My enlarger exposure times are way out of whack

[Rob H]

*snip*

Most, but not all, enlarging lenses have female thread at the front that allows mounting filters, thread-in filter holders, etc.

*snip*

Mine is a Beslar 75mm, as shown thusly.

I don't detect any threads in there, but I guess it could have some.

 

[GregY]

Beseler 23C and 45MX (T)...... have an add-on under the lens filter holder

Under Lens Filter Holder for Beseler 23C and 45M series Enlargers

 

[mshchem]

*snip*

Mine is a Beslar 75mm, as shown thusly.

I don't detect any threads in there, but I guess it could have some.
View attachment 342873

Should be a 39mm lens retaining ring holding the lens on the lensboard. Matt is correct about the dimmer. Beseler had a Resistrol gimmick back in the day, a rheostat to dim the bulb. Presumably it worked for graded paper.

 

[Ian C]

The 3-element Beslar enlarging lenses have no threads at the front of the barrel for filter attachment.

I assume that you are using the 23C enlarger in its standard lamp & condenser configuration. If so, then using a lamp dimmer is a cheap and practical solution to controlling the illumination and, therefore, the exposure time.

Here’s one rated for 75W to 300w. Depending on when your 23C was made, the lamp is either the bayonet base PH-111 or the screw-in-base PH-140. Both are 75 watts, so this dimmer will work with your enlarger.

It is not correct for a dichroic filtered color head that needs the standard 120-volt U.S./Canada current in order to work properly.

https://www.ebay.com/itm/285327922862?hash=item426ede96ae:g:ZhsAAOSwj1NjwGv1&amdata=enc:AQAIAAAA4L9YaxL6CIeinaEOEgHC1Uc460NZ7irEOZnRBzWFRtHacga7dcy1d8gbQK7VOeWeOcFzW3gpi4ajpDw3qIblVfwLYw230z8wwCdqySm6EIGpzCIE6iXTyfCegZA/izwzTPSdmwSmFk4yj8SisVv107rtmI+37ybf3bXXo6/7tc06Nroug10uBxCTczef0PUK26pGiTz1jfo1n3S4tlboFAY/mYFV5PXXWPLNuRrm/XS1/9tlsp6mm1XsuT9pxTvrc66t/op37Q9OguKUXQLtd54dnQD39MwmVMyB6798A8un|tkp:Bk9SR7q7rIukYg

 

[ic-racer]

Accessories for the original Beseler 23, in 1959, helped alleviate the effects of altering lamp voltage, as cautioned in post #25 above.

 

[koraks]

Accessories for the original Beseler 23, in 1959, helped alleviate the effects of altering lamp voltage, as cautioned in post #25 above.

I don't see how visualizing the voltage changes anything about the bulb emitting a different spectrum at a lower voltage (=temperature). There's nothing in that simple system that actually compensates for such differences.

 

[cliveh]

Most of my print exposure times for 35mm negs on 10" X 8" paper are between about 6 and 12 seconds.

 

[Pieter12]

I don't see how visualizing the voltage changes anything about the bulb emitting a different spectrum at a lower voltage (=temperature). There's nothing in that simple system that actually compensates for such differences.

Was variable grade paper even around or common in 1959? If not, the color temperature change with a dimmer probably wasn’t a consideration. If the Beseler has a filter drawer, ND gels are cheap and an easy was to extend exposure time.

 

[DREW WILEY]

Modern voltage stabilizers meant for specific enlarger colorheads typically reduce the incoming rated voltage about 5% to prolong the life of the bulbs, and buffer against moderate surges. It is not a good thing to fool with that ratio and use clumsy rheostatic voltage reducers. And just because ancient Beseler beehive heads are not exactly the same concept, their bulbs should be comparably regulated anyway, for sake of printing consistency and service life.

Better to resort to some kind of ND control than use a rheostat.

 

[koraks]

Was variable grade paper even around or common in 1959?

Probably not, but @ic_racer implied (probably a simple misunderstanding?) that the rheostat and complementary voltmeter would somehow nullify the color temperature effects of dimming an incandescent bulb. That isn't the case, and with both variable contrast materials and color printing papers easily available today, it's a relevant consideration. The 1959 solution does not solve today's challenge.

 

[ic-racer]

Color temp. of the lamp is linked to voltage. You can't measure the color temp, but you can measure and control the voltage.

Color temp. is also linked to printing contrast when using multigrade paper.

Perhaps there is a misunderstanding of the projection printing process. The key concept to multigrade printing is reproducibility between the test print and the final print. Knowing that the lamp voltage is constant from test print to final print takes that variable (lamp temperature) out of the printing process. Essentially nullifying it.

 

[koraks]

Knowing the lamp voltage takes that variable (lamp temperature) out of the printing process.

Only if it's kept constant!

Look, for VC B&W printing it's not going to be a major issue anyway. Let's just drop it.

