Long printing times - when they're really long? :)

Times do seem to be long. Have to assume your making medium size enlargements.

The first question is has the enlarger got the correct wattage halogen lamp(s), as this would make a very significant differance.

The second is the density of your negatives, this can also cause long exposure times.

Typically with a colour head printing on B&W paper I would expect exposures in the range of 15 - 30 seconds printing approx 20 x30 cms and sopping the lenses down to f11 -f16.

Remember that the speed od B7W paper vaies significantly between manufacturers, and this alone can make a differance of 2 stops

Ian

 

I don't think it's that unusual with colour enlargers. My exposure times are often around a minute for a 16x12 (using an LPL C7700), and if you're using warmtone papers, the slower speed will increase exposure time. On the upside, a long exposure makes it easier to dodge areas.

I've found my Nikon lenses just as good wide open as two stops down. Somebody once told me that enlarging lenses are actually optimised for wide open, but I don't know if that's true in general.

 

Zhenya

I found an excellent source for halogen bulbs for my Devere enlarger, it uses 4 120v 300w.

Will have a look for ther website, I think the bulb your after should be available.. Using the correct wattage bulb will make a very big differance, and give you more flexibility.

Ian

 

Try http://www.donsbulbs.com

Ian

 

Richard is correct. Enlarging lenses are fairly good wide-open. The typical recommendation of stopping down at least two or three stops was put in question by Ctein in his book 'Post Exposure', who published the max quality aperture for many enlarging lenses. Many of them performed better wide-open. I have gone to stopping down for just one stop, max two if times are too short for dodging and burning.

Just make sure your safelights are 'safe'. Long exposure times give the gremlins in bad safelights a chance to jump all over your print.

 

The lifespan for enlarger bulbs is because of how they are used. For example my enlarger bulbs are rated at 50 hours but the same bulb used in some other devices is rated at something like 1000 hours. Why? I think the main reason is the constant on/off cycling that enlarger bulbs get. If you treat your household bulbs like enlarger bulbs don't be surprised if they don't outlast the enlarger bulbs.

To the intial question. Are you getting the same long times with both formats? Are you using a smaller lightbox for 35mm? Is the lightbox dirty inside?

I've no problem with times on my Beseler colour head. OTOH my Durst is slower. Both use the same bulbs.

 

First ... Contact Calumet. Their catalogs had an extensive list of enlarging and projection lamps for a wide variety of equipment. I'd be surprised if they did NOT carry the proper "bulb" - at a lower price than original equipment.

Next - I'll apologize in advance for the forthcoming rant. If anyone cares to stick with "but everyone KNOWS", just scroll on down...

For Pete's sake. gang. Give the lens manufacturers a little credit for intelligence. Their designers have long recognized the sensitivity out there to the results of their products. ALL the major manufacturers pay particular attention to resolution, definition, contrast and distortion over any reasonable conditions of use.

There is a major reason why lenses are limited as far as maximum and minimum aperture.... their use beyond the limits available will result in a reduction of image quality. I've read that "enlarging lenses should not be used at their smaller apertures because of diffraction." For crying out loud, gang, there is a reason for a minimum aperture - and that is that beyond that limit - actually quite a bit beyond that limit - there will be a noticeable decrease in quality, but as long as one stays somewhere within the available range, diffraction will NOT be a problem.
Give the Optical Engineers a little credit ... They KNOW what they are doing... and if they did not, they wouldn't last ten minutes at Rodenstock or Schneider, or Fujinon, Nikon, Elgeet, Wollensak...

There would be an interesting exercise -- If anyone believes that the image quality would be materially degraded at the extremes of the aperture choice, they could make test prints, hopefully LARGE ones to magnify quality differences, from wide open through "optimum middle" to extreme closed, paying close attention to focus and reciprocity-influenced exposure - then mix them up and compare the results.

I have not done this ... I have much more confidence in the reputation of the major enlarging lens manufacturers and their designers to justify the work involved.

