hello from marstonfoto

Silly question really. You know that all the EF (and EF-S) lenses do not have an aperture ring so it will have to be  maximum aperture, surely? Well not necesssarily. It is possible to set the aperture of an EF lens but only on a Canon camera and then probably only a digital one with a depth of field preview button. What you do is to mount the required lens, and here it’s only sensible to use a prime lens, turn the camera on to Av mode, set the required aperture and then press the depth of field preview button and while holding that button depressed remove the lens from the camera. The aperture you selected will then remain until you re-mount the lens on a Canon EOS camera and turn that camera on. Whether this has any application to your photography I don’t know. You certainly would not take your Canon dSLR along to set the aperture of a lens to use on another camera! But using Canon EF lenses on other cameras can be useful. Here are two that I use.

The first one is to set the aperture of my Canon 135 mm f2.8 Soft Focus lens to f4 and then use it mounted on one of my Micro Four Thirds cameras. The Soft Focus ring has a very pleasing effect at f4 and the field of view on the camera of 270 mm produces a lovely tight head shot which I use in soft natural light with the camera on a tripod.

The second is to set an aperture of around f5.6 on my Tamron 90 mm f2.8 macro lens. I don’t actually see much point in buying a macro lens for my Micro Four Thirds cameras as I have this Tamron plus a Nikon 105 mm AI lens. Using the Tamron lets me approach jumpy insects from a distance. Obviously there’s no changing the aperture on-site (as there would be with the Nikon lens that has an aperture ring).

In both cases I use my Canon EF to Micro Four Thirds adapter. No information passes from lens to camera and manual focus is necessary but metering works in A mode. With all “foreign” lenses it’s always best to set metering to spot or centre-weighted.

The Four Thirds consortium (Olympus, Panasonic, FujiFilm, Leica,  Sanyo, Sigma and Kodak) proposed and developed an open camera system based on a digital sensor with a diagonal measurement half that of the 35 mm film frame but in a 4:3 aspect ratio with provision for aspect ratios of 3:2 and 16:9 to co-exist. To some extent this mirrors the standard specification of a compact camera but at the time of the launch of the first Four Thirds camera, the Olympus E-1 in November 2003, the Four Thirds sensor at 18 x 13.5 mm was around 9 times larger than the sensor used in most compact cameras. It is 35% smaller than the APS-C sensor used in the majority of digital SLR cameras and about half the size of a full-frame digital SLR. The smaller sensor size allowed for smaller and lighter cameras and lenses. The E-1 was followed by the E-300 and E-500 and the E-330, the latter being the first dSLR to offer “live view” with an articulated LCD. It is a “milestone camera” in the sense that he Live View has subsequently been implemented by all dSLR manufacturers but never better. Following on, Panasonic produced two excellent cameras – DMC-L1 and DMC-L10 – that did not sell very well and Olympus continued with it’s range adding sensor-based image stabilisation in some models. I have an E-330 and  bought an E-520 (one of the image-stabilised ones) but sold it to buy a Panasonic G1 of which more later.

Olympus has produced some superb lenses for the Four Thirds system. Panasonic has made some excellent Leica-designed lenses and Sigma has adapted many of its best lenses for the system but while the Olympus professional-series cameras are applauded and the entry-level ones are appreciated by novices there has been the feeling in the professional photographic press that the system has been waiting for a better sensor or perhaps rather a sensor more finely tuned to the concept. One or two respected commentators wondered if Four Thirds would survive in the digital SLR market.

In August 2008 Olympus and Panasonic announced Micro Four Thirds. This system does away with the mirror-box from the camera design, has permanent Live View, has a smaller lens mount and has a flange back distance about half that of the original Four Thirds. And to prove it, two months later along comes the Panasonic G1 which, although it looks like a dSLR, has a very high quality electronic viewfinder with an articulated large LCD screen and can use most if not all Four Thirds lenses via an adapter. It comes with the first Micro Four Thirds lens, Panasonic’s version of the 14-45 mm “kit” lens and small and light as promised.

