Sunday, March 18, 2018

Building the Pinhole Lab Camera extension and some new materials.

I don't think I have to go into the construction of the Pinhole Distance Reducer. The Pinhole Distance Extension however, although made much like the camera, needs a few special methods.

Links:  Original Lab Camera Description    Construction    Feeding and Use    Link to Templates    Excusado    Reducer and Extension

The first step is of course to glue the template to card stock and cut out the parts. All the parts should be cut a little long.  Every camera is going to have a slightly different dimension, and we want to avoid gaps that could create light leaks. We'll cut them to exact length when they're wrapped around the box. Fold and glue the flaps to mimic the double layered sides of the camera back.

To keep the camera front rigid while you wrap parts around it, you'll have to remove the Pinhole Mount and as we did with the camera, place it in the camera backwards to prevent the sides from squeezing together while you wrap things around it. If you had made a couple of those Reducers, those would also serve well for this purpose.


You'll notice the use of clothes pins for clamps. In the past I've always used binder clips to clamp parts.  Binder clips work really well, but they have two problems.  They're only about 10mm deep so you could only really clamp the edges of a part, and they're almost a little too strong and can leave visible marks. Clothes pins are probably more readily available and per unit, probably much cheaper.  They're not as strongly sprung but that can be made up for by using several of them.  They usually come in packages of 50, so you'll probably have plenty. The gentler pressure also doesn't leave marks and they have a longer throat so you can clamp up to 25mm or so deep.

To start, wrap the Back Extension around the camera front and slide it into the light trap.  Mark where it overlaps and cut it for an exact fit. Since it's not glued to anything yet, you have to hold it together with a piece of tape until it's glued to other parts. It's also a good time to roughen the part where the light trap cover will be glued.


With the Back Extension inserted into the light trap of the camera front, place the Light Trap Extension inside the Back Extension. It should sit right on the Camera front. Mark it where it overlaps and trim it to fit. Try not to have both of the joints in the same place.  Put the two joints on opposite sides of the camera. Again, tape the ends together to hold it temporarily and then glue it in place and clamp it.  Here's a place where the longer reach of the clothes pins really comes in handy.



At about this point, I ran out of Aleens Tacky Glue and started using Elmer's X-treme School Glue, which I think is a little more widely available than Aleens (I got it at Walgreens).  I'm pretty happy with it, especially the dispenser cap that twists open and closed with one hand so I don't have to keep track of a cap, I think it dries a little faster than Aleens (15 minutes), and from using it on a couple other projects, it really does form a strong bond.

Place the Camera back over the Light Trap Extension.  It should slide up right against the Back Extension. Wrap the Light Trap Cover around and mark and trim to fit as before. Draw reference lines so you can make sure everything remains in place when you remove it from the camera front so you don't glue them together.  Roughen the area where the glue will go.  Mark the side of the Extension with the pinholes so you can place it back into the custom fit light trap.  The glued part is now a little far from the edges for clamps to reach, but you can use that infinitely adaptable clamp, the human hand, to hold it in place for a few minutes and read the New York Times or something until it sets.


Most of this will have double layers, but there's still the possibility that light might sneak through some of the joints, so it's probably a good idea to paint the interior.  I've always done that with a fast drying flat black enamel like Krylon, but that requires a pretty well-ventilated environment, has a tendency to get where you don't want it, and it's too cold to use it outside in winter in Wisconsin.

I bought an 8 ounce sample of Behr Ultra Flat Black interior latex wall paint on the internet from Home Depot.  I'm not sure you can get it that way in the store. I think Sherman-Williams also makes something similar.  It's kind of weird stuff.  It comes out of the can like tar and you have to thin it with just a few drops of water. If you get it too thin, it's not opaque.  It is almost completely odorless, cleans up with soap and water and dries to the touch in about an hour.  I used two coats anyway.


I noticed while taking pictures it had the tendency to bow in on the single-layer long side and block part of the image, so an extra layer of card stock on the interior of that side to stiffen it up might be a worthwhile addition.

If you're a regular viewer of our program, you know the next step. Go out with it and take pictures.

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