Surprisingly short exposure times LPL C6700

Laci Toth · Dec 23, 2019

Hi all,

Today I’ve tried a LPL C6700 enlarger. As I print in b&w I set all the colours to zero and even the lever just to be sure. The first few test strips became entirely black no matter what I’ve done with the exposure times. Even if I set it to 0.5 seconds it was black after 20-25 seconds but rapidly even if I’d take the strip out earlier it would be pretty dark.
Then I realized that the aperture was f4 so I thought that could be the problem.
So when I set it to f8 or f11 I could control it somehow and could get okay prints, thought I had to play with the developing times because the exposure times were stil 1s, 1,5s, 2s till 4s because after that the contrast became too high to get a decent print.
The enlarger is mint condition, no faulties or anything not even a scratch, the previous owner only used it a few times.
The lens is a Schneider-Kreuznach Componon S 4/80 also in pristine condition.
The chemicals were fresh, the given dilution was used at 20 celsius degrees.
The papers were carefully stored no accidental exposures or anything I even tried it with a blank one and it remained white.
I’m wondering if anybody knows what could be the problem or what I might have done wrong?

spijker · Dec 23, 2019

What paper (type & size) are you using and what is the power rating (Watt) of the light bulb in the enlarger?

dkonigs · Dec 23, 2019

I have an LPL 7452L enlarger that also had crazy short times like this. My solution was to get ND filters for my enlarging lenses, which helped with the problem of otherwise having to stop them down too far. Of course having a fancy/accurate f-stop enlarging timer also really helps here, so its easier to control small increments.

Laci Toth · Dec 23, 2019

spijker said:
What paper (type & size) are you using and what is the power rating (Watt) of the light bulb in the enlarger?

I use Ilford Multigrade RC. The size is 20x25cm/8x10inch. The prints were 15x15cm/6x6inch, so they were approx. 20cm/8inch far from the lens.
The lightbulb has 100W power.

Laci Toth · Dec 23, 2019

dkonigs said:
I have an LPL 7452L enlarger that also had crazy short times like this. My solution was to get ND filters for my enlarging lenses, which helped with the problem of otherwise having to stop them down too far. Of course having a fancy/accurate f-stop enlarging timer also really helps here, so its easier to control small increments.

Yea, I thought the same that I might need ND filters but it should also has great quality to avoid diminishing to lens quality, but even if that would be a solution I’d be still interested what is the problem, why are these so short exposure times?

ic-racer · Dec 23, 2019

If you are going to use filters for contrast control or print bigger than 6" you will need the enlarger's light output. In your current situation what is the exposure time when using contrast filters and f16?

If you are not going to use your color head for contrast control, then you can use it for density control. The paper is sensitive to green and blue, so blocking that by dialing in a magenta and yellow filter at the same time will diminish actinic exposure to the paper and be the same as a neutral density filter.

I was printing 8x10 size prints, (slightly reduced to fit the whole 8x10 negative on the paper with a white border) last night with my 2000W Durst and at f22 with full filtration for contrast control the time was 3.8 seconds for one of the prints.

spijker · Dec 23, 2019

Ilford MG IV RC is not a slow paper and 15 x 15 cm is fairly small so it's not surprising that you get very short times with the 100W bulb. You can try to get a 75W or even a 50W bulb to replace the 100W bulb or as others suggested use ND filters. Don't be afraid to set the lens aperture to f/16. Yes, it will not be the optimal aperture for your lens but at this print size you'll probably won't see the difference without a magnifier. Give it a try. The advantage is that you'll get a bit more depth of field which could give you better sharpness if your enlarger is not perfectly aligned.

MattKing · Dec 24, 2019

Colour enlargers are usually designed to give good results on colour photographic paper with short exposure times. To do that with colour negatives, you need lots of light.
Use the built in filters to reduce the light intensity. You can also add ND into the light path above the negative, without affecting the quality of the optics.

jimjm · Dec 24, 2019

I have a Saunders/LPL C670 with the dichroic head, which I believe is almost identical to yours, just a bit older version. I have a 100W halogen bulb installed. I always try to close the lens down a few stops, usually to 5.6, 8 or 11, as this is where you will get the best performance from most enlarger lenses.
I usually make test prints at 5x7 inches, with exposure times commonly in the 5 to 10 sec range if I use no filtration (equivalent of grade 2 or 2.5). That's why I use the dual filtration feature of the dichroic head and set it for 32 magenta and 41 yellow, which is also the equivalent contrast of grade 2. The benefit here is that it will lengthen the exposure times to 15 sec or more. The density of your negatives will also have a big effect on print times as well.
If you start printing larger sizes of 11x14 or more, you'll appreciate the brightness of the bulb as your exposure times may extend to more than a minute.
For standard B/W printing, don't vary your development times to compensate for any print exposure or contrast issues. Paper should be left in the developer for the full amount of time recommended by the manufacturer. For Ilford MG RC, that's at least 60 to 90 sec @ 20 degrees, depending on your dilution. Snatching the paper before it's fully developed will result in underdeveloped highlights.

