Adox MCP 312 Question

[Henry Yorke]

I've recently set up a darkroom and have a question about ADOX MCP 312.

According to the info sheet, 312 without any filter is a grade 2. The problem is, my exposure time for this grade is about 3 seconds, max. It's ever so slightly longer when I use the filters in the colour head for higher grades - and even shorter for lower grades. Can anyone tell me what I'm doing wrong? I should be able to have a longer exposure time, no?

My enlarger is an LPL D6700 with dichroic filters. The aperture on the lens is F11.

I'm processing the paper in Formulary 130, 1:1.

Thanks for any info - much appreciated.

 

[Roger Cole]

I haven't used this paper but if the results look ok it's probably just really fast, and/or your enlarger is quite bright. You can add some neutral density to increase the times for dodging and burning or to increase accuracy (it's far easier to time, say, a 20 second exposure within a few percent than a 3 second exposure.) Since this is a color enlarger, just dial in equal additional amounts of each color over and above what you use for contrast control, say +20c, +20m, +20y. You can of course use more or less as needed.

 

[bill spears]

Never used this paper but 3 secs is way way too short, especially at F11. Sounds like something is seriously out of place somewhere. Too bright a bulb is the first thing that springs to mind. You might want to check the lens diaphram to make sure it is actually stopping down ? Also how close is the enlarger head to the baseboard... are you doing very small prints ?

 

[Willie Jan]

When I use my durst 1200 at 8x10" it's 3.7 seconds on F11.
So 3 seconds is possible. As mentioned maybe a less brighter bulb would help you.
I use a 150watt.

 

[Rick A]

Does your enlarger have "light attenuators", that fit into a slot between the light source and mixing box? Some models of Omega enlargers come with several that have different hole patterns(IIRC). These are akin to ND filters to reduce the lamp brightness and lengthen exposure. The alternative is to use a ND filter.

 

[ath]

Henry, what's the paper size? When printing on Agfa MCP 18*24cm I get roughly 15s at f/11 with filtering (colour head).
When you make small prints just stop down to the max. aperture. If the time is still too short you may add filters - equal values of CMY are simply a gray filter and prolong the exposure.

 

[Henry Yorke]

Hi, everyone.

Ath - my paper size is 8x10, printing a 6x6 negative. I've read in a few places that stopping the aperture on the lens right down wasn't a good idea - but I'll experiment with the one I've got.

Rick - I'll check to see if the D6700 does have attenuators - not sure that it does, but I'll have a look.

Willie and Bill - yes, a lower wattage bulb might do the trick - I'll check to see what I have in there.

Roger - thanks for the pointer about increasing ND by dialing in equal amounts of CM&Y.

 

[ath]

Hi, everyone.

Ath - my paper size is 8x10, printing a 6x6 negative. I've read in a few places that stopping the aperture on the lens right down wasn't a good idea - but I'll experiment with the one I've got.

Stopping down a lens beyond f/11 or so introduces diffraction. This gives a slight unsharpness which is completely invisible at the magnification you are using. Stop down and be happy.

 

[pentaxuser]

I haven't used any "new" Adox/Agfa MCP 312 but did use the original Agfa stuff with a 100W tungsten halogen bulb in a Durst 605 and never got exposures this low for 8x10 and 6x6 negs. I can come close with Kentmere VC Select but at 5x7 and f8 and Kentmere is about one speed faster than Ilford whereas Agfa as it was and I presume Adox MCP as it is now and Ilford are about the same speed.

It tends to suggests there is something different about the OP's set-up. Not much margin for dodging. Most 80mm lenses go to F22 so only about 12 secs max and don't most 50mm lenses only go to f16?

5x7 prints' exposure would be very short indeed with no room for dodging at all.

Stopping down might solve the issue but I'd be inclined to look further for a solution.

pentaxuser

 

[Thomas Bertilsson]

Try a neutral density filter for on-camera use. That could give you a few stops depending on what neutral density filter you get. Usually they range from two stops to ten stops.

- Thomas

 

[trexx]

The lamp house should have a lever with three positions. Filtered Hi, Filtered Low and White light. Can you see the filtration change as you change contrast? This may be stuck in white light position.

 

[mr.datsun]

I agree that this is wrong. I use the same paper and I think I have 150w bulb. I usually get around 15s at f5.6 or f8 (I could check my notes, but one of the two) for 10 x 8"-ish enlargements.


