Test strip times and printing times

[Nige]

ahh, you go down the table... not across! doh! I just read across!

 

[Photo Engineer]

ahh, you go down the table... not across! doh! I just read across!

There seems to be an error in row 2. Are my eyes bad? Someone check me out on this.

Thanks

PE

 

[jstraw]

So does anyone here have the experience compare and contrast the f-stop timers that are around?

 

[Tach]

I became familiar with f-stop printing yesterday, via this thread. I'm doing the forehead-slap now too. Duh. I will be using this table:

(One full stop separates each column.)

5.0 seconds 10.0 seconds 20.0 seconds 40.0 seconds 80.0 seconds
5.9 seconds 11.9 seconds 23.8 seconds 47.6 seconds 95.2 seconds
7.1 seconds 14.1 seconds 28.2 seconds 56.4 seconds 112.8 seconds
8.4 seconds 16.8 seconds 33.6 seconds 67.2 seconds 134.4 seconds

And when I'm satisfied, I may invest in an f-stop timer.

I find it easier to go like this

cover at 6 secs
cover at 8 secs
etc for 11s
16s
22s
32s
45s
64s

Just remember the aperture series in your camera and presto! Half-stops logarithmic test strips.

 

[lee]

I use the RH Designs Stopclock timer and it is very accurate and compensates for that problem. It is a little pricey but it a very nice product and I would recommend it to any one wanting to up grade to f/stop printing that is pretty hassle free.

lee\c

 

[David Brown]

I use the RH Designs Stopclock timer and it is very accurate and compensates for that problem. It is a little pricey but it a very nice product and I would recommend it to any one wanting to up grade to f/stop printing that is pretty hassle free.

lee\c

Although I could see the advantages of f/stop test strips, I was skeptical about the need for the RH Designs timer, even after seeing it in action. I made up an extensive table for use with the timer I had and it was working. Then this timer died. So, I splurged and got the StopClock.

Well, what a revelation. Test Strips have never been easier! Then there's the dry-down compensation built in. Oh, and the 2 channels if you want to do split grade. Etc.

 

[Ronald Moravec]

Why would you want to test print by full stop brackets unless you have no idea where to start? The best you will get is one strip pretty close.

My exposures are normally 30 sec. I do an overall 20 sec, cover 1/5 the paper and do 5 sec exposure, cover 2/5, and another 5. I end up with 20-25-30-35-40-45. Then take the best strip time and expose a 10x1 inch strip spanning the darkest and lightest area and give one exposure. In a portrait is is usually from the hair thru one eye, to the clothing. adjust from there

When you learn to expose and develope film properly you will not need the
20-45 test.

 

[jstraw]

Why would you want to test print by full stop brackets unless you have no idea where to start?

I think I missed the recommendation to make full-stop test strips. Was there such a recommendation? I'm considering 1/2 or 1/4 stop test strips.

 

[jstraw]

I find it easier to go like this

cover at 6 secs
cover at 8 secs
etc for 11s
16s
22s
32s
45s
64s

Just remember the aperture series in your camera and presto! Half-stops logarithmic test strips.

I'm thnking that a sequence (for 1/2 stop test strips) would go like this:

expose full sheet for 5 secs = 5
cover all but a strip and expose for 2.1 secs = 7.1
cover all but two strips and expose for 2.9 secs = 10
cover all but three strips and expose for 4.1 secs = 14.1
cover all but four strips and expose for 5.9 secs = 20
etc.

Yes, it's a lot to manage and yes five exposures totalling 20 seconds is different than one exposure of 20 seconds but it would be very close.

I assume that automating this is essentially what the test-strip function of an f-stop timer does. Yes? No?

 

[Ray Heath]

I'm thnking that a sequence (for 1/2 stop test strips) would go like this:

expose full sheet for 5 secs = 5
cover all but a strip and expose for 2.1 secs = 7.1
cover all but two strips and expose for 2.9 secs = 10
cover all but three strips and expose for 4.1 secs = 14.1
cover all but four strips and expose for 5.9 secs = 20
etc.

i don't believe in this requirement to make print exposing conform to the stops progression as used to expose film

especially when it is based on partial stops, partial stop control may well be necessary for slide film, but it is totally unnecessary for negative film exposure

print exposure is a different thing again, who, if you stop kidding yourself, can see the difference in density between 20.9 and 30 seconds

just because a print is exposed at a full, or a partial, stop doesn't mean it's 'right'

 

[Tach]

I'm thnking that a sequence (for 1/2 stop test strips) would go like this:

expose full sheet for 5 secs = 5
cover all but a strip and expose for 2.1 secs = 7.1
cover all but two strips and expose for 2.9 secs = 10
cover all but three strips and expose for 4.1 secs = 14.1
cover all but four strips and expose for 5.9 secs = 20
etc.

