Olympus E330 DSLR for Photomicrography with Older Design Microscopes
Theodore M. Clarke Metallurgical Failure Analysis Consultant tclarke@ligtel.com Jan Hinsch wrote an excellent review article About the Use of Digital Single Lens Reflex Cameras on Microscopes in 2004 for the web journal Modern Microscopy, http://www.modernmicroscopy. com/main.asp?article=33&print=true. The purpose of this article is to demonstrate the capabilities of the new Olympus Evolt E-330 DSLR for use with older design microscopes to capture the full diagonal of an 18 mm field number eyepiece that is not high eyepoint. This camera can be fitted with OM mount film camera lenses

Figure 1

using the Olympus MF-1 adapter. A key requirement I had before purchasing a DSLR was that critical focusing must be possible at the full resolution of the sensor. I asked the Olympus Precision Instruments Group whether Olympus would have a DSLR available with this capability, and learned from them that the new E-330 DSLR would allow a selected area to be displayed at full resolution from the main CMOS sensor for critical focusing. This 7.5 megapixel sensor measures 13 by 17 mm. Before deciding to buy the E-330, I did an experiment with an OM-mm camera and 28 mm f/2.8 camera lens with a 10X eyepieces that were not high eye-point (eye relief), and determined that vignetting was not evident until the camera lens was stopped down to f/8 and that the camera and eyepiece combination magnified the eyepiece field stop by a factor of 1.16. This experiment and the critical focusing capability led me to purchase the E-330 when it first became available on the consumer market. A key application will be its use on the heavy duty bellows of my macro
system that is sometimes used with a scanning light system shown in my web article: http://www.modernmicroscopy.com/main. asp?article=60 in Modern Microscopy. Careful studies with my modified Lomo Biolam microscope using a stage micrometer for the 4X objective and a diatom test slide from McCrone Microscopes and Figure 2 Accessories for the higher power achromatic objectives, indicated that several different eyepiece compensation levels are necessary for best resolution to the edge of the field. The Lomo 10X WF compensating eyepiece was found best for the 10X and 20X objectives in the monocular system shown in Figure 1. This eyepiece is not available in a high eye-point version. A Zeiss kpl eyepiece, with high CDM compensation, was best with the 40X objective. My article on chromatic aberration from mismatched objective and eyepiece combinations has images of a stage micrometer showing that the 4X Lomo objective performs best with a non-compensating eyepiece.1 This 4X objective was used for demonstrating the field size recording capability of the new E-330 DSLR with a 28 mm f/2.8 lens in the MF-1 adapter versus the same field recorded with a Nikon Coolpix 995 digital camera. A DIN 10X 18 mm FN eyepiece, which does not have a high eye-point and is non-compensating, was used for the comparisons. The test specimen is the wing of a housefly. My modified Biolam with its monocular head was used for this study and is described in an earlier article.2 A cable release mount was made for the E-330 similar to the one made for my Coolpix 995. The microscope setup and mounted E-330 are shown in Figure 1 along with a modified Zeiss 25X stereomicroscope eyepiece used as a Klein loupe over the eyepiece to view the image of the light source and aperture diaphragm formed at the rear element of the 4X objective. The camera is mounted on the rigid macro stand with the front of the 28 mm lens almost touching the eyepiece. A threaded ring with a thin washer of darkened aluminum is used as a light shield and is added at the front of the 28 mm camera lens. The top element of the Lomo Abbe condenser was unscrewed so the lower element could be used to illuminate the full field of the 4X objective. The aperture diaphragm just below Figures 3, 4, and 5, top to bottom.

