Novex R Timer - Inner Numbers

[Palmer]

I read an older comment that states the inner ring of numbers on a Novex R enlarger timer is for re-calculating exposure time when you change the enlarger head height to change the print size. The poster said the numbers on the Novex timer in some way correspond to the height markings on Meopta enlargers. Try as I might, I cannot work out how to use those inner ring of numbers to calculate exposure when I change the head height. Can anyone tell me how this works? Much appreciated if you can.

Steve

 

[Palmer]

Well, thanks to everyone who read my post but it seems I'm not the only one who has no idea about this.

Steve

 

[Bill Burk]

I think I get it.

You have found a time at the height you have the enlarger at... you set the inner dial to the height, and leave the main dial at the time you used.

Then you hold inner and outer dial together and move the inner dial to your new height. The outer dial will now point at a new number of seconds, which is the right time for the height you moved to.

 

[Bill Burk]

When I tried to correlate the inner scale numbers to my Omega D-II enlarger, and found some example enlargement X for a variety of heights, and used Kodak Master Darkroom Dataguide to find corresponding times... I came to the conclusion that those numbers are not centimeters of height.

Does anyone with a Meopta enlarger, with a scale on the column, know what measure those numbers are? Or if you have such a scale, can you extend the enlarger to a variety of heights, focus with a 50mm lens, and tell what height the negative stage is above the baseboard... or tell what enlargement X you get.

From some sample numbers we could probably determine what the scale is.

 

[Bill Burk]

So it seems you have to use a chart to figure out what the numbers on the enlarger mean... I can't see the whole chart but if I try to take the silver column as X enlargement, the numbers on the black columns do NOT work with the Kodak Dataguide Enlarging Computer

For example on the Novex R 15 seconds is near 30 "column" value, which is near 5 X. (I know the two pointers can be spread apart but it's easier to imagine when they are aligned).

Then on the Kodak computer putting 15 seconds near 5 X and looking down, say to 3 X, Kodak computer says it will be 6 seconds

Going back to the Novex R, 6 seconds is near 22.

That's between 3.5 X and 4 X on the silver scale.

So there is something funky going on.

 

[AgX]

The outer scale is arithmetric, the inner one logarithmic. (Similar to ASA vs DIN scale.)
Adding 6 units on the inner scale means doubling the value on the outer scale.

But I still do not see how such inner scale substitutes a nomogram to read the new exposure time after changing height.

 

[MattKing]

The outer scale is arithmetric, the inner one logarithmic. (Similar to ASA vs DIN scale.)
Adding 6 units on the inner scale means doubling the value on the outer scale.

But I still do not see how such inner scale substitutes a nomogram to read the new exposure time after changing height.

Try using the difference between the two inner numbers as a measure of how many stops to adjust the exposure.

 

[AgX]

First one would have to know the difference in figures on the height scale relates to the figures on the inner scale.
Without that knowledge one still would have to use the nomogram and leave that inner scale aside.

 

[Bill Burk]

Finally got enough pieces of the Opemus 6 scale to get a good idea what it is...

I confirmed this scale makes sense by using my 75mm, 50mm and 28mm lens and measuring the easel to negative stage in CM... These appear to be sets of enlargement factors and the marking on the Opemus 6 column in CM... with a difference (starting point) somewhere between 21 to 25 CM.

I cannot see a relationship between enlargement factors here, and the Novex R inner scale. The difference in times at different enlargement factors you may derive from this chart, does not agree with the inner scale. Besides the range of numbers on the Novex R is very limited in comparison to the range of heights in this chart.
So almost certainly I can say the scale on the timer does not correlate to the scale on the Opemus 6.

B, 80, 50, 30

1, 6, -, -
1.5, 6, -, -
2, 10, -, -
2.5, 13, 1, -
3, 17, 2, -
3.5, 20, 4, -
4, 24, 6, -
5, 32, 11, -
6, 40, 16, -
7, 48, 21, 2
7.6, 53, 24, 4
9, -, 32, 8
10, -, 37, 11
11, -, 42, 14
13, -, 52, 20
15, -, -, 27
17.5, -, -, 34
20, -, -, 42
23.5, -, -, 53

 

[AgX]

Meopta gives nomograms for scale dependant exposure corrections. These nomograms are based on the used FL, the primary exposure time and the first and second reading of a figure on the collumn.

As said I do not see how the inner scale correlates to this. But I cannot imagine another use either... Someone sure must be faster on the uptake, or has the timer manual.

 

[Bill Burk]

The outer scale is arithmetric, the inner one logarithmic. (Similar to ASA vs DIN scale.)
Adding 6 units on the inner scale means doubling the value on the outer scale.

But I still do not see how such inner scale substitutes a nomogram to read the new exposure time after changing height.

Ah yes it’s obvious. Those inner marks are 1/6 stops. So any calculations you can do in sixth-stops you can apply with that inner dial.
So what can you do mechanically? Can you move it independently of the main dial, then hold it together and turn?
If so I can see some simple ways to use it.
I have an enlarging meter (called a comparator) that has its numbers in the same direction (greater units require more seconds), but is marked in third-stops (instead of sixth-stops). So you can’t directly use an Omega CS-10. Maybe there was a corresponding comparator?