# Enlarger exposure time??

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• 02-19-2009, 03:38 PM
Shangheye
I should have been clearer in my post that the full stops help me since in most cases, I find that I need to know how many more (or less) stops are needed to achieve the required burning and dodging. You can certainly run the exposures on half stops etc, or save that for your second strip (Which I sometimes do to get the spot on exposure or compare two halves of the strip at different grades etc).

You can also buy timers that work based on f-stops rather than absolute time. Don't have one, but I can imagine how much simpler my life would be :D
• 02-20-2009, 10:21 AM
edtbjon
Quote:

Originally Posted by DannL
Why is it important to think in terms of stops at the enlarger? How will that benefit me?

I guess I can't see the advantage to the test strip method that Kal has described (I'm feeling dense today). If I determined that a 36 second exposure is too weak, a 38 second exposure is too dark, and a 37.5 second exposure would be just right, how can I discern information this accurate using the method Kal has described? When dodging, burning, or creating straight prints, I find a second of exposure here, and a second of exposure there to be quite critical to the final print. In Kal's method for example, there would be 32 seconds of exposure time residing between the 32-second and 64-second exposures on the test strip.

The original purpose of this thread is to get the OP started with his printing. But going down the track he will eventually come to where you're at.
As others have said, the benefit of making test (strips) with log changes (2,4,8,16, ...) is so that there is equal difference in exposure between the tests. You work in the same way as with your camera.
So, for starters, making a test strip in full stop decrements is a start. Then when in the ballpark, i.e. somewhere at an exposure time or in between two of them, you can finetune in increasingly smaller decrements.
As someone notes, there are programmable exposure timers, with which you work with the concept of stops instead of seconds. These timers (R H Design and Darkroom Automation.) can be set down to 1/24 of a stop, which should befine-grained enough. (If you miss your half-second, you can always let your hand pass under the lens...)

//Björn
• 02-20-2009, 10:57 AM
Nicholas Lindan
Quote:

Originally Posted by DannL
38 second exposure is too dark, and a 37.5 second exposure would be just right...

That's about 1/50th of a stop difference.

Just for grins - the effect of a 1 second change in exposure:

Base
Seconds --- difference in stops for adding one more second

1.0 -------- 1.00
2.0 -------- 0.58
4.0 -------- 0.32
8.0 -------- 0.17
16. -------- 0.09
32. -------- 0.04
64. -------- 0.02

Information for converting stops<->seconds is available here, and at other locations on the web.

http://www.darkroomautomation.com/su...stopstable.pdf
http://www.darkroomautomation.com/support/grastops.pdf
• 07-07-2013, 09:49 AM
viridari
I referred back to this thread last night when I was getting started with my new-to-me Beseler 23C II and got some very different results. I'm wondering what I might be doing wrong.

After doing a series of test strips with a single image, I got to where the correct exposure was 2s @ f11. The other prints I made last night were mostly 1-2s, some under 1s. I don't know if this enlarger uses an unusually bright bulb or what the deal is. Any suggestions as to what might be different with my setup that's not giving me 20-30s to work with? Is there an assumption of filters being used or something?
• 07-07-2013, 04:39 PM
Noble
Quote:

Originally Posted by viridari
I referred back to this thread last night when I was getting started with my new-to-me Beseler 23C II and got some very different results. I'm wondering what I might be doing wrong.

After doing a series of test strips with a single image, I got to where the correct exposure was 2s @ f11. The other prints I made last night were mostly 1-2s, some under 1s. I don't know if this enlarger uses an unusually bright bulb or what the deal is. Any suggestions as to what might be different with my setup that's not giving me 20-30s to work with? Is there an assumption of filters being used or something?

How big are your prints? My Beseler 23C III is bright. My 8x10 exposures with contrast filters are longer than that but they are still in the single digits. I was thinking of getting a neutral density filter.
• 07-07-2013, 05:23 PM
viridari
I was printing at 5x7, no multigrade filter (don't own the set yet).
• 07-07-2013, 05:34 PM
Rick A
MG filters will act somewhat as neutral density filters, but enlargment times that short smack of thin negatives. You will have to adjust your in camera exposures to account for this. Finding your personal ISO is necessary for quality prints. Read(or reread) the Negative and The Print by A.A.
• 07-07-2013, 05:36 PM
Noble
Quote:

Originally Posted by viridari
I was printing at 5x7, no multigrade filter (don't own the set yet).

I'll have to check my enlarger but 5x7 with no filters might just get you down into the low single digits. I feel your pain. I was surprised about how bright my enlarger was as well. Enlarger lenses can actually accept screw on filters. Depending on the configuration of your Beseler 23 C you may have an upper filter drawer where you can put a ND filter as well and leave the lower filter holder for contrast filters. I guess if you want to have a bulb that is bright enough to make large enlargements at reasonable times you have to accept that it will be ridiculously bright for smaller enlargements.
• 07-07-2013, 05:40 PM
Noble
Quote:

Originally Posted by Rick A
MG filters will act somewhat as neutral density filters, but enlargment times that short smack of thin negatives. You will have to adjust your in camera exposures to account for this. Finding your personal ISO is necessary for quality prints. Read(or reread) the Negative and The Print by A.A.

Are you sure? I use a Zonemaster II to analyze my negatives and I've been developing them to print well with a 2.5 filter. I'm sure if I attempted a 5x7 with no filter on my Beseler 23C III it would be a mid to low single digit exposure. You can't change the density of the negative without changing the contrast.
• 07-07-2013, 05:52 PM
winger
Since this enlarger is new to you, the first thing I would check is to make sure you have the right bulb. Also double check that your lens doesn't have a lever to open it up for focusing and if it was open rather than stopped down.
For a 5x7 from 35mm, I'm fairly sure I use f16 to get times I can use and that still just gets me around 8-10 seconds. I know the old rule about always stopping down two stops from fully open, but I consider that to be bordering on BS, depending on the lens (I have Componon S lenses and they certainly don't suck). If you shouldn't ever ever ever use the other apertures, they wouldn't be there.
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