Yes, it's a lot to manage and yes five exposures totalling 20 seconds is different than one exposure of 20 seconds but it would be very close.

I assume that automating this is essentially what the test-strip function of an f-stop timer does. Yes? No?

I use a 'metronome' (a cheap chinese clock which ticks LOUD).

My sequence goes like this:

Turn on enlarger at tick
at the 6th tick, cover first part of strip
at the 8th tick, cover next part of strip
at the 11th tick, cover next part of strip
at the 16th tick, cover next part of strip
at the 22th tick, cover next part of strip
at the 32th tick, turn off the enlarger

I do not turn off the enlarger for every covering; i'm done in 32 secs generally. It is very simple and fast. Also, you do not have to deal with the problem of figuring out if multiples exposures = single exposure.

My exposures are normally 30 sec. I do an overall 20 sec, cover 1/5 the paper and do 5 sec exposure, cover 2/5, and another 5. I end up with 20-25-30-35-40-45.

In fact, it's the same method as ronald's, but instead of using 20-25-30-35-40-45, I'm using 6-8-11-16-22-32, getting strips spaced exactly half stops.

I don't see the advantage is using your sequence for generating a half-stop test strip; I just remember the aperture progression of a camera for it.

I do have a paterson timer with a print meter. I only use it if times at f/8 get too low, and need consistency.

When you learn to expose and develope film properly you will not need the
20-45 test.

A bit of street shooting with a small rangefinder and no lightmeter may sway your opinion somewhat.

 

[Ray Heath]

I use a 'metronome' (a cheap chinese clock which ticks LOUD).

My sequence goes like this:

Turn on enlarger at tick
at the 6th tick, cover first part of strip
at the 8th tick, cover next part of strip
at the 11th tick, cover next part of strip
at the 16th tick, cover next part of strip
at the 22th tick, cover next part of strip
at the 32th tick, turn off the enlarger

I do not turn off the enlarger for every covering; i'm done in 32 secs generally. It is very simple and fast. Also, you do not have to deal with the problem of figuring out if multiples exposures = single exposure.



In fact, it's the same method as ronald's, but instead of using 20-25-30-35-40-45, I'm using 6-8-11-16-22-32, getting strips spaced exactly half stops.

I don't see the advantage is using your sequence for generating a half-stop test strip; I just remember the aperture progression of a camera for it.

I do have a paterson timer with a print meter. I only use it if times at f/8 get too low, and need consistency.



A bit of street shooting with a small rangefinder and no lightmeter may sway your opinion somewhat.

this non-sensical, what do you mean your 'done in 32 seconds generally' shouldn't it be 'always' done in 32 seconds?

your timing is not half stop intervals, 6 secs +1 stop is 12 secs, 6 +1/2 stop is slightly less than 9, 32 secs is 6 + approx 2 1/2 stops

do you understand what the lens aperture numbers, 22/16/11/8/5.6/..., actually mean/represent

 

[MattKing]

5.6, 8, 11, 16, 22, and 32 would essentially be half stop intervals, so the 6 second first interval is slightly long, but the rest are fine.

I use this method too, or at least one very close to it, because it seems to give a more "linear" progression of tones on the test strip than one with constant intervals. The trick of course is to try to have the optimum exposure somewhere in the middle of the progression, so that you get the most information from the test.

Matt

 

[Ray Heath]

5.6, 8, 11, 16, 22, and 32 would essentially be half stop intervals, so the 6 second first interval is slightly long, but the rest are fine.

I use this method too, or at least one very close to it, because it seems to give a more "linear" progression of tones on the test strip than one with constant intervals. The trick of course is to try to have the optimum exposure somewhere in the middle of the progression, so that you get the most information from the test.

Matt

no, they are not fine, they are grossly wrong

why would would you want to do 5.6, then 8. then 11 etc. your missing the whole point of lamp warm up and cool down

your time intervals don't need to represent stops, though the above doesn't anyway

making it technical and difficult doesn't make it better

to reiterate, the lens aperture numbers and their sequence mean something else, they are not based on time intervals

 

[lee]

Ray,

please tell us your method of testing a print

lee\c

 

[Bob F.]

Clearly, 6, 8, 11, 16, 22. 32 etc seconds are 1/2 stop steps in time (rounded to the nearest whole second). A bit of simple arithmetic involving logarithms or, even simpler, a glance at an f-stop timing chart will set any minds at rest over that issue.

The only small error in the method related that I can see is that caused by the lamp cool-down time, but as this is shorter than the lamp warm-up time (call it under 1/2 a second) it can be ignored in most practical 30+ second exposures. This small error can be easily eliminated by using a card or a hand to block the light from the lens at the last tick, and then turn off the lamp with the light still blocked.

