Best enlarger timer

[MattKing]

Check if your prints come out good with your lens stopped down another click or two. That will depend on the lens.

Or - get a longer lens. A 60mm lens will get your enlarger head farther away from the paper (assuming you're using a 50mm on a 35mm negative).

Those ND filters look like a great option, though.

It seems strange at first, but changing to a longer lens doesn't help.
In an optical system like a projector or an enlarger, the light intensity at the screen or the paper isn't a function of the distance between negative and paper, it is a function of the magnification.
If you are going to make the same size print with the same negative, the resulting magnification will be the same, so the light intensity at the print will be the same, no matter which focal length you use.
The longer focal length may make for more comfortable working space though.

 

[Don_ih]

If you are going to make the same size print with the same negative, the resulting magnification will be the same, so the light intensity at the print will be the same, no matter which focal length you use.

That makes sense.

 

[RalphLambrecht]

In previous years and with simpler , less powerful, enlargers using a enlarging timer that timed in seconds and minutes was not an issue.
I am now faced with much more efficient light sources that are giving me exposure times of about six seconds at F11 printing an 8 x 10.
This gives no 'real' time to manipulate the exposure.
Short of figuring out some sort of ND filter how can I rectify this?
The bulb in my LPL C670 is an odd size physically , it's much smaller than a regular enlarger bulb si It's not easy to just reduce the wattage.

Are timers that time to half of a second necessary?

TB

Ideally standard exposure times are around 16 seconds, which gives a lot of flexibility for dodging and burning.

 

[randyB]

Don't put plastic above the condensers, it can melt. I would get a Darkroom Automation F stop timer. The inventor is right here if you need help. Pricing is quite reasonable. Once you have used a f stop based timer you will understand why these are so popular.

If you want to increase time I would find a neutral density filter a gel in the filter drawer or even a screw-in type filter fitted to your lens. Most lenses are sharpest 2-3 stops down from the maximum aperture.

In all those years of using a plastic/vinyl diffusion sheet in my B22, 23c, 67xl enlargers I never had anything "melt". Plus, in all those years of color printing with individual CC filter stacks above the condensers nothing ever "melted". If your enlarger gets so hot that it melts things then you have problems far worse than "too much light". In my opinion, one possible solution to the original OP problem is to reduce the wattage of the bulb, LED bulbs can easily meet that need, you just need to find one that sort of matches the original incandescent bulb. One thing to keep in mind is that LED bulbs may not have the same color temp (Kelvin temp) as the incandescent bulbs so your photo paper may respond differently (contrast, D-max). A few years ago I made an LED lamp house for my 5x7 enlarger, it works very well but I did notice a slight change in the contrast from my ancient cold light head, I adjust with under the lens gelatin filters.

 

[Luckless]

Whatever timer you go with, I strongly suggest one that works in Stops/EVs of some manner, and one which can at least auto-reset the timer for you. Having your adjustments be based in even stops just like your camera exposures makes test strips far more useful and easier to use than running off linear time like +/- 5 seconds and rechecking, or doing a bunch of exposures and adding 5 seconds to each step.

Sure I can use a regular linear time scale enlarger and a reference chart/try accurately memorizing the steps, or mark up a linear dial timer with a new scale, or,... I could have a computer do it for me.



I ended up building a custom digital timer out of an Arduino Nano, a pair of relays, a few buttons/dials, and a 4x20 character LCD. Also included light meter mode with an Adafruit TSL2591 sensor, but I'm still experimenting and evaluating its usefulness.

For anyone who wants to dive into tinkering with a custom option, I will say that there are better options for micro controllers than the Arduino models. Arduinos are accessible with a solid community backing, but they're also kind of a cramped digital environment to work in. Plenty of room for a simple mode or two, but you can quickly run out of space if you have lots of modes and lots of manual debugging lines to check things are running as expected.

