Friday, 8 July 2016

Formats Compared - M4/3 (Part 3)

This is a test image taken with an ancient Olympus OM 24mm f2.8 at f2.8 on an Olympus EM5 mk2 late on a very miserable afternoon. Nothing amazing about it?  Well actually there is, despite the wide open aperture the central 75% of the frame is incredibly sharp and detailed, that guy you the original image, zoomed in you can easy see his Moustache and Goatee and see that he has his finger scratching his right eye and that he has a pair of gold reflective sunnies on his hat!  Legacy glass and M4/3 can be a great match.

Welcome back to the mini series on sensor format choices and today it is time to examine the M4/3 format.  From the outset the designers intended M4/3 to be the best possible blend of image quality, lens performance, body size and cost effectiveness.  Basically they started with a clean slate and worked forward from there, initially with the original 4/3 DSLR format and then later via the M4/3 mirrorless format. This was a different approach to that taken for the Full frame and APSC formats, the former being a straight carry over from 35mm film and the later a constraint of the very high cost of sensors in the early years of DSLR development and the need to work with lenses mounts carried over from the film era.

In the main the M 4/3 format has never been as popular as APSC, though I imagine the sales still exceed the Full frame format.  Cameras range from quite cheap and cheerful through to high end products that are as sophisticated as the best APSC and Full Frame models, in fact in some instances maybe even more advanced.

Basic Spec: 

M4/3 has a sensor area of 17.3 x 13  225mm, making it about 24% of the size of full frame and about 60% of the standard APSC sensor.  The highest resolution versions are 20 megapixels and the remaining current models are all 16 megapixels, there are a couple of fixed lens M4/3 sensor cameras that use 12 megapixel versions but they are outside our current discussion.


You do not generally buy into the M4/3 format as a cost savings measure compared to APSC, in fact across the board the prices are about the same for any given models target audience level, however it is arguable that the build quality of the mid range M4/3 cameras is a little better than the equivalent APSC versions and in many cases they have additional features over the equivalent APSC models. Lenses are no cheaper, with high end zooms and fixed focal lengths easily being as expensive as their APSC cousins, however they are still vastly cheaper than full frame equivalents.


Despite the much smaller format size the image quality is generally excellent, providing you are not pushing into the high ISO region, which generally you don't need to do anyway, certainly below 1600 ISO there is little to pick between APSC and M4/3 and 100 to 400 ISO is excellent across the board.

Ultimate image quality is less than either full frame or APSC, however the excellence of many of the lenses often makes up for the difference between M4/3 and APSC and it is still perfectly fine for most normal uses.

The main deficit is limited dynamic range, which at best is roughly equal to the older APSC sensors, generally you need to be more careful of highlight clipping.

As far as I know there are no 14 bit versions of RAW files for M4/3, this may have some bearing on extreme RAW file conversions where highlights and shadows need heavy recovery operations.

It is more difficult to get shallow depth of field rendering but with the right lenses still quite possible to get reasonable separation.

Format Options

Generally the 4:3 aspect ratio means less cropping for most uses, other than printing 6x4 inch postcards, which is pretty irrelevant as 6 by 4s only need 2.5 megs to look great anyway.

The native aspect ratio works well for a wide array of printing options but is compromised for 16:9 aspect ratio shooters.

A square pic still maintains 12 megapixels from the standard 16 meg sensor where as a 16mp APSC will drop to around 10.5 megapixels.

The 2 times crop means that one can get some really useful telephoto options from otherwise basic 35mm legacy lenses, for example the cheap and humble old school Nikon 35-70 f3.3 to 4.5 effectively becomes a 70-140 lens which is very useful for portraiture and distant landscape work but only needs to be stopped down 2/3 stop to become critically sharp.

You can crop down to the 1" sensor equivalent and end up with about 8.5 megapixels, which is not that far off the 10 megapixels offered by the original Nikon 1 series cameras.

Due to the light weight and excellent native lenses it is vary easy to do mild image stitches to simulate the look of larger formats and the Olympus em5 mk 2 has a super high res mode that provides files that compete with full frame, provided of course that the subject is still and you use a tripod.


The weight advantage on M4/3 extends well beyond simply having a ligher camera body, lenses are much lighter often 1/3 -1/2 weight of APSC, filters are smaller, ball heads and tripods smaller, monopods smaller and the case/bag needed to hold it all smaller and so on, thus the overall kit weight can be vastly less than even APSC.


Body size can be a bit too small and cramped for some hands, especially when knobs are being operated whilst the camera is at your face, this would be my main complaint.

There is a well known issue with shutter shock within a narrow shutter speed range for some Panasonic and Olympus cameras, these days this can generally be avoided by using the electronic shutter option or at least electronic first curtain options.

The current 16-20 megapixel count found on almost all M4/3 camera represents what is likely about perfect of most everyday photographic needs, enough for very detailed and clear results and a bit of cropping, more than adequate overall quality and reasonable "on card drive" files sizes.

The increased DOF offered by M4/3 can be a bonus for lots of casual and even professional shooting situations.

Less extreme falloff into out of focus for close up subjects can work better for some portraits and close to macro images but makes it harder to get that look so loved in full frame and medium format options.