Is there an "optimal" aperture in lens design? Yes, definitely .. it is part of the Design Specifications, but enlarging lenses (and I'll include all the rest) do not "fall off a cliff" at other apertures.

 

I've not done this over the whole range, and I didn't pay much attention to reciprocity effects, but I have done it over a few f-stops. There are definite and visible differences with my 4-element 50mm lenses (Nikon el-Nikkor f/4, Durst Neotaron f/2.8, and Industar-96U f/3.5), with f/8 seeming best of the apertures I tested with all of them. My 6-element Nikon el-Nikkor f/2.8 shows much less in the way of differences across apertures. Testing across the entire range, I don't know how noticeable those differences would be.

 

Ed. Only veering away slightly from your statement, I hope, but is there any truth in the statement in the F Schultz article on the Colourstar 3000 that when choosing an aperture for exposure it is important to aim for between 5-10 secs. Frances says: shorter exposures may be "hot" (colour balance affected? Unfortunately Frances doesn't elaborate) because of the warming and cooling of the lamp; longer exposures may run into problems with reciprocity failure"

Checking the manual itself, it recommends between 4-10 secs but only mentions reciprocity failure as the reason for this and not lamp heating and cooling. It does go on to say that another channel can be calibrated for printing accurately at 30...80 secs. So its clearly a problem that can be overcome should long exposures be needed.

If short "hot" exposures are an issue and long exposures also unless a channel has been calibrated for it then it may be that while f2.8 or f4 might be OK print resolution- quality wise, both would result in too short exposures and equally f16 may cause reciprocity problems.

So very big or very small apertures are not a problem in terms of resolution but in terms of exposure.

If all, some, none of this is true in practice for colour work, what applies to B&W?

thanks

pentaxuser

 

The warming and cooling of the bulb is relevant, since for a certain period of time after turning the lamp on and off, the bulb will have lower color temperature than expected for constant operation. The duration of this "glow" is independent from the exposure time, and hence the effect varies with exposure time, and is the greatest at short exposure times.

This is why some enlargers have a shutter. The shutter is only released after the warm-up of the bulb and closed immediately after the exposure is finished.

The effect is probably not that important for a b/w enlargement because there is no color balance issue with b/w enlargements. Only if you use variable contrast paper, the contrast may be slightly affected.

It is hard to make any statement about the relevance of reciprocity failure during printing. You would have to consult the data sheet of the paper in question. Some data sheets have graphs for reciprocity failure. If the manufacturer does not provide this information (they should), you could just make a test on your own.

 

This is interesting. It is difficult enough to get information about the color temperature of the various enlarger lamps ... at any time after their initial incandescence ... I have never seen a time sensitive study of color temperature.

If the minimum parameters are limited to 5 - 10 seconds or so - I am not familiar with the ColorStar's response time - I have never really paid attention to that charactersic - it should be possible to burn the lamp for one or two minutes and get some information about any color shift.

I'll try it, as soon as I get the chance. Right now I have an active exhibition taking up a great deal of my time.

There is always the possibility of density changes of the various color layers in the paper due to reciprocity effects. I'll study that as well.

It is always possible to calibrate a channel in the ColorStar using a different time than the recommended five seconds - I have done that with as much as twenty seconds --- I have noticed an overall density reciprocity change (slight) requiring a "n" setting of .05, but I haven't noticed a shift in color balance.

You have piqued my curiosity. Stay tuned.

 

Continuing...

I've investigated the effect of long exposure times on color balance, due to bulb heating.

Using my Omega D5500 - an "EYA" lamp; 82V, 200 Watts, 3300 K color temperature - I've "balanced" the image from a grey card negative, using one of my three (3) ColorStar 3000 Analysers (long story - more later). Setting the exposure time to the maximum available on the D5500's controller, 99.9 seconds, I observed, carefully, the ColorStar's balance indication array over that exposure time. Multiple observations indicate *NO* change - none wahtsoever - in color balance... or exposure.

It should be noted that this is a "modern" enlarger configuration: a halogen lamp with a regulated power supply; fan cooled with an (expensive) "heat glass" IR filter immediately ahead of the lamp. All that may be vastly different from the uncooled, no fan or heat glass, systems of older enlargers.

