Cibachrome-A Exposure Monitor M-3 : 無料・フリー素材/写真
Cibachrome-A Exposure Monitor M-3 / jiifurusu
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
|---|---|
| 説明 | A basic exposure meter from Ilford. This is an old model under the Cibachrome brand and has been out of production for many years.The idea behind the operation is that the "High" and "Low" lamps light up when the received light is above or below the set threshold; the threshold is configured by the two dials. When the received light is exactly at the threshold set, both lamps light up.Other Ilford exposure monitor devices have slightly different operation, supposedly often having just a single lamp and a single dial.How I use it for split-grade printing:Note: Whenever you measure with the exposure meter, turn off your safelight! You don't want it to interfere with your measurements.Calibration, first time:1. Decide on a value that will be the shadow detail target, for example 6-50.2. Place a negative in the carrier, set magnification, focus etc. as usual and keep the enlarger's lamp on.3. Position the exposure monitor's sensor at a shadow area on the enlarger baseboard, i.e. clear area of the negative.4. Adjust enlarger aperture so you hit the value dialed in on the exposure monitor. Maybe adjust the target value you picked in step 1 a bit.5. Make a test strip at maximum hardness (grade 5) to determine the exposure time required to get perfect shadows for the chosen aperture. Write down the time you determine, along with the value set on the exposure monitor.6. Measure the highlight exposure value using the exposure monitor, on your chosen negative and aperture setting.7. Make another test strip, first expose the entire strip at grade 5 with your aperture and time from step 5. Then expose parts at grade 0 to determine the exposure time required to get highlight detail. Write down the exposure time required at grade 0 to get highlight detail, and the exposure value measured in step 6.New negative or magnification:8. Set magnification, focus etc. for the negative.9. Set the exposure monitor to your shadow level and position under a shadow area. Set aperture on the enlarger so you get the correct shadow exposure when exposing at grade 5.10. Measure the highlight value at the aperture found in step 9. If the exposure is close to a previous known highlight exposure, you can print at the time found. Otherwise, go on.11. If you don't have a known highlight (grade 0) exposure time for the highlight value found in step 10, make another test strip to find the time, as in step 7.The idea is that if you have a known shadow value measured by the exposure monitor, and measure a highlight value, you get some measurement of contrast in the negative. When you know the contrast, and have a fixed exposure for the shadows, you can adjust your exposure for the highlights to match the negative's contrast.To do that, you should build a table of highlight exposure times for various highlight values, when the shadow exposure is kept constant.A new table is required for different papers, since emulsions differ. |
| 撮影日 | 2011-12-24 05:39:58 |
| 撮影者 | jiifurusu |
| タグ | |
| 撮影地 | |
| カメラ | NIKON D40 , NIKON CORPORATION |
| 露出 | 0.004 sec (1/250) |
| 開放F値 | f/5.6 |
| 焦点距離 | 50 mm |