Figure 6

Figure 7
this condenser lens element was left fully open and the aperture diaphragm at the end of the fiber optic light-guide end was imaged at the rear element of the 4X objective as shown in Figure 2, taken with the E-330 and the Klein loupe slipped over the eyepiece. The field diaphragm of the collector lens was focused on the field as shown in Figure 3, also recorded with the E-330. Figure 4 shows the fly wing recorded with the E-330 along with segments of the eyepiece field stop visible in the corners of the image. I centered the ring of vignetting when the 28 mm camera lens is stopped down to align the microscope under the camera lens before fully opening the aperture of the 28 mm lens. The E-330 has a second image sensor in the viewfinder system that can be switched on to provide a live display that includes an indication of the number of stops of over or under 1 Clarke, T. M. Chromatic Aberration in Digital Photomicrographs from Microexposure for the selected exposure. A correct exposure can be found scopes Requiring Compensating Eyepieces; Microscopy Today, Vol 12-No. 4, July 2004, 34-36. with few trial exposures based on this reading. These images are dis2 Clarke, T. M. Effects of Abbe Condenser Spherical Aberration on Image Qualplayed on the large LCD on the back of the camera. Figure 5, taken ity; Microscopy Today, Vol 13-No. 2, March 2005, 20-25. with the Coolpix zoomed to its shortest focal length and focused at 3 Clarke, T. M. Fitting a Student Microscope with a Consumer Digital Camera; infinity, shows the full field of the 4X objective and the imaged field Microscopy Today, Issue #02-3, May 2002, 15-18.
stop of the eyepiece. There is some darkening from vignetting towards the edge of the field even though the Coolpix lens aperture was fully open. Figure 6 shows this vignetting getting worse as the lens is zoomed to a slightly longer focal length. The lens was further zoomed until the small field shown in Figure 7 was recorded without vignetting. I hope this photo sequence taken with the Coolpix clearly demonstrates the vignetting problem. Jans article indicates that a high eye-point eyepiece is needed to minimize vignetting with use of a digital zoom lens on a DSLR and that the full field diagonal of the eyepiece is not recorded. He also notes that the auto-focus does not work when the digital lens is used for photomicroscopy. I look forward to using the E-330 with the trinocular head for the Biolam in high NA darkfield imaging of live water organisms. My tests with the diatom test slide indicate that the Lomo compensating eyepiece should produce significantly better image quality than the Lomo Edupointer eyepiece used with the Coolpix 995 as described in one of my earlier articles.3 It seems from my recent tests with the diatom slide that the magnification changer lenses in the trinocular head provide some CDM compensation along with field flattening. References

29 July 2006

By: Tudor Raiciu, Technology and Science Editor

Olympus E330 Review

By LetsGoDigital
LetsGoDigital reviewed the Olympus E330 digital SLR. The E330 is the first camera that offers the comfort and flexibility of continuous live views directly on the LCD. This ground-breaking innovation enables framing of shots without the need to look through the ocular. Users can therefore see what's going on around them while they shoot, which is a significant advantage for reportage or sports photographers - as well as in other situations where it is difficult to frame using the viewfinder, such as under water. LetsGoDigital added: "At least Olympus cannot be accused of lacking creativity, something that is perfectly illustrated by the introduction of the Olympus E330 digital SLR. Not only does the Olympus E330 feature a bold and eccentric design, it is also filled to the brim with peculiarities. Peculiarities that allow us a glimpse into the possible future of digital cameras."The Olympus E330 features a multi-angle LCD measuring 2.5"/6.4cm. It makes capturing shots from unusual angles, such as in crowds or during macro photo sessions, a breeze. To ensure image quality is second to none, Olympus has fitted this model with the latest-generation MOS sensor for high speed and sensitivity, delivering incredibly true-to-life, 7.5 megapixel results. As with all models in the Olympus E-System line-up, users will enjoy the benefits of dust-free photography thanks to the Olympus-exclusive Supersonic Wave Filter. And for the ultimate in versatility, the Olympus E-330 is compatible with the full range of Olympus E-System accessories. It is shipped with a Zuiko Digital 14-45mm 1:3.5-5.6 lens (equivalent to 28-90mm on a 35mm camera).LetsGoDigital concluded: "All in all, the feelings on the Olympus E330 are positively mixed. The image quality should be improved, and the same goes for certain other features such as the live view and the white balance setting. On the other hand, the Olympus E330 is simply a delightfully sassy camera that -in addition to offering a live view- provides the user with a great range of settings that would certainly befit a professional camera. It seems that Olympus use the Olympus E330 mainly to try out a variety of new things on the consumer. And something can always be said for that. A pity, however, that it comes with a slightly higher price-tag than the one attached to the E500. Nevertheless, the Olympus E330 is a more than an excellent camera, albeit one with slightly eccentric whims. But let's be honest: doesn't that have its charms in a world where we already see too much of the same thing?" Visit LetsGoDigital for the full Olympus E330 review.
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