Lookaround Enlarger
|
I have been used this enlarger with great success for years and have refined it a number of times to make it easier to build and use. The basic design will handle up to 2-1/4 in. film of up to 13 in. length. A custom-made fluorescent tube can be made at a neon shop for 2-1/4 negatives. Of course the major expense is the lens. Lenses that cover 4 x 5 inches will cover a 6-1/2 inch panoramic negative. Features: 1. Compact, vertical wall mount. 2. Simple materials and construction. 3. Constant, lamp-on shutter system. 4. Vertical orientation is easy to keep aligned. Refer to the schematic drawing: Wall Bracket (1, 11) - 36 in. steel or aluminum adjustable shelf brackets. Fluorescent lamp (3) - standard 1-1/4 inch x 14 inch, daylight tube and ballast. Focus assembly (10) - 6 in. threaded vinyl plumbing clean-out. Negative carrier (4) - anti-newton ring glass, and plain glass sandwich, black tape, and mat board. Shutter assembly (8) - light duty, 120v. fan motor, mat board shutter. Size adjustment box (5) - wood box with sliding height brackets (12)  The overall width and depth of the main enlarger housing is 5(h) x 18(w) x 7(d). The lamp housing should be made from black Foamcore assembled with hot-melt glue. 1/4 in. plywood is fine but requires more work. Make it just bigger than the lamp with the tube resting tangent to the bottom (2 X 13 in. )opening. Mount the ballast on the outside of the housing. Translucent white plex is not needed in front of the lamp. An alternate lamp design for 2-1/4 negs is available on request. Bend a piece of stiff, white paper in a U-shape to make a reflector. The lamp does not get warm enough to require vents. Tape the top in place with black photo tape or make a shoe-box type lid to allow access to the lamp. The enlarger box. The main enlarger box is made from 3/4 in plywood. Use grade-A material and work carefully to keep everything square. It can be simple or fancy with kerfs for the lens assembly to slide in and out. Use 1/4-20 t-nuts and truss-head screws to fasten the shelf brackets on each side. They have to be readily adjustable to level the enlarger. You can add a filter (3 x 3 filters) drawer made from mat board that goes in a slot in the front of the enlarger box above the enlarger lens. The lens assembly. The lens assembly is made from a standard lens board (or make one from 1/8 in. plastic) screwed to the male threaded portion of a vinyl plumbing clean-out. Cut the square portion away and open a round hole big enough to clear the rear of the lens. Exactly how to make it depends on your lens and lens board. The main idea is to keep it flat and secure relative to the female portion. The female threaded section is screwed to the bottom of the main box or (better) to its own mount board and then slid into slots built into the box. Use pan head sheet metal screws (also glue if needed). Paint the interior flat black. The shutter assembly. The shutter assembly is easier to make than explain. It's design is from an ancient Omega enlarger. It is perfect for fluorescent lamps because it allows the lamp to remain on at all times. The light output, therefore, remains constant. It can be made any number of ways. I use a small cooling fan motor. The motor is mounted next to the lens opening cut in the shutter plate which extends the width of the enlarger and is supported by shelf brackets. The lens extends through this hole so that it is slightly above the shutter. Mount a pivoting shutter (paddle shaped mat board) to the motor armature axis. Cut away all but one blade of the fan and tape the shutter to the remaining blade. Use a thin rubber band and a bumper stop to cause the shutter paddle to return closed when the power is shut off. It takes a bit of trial-and-error but once you see it working it is obvious what to do. Fasten a piece of soft foam material to the bumper to absorb the momentum of the returning shutter. The motor is connected to the lamp outlet of the darkroom timer. The lens shutter should swiftly rotate completely open (about 100 degrees) when you punch the timer, and close completely without bouncing. It is a contraption and may require a bit of tape and bubble gum to work the way you like it. Once it is adjusted it will be trouble free for a long time. The return rubber band eventually rots! The negative carrier. The negative carrier is a tape and mat board affair that I have found the best for long negatives. I use anti-newton ring glass on the top and window glass on the bottom. Use high-quality, black mat board for the main support material. Cut it the same size as the interior dimension of the main box (and the height size adjustment box outside dimensions). Assemble the glass with litho tape or black photo tape. Use fabric tape (duct tape) for a hinge on the long axis of the top glass. Use dense, black paper to cut masks for various negative sizes. The overall design is one you should make to suite the materials on hand and your working preference. I have changed mine over the years many times. Long negs can be a real pain to handle. The AN glass is a real life-saver. The size adjustment box. Make the size adjustment box AFTER all the other parts are complete and assembled. Make from 3/8 in. flake board or plywood, nailed and glued. The adjustment spacers are simply 2 x 3 x 3/8 in. slotted plates with a bolt, washer, and thumb screw. They fit on each end of the box. The box should extend into the main housing at least an inch when set at its highest point. The depth of the box is determined by the lens you use and the size of the prints you make. Make a mock-up box from cardboard to get the exact dimensions. Test the dimensions using the process described below. You may need to make two (tall and short) for different lens/height combinations. The easel, The easel design is very efficient for long sheets of paper. Use two 1 x 10 x 48 inch (this can be smaller if you don't expect to make large prints) particle board shelves screwed and glued together to make a thick, heavy, warp-free plank. Bond a galvanized sheet metal (iron) face, painted flat black, to this with contact cement. Use four sets of 3/4 x 4 in. carriage bolts with two nuts and washers, and 4 x 8 x ½ in ply plates to make leveling brackets. Vinyl magnet strips are used to hold print paper to the sheet metal. This works very well. Paint the interior of the boxes and parts that could reflect light flat black. The shelf bracket rails. Use 3 ft. steel rails. They should be mounted secure and level to a wall that is as free of vibration as possible. You might have to reinforce the wall. A masonry wall is best, of course. It is good to have the rails extend above the highest lamp position so that you can add a small clear acrylic shelf to rest the lamp on while you adjust the negative. With the light above the negative carrier you can see the dust better. Setting up and adjusting the enlarger. Adjusting the enlarger is a by-guess and by-gosh process that is easier with two people. Put a junk negative that has been prepared with diagonal razor scratches corner to corner in the negative carrier. Mount the enlarger mid-way up the shelf brackets. Raise the cardboard size adjustment box mock-up to its highest position and tape in place. Screw the focus mount out to the last two turns. (be careful not to let the lens drop free). Leave the shutter assembly off. With the lamp on, raise the easel from the floor until an image focuses. Measure the distance from the easel to the enlarger. If it is close to your smallest image height, re-mount the enlarger at that distance (from the easel on the floor) on the wall brackets. Adjust the image size box and focus mount again until you get the required size. (I use 4 inches for the smallest and eight inches for the largest.) The combination of lens screw position and shelf mount bracket spacing work together. You move one notch on the wall (about 3/4 inch) and up and down with the screw thread about the same until you find a rough focus. Make marks on the image size box and the shelf bracket to mark the positions for the first size. Repeat the process for each size required. Use a grain focuser for final adjustments and to get the enlarger completely aligned. This requires patient leveling of all components. I have tried various types of fluorescent lamps with this rig. I use variable contrast paper with daylight lamps and it works fine. You can try various combinations of warm to cold lamps to see the changes in contrast and speed they provide. Be sure to let the lamp warm up about ten minutes before you begin work. Incidentally, this lamp design will work on some makes of standard enlargers for an inexpensive cool-light head for 35mm negs. You have to use the shutter with it. The Lookaround Manual How Sharp are the Images? Digital Darkroom Notes The Lookaround Camera LOOKAROUND HOME PAGE |