I am struggling with getting longer than 3 second exposures

snay1345 · May 24, 2010

I have a bessler 23c with a dual dichro head on it. I am trying to print some mf square negs with the final print size being 5x5. I currently have it set to grade 4, and I am printing with a 75mm vivitar lens at F11. I also have two 4x nd filters taped below the conetic device thing and when I print for 3 seconds the exposure is still a little on the dark side. The negatives look perfect as well. They are not too dark and not too light over all, I would say it is a good exposed photo.

I understand that since the head is closer to the baseboard because I am not printing that big of a picture the time will be shorter. But this is crazy. I am doing it wrong and don't know how to fix it. I would put another nd filter up there but I only own two.

Would putting some yellow filter in and then bumping up my magenta make for a longer time? I don't want to keep experimenting like that because I am blowing through paper.

Any suggestions would be great. I am wondering if I need to get a different bulb.

Also my 35mm exposures are in the 5 - 10 second range, although I have not reverted to putting my nd filters on during a 35mm exposure yet.

DLM · May 24, 2010

I have the same enlarger and have never had a problem. Are you sure the lens is stopping down? Some lenses have a lever that opens them up to the widest aperture one way, then when flipped the other way it stops down to whatever the lens is set at. Could that be the case with yours?

bdial · May 24, 2010

You can add some cyan which in combination with the yellow and magenta give you more ND. You may need to experiment some to get the Y/M filtration right for the contrast grades.
Also, the head may have a control that attenuates the light.

Christopher Walrath · May 24, 2010

Posted wirelessly..

My first guess was stop down the lens as well. What aperture are you exposing the paper at?

Rick A · May 24, 2010

The OP shows f11 as the aperture of choice. I concur that stopping down is the remedy. I have to use f32 to get my times extended for 5x7's on my Omega ProLab 4x5. I usually end up with 10-15 second times, depending on the negative. It may be the OP needs to adjust exposures at the camera and developing times to get slightly denser negatives. St. Ansel taught us to expose for our printing preference, not the other way around, which, I think, is what many people do.

Anscojohn · May 24, 2010

Just stopping down to f/16 should allow about a six second exposure. And if it is a three element Vivitar lens, it might be best stopped down more than f/11 anyway.

And, yes, I agree with Rain--your negs may need more density and even more contrast. If you need to use a Nr. 4 contrast, that is a sure sign that neg needs more contrast, unless you are going for some kind of fancy, ultra-contrast print effect.

All things being equal (are they ever??) a diffusion-head enlarger benefits from having a "gutsier" slightly more contrasty negative than a condensor enlarger with a frosted bulb in it.

Ian C · May 24, 2010

Short Enlarging Time on Beseler 23C & Dual Dichro Head

The problem is, of course, that youre only magnifying the negative slightly more than 2.5X to make a 5 x 5 print. Thats very little magnification. The Dual Dichro Head is designed to give plenty of light for reasonably short exposures when making prints of 8 x 10 and larger. Older versions had a 200-watt 24-volt bulb and newer version s have a 250-watt 82-volt bulb. In either case that produces considerable light. Consequently, the projected light at such a small magnification is intense forcing you to diminish the exposure.

You need a digital timer that can be set in 0.1-second increments from 0.0 to 9.9 seconds or longer. That will give you the necessary control of the exposure time.
For example, suppose that your 3-second print is 1/3 stop too dark. Then you need a 2.4-second exposure. This is easily done with a digital enlarger timer.

Assuming a correct exposure of 2.4 seconds, if you raised the head to project a 10 x 10 image then the exposure time would be 9.6 seconds at the same aperture.

If you dont already have a digital timer, they can be bought new from suppliers like B&H, Calumet, Freestyle or used via eBay or sometimes from the APUG Classified ads.

ic-racer · May 24, 2010

bdial said:
You can add some cyan which in combination with the yellow and magenta give you more ND. You may need to experiment some to get the Y/M filtration right for the contrast grades.
Also, the head may have a control that attenuates the light.

Adding cyan is like dimming your safelight, the paper does not notice it, only your eye.

MattKing · May 24, 2010

ic-racer said:
Adding cyan is like dimming your safelight, the paper does not notice it, only your eye.

As long as you add equal amounts of magenta and yellow as well, adding cyan can result in less light intensity.

In other words, if your initial filtration is 30 Y + 15 M (an example) than add 60 of each, resulting in 60 C + 90 Y + 75 M, and you will have decreased the light intensity significantly.

You may have to make a further adjustment to the Y and M amounts, because the dichroic filters may not be linear.

snay1345 · May 24, 2010

Thanks everyone for the replies. I will take some of your suggestions and try them out tonight when I go back in there to print. I will also check the lens to ensure it is stopping down, which I think it is because I always stop it down after focusing and notice the image getting dimmer. I am also going to print the photo cropped to an 8x10 just to see how that works out as well. Thank you all once again.

And do you have any recommendations on brands of a digital timer, I am pretty much operating with a metronome and just the switch right now.

fschifano · May 24, 2010

If you can get your exposures up to around 10 seconds or better,you won't really need a digital timer. A simple Time-O-Lite will do nicely, and will cost you a lot less. They can be found used on Ebay for about $10 or so, and work perfectly. I've been using one for years, and have absolutely no complaints with it.

Nige · May 25, 2010

if your an 'exact' type of person, a digital timer is a must. I once had an analogue timer (name escapes me) but everytime I put it on say 10seconds, it never was exactly 10secs. Did it really matter, probably not, but it drove ME nuts! Replaced it with a Durst Labotim (I think that's the name) and moved on It's a simple device but works well. On my other enlarger I use a colour analyser as a timer (got it with another enlarger) and adjusting it's time can be very frustrating... it uses a wheel to set the time and it's way to sensitive. Depending on how much you can or want to spend, a fancy f-stop timer might be worth investigating.

