Macbeth Densitometer Readings

YCG · Nov 9, 2021

Hello,

I have a Macbeth TR1224 densitometer. I want to use it for light transmission measurements of plastics after some processes.

I have successfully calibrated it with Stouffer step wedges. I am getting four readings R-G-B-V. From which I understand, I should consider the value V(visual). Sadly I could not find a decent document to clarify it, and the Macbeth manual is not that user friendly.

Could someone help me with this?

Thanks a lot.

Bill Burk · Nov 9, 2021

Yes the V is visual channel.

Edit: the following is all wrong (it’s a 106) but leaving it up as a reminder of my misconception….

It has a Wratten No. 90 filter over the photomultiplier tube sensor.

Not surprising that’s the same filter used in Zone VI viewing filters. I think scientists selected its properties of reducing colors to visual monochrome before Ansel Adams decided it does a good job of previewing how things would look in black and white.

Saganich · Nov 9, 2021

Yes, V is for visual. On the older Macbeths, it was the gold dot on the dial for transmission and black dot for reflection.

ic-racer · Nov 9, 2021

What color is the plastic? What is your intention with the measurement?

Bill Burk · Nov 9, 2021

Saganich said:
Yes, V is for visual. On the older Macbeths, it was the gold dot on the dial for transmission and black dot for reflection.

View attachment 290587

Ok I am wrong. It’s a 106 not a 90

Saganich · Nov 9, 2021

Bill Burk said:
Ok I am wrong. It’s a 106 not a 90

I hadn't seen your post before I added that old table, but I think the two filters differ only regarding the properties of the particular photocell used at the time. Likely current or less ancient machines use the 90. My old Macbeth manual actually states the 106's are different for transmission and reflectance and warned about interchanging the wheels.

Bill Burk · Nov 9, 2021

I think I got my impression from taking apart the densitometer for cleaning and what I saw looked like a 90. Even my instructions manusl mentions the 106 and Kodak Filters says the 106 is for visual readings in densitometers… while the 90 is for monochrome viewing.

I’ve been wrong before but this time I made the whole thing up.

YCG · Nov 12, 2021

Thanks a lot for your answers.

ic-racer said:
What color is the plastic? What is your intention with the measurement?

Plastics are clear (PMMA, Polycarbonate etc.). I want to measure the transmission properties after some type of processes. But the main idea is it still good to see through or not.

ic-racer · Nov 12, 2021

YCG said:
...see through or not.

So, if 'seeing' is important, I'd think that all the colors would be important, so I'd test with all 4 channels.

Arthurwg · Nov 12, 2021

"Is this a densitometer I see before me? Come, let me clutch the."

YCG · Nov 19, 2021

ic-racer said:
So, if 'seeing' is important, I'd think that all the colors would be important, so I'd test with all 4 channels.

Thanks for the reply

YCG · Nov 19, 2021

Arthurwg said:
"Is this a densitometer I see before me? Come, let me clutch the."

Macbeth Densitometer Readings

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