ASA film I add another ND filter giving 0.6 density (2 stops) more blocking power.

As I said, the 10 -2 button gives you a flash of 1/100th second. I always use this for film because 1/100th is a good shutter speed.

One of the others is super bright and even though it's a short exposure time it can expose paper for a paper test... you just "ignore" the reciprocity for that situation.

Otherwise the other two buttons 10 -3 and 10 -4 are for "reciprocity studies" - unless you really want to study reciprocity you probably won't use them for that purpose.

Thank you so much Bill!
Very helpful!!

Now the question is much more clear, I will do some tests...

Actually I'm not interested to the reciprocity failure study but if you would like to share your approach with the eg&g sensitometer it would be really appreciated

Thanks again,

MB

 

[mr_coffee]

"With the 10-3 compensator, the exposure for 10-2 was 20.3mcs. I then used ND filters to adjust for the different film speeds. I used .6 NDs. They brought the exposures down to 4.78mcs for 100 speed films, 1.18mcs for 400 speed films, and 0.28mcs for TMZ and Delta 3200."

I have also done that mis-matching of the compensators to help fit the film range to the wedge with the limited ND filters I have.

I really like the concept of those compensators. They will be almost as stable throughout time (unless the plexiglass yellows or something) as a carbon filter, at an order of magnitude less in production cost.

I really can't understand the relationship between the filter compensation and the film speed... could you please
explain me it?

Thank you in advance...

 

[ic-racer]

Do you have the PDF file or actual user's manual for your sensitometer? Also, this Kodak workbook is good reading. If you are already plotting curves, it can be too basic, but I use it as a reference for the units and math. When I do my actual plotting I use a spreadsheet that automatically calculates the slope and speed and shows the ASA triangle points to verify the curve fits the criteria.

: https://www.kodak.com/uploadedfiles...en_motion_education_sensitometry_workbook.pdf