Enlarging - printing f stop chart?

[jay moussy]

Searching the forum for printing information, I often see folks referencing an "f-stop chart" pointing to an outdated non-functioning link.

Where could I find a good f-stop chart, suitable to a beginner?

 

[MattKing]

Courtesy of Ralph Lambrecht and Chris Woodhouse' "Way Beyond Monochrome" - a truly valuable resource.
I only share it here because Ralph has generously done so before here on APUG/Photrio.

 

[tezzasmall]

I love f-stop printing but I don't think that I would be doing it if I didn't have an f-stop timer. That chart above is just a load of gobbledegook to my eyes!

Terry S

 

[MattKing]

I use that chart all the time - it is simple and easy to use!
Find the row with your current exposure time in the highlighted column, decide how many stops you wish to adjust that exposure by, read across the row to the column that matches your needed adjustment, and the number in the box is the correction needed to get to your new exposure time.
EDIT: clarification added

 

[spijker]

I made a simplified version of the table in the Way Beyond Monchrome book, see attached pdf. It uses 1/4 stop increments and the times are rounded to the nearest whole second for times more then 10s. That makes it easier to select it on a regular timer and I find that it's accurate enough. I've used this table for a number of years now and it works for me. Test strip increments are listed as well. So if you want to do a test strip from 20s to 40s in 1/4 stop steps, the time sequence will be: 20s, +4s, +4s, +6s, +6s.

 

[ann]

There is a chart for this in Tim Rudmans book on printing

We have been using this method for over 30 years. At first using a basic timer and just doing the=math in ones head

The school can’t afford to purchase f-Stop timers but we still use+the method=using newer timers
I also printed out a stoffers 21 step wedge image along with a huge chart from Tim and after explaining how this works my students find it easy to do

 

[Sirius Glass]

I multiply or divide my base time by two for an f/stop difference, but I have been know to use Ralph's chart at times.

 

[Doremus Scudder]

I've posted this before, but no one seems to have adopted my simpler method.

F-stop timing is great, since changes in density can be made proportionally, but the numbers one has to deal with can be cumbersome.

The same proportional changes can be accomplished using percentages instead of f-stop numbers.

My test strips are in 25-30% intervals. E.g., an approximate 30% sequence starting at 10 sec. would be: 10 - 13 - 17 - 22 - 29 - 38 (if you cover your test strip and count seconds, it would be: 10 - 3 - 4 - 5 - 7 - 9).

Making exposure adjustments and dodging and burning are just as simple. Dodge 15% here, burn 50% there, etc., etc. I keep the percentages in my print records When scaling a print up or down, I just need to find a base exposure and then figure out my manipulations from there.

Charts are easy to make in whatever percentage intervals you want. I've got 25% and 30% test strip exposures on post-it notes by my enlarger.

Hope this helps,

Doremus

 

[pentaxuser]

I made a simplified version of the table in the Way Beyond Monchrome book, see attached pdf. It uses 1/4 stop increments and the times are rounded to the nearest whole second for times more then 10s. That makes it easier to select it on a regular timer and I find that it's accurate enough. I've used this table for a number of years now and it works for me. Test strip increments are listed as well. So if you want to do a test strip from 20s to 40s in 1/4 stop steps, the time sequence will be: 20s, +4s, +4s, +6s, +6s.

Thanks for that, spijker Ralph's table is great but I find that most if not all of the time I cannot distinguish exposures down to anywhere near 1/12ths. Yours also starts with lower exposures which I often use as well for test strips.

pentaxuser

 

[markbau]

There is a chart for this in Tim Rudmans book on printing

We have been using this method for over 30 years. At first using a basic timer and just doing the=math in ones head

The school can’t afford to purchase f-Stop timers but we still use+the method=using newer timers
I also printed out a stoffers 21 step wedge image along with a huge chart from Tim and after explaining how this works my students find it easy to do

I use the Rudman chart too. His chart goes under 5 seconds (Ralph's doesn't) Often I find myself with crazy short exposure times when printing old 35mm negs.

 

[ic-racer]

"2", "1.4", "1.26" and a calculator. (those are the time multiplication factors for full, half and third stop).

So if your base time is 41 seconds, you know 82, 57.4, and 51.6 are the new times for a full, half and third stop increment.