The initial lamp warm-up time is taken account of for each exposure by the fact that it is included at the start in the first 6 second test strip: it is a constant that is applied to all the timings in the sequence.

In the past I used my laptop to calculate 1/6th stop intervals. There are f-stop timing charts available too. Many people use a metronome in a similar manner; if my current enlarger didn't have a built-in timer with a shutter mechanism, I would still be using one.

Cheers, Bob.

 

[Tach]

this non-sensical, what do you mean your 'done in 32 seconds generally' shouldn't it be 'always' done in 32 seconds?

If I'm doing large enlargements, I'll extend time. If I have an overly dense negative, I'll start at 11-16 secs and extend time to match.

I'm not slavish to procedures, preferring to understand what I'm doing, and tweak where necessary. It may be not your cup of tea, but it works for me.

your timing is not half stop intervals, 6 secs +1 stop is 12 secs, 6 +1/2 stop is slightly less than 9, 32 secs is 6 + approx 2 1/2 stops

The 6 secs is an approximation to 5.6 secs. And even then, 6*1.4142 = 8 secs.
If the rounding bothers you, start exposures at 8 secs.

For cool-down times, see Bob F's post. I have incandescent bulb diffusion and condenser enlargers, so cold light issues don't bother me.

I'm using the lens aperture series as a reminder. Time is one-dimensional, while area is two-dimensional (duh!). So, a half stop sequence in time corresponds to a full stop sequence in area.

I can use any half-stop sequence in time, but a different one requires memorizing yet another set of data, and my head hurts enough already.

do you understand what the lens aperture numbers, 22/16/11/8/5.6/..., actually mean/represent

Better than you understand civility, I guess.

 

[Dave Miller]

Tach,
Quote "Time is one-dimensional, while area is two-dimensional (duh!). So, a half stop sequence in time corresponds to a full stop sequence in area."

This may be misleading. A one stop time difference, i.e. 5 seconds to 10 seconds is exactly the same in printing term as an aperture change of, say, f11 to f8 - or have I missed something.

By the way I use 1/4 stop steps in my test prints, this allows me to cover a couple of stops across my choosen range, and is generally more than enough.
As someone else said in this thread there is no correct printing value, just the most acceptable one that represents the feeling you want to convey.

 

[Tach]

Tach,
Quote "Time is one-dimensional, while area is two-dimensional (duh!). So, a half stop sequence in time corresponds to a full stop sequence in area."

This may be misleading. A one stop time difference, i.e. 5 seconds to 10 seconds is exactly the same in printing term as an aperture change of, say, f11 to f8 - or have I missed something.

I was being unnecessarily convoluted .

I was trying to explain the difference between the f-stop sequence due to changes in aperture (which affect a two-dimensional area) and what happens when you use that sequence for the time dimension, which is linear.

To build on your example, there's a one stop time difference between 5 and 10 secs, but if your aperture ring had a f/5 and a f/10, you'd see that you have two stops between them.

Quite useless trivia, and not to the main point of the post. Also didn't come across right. It'd be better just to disregard this paragraph.

 

[jstraw]

I think I need a compensating metranome.

A "stop" is a doubling or halving of exposure.

F-stop is the focal length divided by the diameter of the aperture. I think that's widely known. In a sense "f-stop" printing is a misnomer because what's being changed is not aperture but rather, exposure time.

The doubling or halving of any arbitrary amount of time is a one-stop change. The algorithm can be applied to any starting exposure...3 secs, 5 secs, 11.347 secs, whatever.

Rounding to the nearest whole second and using a metranome is imperfect. I think it's probably less imperfect than resetting the timer for each strip to the nearest 10th and then having multiple lamp starts and stops.

I think the the important and probably oh-so obvious observation is that a sequence of 5-10-15-20-25-30-35-40 is a sequence of 2 full stops where:

10 is 200% of 5
15 is 150% of 10
20 is 133% of 15
25 is 125% of 20
30 is 1.20% of 25
35 is 1.16% of 30
40 is 1.14% of 35

The sequence of 5, 7, 10, 14, 20, 28, 40 is two full stops in approximate, half-stop increments where the spacing is:

7 is 140% of 5
10 is 142% of 7
14 is 140% of 10
20 is 143% of 14
28 is 140% of 20
40 is 143% of 28

Instead of a sequence of strips with a diminishing amount of difference, you get a sequence of strips with essentially, evenly-spaced amounts of difference. Either the value of this is readily apparent or it's not. I think that it is.

 

[Ray Heath]

I was being unnecessarily convoluted .

