Introduction: 35mm Slide Converter for Cellphone


This image I took of my wife lay unseen for more than 40 years. What other treasures await?

You will need a short length of ABS or PVC pipe, saw, ruler, drill, sand paper (vellum paper and glue optional).

Step 1: Determine the Minimum Focus of Cellphone Camera

1. Set phone camera to highest resolution.

2. Hold the phone in camera mode over some sharp, printed text.

3. Move the phone up and down to get the clearest, sharpest image at the minimum distance from the print. However, do not sacrifice clarity for minimum distance. Error on the side of clarity.

4. With a ruler, measure the distance from the print to the side of the phone facing the print.

Step 2: Saw Slots in the Pipe for Phone and Slides

1. Obtain a short section of 2 inch (i.d.) ABS pluming pipe. Home Depot sells 2ft lengths for about $4 U.S.

2. No more than a half inch from one end you need to saw a slot for the 35mm slide with a band saw, hacksaw or similar. If you make the slot farther away from the end you may get rounded corners on your image.

3. Remove as many burrs from the cut as possible and test the depth of the slot with a unimportant slide to make sure it is deep enough to allow the slide to be centered.

4. Also make sure the slot is wide enough to accommodate the slide, but snug enough that it doesn't fall out.

5. Measure from the slot you just made the distance of the minimum focus of the camera plus one quarter inch and mark it. The amount of tube you leave beyond the phone slot is at your discretion. I left about and an inch and a half.

6. Saw a slot of similar depth parallel to the first slot and in the same orientation.

7. Make another cut to accommodate the phone thickness. Make sure it is of sufficient depth to allow the phone camera lens to be centered in the tube.

8. Remove the cutout at the attached ends of the cut with a drill if necessary.

9. Remove burrs from the cuts and lightly sand.

Step 3: Check Alignment

1. Make sure a slide and camera lens can be centered in the tube

2. Make adjustments as necessary.

3. At this point you may choose to glue some felt or other material in the phone slot to protect the back from scratches, provided the slot is wide enough for the addition. It is optional however. Keep in mind that smartphones are made to be durable. Screens are made of Gorilla Glass that is highly scratch resistant and the backs a fairly resistant as well.

Step 4: Add a Light Diffusing Transmission or Refecting Screen

Since slide photographs are transparencies designed for projection, light passing through them can change the color and show the light source bulb filaments etc. To avoid this, light must be diffused and softened before passing through. There are two options; adding a transmission diffuser over the tube or a reflector in front of the tube. Vellum Paper is a good choice for the transmission diffuser, readily available and not expensive. You can get a tablet of it for about $6 US at one of the office supply stores. Vellum is desirable because it has a featureless, translucent texture that will not produce mottling in the final image like most copy paper.

1. Place a small line of superglue around the edge of the tube adjacent to the slide slot.

2. Place a square of vellum paper over the end of the tube and press into the glue and let set up.

3. Trim the excess vellum with a razor blade.

4. If you find that with your lighting source a single layer of vellum still produces some unwanted background mottling, you can add another layer or try receiving indirect lighting reflected off a piece of copy paper.

Copy paper should work as a reflection diffuser by itself provided it is a few inches away from the end of the open tube. It can either be mounted in a slotted base or folded at a right angle to rest on the table top.

Step 5: Desktop Stand

With this stable configuration I was able to copy from 4-5 slides per minute.

1. Cut a 3-4 inch section of the same pipe in half lengthwise.

2. Saw a V-notch in the rounded side.

3. Super glue the tube in the "upside down" position so that the slot openings face up.

4. Insert phone UPSIDE DOWN in the slot.

5. Try inserting the slide RIGHT SIDE UP. Depending on the settings on your phone, when you turn your phone right side up after taking the picture the image will rotate 180 degrees so no image rotation will be necessary before saving.

Step 6: Take Picture & Crop

1. Wait for the camera auto focus to adjust and take the picture.

2. Crop image and rotate if necessary. Most cell phone have these camera functionions or it can be exported for further editing.

Step 7: Experiment With Lighting Conditions and Diffusers

Pay special attention to images with a lot of white in them like snow scenes. This is where background lighting artifacts will be most noticeable.

Compare the results between the reflection screen and transmission screen.

When editing the image, auto lighting adjust may NOT be the best option.

Step 8: Original Paper Tube Version

My original "proof of concept" made from a wrapping paper tube and packing foam. Actually works pretty well, but is no less work to construct and less durable than my ABS pipe versions.

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