Though I didn’t get one until July 2009, the G1 is what I had wished the Panasonic FZ-50 that I bought in 2006 to be rather than what it was.  The FZ-50 had a 35-420 mm (equivalent)  non-interchangeable zoom lens designed by Leica, full manual control, an articulated LCD and an electronic viewfinder that was just about usable. It produced very good pictures in normal light and although the sensor was 40% larger than that of its predecessor, there was a 25% increase in the number of pixels and the amount of noise generated or the efforts of the noise-reduction software to suppress it were such that images taken at ISO 800 or more were mostly unusable. Such a shame as it was a fine camera let down by its image processing. But here with the G1 is a camera that has a really good electronic viewfinder – certainly sharp enough for manual focusing – a larger articulated LCD (albeit tethered at the side rather than at the bottom where it should be), the comparitively large Micro Four Thirds sensor and the ability to mount other lenses.

And it’s here that I think we are seeing a future big change in the market.  I don’t think that the traditional SLR in its digital form will pass away despite the archaic viewfinder system since this with the huge amount of lenses supporting it provides a complete photographic opportunity and solution. I do think that the only reason to buy into the dSLR Four Thirds market is the excellent lens support from Olympus, Panasonic and Sigma together with the good built-in software but it will perhaps never be the instinctive choice of professional photographers. Micro Four Thirds on the other hand is an exciting opportunity for both manufacturers and users. Panasonic’s GH1 as a hybrid between still and video photography has already made friends. Olympus’s E-P1 (the “New Pen”) is a style achievement as well as a great camera. Panasonic and Leica leave image stabilisation to the lenses. Olympus has it in the camera body. The E-P1 lacks an electronic viewfinder but who’se to say what might be next on their agenda? Panasonic is rumoured to be producing a camera the size of the E-P1 with  an optional EVF. Samsung has an undisclosed agenda and then there’s consortium members FujiFilm and Sanyo to think about. The Micro Four Thirds consortium also has a Unique Selling Proposition. There is already a central update service for firmware and software. Software is very important in the design of the system. For example, lenses are produced without the requirement for them to be 100% rectilinear. Whatever the specific peculiarities of a lens at any particular aperture – such as vignetting or barrel or pincushion distortion – these will be transmitted to the camera so that the firmware can manage them and create correctly processed jpeg images. And the lens profile is embedded in RAW files so that the converters supporting the lenses will present a uniform initial view. Firmware updates is a very important part of the system, giving perhaps a longer life to individual products that would otherwise be possible.

The result of a halved flange back distance has also had benefits in that new lenses can be mounted on Micro Four Thirds systems with adapters. Principal of these are the Leica M bayonet and M39 screw lenses plus their Voigtlaender counterparts and there are now adapters for specialist lenses from Zeiss and others to be mounted directly on Micro Four Thirds systems. RJ Camera in Shanghai has produced a range of mount adapters that are excellent and cheaper than branded varieties. I have a Four Thirds to Micro Four Thirds adapter without the electronic contacts (saving £100) that lets me use my Minolta MC/MD manual focus lenses on my G1 and E-P1 and I also have a Canon EOS to Micro Four Thirds adapter which in itself is not very useful as Canon EF lenses don’t have aperture rings but it does mean that all the lenses that I can mount on my Canon 5D can be mounted on Micro Four Thirds.

Micro Four Thirds is a bandwagon about to roll. Ignore it at yout peril!

