Olympus microscopes and photomicrographic equipment

Attaching a digital SLR camera to an Olympus BX, CX, CKX or IX microscope

Introduction

CAUTION: I have no hands-on experience with BX, CX, CKX or IX microscopes, so the following information has come from Olympus documentation and other sources and may not be correct in every detail.

Olympus produced equipment for connecting their Olympus OM 35 mm film cameras to trinocular versions of their BX and CX compound microscopes and CKX and IX inverted microscopes for photomicrography. These accessories can either be adapted or replaced to allow Canon EOS, Four Thirds, Nikon, Pentax, Sigma, Sony and other digital SLR cameras to be used instead of OM cameras, with the digital sensor located in exactly the same plane as the film.

Starting from the top, you need the following items:

The U-SPT Single Port Tube, the U-DPT Double Port Tube and the PE photo eyepieces may have been discontinued; they are shown in the system chart for the BX51, but not in the system chart for the more recent BX53.

Remote control software makes photomicrography much easier. Instead of peering through the viewfinder or using the small LED screen on the camera, you can use your computer to check focus, compose, set white balance, adjust exposure and take the photograph. Focus stacking software increases depth of field, which often makes photographs appear sharper.

Camera bodies

You do not need a lens on the camera, because the photo eyepiece is designed to project an image directly onto the sensor. The best digital SLRs to use as replacements for an Olympus OM have a 36×24 mm full-frame sensor, for example the Canon EOS 5D Mark II, 5D Mark III and 6D, allowing you to carry on using the same PE 2.5× photo eyepiece and 35 WH 10× or 35 SWH 10× finder eyepiece.

A cheaper option is a digital SLR with an APS-C sensor (22.2×14.8 mm), such as the Canon EOS 7D, 40D, 50D, 600D (Rebel T3i) and 1100D (Rebel T3), but the smaller sensor results in a significantly smaller field of view unless a very expensive PE 2× photo eyepiece is used.

It is possible to use digital cameras with a Four Thirds sensor (17.3×13.0 mm), but even with a PE 2× photo eyepiece the camera’s field of view is substantially smaller than the viewing eyepieces.

Vibration from the camera’s mirror and shutter can be a problem when taking photographs through a microscope. Traditional solutions include electronic flash, long exposure times, mirror pre-release, and stands that support the camera independently of the microscope.

Canon EOS digital cameras from the 5D Mark II, 7D, 40D, 450D and 1000D onwards have a Live View Silent Shooting mode that makes them particularly suitable for photomicrography. In this mode, vibration is almost eliminated, because the exposure is started electronically while the mirror is already raised and the shutter is already open. This is also referred to as EFSC or electronic first shutter curtain. EOS cameras also come with EOS Utility software that allows the camera to be controlled via a USB connection from a computer, allows the computer screen to be used for checking focus and composition, and allows images to be saved directly to the computer.

The camera body is connected via a lens adapter to the camera adapter.

Lens adapters

The lens adapter connects the camera body to the camera adapter, and ensures that the digital sensor is located in exactly the same plane as the film in an OM camera.

For Canon EOS camera bodies, new lens adapters are readily available on eBay to enable these bodies to be fitted to the top of the Photomicro Adapter L instead of an Olympus OM camera. These adapters convert the OM bayonet on the Adapter L to an EF bayonet, and exactly compensate for the 2.0 mm difference in registration between OM and EOS bodies.

Adapter for mounting an OM lens on a Canon EOS camera

Front and rear of adapter for mounting an OM lens on a Canon EOS camera

There are 3 types of adapter for using Canon EOS bodies – no chip, AF confirm chip and EMF chip. The features of the 3 adapters are:

no chip AF confirm EMF
M (manual exposure, user sets the shutter speed) Yes Yes Yes
Av (auto exposure, camera sets the shutter speed) Yes Yes Yes
Spot, partial, centre-weighted and evaluative metering Yes Yes Yes
Confirmation of manual focus by beeping and by flashing one or more of the AF points in the viewfinder No Yes Yes
EXIF lens data fixed at 0 mm for focal length and F/0 for aperture Yes No No
EXIF lens data fixed, e.g. 50 mm for focal length and F/1.4 for aperture No Yes No
EXIF lens data can be changed by user No No Yes

For Sony NEX, Four Thirds and Micro Four Thirds camera bodies, new lens adapters are readily available on eBay to enable these bodies to be fitted to the top of the Photomicro Adapter L instead of an Olympus OM camera.

