P3D Some hacker projects (long)

[Tom Deering <tmd@xxxxxxxxxxx>]

As some of you know, I tend to use my stereo photo hobby as an excuse 
to tinker.  Here's a summary of some projects I've worked on over the 
past two months.  I hit upon a plan which has freed up a lot of time 
for photo projects.  It included quitting my job. :^)

(1) Pentaprism previewer.  I wanted to be able to preview my slides 
without mounting them.  Honestly, I'm too excited to wait.

I made the viewer out of plexiglas.  The interocular is not 
adjustable, so it works okay for me and my wife, but other people 
have trouble. Has a built-in florescent light source.  The penta 
prisms I used were from 35mm cameras, so they have a 2:3 aspect 
ratio.  (I shoot medium format, which is square.)  When I get the 
slide far enough away to see the whole thing, the image is kind of 
small.  But good for a preview.

(2) Filter holder.  I  made some gradient filters and filter holder. 
They are based on the "p" series cokin filters, cut in half and 
mounted on plexiglas.  They work very well, and were not expensive to 
make.

(3) Pole "tripod".  I often want to get up off the ground, higher 
that I can get with a tripod.  To help me, I built a camera support 
that uses a ratcheting web belt to secure it around any pole or 
column.  I used it to attach a camera to one of the columns near the 
Bethesda fountain in Central Park the other night. Works pretty well 
if the pole is steady.  Light poles vibrate if there's wind.

(4) Backpacking non-tripod I.  This is a super simple camera support 
for deep woods use.  It has a cheap ball head on top, and coarse wood 
screw threads on the bottom. To use, drive the threads into nearby 
stump and presto.  Backpackers often cut the handles off their 
toothbrushes to save weight, so a regular tripod is WAY too heavy. 
Problems: useful stumps are not as common as you might think. Also, 
they tend to be too low to the ground and nearby items are often too 
close for stereo photography.  But is light.

(5) Backpacking tripod II.  I am in the process of building am ultra 
lightweight tripod for backpacking.   I have three 5/8 inch carbon 
rods, which are amazingly strong and light.  Whether it will be 
useful at all, I don't know yet since it's not finished. I missed a 
ton of nice scenes this fall for the lack of a tripod.

(6)  High speed strobe trigger.  I have wanted to do this for a long 
time, but could not justify the expense of an electronic trigger.  I 
found several simple circuits on the internet, and I built one. Works 
great!  I was able to freeze a balloon halfway popped.  I haven't 
taken any stereo pictures yet, but I'm anxious to try it. Still want 
to build the electronic delay.

(7) Electronic shutter control. (Only partially done.)  I want to 
build an electronic shutter release.  The idea is to attach a box to 
a shutter cable.  You set the box for a given delay time and a given 
exposure.  Say for instance, you could set it for a 40 second delay, 
then open the shutter for 0.5 seconds.

This appeals to me for two reasons.  One, I often want to get into 
the picture, but the 5 second built in timer of the camera is too 
brief.  I may need to climb a rock or walk into a stream.  A bigger 
problem is that I usually shoot long exposures on a steady tripod. 
The slowest speed on the sputnik is 1/15.  I count in my heat to 
estimate quarter and half second exposures, but it's not accurate 
enough. Plus, the built-in timer can't make a two second exposure.

I plan to use a microprocessor to control the timing, and an LED 
readout to set the timers.  I've found the processors and solenoid, 
need to buy parts. I think I can teach myself the assembly language 
programming.

(8) European tripod adaptor.  I have a couple of cameras with the big 
3/8 thread instead of the modern 1/4 thread.  On my way up to Baxter 
State Park, I stopped at my uncles in Portland.  He let me borrow his 
shop for an afternoon, so I made two adaptors.  Basically just a 
small tube threaded on the outside and on the inside. I have a couple 
tripod heads that have both threads, so I only need this for special 
cases.

(9)  MAOFD calculator.  As some of you know, I like to know what my 
stereo parameters are.  I have used spreadsheets in the past, but I 
don't tote a laptop into the fields very often, and paper graphs are 
a poor alternative.  About six months ago I bought some inexpensive 
programmable calculators.  Just recently got off my butt and 
programmed one to calculate all of the stereo parameters, based on 
Bercovitz's MAOFD formula.  I punch in the far distance, and it 
responds with the near point. Ten other parameters remain in the 
memory, such as hyperfocal distance, optimal focus target, etc.  I 
wrote a second program can calculate camera shift for slidebars, but 
I haven't used it yet.

(10) Spot meter adaptor. This was pretty simple to make, I wonder why 
more people don't do it.  I made an adaptor for my Gossen Luna Pro 
light meter to let me take spot meter readings.  The main part is a 
piece of 3/8 ID plastic tubing with a tube of shiny mylar slid 
inside.  A little frame keeps it centered over the photocell.  It's 
the same effect you would see if you looked down a toilet paper tube, 
a greatly narrowed view.  The reflective mylar brightens the sample, 
but I still lose 2 stops.  My meter lets me dial in a correction 
factor, which fixes it.  Perfect for the new modified zone system 
I've been using lately with great success.

(I didn't include projects completed before August, nor the ones that 
failed miserably.  You get those from time to time.  Most notable was 
the LED based slide illuminator.  After designing my own "rock 
tumbler", I tumbled LEDS to "frost" them.  Everything worked 
perfectly, except now none of the LEDS light.  Might have been the 
static. $60 worth.)

Comments on any of the above?

Tom Deering