This is the mount end of a lens that is about to be mounted on a Canon EOS camera. If you know this mount and have sharp eyes you will see that there are two things wrong with it. Firstly the electronic contacts are stuck on rather as an afterthought and secondly the lens is not an EOS lens. In fact this is a Nikkor 24-120 mm f3.5-5.6 D lens mounted on a Nikon to EOS EF adapter and the electronic contacts are there to fool a Canon EOS camera into thinking that the lens is an EOS f2 manual lens so that the camera will  beep and show an in-focus light when manual focus is correct. Because this lens has an aperture ring and a manual focusing ring we can mount it onto any camera body for which there is an adapter and use it in aperture-priority metering mode with manual focusing. And because the Canon EOS EF lens mount is both wide and has a short lens-to-sensor distance more lenses made for other mounts have adapters to it than any other lens mount. For example I have adapters for Nikon F, Contax/Yashica, Olympus OM, Leica R, Pentax K, Praktica Bayonet, Tamron Adaptall II and the early “universal screw” 42 mm mount popularised by Praktica and Pentax and many other manufacturers. These adapters all just consist of mechanical mounting rings in and out set into a ring that acts as a spacer to move the incoming lens flange back to the distance it had originally from it to the film plane. That distance is referred to here as the LFD and because of a requirement to make an adapter at least as deep as 1.5 mm the LFD of lenses to be attached to a Canon EOS EF  body must be the LFD of the Canon body at 44 mm plus that distance. So it’s lenses that had an original LFD of 45.5 mm or greater that can be mounted and function as they were originally designed to do. The list of these lens mounts starts with the Pentax K mount, being the closest,  and includes all those mentioned above plus the Contax N mount and lenses for Medium Format camera for which there are adapters to their 35 mm counterparts.

It is possible for adapters to be made for lenses that do not conform to the rule above by providing a lens or lenses in the adapters so that the adapter effectively becomes a teleconverter and thus can be mounted further back. For example when Canon commenced the EOS range of cameras and lenses, its excellent range of FC and FD mount lenses could only be used on EOS cameras with a special lensed mount that magnified the image by 1.2 times. Compared to modern teleconverters that have between 4 and 7 glass elements, this adapter had two elements and was dropped fairly soon after the EOS launch. I do have a lensed Canon FD to Canon EF adapter but it reduces image quality. I also have a Nikon F to Pentax K lensed adapter that is similarly inferior.

Of the main digital SLR manufacturers at August 2009, excepting Four Thirds for which see later, only two provide continuity for their manual focus lenses in the digital age. Pentax (with Samsung) gets the gold star because all digital Pentaxes will directly accept, meter and confirm focus of all manual lenses for 35 mm film right back to 1947 (the screw ones have an adapter that fits in the throat of the lens mount) and with an additional mount for the 645 lenses. Nikon gets the bronze star for the fact that the “enthusiast” and professional digital bodies (but not the “consumer” or entry-level ones) will mount and meter lenses from 1977 onwards. The only other mount for which these two cameras have adapters is Leica R. As with Canon, Minolta left its manual focus lenses unsupported when it moved to the AF mount that is now the Sony Alpha mount and there are several manufacturers of cameras and lenses for which no adapters are available to the 35 mm full frame or APS-C cropped digital formats. Konica A, Fujica X, Minolta MC/MD, Rolleiflex QB, Exacta, Topcon, Miranda bayonet and 44 mm screw, Mamiya CS and E – all mounts for which there were fine lenses – are lurking in or on the edge of the dustbin of history. I am hoping to persuade RJ Camera to produce an adapter for the Mamiya CS mount.

These lens mount adapters referred to are not expensive as they do not convey any electronic information. The ones without the focus-confirm chips vary in price from £6 to £13 and those with the chips are around £15 to £20 depending on quality. Note that these prices are for Chinese ones which do vary in quality. The RJ Camera ones are very good quality and I can recommend the ones sold by the “pixlamb” and “photobits42″ shops on eBay. Outside of eBay there are the Novoflex and CameraQuest ones that typically cost US $120 or more.

The Four Thirds consortium (Olympus, Panasonic, FujiFilm, Sanyo and Kodak) developed the open standard for the Four Thirds lens mount and to date there are cameras from Olympus, Panasonic and Leica using the mount. At 38.67 mm LFD it opens the possibility of adapters being available for Konica A, Canon FD (directly), Fujica X, Minolta MC/MD and AF, Rolleiflex QB, Exacta and Topcon. All of the adapters mentioned earlier are also available for the Four Thirds Mount so now a great part of sixty years of lens production (or what’s left of it) can be used on digital cameras.