Too short exposure time

ignacj · Mar 8, 2010

I'm having a problem with very short exposure times (under 2 secs) on my 45M. Following is the setup...

Beseler 45M (condenser)
150W bulb
no filter
f16 aperture
Adorama VGRC paper (ISOP 640, grade 2 without filter)
Dektol 1:2 (~1 min dev time)

I am getting a new 75W bulb, but I don't think this will significantly increase the exposure time. I'm also considering ND filter, but I cannot locate correct size (under the lens type). 45M does not have filter drawer as newer models (contacted KHB if retrofit is possible).

Negatives (35 and 120) are exposed/developed correctly and look fine when scanned on Epson.

Any suggestions are greatly appreciated!

Thanks
ig

nworth · Mar 8, 2010

I run into this problem with my 35mm enlarger. My solution was to put a neutral density filter in front of the lens.

Ben Taylor · Mar 8, 2010

I had a similar problem some years ago, discovered the fault was with my enlarging lens.

The lens had a ring you twist to fully open for focusing. I eventually discovered that when I turned this ring back to stop the lens back down to my selected aperture it would only party close the aperture blades, so I was using a much wider aperture than I thought. The solution was to focus first with the widest aperture selected, then stop the lens down.

Ronald Moravec · Mar 8, 2010

Put some tracing paper or make a ND filter from 4x5 film exposed to Zone 5 and put it above the condensers.

Buy an Aristo variable resistor. Expensive but well made. Good for 3 stops.

Make a resistor from a wall dimmer and 4 way box.

I find it very hard to believe you don`t have very thin negatives. Hold one up to a 60 watt bulb and look thru the darkest part. You should block most of the light.

If you are detirmining a neg is good by how it scans, you should revise your method and contact print it on #3 paper. That will give you a decent scanning neg depending on the film as some films scall better than others although they can print correctly.

Mainecoonmaniac · Mar 8, 2010

How about an ND filter above the negative near your light source. Rosco, the maker of theater light gels makes ND filters one, two and three stop increments. http://www.amazon.com/Rosco-Cinegel-Neutral-Density-Lighting/dp/B000B73PBS The gels are made for hot lights.

Good luck!

ignacj · Mar 8, 2010

Ben,

I can see aperture changing diameter as expected when off the enlarger. I do not think I have any additional controls that would prevent it from closing when on the enlarger.

Ronald,

Negs are fine. Dark areas are dark as you describe. Instead of using wall dimmer, any reason not to use a corded night-lamp remote dimmer with enlarger? Thanks

Mainecoonmaniac,

I use Rosco color gels with my studio lights and was not aware they made ND gels as well. I'll give it a try! Thank you!

fotch · Mar 8, 2010

The 75w bulb should double the exposure. A light dimmer is worth a try, the night light one you spoke of, just make sure it will handle the wattage.

Sim2 · Mar 8, 2010

Hallo,

I have experienced a similar problem with my enlarger. I have used it for 35mm (with a 35mm neg mask) and only recently started to use it for 6x6 (with a 6x6 neg mask). The times for 6x6 have been considerably less than with the 35mm - I have put this down to the amount of light available to be passed through the 6x6 neg is greater than the amount of light available to the 35mm neg, condensers cannot be adjusted for different neg sizes.

The Rosco ND filters were suggested to me in my thread, and that is a route that I will be exploring shortly.

Dimming a bulb might result in colour temperature shift which may affect the response of variable contrast papers.

Sim2.

ignacj · Mar 8, 2010

Sim,

35 to 6x6 move make sense. The problem is that even my 35mm are around 2.5 - 3 seconds exposures.

My only concern about *mart type of dimmers is to the fact that they are TRIAC based (pulsating current) and how could that affect enlarger (beside possible temp shift). I already have a couple of them, so I'll give them a try (with VC paper) in next couple of days. ND gels are on the way. I'll report back how (and if) it all works out.

ig

timk · Mar 9, 2010

make sure the bulb is the correct type for your enlarger, and that the power supply is correct.

What size are you enlarging to? The smaller the print the shorter the time.

ricksplace · Mar 9, 2010

Interesting. I use a Beseler 45mx for b&w with a 150 watt bulb. I usually print between 10 and 20 sec for most negs from 35 to 4x5 at f11. I use componons. I print on lots of different papers, some slower than others. Does your 45m not have a filter drawer? Weird. My 45mx takes 6x6" vc filters above the condensors.

ignacj · Mar 9, 2010

ricksplace,

I have 45M. It does not have a filter drawer and according to KHB I would have to upgrade entire condenser housing. I suspect that would cost more than what I paid for enlarger itself. For time being I'll go with 75W photo bulb and Rosco ND over the condenser glass.

timk,

I was fiddling with 4x6 crop out of 8x10 projection from 120 film. 35mm covering 4x6 was tad slower at around 2.5-3 seconds.

thanks

wclark5179 · Mar 9, 2010

Let me preface by saying I've got Omega B22 Enlarger with a Dicro Color Head.

But reading your memo & looking at your enlarger I see it calls for a 150 watt bulb. Gosh that's a lot of light & heat. Just thinking.. I'd try a compact fluorescent bulb, the type where the bulb is inside a plastic container that looks like a regular bulb. The compact fluorescent bulb w/o the container probably would show the tube configuration on your prints! Another thought as I was in Home Depot the other day I see they have some LED bulbs.

