Notes to Shelf

This year my birthday present was a microscope; Celestron 44104. Işıl knows that I’m interested in macro- and micro-photography (the correct terms are photomacrography and photomicrography but oh well) so it was a perfect gift indeed.

It’s a basic compound microscope but more than enough for a starter, it has exchangeable objectives, oculars (eye pieces), pretty robust frame, focus and axis knobs, sub-millimeter scale for x, y, and z axes even an Abbe condenser.

Visualizing and seeing the world in a way which lie outside of my eyes’ capability range always excited me; seeing the very slow/fast events, seeing the very small/large objects, seeing the things in non-visible light spectrum, seeing very dim objects etc. So here I’m with the device which will let me to see the very small. I’ve spent many days checking out the samples that came with the microscope; a set of 100 pre-prepared slides. Işıl taught me the basics and also explained me the different types of human cells etc. I’ve also read a lot about microscope technologies and how to use them. There are two very extensive online resources for microscopy, www.olympusmicro.com and www.microscopyu.com . They are from two big microscope manufacturers; Olympus and Nikon and are curiously similar to each other. I’ve learned the basics of many microscopy techniques, such as dark field, phase contrast, confocal, objective design goals, optical trade-offs, eyepiece designs etc etc. Very fun stuff to learn. Check those sites out if you are into optics.

Seeing the internals of cells and such is fun, but I know that a bigger fun would be checking out the 3D objects. Since microscopes have a very shallow depth of field (few micrometers), viewing thick objects with high magnifications usually gives you nothing but a blurry image with a very narrow sharp-focused band. Something like this (even shallower)

Although still very interesting, seeing the whole thing in sharp focus would give you better ideas about the tiny thing’s form. Fortunately enough there is a computational method called focus stacking which combines many shallow depth of field images to generate a single deep focus image. So I had to find a way to attach my camera to my brand-new microscope so that I can try focus stacking.

You can take a photograph by pointing your camera through the eyepiece opening but there are many problems with this approach. First you can’t keep the camera stationary and the image is very sensitive to camera position, thus each image shows different sections of the specimen. Second, if your camera has a lens which is not very small in diameter, the image doesn’t fill the frame; image will be visible in the frame as a small cropped circle, rest of the frame will be black. The reason is that the normal eyepieces are designed for your eyes which have very small lens diameter and can go very close to the eyepieces.

There are digital eye pieces that you can insert into the microscope tube instead of a normal eyepiece but they are not cost-effective in my opinion. Cheap ones are toy-like providing only 640×480 pixel resolution and still around $100. Probably their optics are not the best either. There are of course good ones but they are starting from $400; too expensive for a new hobbyist. I already have a decent camera (Canon G10), I want to use that with my microscope if possible.

There are some other (potentially cheaper) methods for photomicrography

1- Use a camera with small objective diameter with a normal eye-piece.

2- Use a camera with normal objective diameter but use a tele-lens so that the small cropped circle fill the whole frame.

3- use a special photo eyepiece which will project the image directly on you camera’s CCD; you don’t need to use a lens. Well this works with cameras which have removable lenses (e.x. SLRs). Mine is not removable.

All of the above solutions require two adapters:

A- mechanical adaptation so that you can “attach” your camera to the microscope tube.

B- optical adaptation so that the image is formed on your camera’s sensor

I’ve bought few cheap mechanical adapters for canon G10, the lens attachment kit with 58mm thread, an 58mm to 42mm (T-Mount) step down ring and a T-mount eyepiece holder. Although when combined they let me to achieve the mechanical adaptation, it failed on the optical one. The camera lens can’t come close enough to the eyepiece. I guess the eyepiece holder is for photo eyepieces, not for normal ones. Gah! Anyhow most of those mechanical adapters are useful for other tasks too, I’ll use them somewhere.

So my remaining options are: I could buy a tele-converter (option 2) for my G10 and try that but it’s a not a guarantee that it’d work, it’s jut a 1.4x tele. I could also buy a photo eyepiece (option 3) but they are expensive and still no guarantee there either. While searching the web for solutions I come up with many old setups where people used Nikon Coolpix 995 camera with their microscope using various mechanical adapters. Since CP 995 has a very small objective diameter (28mm), it’s a good solution indeed (Option 1). Guess what? I still have my old CP 995 which I kept using until 2 years ago. I knew I would re-use that.

The camera is 10 years old, its sensor is about to die, half of the pixels are dead/stuck and even in its best days it had very bad light gathering capabilities compared to today’s cameras. But well it will let me to try the basic ideas, such as focus stacking. If it becomes a more serious hobby, I can definitely seek and buy better stuff as this setup will teach me what I need.

I purchased a very cheap ($5) 28mm filter set and super-glued one of them to one of my eye pieces. The eyepiece is still usable for looking through with naked eye. So this concludes the very cheap and dirty v1.0 of my photomicroscopy setup:

Next: I’ll post some cute and creepy creatures. Stay tuned…