Time Lapse Microscopy with a Digital Camera
Notes from March, 2001:
Since the spring of 2000, we have made a couple of advances. There is now another camera solution: the higher end Epson cameras can also do time lapse. They have the additional advantages that the shortest interval is 10 sec (as opposed to 1 min for Kodak) and it is usually much easier to specify the time lapse settings on the Epson. The two cameras we have tried are the PhotoPC 800 and the PhotoPC 3000Z.
Another possible big advance was made in summer 2000. The general idea is that the camera is optically similar to the eye, so that a simple way to couple the camera to a microscope is to position it at eyepiece of the microscope just where the eye would normally be. Of course, this was well known to many people already, but somehow we had to rediscover it. The difficulty is in positioning the camera in just the right way, and just the right zoom, to avoid vignetting. It's not really under control by us yet.
The Kodak DC220, 260, 265, 290 seem to be the only consumer digital cameras that can do time lapse on their own. The DC220 is longer produced, but can be gotten on eBay for $325 (refurbished; April 2000)
To hook a DC220 onto a microscope, it is necessary to remove the lens. So I did that
This required taking a camera apart
The lens assembly has a lot of parts
I removed all lens and zoom apparatus, as well as the shutter. But I left the shutter holder alone, because there was a ribbon cable connecting to it. I didn't want to cut the cable because it might cause an error message in the camera software. The shutter holder was jammed onto the holder for the CCD chip. There was a bit of grease that got onto the CCD chip window.
Coupling to a dissecting microscope: the pieces (note sawed off 50 ml centrifuge tube). Fully assembled
First attempt: radish seed (30 min
time intervals; April 11, 2000)
problem: wildly varying exposure times. This is because the exposure meter is on the camera body rather than at the CCD. Also, the ambient light from day to night was changing
Second attempt: frog oocyte maturation
(2 min time intervals; reduced in size by 50%)
Microscope and camera were more or less sealed from extraneous light using aluminum foil, resulting in more uniform exposure times. Note appearance of the "white spot" at the animal pole (in middle of pigmented half of egg) and then a spreading of the pigmented region.
Third attempt: mouse oocyte
maturation (2 min intervals)
The camera was hooked up to a inverted microscope photo port. The chip is quite small compared to 35 mm film negative, so the field of view is small compared to what is seen in the eyepiece. Although the image is not great, and there is material on the CCD chip window, note germinal vesicle breakdown in early part of the movie, then apparent formation of the first polar body, which may have gotten resorbed in this case.
Fourth attempt: radish seed again
(10 min time intervals, cropped and reduced; April 27, 2000)
Exposures are still a little bit varying. The seedling moved out of the field and had to be re-positioned. Otherwise, this is a step forward!