 

[ic-racer]

For example, the chart above shows that a lamp driven at

Only if it's kept constant!

Exactly! That is what the voltmeter and voltage control are for.

 

[Rob H]

So, at a lower voltage, is it going to be more contrasty or less contrasty?

 

[MattKing]

So, at a lower voltage, is it going to be more contrasty or less contrasty?

It is going to be different contrast.
More importantly, it will be difficult to achieve consistent, session to session contrast, because there will be more variation over time - particularly if you need to replace the bulb.
In contrast (pun acknowledged), a sheet of ND filter in the filter holder should permit more consistency.

 

[koraks]

So, at a lower voltage, is it going to be more contrasty or less contrasty?

There will be less blue in the spectrum and hence, each VC filter will print a little less contrasty with a lower voltage and color temperature than at a higher voltage.
I don't know how big the difference will be and if it's worth fussing about in the first place. I doubt it, to be honest.

 

[faberryman]

What color temperature are multi-contrast papers calibrated for out of the box? I checked out a few enlarger bulbs and found some were 2900K, some were 3200K, and some were 3400K. There may be others having different color temperatures. I know my Aristo cold light head does not give me the full range of contrast grades, and that the grades are a little different than those marked on the filters. I do not have the updated WA45 tube.

 

[L Gebhardt]

What color temperature are multi-contrast papers calibrated for out of the box?

Ilford claims unfiltered the paper has a contrast of 95 (grade 2). I assume this is with a normal incandescent enlarger bulb, so around 2900K, but they do not say. They also don't say if it's a condenser or diffusion light source which probably makes just as much difference. Many diffusion enlargers use halogen bulbs that are more like 3300K. That may somewhat equalize the contrast between the condenser with a warmer bulb.

 

[MattKing]

What color temperature are multi-contrast papers calibrated for out of the box?

From the datasheet for the current RC papers:

and:
Exposing light sources
MULTIGRADE RC papers are designed for use with most enlargers and printers, that is, those fitted with either a tungsten or tungsten-halogen light source. It is also suitable for use with cold cathode (cold light) light sources and LED exposing heads designed for variable contrast papers. Other cold cathode (cold light) and pulsed xenon light sources may give a reduced contrast range.
The three emulsion components that together control the resulting contrast have different sensitivities, so they would most probably be functional with a variety of colour temperatures.

 

[faberryman]

I have seen the spectral sensitivity chart. I do not know how to correlate the numbers there expressed as wavelengths in nanometers to color temperature expressed in degrees Kelvin, so I cannot deduce how a change in color temperature might affect (if at all) contrast on the variable contrast papers.

Likewise, the information on light sources provides no information about how the color temperature of the light source may (or may not) affect contrast on variable contrast papers, or for what color temperature the paper is calibrated.

If the OP is being counseled not to use a dimmer on his enlarger bulb because it will change the color temperature of the light, it would be helpful if he could be shown the impact of a change in color temperature on contrast.

Let's say he is using a 120V PH111A bulb which has a color temperature of 2900K. To extend exposure time he drops the voltage to 110V using a dimmer. What is the resulting color temperature? What is the effect of the resulting different color temperature on contrast? Does a #2 filter now act like a #1 filter, or something else? The same questions arise with the use of a 120V PH213 bulb which has a color temperature of 3400K. Will a 2900K bulb print the same contrast as a 3400K bulb? If not, are there conversion charts? I have seen a contrast filter conversion chart for my Aristo cold light head.

 

[GregY]

To go back to the OP's post, a 5x7 is a small print. I have a Durst 138 and a Beseler 45MXT with a Zone VI VC head. My print times would also be very short.... especially with RC paper ( which i don't typically use.) As mentioned Foma or Ilford WT FB would provide longer exposure times.

 

[Pieter12]

To go back to the OP's post, a 5x7 is a small print. I have a Durst 138 and a Beseler 45MXT with a Zone VI VC head. My print times would also be very short.... especially with RC paper ( which i don't typically use.) As mentioned Fomabrom or Ilford WT FB would provide longer exposure times.

I get very similar times with ilford RC & fb papers.

 

[GregY]

I get very similar times with ilford RC & fb papers.

Ilford warmtone & Foma fomatone are slower papers....as are most warmtone papers

 

[Pieter12]

Ilford warmtone & Foma fomatone are slower papers....as are most warmtone papers

I was comparing neutral glossy times.

 

[GregY]

I was comparing neutral glossy times.

"My print times would also be very short.... especially with RC paper ( which i don't typically use.) As mentioned Fomabrom or Ilford WT FB would provide longer exposure times."

I had specified warmtone. i'd just add the Beseler under the lens filter holder, and/or try some slower papers before i went to changing the electronics of my enlarger. In addition to me a 5x7" is a workprint or snapshot...not much real estate there to worry about dodging /burning.