So, when using contrast grades 0 to 1.5, use "2" or "1.4"

When using contrast grades 2.5 and higher, use "1.26"

 

[markbau]

"2", "1.4", "1.26" and a calculator. (those are the time multiplication factors for full, half and third stop).

So if your base time is 41 seconds, you know 82, 57.4, and 51.6 are the new times for a full, half and third stop increment.

So, when using contrast grades 0 to 1.5, use "2" or "1.4"

When using contrast grades 2.5 and higher, use "1.26"

I'm quite dyslexic when it comes to math (seriously) Whilst I understand the first part of your post perfectly I was wondering if you could explain the last two lines please.

 

[silveror0]

"2", "1.4", "1.26" and a calculator. (those are the time multiplication factors for full, half and third stop).

So if your base time is 41 seconds, you know 82, 57.4, and 51.6 are the new times for a full, half and third stop increment.

So, when using contrast grades 0 to 1.5, use "2" or "1.4"

When using contrast grades 2.5 and higher, use "1.26"

I'm quite dyslexic when it comes to math (seriously) Whilst I understand the first part of your post perfectly I was wondering if you could explain the last two lines please.

Also explain what multipliers to apply when using contrast grade 2.0; it's conspicuously not addressed.

 

[RalphLambrecht]

I use the Rudman chart too. His chart goes under 5 seconds (Ralph's doesn't) Often I find myself with crazy short exposure times when printing old 35mm negs.

<5s is not printing time;it's a flash exposure;mine starts at 16s, which I think is the min printing time to allow for some dodging;any less and dodging starts getting tricky.

 

[Doremus Scudder]

"2", "1.4", "1.26" and a calculator. (those are the time multiplication factors for full, half and third stop)...

So let's see... a full stop change is 100% more exposure, a half-stop is 40% more and a third-stop is roughly 25% more. I can figure all that without a calculator or a fancy timer.
So, using your example, a base time of 41 seconds plus 100% gets me 82 seconds. Plus 40 percent (4.1 x 4) gets me 57.4 and plus 25% (4.1 + 4.1 + 2.05) gets me 51.25 (really close to the third-stop increment; only 0.35 seconds difference. I defy anyone to tell the difference between prints made at 51.6 and 51.25 seconds...). And I can do all this in my head in a fraction of a second. And, I can easily use intermediate values, e.g. 35%.

I still think you guys are wasting time with f-stops instead of thinking in percentages.

Best,

Doremus

 

[pentaxuser]

"2", "1.4", "1.26" and a calculator. (those are the time multiplication factors for full, half and third stop).

So if your base time is 41 seconds, you know 82, 57.4, and 51.6 are the new times for a full, half and third stop increment.

So, when using contrast grades 0 to 1.5, use "2" or "1.4"

When using contrast grades 2.5 and higher, use "1.26"

I follow the multiplication factors for the full, half and third stops but what is the connection between grades 2.5 and using only 1.26? Is it simply that in a low contrast print negative the test strips need bigger fractions of stops to be able to distinguish each strip properly compared to high contrast prints?

pentaxuser

 

[ic-racer]

I'm quite dyslexic when it comes to math (seriously) Whilst I understand the first part of your post perfectly I was wondering if you could explain the last two lines please.

A one-third stop change of exposure for a print on 00 paper is not detectable by my eye.
A one-half stop change on a print on 5 paper is huge, way too much.

You can see here. The exposure sequences below are at one-half stop for each gray bar. See how much difference in gray print value one-half stop makes on 5 paper. Compare that to 0.

How does this work?

When printing on 5 paper, if you want 'just a little' more exposure, use one-quarter stop (1.19).
When printing on 0 paper, if you want 'just a little' more exposure, use whole (2) or half stop (1.4).

 

[ic-racer]

This plays out every day in my darkroom. I don't use conventional test strips. I place a chunk of paper on the projected image of an important element of the final print and guess the first exposure. Based on that I guess the next value, again exposing the next chunk of paper to the same part of the image.

Knowing how the paper will respond lets me zero in on perfect exposure very fast. I know that if I do 1/4 stop increment on 0 paper, I'll be there all day making these test exposures. Likewise if I ever give one stop more exposure when using 5 paper it will usually be way too dark.