Main custom mode I wanted on mine was being able to run a series of exposures. So I can set my starting EV, the size of the step in EV for a series, and it will auto-run the next exposure at the press of a button. Combined with a simple paper holder made out of card stock with a set of notches cut in it for spacing, and a cover sheet from a piece of black card stock, I can quickly set my series, load a 4x5 test sheet, align to take a test strip off my negative, tap a button for the exposure, pull paper carrier to next slot, tap button, repeat.

Quickly gives me an evenly spaced set of exposures of the same patch of my photo, and I can either make an estimate for a full size trial run off that, or decide what parameters to adjust for my next test run. No more flubbed times from manually adjusting a timer dial for each exposure.

 

[mshchem]

In all those years of using a plastic/vinyl diffusion sheet in my B22, 23c, 67xl enlargers I never had anything "melt". Plus, in all those years of color printing with individual CC filter stacks above the condensers nothing ever "melted". If your enlarger gets so hot that it melts things then you have problems far worse than "too much light". In my opinion, one possible solution to the original OP problem is to reduce the wattage of the bulb, LED bulbs can easily meet that need, you just need to find one that sort of matches the original incandescent bulb. One thing to keep in mind is that LED bulbs may not have the same color temp (Kelvin temp) as the incandescent bulbs so your photo paper may respond differently (contrast, D-max). A few years ago I made an LED lamp house for my 5x7 enlarger, it works very well but I did notice a slight change in the contrast from my ancient cold light head, I adjust with under the lens gelatin filters.

Leds can get hot too. Purpose built heads like Heiland are cool because the ac to DC transformer is not in the light source like Edison base leds.
Leds like Heiland uses are purpose engineered, work great with multigrade papers.

Most leds don't work well in an enclosed space, the transformer in the base of the bulb gets too hot and fails.

There should be a filter drawer below the condensers and above the negative carrier, this is where any neutral density filter should go.

Follow the manufacturer instructions, you can try a smaller bulb but 75W is a small bulb. Could be the simplest explanation is the OP needs to increase the density of their negatives.

 

[mshchem]

Ideally standard exposure times are around 16 seconds, which gives a lot of flexibility for dodging and burning.

Ralph wrote the book, literally! I suggest buying both editions!

 

[Doremus Scudder]

Check if your prints come out good with your lens stopped down another click or two. That will depend on the lens.

Or - get a longer lens. A 60mm lens will get your enlarger head farther away from the paper (assuming you're using a 50mm on a 35mm negative).

Those ND filters look like a great option, though.

Don,

Just to clarify: Using a longer lens to get the same print size will not result in a longer exposure time. The same portion of light is hitting the paper at the same intensity with both the short and the long lens. It's just that the shorter lens has a wider angle of projection and the longer has a narrower angle. Since the light is focused and directed, the inverse square law does not apply here. If the image size (read magnification) is the same, and the f-stop is the same, and the enlarger-light intensity the same, the exposure time will remain the same too.

Best,

Doremus

 

[MattKing]

On the subject of using an LED bulb instead in a condensor enlarger designed for a teardrop shaped bulb:
1) with condensor enlargers in particular, the placement of the "filament" is important. Any LED bulb should probably mimic that; and
2) the colour temperature and "CRI" of the LED bulb may or may not give you the information that you need about the suitability of that bulb for variable contrast printing, because LEDs have spectra that includes spikes and valleys, and if those spikes and valleys coincide with the colour of light that the various emulsion components are either most sensitive to or least sensitive to, the contrast response of the filters and paper may be much less predictable.

 

[Don_ih]

Using a longer lens to get the same print size will not result in a longer exposure time.

@MattKing already said as much. Once I thought about it, it made sense.

 

[bernard_L]

Thanks - here is the incandescent bulb:
View attachment 334566

My Beseler 67CSXL (bought 1983) takes the same bulb. When the original bulb died, I could find no 220V replacement; bought a 120V from KHB, and rigged up a transformer. Then, out of curiosity, I tried a regular-sized 220V 75W halogen bulb. Test, works equally well. Keep in mind that a "condenser" enlarger is not a point source enlarger, so it makes sense that it's not that sensitive to the size of the light source.
Epilogue: having paid dearly for the imported bulb (shipping, customs, brokerage) I keep it in use, with the transformer.