Additionally, I've watched, carefully, color balance "drift" over a six or seven HOUR enlarging session - the greatest change I've seen is 1 (ONE) CC (magenta).

Reciprocity of color paper, with its multiple color layers (I imagine each layer has its own charateristics) is something else again.

That is next on my "curiosity" schedule.

 

Same arrangement, save for a fourth ND, on my now
shelved Meopta. I found by your same test that the
bottom diffuser was too thick in center and caused
the "graying" to lighten as center was neared.

If I could find a condenser head for that Meopta I might
be able to use it. I've a mind to sell it but who wants an
enlarger that vignettes and towards center at that? Dan

 

Dear Pentaxuser,

As Frances Schultz's husband, perhaps I may step in here.

The heating and cooling of the lamp is indeed the factor that is relevant. Yes, there is a risk of a shift towards red: sorry she didn't say any more about it, but there are always word-count constraints. The shift varies from enlarger to enlarger depending on wattage, voltage, bulb design and (as usual) intangible variables such as the phase of the moon. By 5 sec minimum this should be negligible with all designs; with some, it may be OK at 3 or so.

As for the 'is there any truth in it', well, yes, we try to make most of what we write reasonably true. We are among the ever-fewer journalists and authors who do this because we love it. It sure as hell isn't for the money!

Cheers,

Roger (www.rogerandfrances.com)

 

I'd agree. Most enlarger lenses I've tried, good or bad, regardless of the number of glasses (3, 4 5 and 6 in the ones I've used), have a 'sweet spot' which may be limited to a single aperture (such as f/5.6-and-a-half = f/6.8) or may extend across a couple of stops or more. In this 'sweet spot' results are visibly better than at larger or smaller apertures.

I'd also agree with Ed that manufacturers ain't stupid, but add to his observations that sometimes the maximum and minimum aperture are there to be used only in desperation: wide open and f/16 (or f/22 if available) are unlikely to be the optimum.

Cheers,

Roger (www.rogerandfrances.com)

 

Roger. Thanks for the reply. I should have read my post more carefully before sending. An unfortunate phrase that I used unthinkingly does give the impression that by implication I was calling your wife's truthfulness into question. This of course wasn't my intention and I apologise for this. Please convey this apology to her.

I should simply have asked the question in a neutral manner what effects short exposures have on colour printing and what factors play a part in such effects.

You and several others have been good enough to answer. I had received a copy of your wife's article with my secondhand Colourstar and found it a useful read, especially as it was written from the point of view of someone getting acquainted with the Colourstar as I was.

I had found the actual manual quite hard going. Like most user manuals they are written by people who are too familiar with the equipment to recognise the difficulties a newcomer might have. Her step by step approach written in an easy to understand manner was very helpful.

It's a pity that Frances wasn't given the space to expand. I might have learned to recognise when fully intergrated measurement was most and least appropriate and how to tackle other printing difficulties.

I previously used a Paterson analyser which only had a fully intergrated measurement system and lacked the sophistication of the Colourstar. However I have to say that in a comparison of prints produced with both analysers I cannot honestly say that the Colourstar prints have been better.

I have yet to find a good "How to" colour neg printing book( any suggestions welcome) which comes close to the books that exist on B&W and courses on the subject seem to have gone the way of the airship as a means of flying.

Maybe Frances and other practioners could be persuaded to pen some articles but that's another issue.

pentaxuser

 

It is a Opemus 6 with Color 3 head. I bought my
first 6 in 1961. I liked it so bought again in 1999.
VC papers are what I had in mind but have gone
back to Graded.

I've a new Beseler 23CIII in mind. If Meopta had
a US distributer I'd consider the Magnifax, condenser.
They do a fine job of metal work. Their castings are
very well done. Dan

 

Dear Pentaxuser,

Your apology is more than accepted. I didn't mean to sound quite as pettish when I replied, so I apologize too. Frances is perfectly happy.

Cheers,

Roger