The problem with the conventional 'test strip' is that each strip is on a different part of the image. This did not make sense to me in 1973 when, I was shown how to do it, and still does not fit my workflow.

 

[spijker]

I still think you guys are wasting time with f-stops instead of thinking in percentages.

In essence you've pre-calculated 21/2, 21/3 and probably 22/3 and remember the result as +40%, +25% and +60%. You can take that approach one step further and pre-calculate a range of times that you often use and write down the results. Then you don't have to calculate them while printing. And if you print often enough you'll remember the whole sequence anyway. For me that is 10s to 67s in 1/4 stop increments. I don't use anything outside that range and know it by heart now. I don't need to check my chart anymore. I find that easier than calculating on the fly 5 times for a test strip. The only math I need to do is subtracting two values for burning and dodging. That's easy too. In the end it is all what you prefer.

 

[pentaxuser]

The problem with the conventional 'test strip' is that each strip is on a different part of the image. This did not make sense to me in 1973 when, I was shown how to do it, and still does not fit my workflow.

Thanks for the clear explanation. For this next piece of information which may be useful I need to thank Ralph Lambrecht. He spotted this very problem and devised a test strip printer that allows the user to easily expose the same strip each time. It's a great piece of kit. It gives 7 exposures of the same part of the print projection on a 5x7 piece of paper.

The only drawback and it is only a slight drawback is that each strip shows only a small part of the projection. Sometimes this strip ( slightly less than 1 inch as there are clear white borders built in as well) is fine but often a bigger strip would be advantageous. With hindsight I wonder if Ralph might have settled on 4 strips by increasing the size of the opening where the strips are exposed. It is possible to use the strip markings on the printer without using the narrow opening to create 3 strips but it requires two masks and moving the whole 5x7 sheet so more manipulation but doable

If any of this is confusing and I think it may be but anyone would like to know more then have a look at Ralph's test strip printer. It should be clear what I am talking about once you see how it works. You can make one for yourself as Ralph supplies complete instructions and dimensions

So thanks Ralph

pentaxuser

 

[RalphLambrecht]

So let's see... a full stop change is 100% more exposure, a half-stop is 40% more and a third-stop is roughly 25% more. I can figure all that without a calculator or a fancy timer.
So, using your example, a base time of 41 seconds plus 100% gets me 82 seconds. Plus 40 percent (4.1 x 4) gets me 57.4 and plus 25% (4.1 + 4.1 + 2.05) gets me 51.25 (really close to the third-stop increment; only 0.35 seconds difference. I defy anyone to tell the difference between prints made at 51.6 and 51.25 seconds...). And I can do all this in my head in a fraction of a second. And, I can easily use intermediate values, e.g. 35%.

I still think you guys are wasting time with f-stops instead of thinking in percentages.

Best,

Doremus

believe it or not but, I can definately see the difference of a 1/12 stop in highlights and midtones and f-stoptiming is just as easy as percentages;yet to me,easier to record and remember. A good f-stop timer is an invaluable tool in the darkroom for every dicerning printer.

 

[Doremus Scudder]

Ralph,

To each his own. I imagine working with an f-stop timer greatly reduces the amount of mental gymnastics one has to do. I print with a metronome, so percentages work best for me. The result is the same: proportional exposure control. It just seems like a lot of people here like to do a lot of calculating with square roots while in the darkroom. I prefer to make prints.

Best,

Doremus

 

[MattKing]

I have the half stop (time) progression memorized - 4, 5.6, 8, 11, 16, 22, 32, 45, 64 .....
I wonder why it was so easy to remember?

 

[RalphLambrecht]

Ralph,

To each his own. I imagine working with an f-stop timer greatly reduces the amount of mental gymnastics one has to do. I print with a metronome, so percentages work best for me. The result is the same: proportional exposure control. It just seems like a lot of people here like to do a lot of calculating with square roots while in the darkroom. I prefer to make prints.

Best,

Doremus

me too and Yes; to each his own;to a photographer, f/stops feel more natural than percentages;f/stops are a key variable for photographic exposures; in the field,exposing negatives,working with filters,belloes extensions;why not in the darkroom too?

 

[jay moussy]

Highly informative, all a bit overwhelming to this beginner..!