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Instruction Manual for the Comparator 100
The JOBO Comparator is an electronic measuring instrument for the determination of exposure times for black and white and color enlargements. It is suited for the following applications:
- Determination exposure time for all black and white enlargements
- Determination of exposure time for color enlargements of slides or negatives
The operation is simplified by the use of LED’s to guide you to the proper exposure time.
1. Contents
- 1. Contents
- 2. Power Supply
- 2.1. Loading of the battery
- 3. Programming Comparator 100
- 3.1. Entry of the determined exposure value (selective)
- 3.2. Entry of the determined exposure value for full area (integrated) measuring with black and white, and color
- 4. Measuring of exposure values
- 4.1. Measurement with constant exposure time
- 4.2. Measurement with constant aperture
- 5. Special indications
- 6. Mounting of the diffuser
- 7. Maintenance and care
- 8. Dimensions
- 9. Service
- 10. Scope of delivery
2. Power Supply
The JOBO Comparator 100 is powered by a 9 volt battery (not supplied with unit). After loading the battery and switching on the unit, the Comparator is ready for operation.
2.1 Loading of the Battery
The following batteries can be used for the Comparator: e.g. Duracell NN 1 604/6 LR61/9V or equivalent types of other manufacturers. A sliding cover an the back of the unit gives access to the battery compartment
3. Programming the Comparator 100
Note: During programming and during all measuring processes the safelight and all other darkroom illumination must be off. The photocell will respond to any light. To program the Comparator you must first make what you consider an Ideal print without using the Comparator. The exposure values (enlarger height, F-stop of the lens, paper grade and exposure time) must then be used to program the Comparator for future use. The JOBO Varioformat Easel and Test Printer are valuable aids in determining the exposure values.
3.1 Entry of the Determined Exposure Value for Selective (Spot) Measuring for Black and White
The enlarger height and lens aperture should be the same as for your ideal print and the negative for that Print should be in the negative cagier of the enlarger. Turn on the enlarger.
Turn off all darkroom light. With the main switch 5, turn on the Comparator. At this point one of the two red LED triangles 1 will be lit. The time scale dial 6 is set to the exposure time you used for your ideal print. Place the Comparator on the easel of baseboard so that the measuring cell 3 covers the lightest part of the projected negative still shows some details. Choose this spot as close to the center area of the negative as possible. With the Comparator in place, turn the adjustment knob 2 until the balancing lights 1 change from a red triangle to the green center LE D. Individual settings can be noted on the while border in pencil. After that do not change the position of the adjustment knob 2 anymore.
Your Comparator is now set for the paper you have been using. It is programmed. Now you can determine exposure time required for an unknown negative used with this paper.
3.2 Entry of the Determined Exposure Value for Full Area (Integrated) Measuring with Black and White and Color
The diffuser supplied with the Comparator should be placed under the enlarging lens in the light path of the projected negative or slide. The entry of the exposure value should then be entered into the Comparator as described in 3.1 above.
4. Measuring of Exposure Values
Place an unknown negative or slide in the enlarger, focus, and select the picture details to be printed. The Comparator is placed on the baseboard or easel so that for selective measuring the lightest part of the negative or slide, which still shows some details, is projected onto the measuring cell 3. For full integration measurement, swing in the diffuser disc. Turn the Comparator on with switch 5, and the exposure value can be determined in two ways:
4.1 Measurement with Constant Exposure Time
For this method the time determined in making your ideal print is set with the time 3. The aperture of the enlarging lens is now changed unfit the balancing lights 1 are adjusted to display the green LED only. You may now expose the paper for the time indicated, set in the procedure above.
4.2 Measurement with Constant Lens Aperture
For this measuring method the enlarging lens is set to the desired aperture, and the time scale 9 is turned until the balancing lights 1 have only the green LED burning. The exposure time thus found is transferred to the timer and the exposure is made. If the unit cannot be adjusted by turning the time scale 3, select a different lens aperture.
5. Special Indications
- TIME SCALE 6 does not light when unit is turned on… Battery exhausted
- LEFT RED LED lights up, and no adjustment will change it… Too much light
- RIGHT RED LED lights up… Too little light
6. Mounting of the Diffuser for Full Area (Integrated) Measuring
Remove existing red filter from the mounting, place it on the diffuser, mark and cut out and place diffuser in the mount instead of the red filter.
7. Maintenance and Care
The Comparator 100 does not need any special maintenance. However, the measuring window should be kept clean, because dust and dirt on this spot can lead to inconsistent results. The measuring window is easiest cleaned with a cotton ball or Q-Tip. When not in use, the instrument should be stored in a cool and dry place. Just like any other precision-measuring instrument, the Comparator, too, must be protected from excessive heat, humidity as well as from shocks and impacts.
8. Dimensions
- Width: 3 inches (76mm)
- Length: 5-1/2 inches(140mm)
- Height: 1-1/8 inches (28mnn)
9. Service
If, in spite of sufficient battery power, the Comparator does not work, or shows troubles, we recommend sending it to our service depart for a check and possible repair. Contact your dealer from where you purchased your item.
10. What is Included With the Comparator 100
- Comparator 100 (#6252)
- Diffuser (#65022)
- Instructions (#66061)
(The battery is not included.)
Balancing lights for time adjustment, proper exposure is indicated when center (green) LED is lit
Adjustment knob to set paper sensitivity
Measuring cell
White area an aid in finding a suitable measuring spot
ON-OFF switch
Time Scale backlighted adjustable dial with range from 1.5 to 30 seconds
Cover of battery on back of unit
Back to TopIf you have any questions, contact us utilizing one of the following methods:
Equipment or Processing Questions:
- Phone: Customer Service Department (734) 205-9421
e-mail: tech@jobo-usa.com
Repair Questions:
- Phone: Repair Department (734) 205-9420
- e-mail: repair@jobo-usa.com
JOBO Contacts
- Telephone (734) 677-6989
- Fax: (734) 677-6963
- Postal address
- P.O. Box 3721, Ann Arbor, MI 48106
- Shipping Address
- 4401 Varsity Drive, Suite D, Ann Arbor, MI 48108
- Electronic mail
- Sales: sales@jobo-usa.com
- Equipment & Processing Questions: tech@jobo-usa.com
Repair Information: repair@jobo-usa.com - Shipping or Billing Questions: help@jobo-usa.com
Webmaster: webmaster@jobo-usa.com
Send mail to webmaster@jobo-usa.com with questions or comments about this web site. Copyright © 1997-2005 JOBO Fototechnic, Inc. All rights reserved. Information in this document is subject to change without notice. Other products and companies referred to herein are trademarks or registered trademarks of their respective companies or mark holders. Copyright to all of the photographs displayed on this site is owned by each of the photographers. You may not sell, publish, license or otherwise distribute any photographs without the written permission of the photographer.
This page last updated on 03/20/02