Have you got one of those (e.g. Schneider Componon S) lenses with a lever that overrides (opens up) the aperture setting whilst focusing? i.e. Could you be printing at f2.8 or 4 without knowing it? As mentioned the bulb wattage if the other thing to check.


You shouldn't need to shut down to f11 or beyond so something needs fixing. Of course, ND filters would work but I kind of feel that that would be a bodge instead of understanding the cause.

 

[Henry Yorke]

Thanks, everyone, for your help.

Okay - I checked the Saunders / LPL D6700 enlarger that I have.

There are no attenuators on this enlarger.

And the lamphouse doesn't have those three position you mention, Trexx.

I had a closer look at the enlarging lens I have - it's a 90mm Roganar-S (I'm waiting to pick up a 6-element lens, but it'll do in a pinch). It stops down from f4 to f22 without a problem.

The thing is, when I compared it to the only other enlarging lens I have (a el-nikkor 50mm), it seemed as if the aperture curtain is off by about a stop. That is, what is f8 on the el-nikkor looks to be a little over f11 on the Rodagon when I eyeball the two curtains. Can two lenses of different lengths be compared this way?

I don't know if a stop difference will be the solution here - but I can't see anything else on the enlarger that would indicate anything else. The lamp is an 85W. It's housed properly. The condenser screen is in place.

It'll be the weekend before I can get back into the darkroom to experiment - but it's a real puzzler for me.

Thanks again for everyone's help.

 

[Henry Yorke]

Correction - I just had a closer look at the two lenses and the Rodagon curtain seems to be off by two stops. So, I guess, my question is, should two lenses of different lengths have the same looking aperture curtain when I look down the front of each lens?

 

[2F/2F]

Doesn't your lens have at least one more f stop you can use on it? It's just like a camera; stop down if there is to much exposure in the desired exposure time. With most medium format enlarger lenses, f/11 is two or three stops from wide open. You can easily go a few stops farther without sacrificing quality, especially in the small enlargements you are doing. It is also possible that your negs are thin.

 

[2F/2F]

...should two lenses of different lengths have the same looking aperture curtain when I look down the front of each lens?

No way! The "f" in an f number stands for "focal length," and the slash indicates division, with the result being the effective aperture diameter. With that info, you can figure out the rest: two different focal lengths divided by the same number equal two different effective aperture diameters. The aperture corresponding to f/11 on one FL lens is not the same size as the aperture corresponding to f/11 on another FL.

I would check out a basic photo text from the library. It will explain the basics of f stops. "Photography" by London and Upton is a good standard to check out. It will also give you a guide on how to judge the exposure and development of your negatives, and how to troubleshoot printing problems like the one you are having. They are also common in used book stores and thrift shops, usually for very cheap. Any edition is fine. (Some editions are by Upton and Upton, not London and Upton. I believe they were married at one point, and then not, or vice versa.)

 

[Henry Yorke]

Sigh - there's my ignorance carrying me only so far again.

Thanks for the note and the book suggestion, 2F/2F.

Just casting about for a solution to this problem.

Thanks again for all of the help.

 

[Willie Jan]

If you want the best quality then sto down the lens for 2 stops. So a 5.6 lens it's working range is F11 for best quality. (leave it there..)

Second you must optimize you negative for best print quality (range of gray levels). Someone mentioned 15 secs. This is possible, but could also be the cause of a denser negative. What works for him, is not sure it will work for you...

At last a print time comes out of all your variables. Maybe i would use lightbulb replacement with a lower value or take a longer lens so the distance is longer between lens and paper (increase time). A second benefit is that when using a longer lens, you use lens part of the lens glass (only the middle part) so the sharpness will increase a little bit.

I assume you want longer times to work on your image (burn)

 

[2F/2F]

Sigh - there's my ignorance carrying me only so far again.

Thanks for the note and the book suggestion, 2F/2F.

Just casting about for a solution to this problem.

Thanks again for all of the help.

I wouldn't be down on yourself about it! There is nothing wrong with ignorance; the word carries a bad connotation, but IMO it is not a bad thing in and of itself. One does not learn much without it, the way I see it. I would guess that most photographers learn from other photographers correcting their mistakes more than they learn from books. I certainly did. But a book is a good starting place to be exposed to some basics if you cannot get into some sort of local class.