Small M4/3 cameras can be used on selfie sticks and most work fine on lightweight tripods.
(especially if the camera LCD flips and flops to suit)

M4/3 requires less powerful flash equipment both in studio and the field due to the use of wider apertures for most shots.

It is easier to balance artificial light sources and flash as the working aperture can be wider which helps keep "ambient to flash exposures ratios" closer together.

Generally most kit lenses and all other M4/3 system lenses are very sharp and have even clarity across the entire image field, considerably more so than the equivalent APSC and Full Frame offerings.

Lenses of moderate aperture can be very compact which can make for a very lightweight full featured kit.

In theory a 14mm M4/3 lens should be the same as an 18mm on APSC and 28mm on full frame, in practice this is not the case, the 4/3 aspect ratio means the total angle of view across the frame horizontally is less.  This means you have a greater need for wider angle lenses on M4/3 but there is not as great an array of options once you go below 14mm when compared to the APSC and FF formats.

Most people refer to M4/3 as having a 2x crop factor compared to full frame cameras but when you take the aspect ratio into account it is actually a bit more than that.  Swings and roundabouts as the horizontal view is a bit tighter than 2X but the vertical view a bit less.

M4/3 better lends itself to video assuming the camera maker has taken this path as a priority, the smaller sensor is more easily cooled when used for heavy demand applications like 4K video. The Panasonic GH series remains to this day the ultimate all purpose hybrid video camera when you want great quality in reasonably light package, the Sony A7 FF models arguably have better ultimate file quality but lack the extreme flexibility of the GH series.

Most shots can be taken at apertures of f5 or wider (lens permitting) so shutter speeds can be faster or the ISO lower, this aspect combined with very effective image stabilisation can make M4/3 the most practical option for real world use low light usage.  For example an Olympus or Panasonic 25mm f1.7 lens can actually be shot at f1.7 with still reasonable DOF and excellent edge/corner sharpness, combined this with 5 axis IBIS and a moderate ISO and you can shoot confidently in available darkness quite easily.

Image stitching can work really well due to light weight of the cameras, making rigs smaller and easier to use, additionally the typically very even cross-field performance of lenses means you get very few resolution holes in the resulting stitched images.  Many lenses such as the olympus 45mm f1.8 exhibit almost identical corner and centre performance with negligible vignetting making stitching very easy and requiring only minimal frame overlap, which means the total file size for the full image is less for any given resolution.

An M4/3 camera combined with one of the excellent *native macro lenses is a very workable solution for slide and neg scanning giving a little more flexibility in focus accuracy than the larger formats with more than sufficient resolution. Using the Hi Res mode on the Olympus EM5 mk2 will give very high resolution slide and neg scanning that is capable of getting all the detail out of super fine grained monochrome films such as Kodak Tech Pan.

The M 4/3 format when used with native macro lenses is the most practical option for hand held macro, basically you can get automated image stacking, wider working apertures (meaning lower ISO or faster shutter speeds) very quick auto focus and more extended depth of field.

* The 40-60mm macro lenses designed for M4/3 are probably the best Macro lenses ever produced for any format


Despite the suitability of the format to shooting long telephoto shots it is difficult to find truly exemplary lenses (either native or adapted) many legacy lenses exhibit horrible longitudinal chromatic aberration on M4/3 sensors once the focal length goes beyond 200mm but in the 50 to 150mm range (which equates to 100 to 300mm full frame) there are several excellent options.

Wide apertures lenses generally show excellent resolution, even wide open.

C mount lenses work better on M4/3 than other formats.

You can adapt almost any lens to M4/3 other than Sony A (NEX type) and Fuji Mirrorless, Canon M and Nikon 1 lenses. (in other words lenses from other mirrorless formats don't work...unfortunately, though it is possible to adapt manual 4/3 lenses to Sony E mount, though I am not sure why you would.)

Most kit lenses are able to work excellently at the widest setting and performance remains very consistent across the focal length range. As a breed M4/3 kit lenses, both standard focal length and telephotos are probably the best performing and some are quite excellent.

Adapted lenses from 35mm film cameras in particular only use the sweet spot of central lens performance making for very even cross frame clarity and almost zero vignetting even with average grade optics such as the 35-70 Nikkor zoom.

The addition of Metabones or similar speed boosters adds to the low light ability of the system giving sub f1 options and turning moderate speed 35mm fixed lenses like the Nikon 50mm f1.8 into well performing f1.4 jobbies.  The adapters add 5mm less length than a standard lens adapters. Many APSC lenses that have slightly larger than APSC image circles can also be used with a handy speed boost on the M4/3 mount.  The 4/3 versions of the Speed Booster generally offer superior performance to the APSC versions.


When I set out to write these articles I was not expecting M4/3 to show so many advantages, but that's how it seems to have worked out and probably explains why many M4/3 owners are so endeared of their systems.  If I was starting out and looking for the best overall option to cover the greatest array of needs I would probably go with a combo of M4/3 for general work and Full Frame for Portrait and specialised professional jobs, skipping the APSC middle ground.  

As it is I have all three systems and they fulfil different purposes, I must add however that an odd thing has happened of late in that my M4/3 gear is being used more for commercial work and earning its keep by being easy to use and highly practical for many paying jobs.

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