| Photography Forum: Darkroom Techniques Forum: |
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Q. Ilford Multigrade IV paper ASA or IOS speed
Asked by Peter Araiza
(K=83) on 1/14/2006
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I have Luna Pro F meter with the enlarger attachment to calculate printing time. Am going to use Ilford multigrade IV fiber base paper. The ilford web site says, and i quote:
ISO paper speed.
Multigrade IV FB fiber unfiltered, has a paper speed of ISO P500.
It also gives a small chart that says, and i quote:
Multigrade IV FB fiber paper and Multigrade filters
Filter-----00---0---1---2---3---4---5
Speed (P)200-------------200-100-100
Am i correct in understand that, if i want to use the paper with out any filter. I would just set my meter to 500 ASA.
Is the ISO paper speed equivalent to a film ASA speed.
If not, how do you convert ISO paper speed to ASA film speed.
I know there are other way's of determining printing time, by making time intervals on a sheet to see which tone is better, but i want to use my meter. I hope someone can help. Thank You.
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Helen Bach
(K=2331) - Comment Date 1/14/2006
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Peter,
The ISO speeds of paper and film are completely different, unfortunately. Hence the 'P' in front of the paper ISO speed.
The speed of B&W paper and print film (ie the stuff used to make a positive film image from a negative) is more like EI 6 (effectively the same as 6 ASA). Definitely not 500! I guess that you should make test strips to determine the meter speed setting.
I'm afraid that I'm not familiar with the Luna Pro as an enlarging meter. I used to use an Ilford EM-10. I calibrated it using test strips, and based my exposure on the 'maximum black' method, which some people deride. You pick the part of the neg that you want printing as black on the paper, and measure that.
Best,
Helen
Notes, not necessary to read them:
'ASA' is no longer the current standard for film speed, by the way - ISO is, but the number is the same (simple version - I won't go into the whole story) in practice. I'm sure that for the vast majority of photographers ASA and ISO are interchangeable. EI is exposure index - a way of quoting a speed that has not been determined by an ISO (or ASA or DIN) test.
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Peter Araiza
(K=83) - Comment Date 1/15/2006
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Dear Helen: Thank you so very much for writing back. With the Luna Pro F meter, you set your film speed on the meter, then take an incident reading of your subject. It has a dial that you turn until the meter zero's out or null. Then you look at the dial, and it shows you all the corresponding shutter speeds, and aperture you can use for that amount of light on the subject. I bough it on e-bay with it's enlarger attachment, but no instructions. So, because i know what aperture my enlarger is set at. All i would have to do is place the meter under the projected light, with the negative, and read the corresponding time. The key here would be to know what equivalent the paper speed is to film speed.
Please bear with me. I know am a little dense. I think my mother dropped me on my head a few times as a child. So how did you arrive at the conclusion that paper speed is closer to a film speed of ISO 6, and are all papers somewhat at a ISO of 6. Again Thank You. Peter.
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Helen Bach
(K=2331) - Comment Date 1/15/2006
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ISO 6 is just an estimate. I got there like many others - by playing with pinhole cameras when I was a kid. B&W printing paper was the most common material for the 'film' but I also used 'Fine Grain Safety Positive' which is a printing speed, blue-sensitive 35 mm film mainly intended for printing movies. I still use that in a 35 mm camera.
However, that doesn't mean that you should set the meter to 6 when using the attachment - which has its own cell, so doesn't necessarily use the standard speed settings. The intruction manual is available on the Gossen website - in German. If you go over to photo.net and search on 'gossen lab instructions' you will see that someone has already translated them, and so you may wish to email the guy.
Best,
Helen
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Peter Araiza
(K=83) - Comment Date 1/15/2006
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Thank You Helen your an angle. I will look it up on the Gossen website. Peter.
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