As concerns the OP's problem. You might try a low-medium power LED bulb (say, 25W tungsten equivalent), 4000K, size A19 or A15 or S11. Not guaranteed to work, but cheap experiment. Check what goes on with variable contrast grades.

 

[MattKing]

My Beseler 67CSXL (bought 1983) takes the same bulb. When the original bulb died, I could find no 220V replacement; bought a 120V from KHB, and rigged up a transformer. Then, out of curiosity, I tried a regular-sized 220V 75W halogen bulb. Test, works equally well. Keep in mind that a "condenser" enlarger is not a point source enlarger, so it makes sense that it's not that sensitive to the size of the light source.

This may very well vary from enlarger to enlarger - but point taken.
I would expect that it is the positioning of the light that matters most.

 

[Xylo]

Don,

Just to clarify: Using a longer lens to get the same print size will not result in a longer exposure time. The same portion of light is hitting the paper at the same intensity with both the short and the long lens. It's just that the shorter lens has a wider angle of projection and the longer has a narrower angle. Since the light is focused and directed, the inverse square law does not apply here. If the image size (read magnification) is the same, and the f-stop is the same, and the enlarger-light intensity the same, the exposure time will remain the same too.

Best,

Doremus

Actually, the inverse square law always applies no matter what. There are no exceptions in physics.
You have a finite number of photons that get emitted by the lamp.
When you use a longer lens, the light cone is bigger than when you use a short lens at a given distance.
What makes the image size the same is the negative holder itself which absorbs all the photons that fall outside of the negative place.
To focus a longer lens, you need to put it further away from the negative than with a short lens.
Since you project a smaller negative, you need to rise the head more to get the same size image. That means that more photons get absorbed by the negative carrier and the internals of the enlarger.

I really like an analogy I once heard in College. Light is like peanut butter. If you spread a teaspoon of it on a slice of bread, you'll have a pretty thick coating. But if you double the size of surface to coat, increasing it to four slices, you'll have only enough peanut butter to lightly cover them.

Cropping an image at it's source doesn't condense light in a smaller area.

I just measured it using my enlargers.
6x6 negative focused to a 10x10 with a 135mm: 27 inches from lens to baseboard.
6x6 negative focused to a 10x10 with a 75mm: 16 inches from lens to baseboard.

If it didn't have any effect, the projectors in movie theaters wouldn't need such powerful bulbs.

 

[albada]

For anyone who wants to dive into tinkering with a custom option, I will say that there are better options for micro controllers than the Arduino models. Arduinos are accessible with a solid community backing, but they're also kind of a cramped digital environment to work in. Plenty of room for a simple mode or two, but you can quickly run out of space if you have lots of modes and lots of manual debugging lines to check things are running as expected.

Agreed. I used an Arduino Uno for my combined timer and LED-head controller, and ran out of both flash and RAM. I switched to the development board for the PIC18F57Q84; here's the link in Mouser: PIC18F57Q84 CURIOSITY NANO EVALUATION KIT. I didn't use the Raspberry Pico because I didn't know it existed -- ignorance.

What do you use instead of an Arduino?

Mark

 

[MattKing]

Actually, the inverse square law always applies no matter what. There are no exceptions in physics.
You have a finite number of photons that get emitted by the lamp.
When you use a longer lens, the light cone is bigger than when you use a short lens at a given distance.
What makes the image size the same is the negative holder itself which absorbs all the photons that fall outside of the negative place.
To focus a longer lens, you need to put it further away from the negative than with a short lens.
Since you project a smaller negative, you need to rise the head more to get the same size image. That means that more photons get absorbed by the negative carrier and the internals of the enlarger.