For Minolta AF/Sony α camera bodies, there are new adapters on eBay that might be suitable for use with a Photomicro Adapter L. The adapters are thick but they include a lens, so they might allow OM lenses to focus to infinity; if this is the case, then they probably are suitable.

For Canon EOS, Minolta, Nikon, Olympus E, Panasonic, Pentax, Sigma, Sony α, Sony NEX and other camera bodies, new T-2 lens adapters are readily available on eBay to enable these bodies to be used with alternative camera adapters that have a T-2 fitting on top.

Camera adapters

Olympus Photomicro Adapter L

Olympus produced the Photomicro Adapter L to allow their Olympus OM 35 mm film cameras to be used for photomicrography with trinocular versions of their BX, CX, CKX and IX microscopes. Lens adapters are easily available on eBay to convert the OM rear lens fitting on the top of the Adapter L so that Canon EOS, Four Thirds and other shallow-bodied cameras can be used instead of OM cameras, with the digital sensor located in exactly the same plane as the film.

The bottom of the Adapter L clamps on to the circular dovetail on a photo tube, which in turn fits onto one of the trinocular heads for BX, CX, CKX or IX microscopes.

The Adapter L was originally finished in grey to match the BH microscope. The finish was later changed to cream to match the BH-2 microscope. There is not a white version to match the current microscopes.

Alternative camera adapters

If you want to use a Nikon, Pentax or other deep-bodied digital SLR, it is not easy to convert the Adapter L, but there are at least 3 sources of alternative adapters that attach to the Olympus 38 mm circular dovetail at the bottom and take a T-2 mount at the top. I have not seen any of these adapters, so please contact the manufacturers to ensure that they are suitable.

1) Richard J. Kinch (Olympus 38mm Dovetail to T-mount Adapter) makes an adapter that maintains the proper 150.0 mm distance from the lip on which the top section of an NFK eyepiece rests to the plane of the sensor.

Richard J. Kinch’s adapter for Olympus 38 mm photoport

Richard J. Kinch’s adapter

2) Martin Microscopes produce their MBH2T adapter; this is not listed on their website so you need to contact Martin Microscopes.

3) Diagnostic Instruments produce their PA1-10A adapter.

Diagnostic Instruments PA1-10A adapter

Diagnostic Instruments PA1-10A adapter

Photo eyepieces

Olympus PE 2.5× photo eyepiece

To project the image produced by the objective and the tube lens onto the sensor in the camera body, special photo eyepieces that sit inside the circular dovetail on the photo tube are used, not the viewing eyepieces.

The PE photo eyepieces are designed for photomicrography with the UIS and UIS2 objectives that are supplied with the BX, CX, CKX and IX microscopes. They are also suitable for the older UIS objectives.

For digital SLRs with a full-frame sensor, such as the Canon EOS 5D Mark II and Mark III, the most appropriate photo eyepiece is the PE 2.5×.

For digital SLRs with an APS-C sensor, such as the Canon EOS 7D, 40D, 50D and 550D, the most appropriate photo eyepiece is the PE 2×. Unfortunately, these are uncommon and expensive. The PE 2.5× can be used, but the small sensor significantly restricts the field of view.

For digital SLRs with a Four Thirds sensor, the most appropriate photo eyepiece is also the PE 2×, but the small sensor means that the camera’s field of view is substantially smaller than the viewing eyepieces.

The PE 3.3×, 4× and 5× photo eyepieces can be used when higher magnification (with a correspondingly smaller field of view) is required.

None of the photo eyepieces can cover the field of view through the superwide trinocular heads.

The older NFK and FK photo eyepieces are not suitable for use with UIS or UIS2 objectives, and they are too small to fit the photo tubes.

