The Computar dL 55mm F1.9 enlarger or enlarging lens is described below.
 

Computar dL brochures
 
The Burleigh Brooks Optics Inc. brochure for the Computar dL line of enlarger or enlarging lenses is partially reproduced below. See the full brochure here Computar dL Enlarging Lenses

	Burleigh Brooks Optics Inc. Computar brochure published 1977[1]

This pamphlet below is from KYVYX Corp. See full pamphlet here Computar dL Enlarging Lenses

	High res file of the above (opens in a new window)

Sample images

These sample images below were taken with a Sony A7RII and are shot wide open at F1.9 unless stated otherwise. RAW files were converted in C1 with minor sharpening. The resized images have had minor sharpening to compensate for resizing. The 100% crops have had no additional sharpening after initial conversion from RAW files.

The Computar dL 1.9/55 was mounted to the camera using a simple M42 helicoid to provide focusing. The lens has an M39x1 mount so an M39x1>M42x1 adapter is used to mount the lens to the front of the helicoid and an M42>E-Mount adapter at the rear of the helicoid to fit the helicoid to the camera. Infinity focus is easily achieved with a 17mm-30+mm adapter although this is largely due to the very short flange distance of the A7RII being only 18mm.

The images below are from two samples of the Computar dL 1.9/55 and their serial numbers will be used to differentiate them (if known). They are both FAULTY! They both have minor separation or delamination as is common with this lens. The degree of image degradation due to the separation is impossible to judge without direct comparison with a perfect sample lens. These sample images none the less give a good idea of the rendering of this lens.

Vignetting is a definite problem with the Computar dL 1.9/55 mounted on a Sony A7RII using the method described above. The cause of the vignetting may be the M42>E-Mount adapter itself however until further testing the cause is not certain. The vignetting is not always obvious or objectionable, however it is there, only in the extreme corners.

The Computar dL 1.9/55 appears to have strong overcorrected spherical aberration which gives a harsh background bokeh. This harsh bokeh can be used to advantage in the right circumstances.

	The harsh bokeh is immediately evident in this close up.
	Unsharpened 100% crop from the above image.
	Longitudinal Chromatic aberration is quite noticeable