John Koehrer · May 27, 2010

Or, raise the enlarger with a longer focal length lens 80mm or 100 will get you back into normal exposure land.
If you're looking for consistency go for the longer exposure. You will alos be able to burn & dodge if you need to.

Rick A · May 27, 2010

I firmly believe that exposing for slightly denser negatives or developing a tad longer will give you the enlarging times you seek. I routinely print small enlargments that require my 4x5 Pro Lab to be set as low as the head can be set on the column. This gives 5x7 from a 35mm neg. My printing times are running around 20 -35 seconds (50mm el-nikkor @f11). Thin negatives will give short times. Although the negatives may look "good", the proof is in the printing.

Mainecoonmaniac · May 27, 2010

Maybe try an ND filter.
Dead Link Removed

A .3 ND filter (1 stop) will double your time. I'm sure you could sandwich them for greater density. Remember to put it above your neg preferably at the light source to prevent image degradation.

sepiareverb · May 27, 2010

I'll second the longer lens as a start. Also, there may be a lower wattage bulb that will fit- I know some of the Beseler heads can take different bulbs than the 'stock' one. We had a color head at work that needed a beefier bulb to eliminate really long exposures.

My LPL takes two different bulbs, I swap out the stronger one when printing smaller than 810.

ic-racer · May 27, 2010

John Koehrer said:
Or, raise the enlarger with a longer focal length lens 80mm or 100 will get you back into normal exposure land.
If you're looking for consistency go for the longer exposure. You will alos be able to burn & dodge if you need to.

Only if the longer lens is dirty. Otherwise light energy doesn't just disappear that easily in this universe

David A. Goldfarb · May 27, 2010

ic-racer is correct. Third time in two weeks this has come up--exposure time depends only on magnification and aperture, not focal length. A longer lens (discounting minor factors like differences in transmission and coatings from one lens to another) will indeed get you further from the paper, but if the print is the same size, then the exposure will be the same, regardless of focal length.

totalamateur · May 28, 2010

I'm doing 4x5's on a 23c, (cropping like hell) and I find that even with a highly underexposed negative (2 - 4 stops) my exposure times@ F11 from 9" are 10 - 20 seconds. I don't find that changing the filter setting on the dichroic head makes more than a stop or two difference. If I had to guess, someone stuck the wrong bulb in your englarger, or your lens is jacked up.

Edit: but then again; I don't know what I'm doing...

John Koehrer · May 28, 2010

I know I shouldn't ask but......
Using a longer lens & raising the head doesn't increase exposure time? Isn't that changing the magnification?
When I change magnification, say 5X to 10X I compensate by opening/closing the aperture of the lens or adjusting time.

So, with a 50mm lens, 35mm negative, 5X(5X7) enlargement gives me 10 sec @ f8
Then 100mm lens, the same 35mm negative, 5X(5X7) enlargement also gives me 10 sec @ f8 with the enlarger head being ~2X higher than the first example?

David A. Goldfarb · May 28, 2010

Magnification is the ratio of the size of the projected image to the size of the negative. If the size of the negative and the size of the projected image are constant, it doesn't matter what the focal length of the lens is. The column height will change, but the magnification ratio does not change, and therefore the exposure does not change (setting aside minor factors like lens coatings).

So yes, if a 5x enlargement gives you 10 sec at f:8, that should be the exposure no matter what lens you use, even though the column height changes.

fschifano · May 28, 2010

No, the magnification is exactly the same. In both cases you're starting out with the same negative size to get the same size print. So how is that changing the magnification? So if you're getting ten seconds at f/8 to make a 5x7 print through a 50 mm lens, the exposure time will be very close when making the same sized print through a 100 mm lens. There may be some differences. One lens may have better coatings than another, making it more efficient. With modern enlarging lenses, I wouldn't expect too much difference there. What can extend exposure time with the longer lens is the increased bellows draw needed to focus the thing. Just like with a camera, you need to factor in the bellows extension.

David A. Goldfarb · May 28, 2010

fschifano said:
What can extend exposure time with the longer lens is the increased bellows draw needed to focus the thing. Just like with a camera, you need to factor in the bellows extension.

No, that's not the case either (though the preceding statement is correct--5X is 5X). You can calculate bellows exposure factor on the basis of magnification alone, independent of the focal length of the lens or the bellows extension, since the magnification is a function of those factors.

Exposure factor=(1+magnification)^2

That's how devices like the QuikDisk and the similar product from Calumet with a target that's placed in the scene and a ruler that's marked in stops to measure the image on the groundglass work.

snay1345 · May 28, 2010

Thanks everyone, I think what the problem was is I was just too close to the paper with the lens. I tried some more 35mms and was able to get the printing times back into the 20 - 30 second range which is where I like it. I am going to go out looking for a lower watt bulb though to see what kind of effect that has as well.

John Koehrer · May 28, 2010

Sorry to be so dense today.
What I understand then, is when I change from 5X to 10X the difference in exposure is strictly from the difference in the size of the projected image.
Assuming same lens/negative & the only thing changed is print size.

edit:
Using the example of the Quick Disk, I begin to see the light.

I am struggling with getting longer than 3 second exposures

snay1345

DLM

bdial

Christopher Walrath

Rick A

Anscojohn

Ian C

ic-racer

MattKing

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snay1345

fschifano

Nige

John Koehrer

Rick A

Mainecoonmaniac

sepiareverb

ic-racer

David A. Goldfarb

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totalamateur

John Koehrer

David A. Goldfarb

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fschifano

David A. Goldfarb

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snay1345

John Koehrer

I am struggling with getting longer than 3 second exposures

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