Olympus U-SPT Single Port Tube

Photo tubes

The Photomicro Adapter L clamps on to the circular dovetail that is located on top of the U-SPT Single Port Tube or the U-DPT Double Port Tube for BX, CX and CKX microscopes.

It can also be attached to the circular dovetail on top of the IX-SPT or IX2-SPT Single Port Tube for IX microscopes.

The photo tubes incorporate a 38 mm circular dovetail, and the PE photo eyepiece sits inside the dovetail.

The bottom of the photo tube attaches to the top of a trinocular head.

Finder eyepieces

Olympus made 10× finder eyepieces that are used in the right-hand eyepiece tube and show the rectangular field of view for the PE 2.5×, 3.3×, 4× and 5× photo eyepieces with 35 mm film, and of course these work perfectly with full-frame digital SLRs. A normal viewing eyepiece is used in the left-hand eyepiece tube. There are 2 versions, for the WH and SWH series of eyepieces.

There is a small locating screw that fits into a slot in the right-hand eyepiece tube and prevents the lower part of the eyepiece from rotating. This is necessary to stop the rectangles being rotated out of alignment with the camera, and to allow the top part to be rotated for focusing.

The finder eyepieces include double cross hairs; rotate the top part of the eyepiece until you can clearly see the fine double lines of the cross hairs. Once this has been done, the subject plane that is in focus at the same time as the cross hairs will also be in focus on the film or sensor.

The finder eyepieces can be convenient, because they let you check what the camera will see without moving your head to look through the camera or at the computer screen, but they are not essential.

Trinocular heads

Trinocular heads for the BX, CX, CKX and IX microscopes have a pair of inclined tubes for binocular viewing plus a connector for attaching a photo tube.

Suitable trinocular heads include the U-CTR30-2, U-TR30-2, U-ETR3, U-SWTR-2, U-SWTR-3 and U-SWETR.

With the standard trinocular heads, the image seen through the right viewing eyepiece should automatically be in focus at the same time as the image on the sensor of the digital camera. The viewing eyepiece tube for the right eye is not adjustable, and has a slot for aligning a finder eyepiece. The viewing eyepiece tube for the left eye is adjustable, so that the image seen through the left eyepiece can be brought into focus with the view through the right eyepiece.

On the superwide trinocular heads, both eyepiece tubes are fixed but the superwide eyepieces incorporate dioptric adjustment. To make the viewing eyepieces parfocal with the camera, first focus the image from a low-power objective seen through the camera. Then, without touching the microscope’s coarse or fine focus knobs, adjust the left and right viewing eyepieces to bring the images seen through the eyepieces into focus.

Remote control software

To make the best use of a digital SLR, you need to abandon the way you worked with 35 mm film. Remote control software such as EOS Utility for Canon digital SLRs lets you connect the camera to the USB port of the computer. Then you can display the image from the camera’s sensor on your computer screen so that you can check focus, compose, adjust white balance and exposure, and take the photograph. Images are stored on your hard drive. There is no need to touch the camera except to turn it on and off.

Canon EOS Utility software

Canon EOS Utility software

Canon EOS Utility software

Camera and image controls in Canon EOS Utility software

Using the camera this way drains its batteries quite quickly, so it is a good idea to use a mains adapter.

Focus stacking software

A common problem when starting photomicrography is a perceived lack of sharpness in the photos, compared with the view through the binocular eyepieces. Often, the cause is not a fault with your equipment or technique, but shallow depth of field. The solution is to take a series of photos focused at different points, and then use focus stacking software that selects the sharpest parts of each image and combines them to produce an image with good depth of field.

Mallow pollen grain

Mallow pollen grain, stack of 12 images (left) and single image (right)

The two most popular stacking programs are Zerene Stacker (the one that I use) and Helicon Focus.

Further reading

For more information, see the following pages:

For information on how to use cameras with other Olympus microscopes, see the following pages:

Send comments or questions to Alan Wood

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Created 12th February 2012   —   Updated 17th November 2016
Copyright © 2012–2016 Alan Wood

Olympus microscopes and photomicrographic equipment

Olympus OM system close-up and macro equipment