Some thoughts on the options available to the hobbyist for directly
capturing digital microscopy or macroscopy images.

A few years ago there weren't that many affordable options for the hobbyist to capture digital images directly from the microscope. Nowadays the prices of camcorders, digital stills cameras, video security cameras and even dedicated systems are dramatically dropping in price and they are all being used by enthusiasts for image capture with a microscope.

If starting out, choosing which method to use can be tricky, so this article attempts(!) to summarise routes for directly capturing macro/micro digital images. It's compiled from the author's admittedly limited experiences as an amateur and from comparing notes with fellow enthusiasts with different set-ups, but hopefully it may be useful. Links to Micscape and other resources where enthusiasts have displayed the images from the different routes are given.

What is not covered:

Indirect digital image capture routes i.e. scanning photographic material (slides, prints) and the capture of video frames from tape. Only direct methods are covered i.e. the projected microscope image is stored directly in digital format.

Dedicated microscopy image capture systems approaching professional use (and professional price tags!) also aren't covered, the author has no experience of these and probably outside the pocket of most enthusiasts.

Some routes employ consumer items that weren't specifically designed for microscopy use - so there can be pitfalls. Before spending any money, it's a good idea to ask people with a similar system as to how it performs. However, if you already have a camcorder, computer 'view-cam' or digital stills camera, it does no harm to try it - if it doesn't work - no expense is incurred, and could give a feel for what sort of system will suit. If starting out some of the questions to ask when choosing the best route are:

• Is video as well as stills capture important?
• What are the images for: large prints/screen images or Web articles with
  modest images and/or smaller prints.
• Do you want to use existing kit e.g. camcorders, digital stills camera?
• Does it need to be a dedicated set-up, or occasional use of e.g. the family's camera?
• Last but not least, how much do you want to spend?

For clarity the main features are summarised in the table below.

 

Considerations

Camera Resolution - for Web articles or small prints a modest resolution system may be quite acceptable, but for large prints or screen images to show the finest detail a high resolution system will be needed. Camera resolution is closely linked to the number of pixels on a stills camera sensor. Until recently microscopy enthusiasts wanting digital stills had no option but to capture a still frame off a video camera sensor (the route I and many others still use). But consumer still digicams now offer much greater pixel counts 'for the buck' and arguably the better bet for the highest quality still images from a microscope (but see potential problems in table).

Many of the considerations such as pixel count, resolution and their relation to print/screen image are common to digital photography in general. Good articles discussing these criteria are on the New York Institute of Photography's on-line tutorial and some excellent digital camera review sites e.g. Imaging Resource, Digital Photography Review and the Megapixel monthly on-line magazine.

If the very highest quality is required, the indirect digital imaging route (not covered here) is probably still the best i.e. using photographic film and a high quality film scanner (or third party PhotoCD production). But the convenience and speed of results from direct digital imaging and cost comparisons is probably making many people review their need for the highest quality.

Vignetting - this depends on how fully the projected image covers the sensor and can vary from a circular image with black surround to just some light fall off in the image corners. Projecting only the central area of the microscope image to ensure no vignetting can be a benefit, as for many modest microscopes without flat-field (plan) optics the quality is best in the field centre. Vignetting in a high resolution digital image can also be cropped without loss of quality. However, if vignetting is severe it could limit image quality. Unfortunately the extent of vignetting is hard to predict, as consumer camcorders, digital stills cameras etc. weren't designed for microscopy. So it's 'try it and see' for a specific 'scope and camera set-up to assess if it is a problem, and one reason why it's worth asking around about a camera. Vignetting can often be minimised by experimenting with simple supplementary lenses but they will require careful alignment and inconvenience may 'kick-in' as a consideration.

Convenience - from my own experiences, I would rate this as one of the most important criteria. If a set-up takes a lot of aligning and general messing about to take a piccie, the chances are it won't get used much. Whereas a system that is quick and convenient and delivers the basic quality needed, will get used. Convenience is closely linked to quick and accurate alignment of the camera on or above the 'scope. If it doesn't have a dedicated adaptor a homemade one could be made.