I was trying to explain the difference between the f-stop sequence due to changes in aperture (which affect a two-dimensional area) and what happens when you use that sequence for the time dimension, which is linear.

To build on your example, there's a one stop time difference between 5 and 10 secs, but if your aperture ring had a f/5 and a f/10, you'd see that you have two stops between them.

Quite useless trivia, and not to the main point of the post. Also didn't come across right. It'd be better just to disregard this paragraph.

duh, excuse me, i was being civil, and you answered my question, you don't understand what lens aperture numbers mean

5 secs + 5 secs is double the amount of time ie +1 stop

changing the lens aperture from f11 to f8 passes double the amount of light ie +1 stop

aperture numbers are not 'normal' numbers, they are derived by dividing the focal length by the aperture diameter, ie they are relative to the lens focal length

it also means they are tied to calculations of area of a circle, (2 pie r squared, for want of better way to write it), so each successive number does not 'appear' to be half or double, but its light passing ability (it's area) is half or double

to then 'fudge' time durations to match f number sequences is non-sensical and pointless, the two things are different measures

Lee, i already explained my method, though my main point is, it doesn't have to complicated

 

[MurrayMinchin]

My Forehead-Slap

I think I need a compensating metranome.

Then again, if you use a variable contrast head, maybe not

Way back in the mists of time when I printed with a cold light on graded paper, my Zone VI compensating metronome timer was close to THE BEST piece of gear I ever bought as it allowed slam-dunk-consistant-exposures.

(For the uninitiated, the timer will give identical exposures to the paper whether the light is cold or warm. When the light is cold three 'seconds' would be, beeeeeeeep beeeeeeeep beeeeeeeep. When the light source was warm three 'seconds' would be, beeep beeep beeep. Both exposures, as far as the paper is concerned, would be identical).

Then I got a Zone VI variable contrast cold light head, plugged the compensating metronome timer into it, and became confused by weird shifts in contrast. My forehead-slap moment came weeks later when I realized the compensating metronomes photo-cell could only measure the amount of light, not the colour of the light.

Here's an example. If you find an exposure that looks good but you decide to reduce the soft light a bit, not just the soft light exposure changes, everything changes. The timer, reading that the total amount of light has reduced, will add "more time between the beeps" to compensate for the reduced exposure - - - get ready to slap your forehead - - - this means that to compensate for the reduced light output from the soft light, the hard light (which you never touched) stays on longer. D'OH!

I now use an electronic metronome. The Zone VI variable contrast head I have at least has a 'ready light' that turns on when it has stabilized. Now when I change one light source and keep the exposure time the same, I know only one thing has changed.

There's never, ever, a simple answer to anything worthwhile in life!

Murray

 

[RH Designs]

to then 'fudge' time durations to match f number sequences is non-sensical and pointless, the two things are different measures

The result on the paper (or film, come to that) depends on the volume of light delivered to it, and this is the product of the lens aperture and the exposure time. Adjusting either affects the result. So it makes perfect sense to use a logarithmic sequence of exposure times as well as lens apertures. Yes, they are different measures, but the effect on the exposure is exactly the same.

Look on your camera: do you not see a similar logarithmic sequence of shutter speeds? Nobody questions that. So why is nonsensical to use a similar sequence when making a print?

As for bulb warm-up and cool-down, these largely cancel each other out and the effects on any but the shortest exposures are minimal in my experience.

 

[RalphLambrecht]

1) Do you make one expsoure for the total time? or
2) Do you repeat the series of exposures that made up the test strip? or
3) It doesn't really make a difference

Todd

Todd

Make the print exposure for the same time and in the same way as you did the best test exposure. For your interest, my free article on f/stop timing, which includes a table, is still available on my website at:

Dead Link Removed

 

[jstraw]

The result on the paper (or film, come to that) depends on the volume of light delivered to it, and this is the product of the lens aperture and the exposure time. Adjusting either affects the result. So it makes perfect sense to use a logarithmic sequence of exposure times as well as lens apertures. Yes, they are different measures, but the effect on the exposure is exactly the same.

Look on your camera: do you not see a similar logarithmic sequence of shutter speeds? Nobody questions that. So why is nonsensical to use a similar sequence when making a print?

As for bulb warm-up and cool-down, these largely cancel each other out and the effects on any but the shortest exposures are minimal in my experience.

It occurs to me that if you use a sequence of exposure strips on a sheet of paper and then decide on a base exposure from those choices, you can make another test strip with your timer set to that amount of time. You can observe the difference with your binocular, wetware metering system and make a decision about a minor adjustment (if needed) based on empirical observation. You could even develop a chart for these compensations..ie how much to add or subtract for any number of eliminated start/stop cycles when extrapolating an exposure from test strips.