Using digital Photgarapy to analyze cannon shots

[Double D]

JohnN has opened a whole new field for analyzing cannons shots using still video shots.

John what equipment do you need to use the video decompiler?  Video camera of course and the decompiler also. What else?

Tell us the mechanics.

I notice my Digital still camera make short movies as well as sequential photos.  I wonder if I can take them apart?

[John N]

Double D,

I use a Cannon Power Shot A70, just a regular digital camera (3.2 mega pixels) I picked up on buydig.com for $220. Like most basic digital cameras, this one takes short video clips (this one will do 30 seconds max at 640x480 resolution, AVI output and 15 frames per second). I download the video clips to my PC and view them at 200% using Windows Media Player. The cool thing about the media player is that you can view one frame at a time and toggle back and forth between frames to analyze the shot.

As far as the video decompiler software, I just did a search on Google and tried the first entry displayed, video decompiler software from onestopsoft.com. I downloaded their trial version (free for 5 days) to convert the individual movie frames to JPEG pictures. There seem to be more than a few websites offering this type of software.

In short, anyone with a basic digital camera and a PC can do this!

Here's a sequence that shows the effects of recoil on a swivel gun mount. The first picture shows the gun just before firing followed by the next two frames. Using media player you can clearly see flexure in the mount by toggling between the 1st and second frames. By frame 3 the homemade carriage has begun to move under recoil thus relieving the mount of some of its stress and allowing it to straighten out.







Here are some close-ups of the first two pics. If you save and view as a slide show, you can clearly see the entire swivel gun rear back while the “carriage” has not yet begun to recoil. Pretty neat!

[John N]

Just to add some encouragement for others to try this out, here is a 0.6 second sequence of a waste powder burn (less than an ounce). I’m sure some of you have cameras that record 30 frames a second and can capture twice the action.

[Double D]

While cruising around in Windows Explorer I found  Windows movie maker.  It seems to do some of this stuff.  I need to play more with it. andsee what I can do.  

What I did get was pretty low resolution.

I think I am going out to the range next week and I will definitely have to do some experimenting.

[Cat Whisperer]

John N -

Good sequences of pictures!  You've motivated me - and I dug out my motor winder for the 35mm.  Probably won't go near fast enough but it may get a picture that would otherwise be lost.

I like your swivel gun too!  That may be the easiest mount for me to build for my Napoleon.  (It doesn't kick much with golf balls (1-7/8" bore) but I'm concerned about with lead spheres.  What do you shoot in yours?  How dramatic is the recoil?

[John N]

Double D:

I played with windows movie maker but haven't done anything with it. Simply playing movie clips with windows media player works great for me. If you stop the clip and use the mouse to advance the movie to single frames, you can analyze the shot really well. I have some clips that show the projectile in flight for nearly a second before they sail out of sight.

CW,

A motor drive 35 mm should work pretty good. Plus you'll get high resolution prints. Do you develop film yourself or have a contact sheet done of all the frames? I have a Nikon Cool Pix 5400 digital camera that takes 7 continuous frames at a rate of 2.5 shots per second, but results are hit and miss with that, mostly miss. How fast does your motor drive operate?

As far as the swivel gun, it's a golf-ball sized 30" tube and swivel mount obtained from Canadian Cannon Company:



I wanted to mount this on something other than a sheet of plywood. I was especially concerned about the recoil affect on the swivel mount which from a strength point is inherently weaker than other mount designs.  The "carriage" was put together in an afternoon using regular building lumber and some caster wheels. I'll probably build a permanent carriage out of oak along a similar design but with axles and wheels instead of castors. However I definitely want something that rolls backwards to take up the recoil energy.



So far I've only shot blank loads at 500 grains and golf balls at 250 grains. The gun recoils backwards about a foot to a foot and a half.

[Cat Whisperer]

CW, A motor drive 35 mm should work pretty good. Plus you'll get high resolution prints. Do you develop film yourself or have a contact sheet done of all the frames? I have a Nikon Cool Pix 5400 digital camera that takes 7 continuous frames at a rate of 2.5 shots per second, but results are hit and miss with that, mostly miss. How fast does your motor drive operate?.....

John N-
What I have is the M4-2 winder on the M4-P (Leica).  So it will only do 3 or 4 fps, but the images WILL be crisp.  Using either a 35 or 90mm.  I took 5 courses at ISU in still photography a long time ago and did process my own B&W and color up to 4x5 film size - haven't touched it for decades.  The Nikon Cool Pix is highly rated for it's quality of pictures (even on the LUG forums!).  I am doing most everything here with an older Sony DSC-P20 which does the generic job.

[John N]

CW,

Good luck with the photography! I took advantage of daylight savings time and fired my 1/5th scale 24 pounder after work with a 500 grain blank load. As is the case with most video clips, I can only capture 2 frames of flame cloud / flame trail with my camera which does 15 frames per second. With my Nikon shooting continuous mode, I'm lucky to get one of these moments in one out of 5 or 10 shots. Things happen pretty fast I guess.