 

Additional comments

Video stills from a security video camera

This is my current route for Web work (I don't do prints) because I've had the set-up for video work for some years before other options like digital stills cameras became available. Now 'home security' is very popular, many cheap high resolution cameras are available new from electronic catalogues and good secondhand units are often available. John Garrett shows in a Quekett website article some excellent results with a system bought from a secondhand sale. Commercial adaptors to connect the 'C' mount of the camera (with no lens) to the eyepiece tube with or without eyepiece are also available. This allows quick installation with alignment guaranteed, and for my set-up gives no vignetting as only the middle of the field is captured - which suits my 'non-plan' microscope optics.

Video camera sensor resolution is usually quoted in no. of horizontal line pairs resolved whereas stills camera sensors are quoted in pixels. High res. colour video cameras are expensive but B&W ones quite cheap. I use a 430 line colour video camera which is fine for web work, with occasional use of a 560 line B&W model for subjects which demand high res. like 'diatom dotting'.

With appropriate adaptors, very versatile digital macroscopy systems can also be put together using existing SLR lenses, photo-enlarger lenses etc. See 'Digital macroscopy on a shoestring' by John Wojtowicz and 'Microscopy without a microscope' by the author.

For getting started cheaply and for work where colour isn't vital, a B&W camera may be fine. Image right: the detail of the diatom Nitzschia obtusa, 95X objective, no eyepiece, still from a 560 line B&W video camera using Snappy 2.0 capture box.
	For many subjects colour is better and the lower resolution of affordable colour video cameras will be fine. Image left: Vitamin C crystals using crossed polarising filters. Still from 430 line colour security video camera, 3.5x objective, no eyepiece.

Consumer digital cameras

I've tried my Fuji DX-10 digital camera over the microscope and found it tedious as it has a tiny square mounted lens which has to be precisely aligned and prefer the security camera. If you are able to make a quick and easy way of aligning the camera over the 'scope it could be the preferred route if a digital camera is available. Tony Saunders-Davies on the 'Quekett' web site has put together a nifty adaptor for his Fuji DX-7 camera and achieved good results. Paul James, UK is getting stunning results with a modest Olympus C-830L both over a microscope and with close macro using a simple supplementary lens.

Some digital cameras have filter threads on the lens mount now which should make the purchase or manufacture of an adaptor easier. Depending on the weight balance of the camera you may need additional support for the camera rather than relying on the lens mount to support it.

For reports of experiences with digital cameras: see the Microscopy UK Forum, the Quekett web site article or try a Deja News 'Powersearch' with keywords to search the sci.techniques.microscopy newsgroup for the recent discussions on using digital cameras e.g. Nikon Coolpix models on a microscope.

Video conferencing cameras

A new source of cheap video camera with potential for microscopy is the 'view-cams' for computers e.g. for video conferencing etc. How well they work for microscopy could depend on the model as the resolution isn't always that high. Martin Mach has achieved impressive image captures with one very good value high resolution model, the Compro PS39 (<£100)- even at the limit of optical microscopy to resolve diatom structure. A reader who emailed me though has found using another makers view-cam model found severe vignetting when used over a microscope despite trying various relay lenses. So sharing experiences with different models is valuable.

In the Autumn of 1999 digital macroscopy and microscopy entered the toy/consumer market with the Intelplay QX3 video microscope for less than $100! The maker's web page shows a wide variety of images and Rudolf Baumueller shares his own impressions and results of the QX3 in a Dec. 99 Micscape article.

 

One final thought. There are so many options now for the hobbyist to capture stills from the microscope that there's probably no ideal route. The 'best system' is the one that works for you and gives the quality needed .... within your budget!

Comments to the author Dave Walker welcomed. Why not share your own experiences of image capture? For example, building up a database on Micscape of readers experiences of consumer digital stills cameras or camcorders when used with a microscope, would be useful for other hobbyists starting out.

Acknowledgements. Thanks to my colleagues whose material is linked to above for sharing their thoughts on digital microscopy.

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Published in the December 1999 edition of Micscape Magazine.

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