Metering with the Gossen Lunasix Enlarger Attachment

[jfdupuis]

Hi,

Yesterday I tried to use the enlarger attachment for my Gossen Lunasix 3s for the first time without great success. How do you meter with it ?

Once back from the darkroom, I found a german version of the attachment manual. From what I understand of the manual, you should measure the contrast by looking at the brightest and darkest area on the easel. This should establish the grade to use. Then the manual says to measure the brightest area to determine the exposure. That sounds not so bad, but it's the opposite of what I'm used to do so far. That is, test strip to establish the exposure time for the highlight, then adjust contrast to get the desired black.

Also, as the light is quite dim under the enlarger, do you meter wide open and adjust the exposure according to the used aperture ?

Regards,

Jeff

 

[Santiago]

I have the english manual for the luna pro[1] enlarger attachment, which is very similar or the same, I believe. PM your mail and I'll resend it.

You can go upstairs or downstairs. That is, you could fix highlights, and reach black shadows via contrast, or you could fix black, or reach highlights via changing contrast. It's easy to meter shadows, as the projected image is brighter.

That's the theory. In practice, changing contrast affects both shadows and highlights, as the ISO point is matched to middle gray. I use my enlarger attachment to get into the ballpark of a metering strip, and do 1/3 or 1/2 stop steps centered on the time given by the attachment.

I meter at the working aperture. My luna pro is very sensitive and has no problems.

[1] Thanks to Niels Rassmuss.

 

[ic-racer]

That is, test strip to establish the exposure time for the highlight, then adjust contrast to get the desired black.

I'd just keep doing that.

I have an enlarger meter, but mostly use it to answer certain technical questions or to calibrate or compare something. I don't use it for making fine prints.

 

[Blighty]

It's certainly no real substitute for something like the RH Designs Zonemaster II. I use the LAB attachment (to give it its proper name) on my Profisix for checking that light output on my enlarger remains consistent from print to print. It is rather good when making quick work prints. If you're interested, I can tell you how it's done! Regards, Niels rasmussen.

 

[BetterSense]

Enlarging meters aren't very useful unless they are really good and expensive. The one time they are useful is when you want to change print sizes. Then you can meter the light falling on the baseboard at the one magnification (you can remove the negative carrier) and then when you reach the new magnification, you can see how many stops you should add to the time (or just adjust the aperture so the reading is the same and then use the same time).

 

[Lee L]

Enlarging meters aren't very useful unless they are really good and expensive.

Entirely untrue. The Darkroom Automation enlarging meter at $94 is excellent and deadly accurate, repeatable within about 0.02 stops (judging from my use) and reading to 0.01 stops. It is useful for much more than metering exposure change with magnification. It can be used as a baseboard densitometer and can be used to determine tone placement and proper contrast grade. I've also used the Gossen enlarging attachment on a Luna Pro in a similar fashion, and it comes with instructions for measuring both exposure and contrast.

Actually, with a little bit of applied intelligence, the Luna Pro could be used with the great information supplied on the Darkroom Automation web site, as it can read in stops just like the DA enlarging meter.

You may want to make adjustments for artistic reasons, but an enlarging meter can get you to the first good base print with greater speed if you learn to use it properly.

Lee

 

[jfdupuis]

Thanks all. I'll give it another try with your comments in mind.

 

[Nicholas Lindan]

The Darkroom Automation enlarging meter at $94 is excellent and deadly accurate, repeatable within about 0.02 stops

Not to gild the lilly, but an incandescent lamp's light output increases by about 0.02 to 0.03 stops as it warms up - takes about a 30 seconds to a minute for a PH21x. If you are using an incandescent light source this may be the reason for the repeatability issue. Large temperature swings can also cause differences in readings.

 

[markaudacity]

Trying to do similar, and very surprised to find that none of the discussions I’ve found offer the crucial piece of information without which any enlarging meter is useless: what is the speed of the paper?

 

[ic-racer]

Trying to do similar, and very surprised to find that none of the discussions I’ve found offer the crucial piece of information without which any enlarging meter is useless: what is the speed of the paper?

Enlarger meters usually are calibrated to the paper. Some times, calibrated to a fine print on a given paper. Also calibration to black or white can be done. Which meter do you have in mind? Which paper?

More valuable information on Nicholas Lindan's site.

http://www.darkroomautomation.com/support/index.htm

 

[hoganlia]

I found an English version of the User Manual. I still have questions but it's a starting point.

User manual Gossen LAB (English - 6 pages)

Manual Gossen LAB. View the Gossen LAB manual for free or ask your question to other Gossen LAB owners.

www.manua.ls

 

[Chan Tran]

Unlike exposure meter or light meter the enlarging meter doesn't need to be absolute accurate. It has to be linear and good repeatability and sensitive in low light. So a meter designed for the task doesn't have to be expensive but rather specifically designed for the task.

 

[Nicholas Lindan]

Unlike exposure meter or light meter the enlarging meter doesn't need to be absolute accurate. It has to be linear and good repeatability and sensitive in low light.

It's not just linearity and repeatability; the meter also has to provide adequate resolution. Without resolution linearity and repeatability can not be assured. Sensitivity and stability are, of course, additional requirements.

But, I'll counter that an enlarging meter does have to be calibrated to some standard. This can be the user's own standard, as when calibrating the meter to the user's own paper, or a published standard where the manufacturer calibrates each meter to an illumination standard.

It's a lot cheaper, in both time and money, to have a meter that has absolute calibration. It also allows the manufacturer to publish charts of paper speed, making life easier if you are using one of the published papers.

 

[hoganlia]

Unlike exposure meter or light meter the enlarging meter doesn't need to be absolute accurate. It has to be linear and good repeatability and sensitive in low light. So a meter designed for the task doesn't have to be expensive but rather specifically designed for the task.

I have a Gossen Lunarsix and from what I have been lead to believe it's a good metre

 

[hoganlia]

It's not just linearity and repeatability; the meter also has to provide adequate resolution. Without resolution linearity and repeatability can not be assured. Sensitivity and stability are, of course, additional requirements.

But, I'll counter that an enlarging meter does have to be calibrated to some standard. This can be the user's own standard, as when calibrating the meter to the user's own paper, or a published standard where the manufacturer calibrates each meter to an illumination standard.

It's a lot cheaper, in both time and money, to have a meter that has absolute calibration. It also allows the manufacturer to publish charts of paper speed, making life easier if you are using one of the published papers.

Yep. I am gradually getting my head around paper ISO and how to calculate for that in the metering. I'm using Fomaspeed Variant 132 and I have the ISO table for that....

there will be questions...