A simple ongoing guide to light reflective photomicrography

[Swwils]

First of all this my ongoing guide to my experiments to photographing very small, or very heavily magnified objects - this means the use of a microscope.

Because of the precise nature of photomicrograpy this guide will include: (I say precise, but a certain amount of lee-way is available)

• Confusions
• Approaches
  
  • Reverse lens
  • Microscope
• Focal plane (planning)
• DOF and subjects (execution)
• Tips / tricks / "oh god dont do this"'s(Review)

Common Confusions
The biggest common confusion with photomicrography is simply a mix-up between it, and micro-photography. Micro-photography is the process of taking a normal sized subject, and making it very small photographically (think secret messages/codes spy films...) Whilst photomicrography is the exact opposite - and is alot more fun.

Approach

Reversed Lenses

To get a decent amount of macro, you can simply use a regular lens reversed. Zoom or prime (both behave differently e.g. with a zoom can give you the option to be further away, which reduced magnification but increases DOF - and in this macro world, DOF is very very precious) - To understand how this works I could go heavily into how the focal plane of the lens is being adapted to get the macro. But I won't just yet. Its easier to experiment yourself and see it in action.

A kit lens works great for this, and it will really let you get to grips physically with what's going on for when you switch to a microscope.

Just unattach your lens, flip it around and hold it in position; get very close to your subject (moving closer/further away is your focus) and then snap away! - You can get special reversing rings for canon/nikon.

Obvious example:

- you can just hold it on, use some non-marking tape or construct/buy an adaptor. Its easy enough to hold with your fingertips and operate the camera as long as you can rest it on a table.

My canon kit lens says that closest focus distance is 0.28m for macro. It can obtain shots like this:



Reversing the lens reduces my focusing distance to around an inch from the new "front" element. ( this the actual distance under normal mounting from the back lens element to the sensor), but obtains images like this:



A lens the regular way around pointed at something big will make the image on the cameras sensor very small. So that's big to small. When you flip it around, you go from small to big, and that = macro. Obviously its not without its flaws, but a standard 50mm prime or kit lens works great, they have very little glass and so the image quality is superb. - If you want to take it even further, with a special reversing ring, you can attach a reversed lens then a lens the right way round. - This gives you a whole extra focal distance BEFORE the "magnifying" reversed lens. - a setup like that can get pretty close to microscopic especially if the lens before the reversed one is a zoom.

One of the most important things reversed lens macro can teach you is that DOF becomes very narrow, and that there are limits to the position of the sensor from the back element of the lens. - This becomes very important with microscopes - as this position an only be changed by altering focus (moving back/forward with the reversed lens) - but in a microscope the focus range is limited by the stages movement... And so, if your sensor is too far away from the correct image projection plane on your microscope, you wont ever be able to get correct focus onto it.

Microscopic

Obviously the best piece of EQ to have for this would be a microscope. - I have access to light microscopes at college and they all follow a similar design. (Sub £1000 microscopes wont have camera attachments) - and so you will need to make/beg/borrow/find one. Believe it or not they are simple to make.

Documentation for doing this yourself is very limited. - All I could seem to find was opticians who converted Film SLRS, and then university set-ups with large computer controlled CCD arrangements. Or professional class optical scopes worth over £5000 - There seems to be no middle ground for someone with a borrowed/cheap mono microscope and a couple of slides to look at.

A microscope is very much like a camera, its a camera that magnifies - and with magnification comes loss of DOF. Microscopes have tiny tiny DOF. - But they still have apertures, focus controls and a eyepiece that you can manipulate.

To be continued with images...