PEAK Model 2000 Enlarging Focuser
This is the PEAK Model 2000. We believe it to be the very finest enlarger focusing device available today. Use of the focuser guarantees that there will be extremely sharp focussing not only at the center of the field but everywhere in the field. As the manufacturer says: "You will be able to demonstrate the full performance of your enlarger and obtain pictures of unparalleled sharpness". After using this in our own darkroom, we believe that this a true and correct claim.
Specifications of the Model 2000:
Mirror: 86 x 26 mm
Size: 80 x 160 x 140 mm
Net weight: 343 grams
Accessories: BG Filter
Using the Focuser - Some Practical Comments:
First, turn on the enlarger light source and place the focuser on the enlarging easel. Then, with the aid of the loupe, make an adjustment using only the eye as a guide, to the point that the image on the easel is the very sharpest as seen by the viewer's eyes.
Next adjust the focusing of the enlarger to obtain a nearly-sharp enlarged image of the negative on the easel, and place the focuser on the easel, so that the most important portion of the image will appear in the visual field of the loupe.
Finally, make a fine adjustment to the focus of the enlarger to the point that the silver grains of the negative and the profile of the pattern negative can be clearly seen simultaneously.
Following this above procedure, the sharp focusing of the enlarger can be obtained. Then remove the focuser from the easel, please a single sheet of photographic paper in the easel and make the exposure.
Special Features of the Model 2000:
This model employs Kellner's loupe and a mirror of 86 mm in length. Since the loupe portion is arranged to allow swinging, focusing is possible within the range in which the optical axis of the enlarger lens forms an angle of about 30° with the optical axis of the loupe. The Model 2000 has an aluminum die-cast body in high quality black-paint finish.
Tips for use
Focus Deviation Due to Thickness of the Paper:
When using the focuser, attach a small piece of photographic paper, of the type that is to be used, at the bottom of the focuser, and in that way, the deviation due to the thickness of the photographic paper can be eliminated.
Iris Stop at Focusing:
Open fully the iris of the enlarger lens at the time of focus adjustment and click down on the stops to the point that would actually be getting used for the printing. There might be a focusing shift due to the spherical aberration of the enlarger lens.
Main Point Measurement:
Measure the focus by placing the focuser so that its center is positioned over the most important part of the field to be printed and then carry out the procedure with the focuser positioned at that spot.
It is important to not enlarge an image that exceeds the specifications for the lens being used in the enlarger, other wise aberrations of the lens will occur and there will probably be a difference in the degree of focus between the center spot of interest and the peripheral points in the image. Even if an enlarger with an automatic focussing feature is being used, it is still recommended that the degree of focus is validated from time to time.
Use of BG Filter:
For black and white photo finishing, and it is desired to have a more precise enlargement of the negative, use the focuser after fitting the BG filter to its eye piece. The use of this filter will permit the coincidence between the wavelength sensitive to the human eye vs. that to be enlarged.