Micro-Tech-Lab Newsletter from 20.11.2008

ID165

Micro-Tech-Lab Newsletter from 20.11.2008

The december issue of our newsletter is dedicated to the topic of photography through a microscope. After receiving an increasing number of enquiries from our customers, we decided that it would be useful to shed some light on choosing a suitable camera for taking images using a microscope.

Using full-frame digital SLR cameras in microscopy
The use of large sensors in microscopy does not have as many advantages as it does in conventional photography. Having a high number of pixels is also not hugely significant, as the image resolution is exclusively determined by the numeric aperture of the lens. Other camera features, on the other hand, such as colour depth, signal to noise ratio and light sensitivity, are far more important.
A whole range of camera components are responsible for creating high-quality microscope photos. Therefore it is important that each of these components is of high quality, as the entire chain can only be as strong as its weakest link. This signal chain consists of a sensor, an amplifier, an analogue-to-digital converter (ADC) and a digital signal processor (DSP).
Picture 1: Signal chain

View Image

When the photon strikes the sensor chip, it is stored as an electrical charge. This electrical charge is proportional to the number of photons present. The analogue voltage is increased by the amplifier before it reaches the analogue-to-digital converter (ADC). Only now does the information exist in digital form. Next, the digital signal processor (DSP) optimises the colour reproduction, and finally the data stream is processed for storage on the flash memory card (CF/MMD card).
As a rule, full-frame digital SLR cameras contain only top-quality components, and for this reason they tend to fall into the higher price bracket. Professional features such as remote control, mirror lock-up, LiveView and HDMI output generally come as standard on these models.
In addition, the colour depth of each colour channel is also important. Each basic colour (red/green/blue ==> RGB) has a resolution of between 12 and 16 bits. The higher this value, the more precise the reproduction of nuances in colour. If this number is multiplied by three (for each of the three basic colours) the result is the total memory depth of the colours that will be reproduced. At a resolution of 14 bits per channel, the result is a colour depth of 42 bits. In comparison, cheap compact cameras have only a 24 bit colour depth. The uncompressed data is stored in RAW format. Since this format has a larger storage requirement, users usually select the JPG format instead, which means that a lot of information is lost. Depending on the JPG image’s level of compression, a choice has to be made between storage space reduction and quality.

Overview of some current cameras

	Format (mm)	Colour depth (bits)	ADC	HDMI	LiveView	Number of pixels (megapixels)
Nikon D3	24 x 36	42	14 bits	Yes	Yes	12
Nikon D300	23.6 x 15.8	42	14 bits	Yes	Yes	13
Canon EOS 5D Mark II	24 x 36	42	14 bits	Yes	Yes	21
Canon EOS 1000D	22.2 x 14.8	42	n/a*	No	Yes	10
Olympus E3	17.3 x 13	36	n/a*	No	Yes	10
Olympus E-520	17.3 x 13	36	n/a*	No	Yes	1

* no information available from the manufacturer

For professional use in microscopy, we recommend high-quality full-frame digital SLR cameras, particularly in the case of special processes (e.g. fluorescence microscopy). In addition, we offer special LM digital adapters for full-frame sensors, which guarantee optimum illumination. To help make your choice easier, we have created a special page on our website:
http://www.lmscope.com/produkt22/Camera_Ranking_en.shtml

Conclusion: If microscope photos of extraordinary high quality are important to you, then you should always choose a digital SLR camera with a full-frame sensor. It should be mentioned, however, that cameras with a half-frame sensor or a four-thirds chip can also provide very good results. Here, it is particularly important that the camera used is equipped with a LiveView function and mirror lock-up, as only this will enable you to achieve the optimum level of focus that you require.
A preview of issue 3 of our newsletter:

Improving optical resolution through microscopic mounting media.

Micro-Tech-Lab Newsletter from 09.07.2009

Micro-Tech-Lab Newsletter from 28.10.2009

Micro-Tech-Lab Newsletter from 14.04.2010

New LM Digital Adapter for:

Canon EOS 1D X / Nikon D4 / Canon EOS 1D Mark IV / Canon EOS 60D / Canon EOS 600D / Sony NEX-5N / Nikon D3S / Canon EOS 5D Mark II / Canon EOS 7D / Canon EOS 550D / Rebel T2i / Kiss X4 Digital / Pentax K-5 / Sony Alpha 55 / Sony Alpha 580 / Sony NEX-C3 / Sony NEX-7 / Sony Alpha 65V / Sony Alpha 77V / Nikon D3x / Canon EOS 1100D / Nikon D7000 / Sony Alpha 33 / Sony NEX-5 / Sony NEX-3 / Sony Alpha 35 / Olympus E-5 / Pentax K-r / Canon EOS 1D Mark III / Nikon D5100 / Nikon D700 / Nikon D3 / Panasonic Lumix DMC-GX1 / Olympus E-30 / Olympus E-3 / Olympus E-620 / Canon EOS 1Ds Mark III / Canon EOS 500D / Digital Rebel T1i / Sony NEX VG10 / Olympus E-600 / Nikon D300S / Panasonic Lumix DMC-G2 / Pentax K-x /

High-end intermediate optics for connecting microscopes to:

digital compact cameras
digital SLR cameras
digital camcorders
video cameras
professional studio HDV camcorders

[Further information amd prices]

Which digital camera functions best on a microscope?

Convert your digital SLR camera into a professional microscope

Special mounting media for microscopy

Tips and tricks to connect your digital camera and to process digital images

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