Laci Toth · Dec 24, 2019

ic-racer said:
If you are going to use filters for contrast control or print bigger than 6" you will need the enlarger's light output. In your current situation what is the exposure time when using contrast filters and f16?

If you are not going to use your color head for contrast control, then you can use it for density control. The paper is sensitive to green and blue, so blocking that by dialing in a magenta and yellow filter at the same time will diminish actinic exposure to the paper and be the same as a neutral density filter.

I was printing 8x10 size prints, (slightly reduced to fit the whole 8x10 negative on the paper with a white border) last night with my 2000W Durst and at f22 with full filtration for contrast control the time was 3.8 seconds for one of the prints.

I don’t have contrast filters. I used instead the colour dials. But the paper was still all black. It might happen that if I use f8, f11 and so on and make larger prints and use the dials I’ll get longer exposure times.

Laci Toth · Dec 24, 2019

spijker said:
Ilford MG IV RC is not a slow paper and 15 x 15 cm is fairly small so it's not surprising that you get very short times with the 100W bulb. You can try to get a 75W or even a 50W bulb to replace the 100W bulb or as others suggested use ND filters. Don't be afraid to set the lens aperture to f/16. Yes, it will not be the optimal aperture for your lens but at this print size you'll probably won't see the difference without a magnifier. Give it a try. The advantage is that you'll get a bit more depth of field which could give you better sharpness if your enlarger is not perfectly aligned.

I might try to replace the bulbs or make larger prints. Thanks for the suggestion!

Laci Toth · Dec 24, 2019

jimjm said:
I have a Saunders/LPL C670 with the dichroic head, which I believe is almost identical to yours, just a bit older version. I have a 100W halogen bulb installed. I always try to close the lens down a few stops, usually to 5.6, 8 or 11, as this is where you will get the best performance from most enlarger lenses.
I usually make test prints at 5x7 inches, with exposure times commonly in the 5 to 10 sec range if I use no filtration (equivalent of grade 2 or 2.5). That's why I use the dual filtration feature of the dichroic head and set it for 32 magenta and 41 yellow, which is also the equivalent contrast of grade 2. The benefit here is that it will lengthen the exposure times to 15 sec or more. The density of your negatives will also have a big effect on print times as well.
If you start printing larger sizes of 11x14 or more, you'll appreciate the brightness of the bulb as your exposure times may extend to more than a minute.
For standard B/W printing, don't vary your development times to compensate for any print exposure or contrast issues. Paper should be left in the developer for the full amount of time recommended by the manufacturer. For Ilford MG RC, that's at least 60 to 90 sec @ 20 degrees, depending on your dilution. Snatching the paper before it's fully developed will result in underdeveloped highlights.

I’ve tried with grade 2 then 0 then 5 with the given Kodak filtration values and all what I got was a black sheet. Though that was with aperture f4 so I give it a go with f8, f11 so it might change and also will make larger prints. Previously I used a C7700 without any problem, it worked like a charm.

MattKing · Dec 24, 2019

Make sure that as you adjust the filters they are actually engaging. Does the colour of the light at easel level appear to be changing as you adjust the dials?

Laci Toth · Dec 24, 2019

MattKing said:
Make sure that as you adjust the filters they are actually engaging. Does the colour of the light at easel level appear to be changing as you adjust the dials?

Yes they are. Today I’ve tried it with grade 2 and could get longer exposure times but then the quality of the print wasn’t as nice as with filtration. The details wasn’t as sharp and separate.

Laci Toth · Dec 24, 2019

Laci Toth said:
Yes they are. Today I’ve tried it with grade 2 and could get longer exposure times but then the quality of the print wasn’t as nice as **with** filtration. The details wasn’t as sharp and separate.

**without**

MattKing · Dec 24, 2019

That means that the grade 2 setting is giving you less contrast - try grade 3.

Laci Toth · Dec 24, 2019

MattKing said:
That means that the grade 2 setting is giving you less contrast - try grade 3.

I work during Christmas but will have two days off on Friday and Saturday and give it a go and let you know about the outcome.
Thanks!

Laci Toth · Dec 27, 2019

MattKing said:
That means that the grade 2 setting is giving you less contrast - try grade 3.