Thought I'd mention this.

Another more expensive option is to find a color head.

bdial · Mar 9, 2010

Print with a #2 filter, doing that, and lowering the wattage should take care of things. As a side benefit, your exposures will be consistant across the paper grades. The problem may recur if you do graded paper, but solutions already mentioned should take care of it.
Fluorescents have an after-glow effect that may cause problems.

Ronald Moravec · Mar 9, 2010

a night light dimmer might not handle the wattage.

ricksplace · Mar 9, 2010

ignacj said:
ricksplace,

I have 45M. It does not have a filter drawer and according to KHB I would have to upgrade entire condenser housing. I suspect that would cost more than what I paid for enlarger itself. For time being I'll go with 75W photo bulb and Rosco ND over the condenser glass.

Bummer. I just gave away a set of under the lens variable contrast filters including the little shelf thingy that attaches to your enlarging lens that the filters sit in. I read an interesting test regarding degradation of the image from under the lens filters (might have been here) and the findings indicated that, so long as your filters are clean, no discernable degradation of the image resulted from the use of under the lens filters.

I'm unfamiliar with the 45M. Is that the single column 4x5? I wonder if the condensor head from a 45MX would fit on the 45M? So many beseler parts are adaptable. You could probably get the condensor head for a 45MX pretty cheap.

Mainecoonmaniac · Mar 9, 2010

I hope this helps. I have a 45MX but with a dichro color head and the printing times are reasonable for me. I hope your condenser head has a filter drawer to accommodate the filter. If you don't I think it might be OK just to make a permanent installation. Those Rosco gels are made hold up against heat for a long time. If it burns up in your enlarger, just cut another piece to replace it. I wouldn't use them in front of the enlarger lens because they're not optically that good. Keep me posted.

Joe VanCleave · Mar 9, 2010

150 watts seems way too hot for a condensor enlarger.

Regarding dimming bulbs electrically, a conventional resistance-type of dimmer control reduces the voltage to the filament, causing the color temperature of the light to shift to the orange. This can cause you all kinds of problems with contrast control when using VC paper.

The best type of light dimmers use a triac to "chop" the duty cycle of the AC sine wave, delivering less power to the lamp but keeping the peak voltage the same, resulting in less color shift. I'm not sure of how easy these are to obtain; the new CF bulbs have a similar issue, they can't be dimmed with a resistance-type of control without flickering wildly; perhaps there are new light dimmer switches, compatible for CF's that will work in this application.

However, it sounds to me like the enlarger needs an enlarger-grade lamp of much lower wattage.

~Joe

naugastyle · Mar 9, 2010

I don't actually know what bulb I have but I use a 45MXII and will say that Adorama paper is simply VERY fast. I do not have short exposure times with other papers, only this one. Actually, and also Foma Variant III RC but not AS short as Adorama RC.

ignacj · Mar 9, 2010

Ronald,

My night switch can handle 300Watts.

ricksplace,

45M is "dual-column" - is that's right was to describe it? It looks exactly like the current model (45MXT) that bandh carries but comes in very retro baby-blue color!

Mainecoonmaniac,

No filter drawer on 45M, only small drawer right above the lens for VC filters. These are approximately 2 1/4" x 2 1/4" (60x60 mm) size. I cannot find and ND filters in that size and I do not want to use Rosco (or anything that I would dare cutting to size) between film-lens-paper. Rosco on top of condenser lens with new 75 watt bulb sounds like the solution.

Joe,

Believe it or not, 150 watt (PH212) is a standard lamp for 45MXT - and is what I found inside my 45M.
I believe the night-lamp dimmer I got is TRIAC type - on lower setting you can hear buzzing and those energy-saving fluorescent swirly bulbs will visibly flicker! Also, it does not heat up at all, so I'd guess it's not really reducing the voltage, instead it's pulsating/chopping it. Now is this safe for PH bulbs? Not that it matters considering $5 price tag, but I'd hate to be out of luck and waiting for yet another Adorama shipment!

ignacj · Mar 9, 2010

naugastyle,

What sort of exposure times do you get with Adorama papers?

ig

naugastyle · Mar 9, 2010

OK, bearing in mind I only have the 4x6 Adorama paper and I haven't used it since switching to the 80mm lens which has smaller aperture options...generally f/16 and 5-6 seconds (filtered). The 50mm lens can be turned past f/16 for some reason, and even though there's no other aperture marked it does get dimmer, so sometimes I've had to turn it to this smallest unmarked point to get to the 5-6 seconds. I got longer times with split-grading, though. I should try again with the 80mm and brighter daytime negatives sometime.

ignacj · Mar 11, 2010

Happy to report Rocso ND.9 gel on top of condenser lens combined with new 75W bulb brought my exposure (120 6x7) times to a very workable 12-16 seconds range. I'll likely slow it down even further with ND.6/.3 as needed. Since these exposure times are easily replicable, I decided not to use the night-lamp dimmer. Thank you for all your suggestions and ideas!

ig

Too short exposure time

Privacy & Transparency

Privacy & Transparency