I really like an analogy I once heard in College. Light is like peanut butter. If you spread a teaspoon of it on a slice of bread, you'll have a pretty thick coating. But if you double the size of surface to coat, increasing it to four slices, you'll have only enough peanut butter to lightly cover them.

Cropping an image at it's source doesn't condense light in a smaller area.

I just measured it using my enlargers.
6x6 negative focused to a 10x10 with a 135mm: 27 inches from lens to baseboard.
6x6 negative focused to a 10x10 with a 75mm: 16 inches from lens to baseboard.

If it didn't have any effect, the projectors in movie theaters wouldn't need such powerful bulbs.

Sorry - this only applies for enlargers that allow you or require you to move the negative carrier and/or the condenser(s) in relation to the light source - e.g. a Beseler 23C. That movement has the effect of changing the intensity of the light passing through the negative.
The OP's LPL enlarger keeps those distances fixed.
If you use an enlarging meter, you will discover that your two 10x10 images will have essentially the same intensity, if the f/stop is the same. There might be a small difference arising out of the effects of flare.

 

[Hilo]

In previous years and with simpler , less powerful, enlargers using a enlarging timer that timed in seconds and minutes was not an issue.
I am now faced with much more efficient light sources that are giving me exposure times of about six seconds at F11 printing an 8 x 10.
This gives no 'real' time to manipulate the exposure.
Short of figuring out some sort of ND filter how can I rectify this?
The bulb in my LPL C670 is an odd size physically , it's much smaller than a regular enlarger bulb si It's not easy to just reduce the wattage.

Are timers that time to half of a second necessary?

TB

The best timer is the one you use and are happy with.

In my case, since no later than the mid-eighties, this has been the Kearsarge 301 which is a digital timer that also does 1/10 of a second.
I never needed to change, and in fact I got two more of them over the years. Two timers are permanently connected to one enlarger each, the third timer sits between two more enlargers and I use a switchbox to go from one enlarger to the other.

I use condenser enlargers only: Focomat Ic and IIc, a wall mounted Durst L1000 and a modified Valoy II that allows up to 50x60cm (20x24in.). All enlargers have 150watts bulbs. My smallest size is 24x30cm (workprints) and their basic exposure is about 20 seconds with the lens 2 stops closed. The basic exposure of 50x60cm is about 70 seconds, except with the Valoy II it is about 45 seconds (the bulb sits closer to the negative). The exposures of the Durst are a bit longer, I believe this is due to the light system that involves a mirror.

These exposure times are based on closing the lens two stops. When exposures are longer than this, I will open the lens one stop and in a rare case even fully open.

These exposure times I mention are with 35mm negatives, using Focotar lenses mostly, which open at 4.5. Sometimes I switch to Meopta Meogon 50 or 60mm lenses that open at 5.6. Their exposures are longer.
Doing medium format, the exposures are shorter by about 25%. I use the Focotar 100mm which opens at 5.6, or several (100mm and 135mm) Schneider lenses in the L1000.

When printing I hardly think about any of the above. Perhaps never.

 

[Nicholas Lindan]

...using a enlarging timer that timed in seconds and minutes was not an issue.

Arrrrgh...it just hit me. Timing exposure in minutes and seconds! I must have done this when making 20x24" prints. I used a GraLab with my enlarger, not thinking twice about it (until now when I have become enlightened and a bit of a proselytizing twit).

Figuring exposures in those dim years must have been a treat: Adding a 1/2 zone of tone by increasing exposure by 25%, with a base of 2 minutes 35 seconds would have gone like this:

Let's see: "2'35" is 155 seconds; 25% of 155 is 39, call it 40; 155 + 40 is 195; 195 seconds is 3 minutes and 15 seconds. And then crank around the hands of the GraLab.​

As compared to just adding the ~1/4 of a stop by bumping the exposure from 7.3 stops to 7.6 stops.

At the very least an enlarger timer should work 1 to 999 seconds, setting exposure time in minutes adds nothing of value. Doesn't add much of value to development times either.