So I’ve tried it with grade 3 and it was indeed way better and I could increase the exposure time till 13 seconds which resulted giving a better contrast than the previous, the one without filtration. I realised though that it was far not as sharp as the previous, which was tack sharp. I then made another print with grade 3 1/2 just for curiosity and I bumped into the same problem; the lack of sharpness. Every time after I set the filtration I double checked the sharpness with the micro focus finder before I made the prints just to be sure.
What do you think might be the solution?

MattKing · Dec 27, 2019

Focus by eye instead, at the maximum aperture setting on the lens. If necessary, use a magnifying glass or higher power reading glasses to aid in evaluating the focus.
Then carefully stop the lens down to the working aperture, allow any vibrations to settle, and try a print.
Your focus finder might be damaged.

Laci Toth · Dec 27, 2019

MattKing said:
Focus by eye instead, at the maximum aperture setting on the lens. If necessary, use a magnifying glass or higher power reading glasses to aid in evaluating the focus.
Then carefully stop the lens down to the working aperture, allow any vibrations to settle, and try a print.
Your focus finder might be damaged.

Thanks for strengthening my intuition because that’s exactly what I was thinking today about the focus finder. After every focusing with it I had to focus a tiny bit more to get the maximum sharpness.
Once I even checked it with a macro lens to be sure.
I usually set the focus on maximum aperture then I stop down.
I give it another go I might succeed.
Thanks again, will need a few days again then I get back to you.
Have a nice weekend!

Ian C · Dec 28, 2019

You mention using an 4/80 Componon-S lens. I presume you’re enlarging a 120 roll film to make an 8" x 10" print. That indicates a magnification of about 3.8X or less, depending on the sizing of the projection. At such a low magnification, the projection will be relatively bright, resulting in short printing time. For smaller prints the exposure time will be very fast.

An ND filter can easily be attached to the lens if wanted with a cheap step-up ring. For example, I use a 43 mm to 52 mm step-up ring on my 4/80 Componon-S with my 52 mm filters.

https://www.bhphotovideo.com/c/product/809758-REG/Sensei_sur4352_43_52mm_Step_Up_Ring.html

I think that you need a glass negative carrier to keep the negative flat. Negatives tend to belly up, defocusing all or part of the projection as the negative warms from the heat of the lamp.

Laci Toth · Dec 28, 2019

Ian C said:
You mention using an 4/80 Componon-S lens. I presume you’re enlarging a 120 roll film to make an 8" x 10" print. That indicates a magnification of about 3.8X or less, depending on the sizing of the projection. At such a low magnification, the projection will be relatively bright, resulting in short printing time. For smaller prints the exposure time will be very fast.

An ND filter can easily be attached to the lens if wanted with a cheap step-up ring. For example, I use a 43 mm to 52 mm step-up ring on my 4/80 Componon-S with my 52 mm filters.

https://www.bhphotovideo.com/c/product/809758-REG/Sensei_sur4352_43_52mm_Step_Up_Ring.html

I think that you need a glass negative carrier to keep the negative flat. Negatives tend to belly up, defocusing all or part of the projection as the negative warms from the heat of the lamp.

Thank you, I really appreciate it! Will have a look at these! Many thanks again for these suggestions and useful infos!

138S · Dec 28, 2019

Laci Toth said:
Even if I set it to 0.5 seconds it was black after 20-25 seconds but rapidly even if I’d take the strip out earlier it would be pretty dark.

Is your paper good? Was it exposed to light ? Develop an unexposedpaper to check,

0.5s is quite a short time...

If you have too much power then replace the bulb with a lower watts one, you'll have the power you want and you'll have less reheating.

Laci Toth · Dec 28, 2019

138S said:
Is your paper good? Was it exposed to light ? Develop an unexposedpaper to check,

0.5s is quite a short time...

If you have too much power then replace the bulb with a lower watts one, you'll have the power you want and you'll have less reheating.

Ye, the paper is alright, I even checked one without exposing it to light and dropped it in the developer tray and it stayed white.
I’ll make bigger prints and also will dial filtration and might check below the lens filters as after the using its own filtration control resulted in less sharp outcomes. Some say it can happen due to the lack of flatness of the negative but I made two prints one after the other and the one without filtration was tack sharp the other with own filtration control, grade 3 was a bit blurred at the edges and was not as sharp overall.
...and yes to get less powerful bulbs can also be a solution...
Don’t know, will need to experiment, I got so many nice ideas from lovely people that it’s on me from now.
=)

Surprisingly short exposure times LPL C6700

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Surprisingly short exposure times LPL C6700

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