 

[Xylo]

Sorry - this only applies for enlargers that allow you or require you to move the negative carrier and/or the condenser(s) in relation to the light source - e.g. a Beseler 23C. That movement has the effect of changing the intensity of the light passing through the negative.
The OP's LPL enlarger keeps those distances fixed.
If you use an enlarging meter, you will discover that your two 10x10 images will have essentially the same intensity, if the f/stop is the same. There might be a small difference arising out of the effects of flare.

You suddenly had me doubting what that physics teacher thought us all those years ago. So I decided to do an empirical test and you are definitely right. It doesn't have much effect at all.

I setup both an 80mm and an old 150mm I had at the bottom of a cupboard and did a comparison using my Sekonic meter in EV mode. While I couldn't get the bellows to focus the 150 and had horrible light fall-off due to the inappropriate condensers being used, there was about a 1 EV difference between both... Which could be due to either the wrong condenser set, the lens design, number of elements or type of glass used. The only really good thing is that I would have gained a lot of room for dodging and burning.

Thanks for making me doubt. I just love being wrong and learning new stuff
(and I can't believe that that teacher got paid for telling kids a bunch of bull, though he wouldn't be the first to be on that list)

 

[MattKing]

You suddenly had me doubting what that physics teacher thought us all those years ago.

I expect your physics teacher mistakenly applied the rule that applies to an optical system that doesn't focus to one that does.

 

[Roger Cole]

ND filter in the enlarger is my choice too. An 0.6. Wratten ND sits nicely atop the lens, and you can still see what you are doing. You can also increase your camera exposure. Two stops greater camera exposures will give roughly double print time (compared to perfectly exposed negatives).

Well sure, at the risk of pushing highlights onto the shoulder - most modern films have little shoulder but a few do and all will if highlights are pushed up far enough - and substantial increases in graininess. I’d never expose more in the camera just to get longer enlarger exposures.

 

[ic-racer]

The reason a longer lens is not going to help is that, although the physical aperture is larger at a given f-stop, you can't stop any farther down, because the diffraction effects are magnified. So if you prints are telling you to not go beyond F11 with a short lens, you will also be limited to F11 with the longer lens, even thought the opening is physically bigger.

 

[Doremus Scudder]

Nicholas,

I see your point in using an f-stop timer if your exposures are in the many-minutes range! I use percentages, but rarely have an exposure that exceeds one minute, even with large prints. At any rate, I count seconds and don't worry about converting 75 seconds to 1 min. 15 sec., so figuring 10%, 20%, etc., is still easy to do in my head.

My GraLab digital timers (450s I think) go from one to 99 seconds. They are permanently set on 99 seconds, the metronome function is on and I simply count. I use a card to start and stop exposures. Sometimes, when I have a lot of burning to do, I'll have to step on the footswitch a time or two more. No problems there.

I like longer exposure times because they a) allow me more time for dodging and b) take the inaccuracies out of the entire procedure. The longer an exposure time is, the less a one-second discrepancy makes any difference.

I'd go crazy having to set the hands on an old GraLab 300 for every exposure! Heck, I'd go crazy having to set any timer for an exposure. I've set mine exactly once per unit in all these years.

Best,

Doremus

 

[ic-racer]

Since the concept of over-exposed negatives was mentioned, one might want to take note of the information presented in the diagram. It indicates that over-exposure of negatives (to make them denser for printing) would work best when contact printing. Over exposure can diminish image quality after 1 or 2 stops if the negatives are used for enlarging.

 

[cliveh]

Since the concept of over-exposed negatives was mentioned, one might want to take note of the information presented in the diagram. It indicates that over-exposure of negatives (to make them denser for printing) would work best when contact printing. Over exposure can diminish image quality after 1 or 2 stops if the negatives are used for enlarging.

I am interested in the axis that defines print quality. Can you please explain?

 

[Nicholas Lindan]

I am interested in the axis that defines print quality. Can you please explain?

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