Reviewing camera equipment often requires us to compare specifications because each system is different, beginning with the sensor size. One of the most common comparisons involves focal length equivalence, a topic that often generates some confusion. The most recent example we’ve encountered concerns the new Olympus 300mm f/4 Pro (see our review here) that gives the equivalent focal length of 600mm on a full-frame camera. Not only have I read many discussions, but I’ve also received a few comments stating that this comparison is not fair and that a 300mm is a 300mm lens regardless of the sensor that resides behind it.
Is it correct to compare the M.Zuiko 300mm to a 600mm lens designed for a full-frame system?
In this article, I will try to explain why in my opinion the comparison isn’t unfair. But let’s start by brushing up on few concepts to make sure we have the correct basis from which to start.
First I want to talk about angle of view (also known as field of view) which is the largest view a sensor is able to “see” through a lens. For me this is important because it has a concrete impact on the composition of my image.
Then there is the “full frame” reference. In most cases, it is related to the 35mm format (36x24mm) which was the most popular film back in the day. (Note that the full-frame term is also used for medium format.) When the first digital cameras came out, their digital sensors were smaller than the 35mm format. As a result the angle of view we used to know and love with a 36×24 film lens was narrower on those digital cameras. This introduced the crop factor as we know it today. We had to learn to calculate what angle of view a lens designed for 36×24 would give on the smaller sensor. The easiest way became to mention the equivalent focal length simply because we refer to lenses according to their focal length more than the angle of view they produce. However, remember that technically, if I use a lens on a smaller sensor than the one it has been designed for, it is the angle of view that changes, not the physical focal length.
Today things have become more confusing because we have several camera systems on the market each with different sensor sizes including a digital 36×24 that matches the 35mm film format. It is not just a matter of comparing focal lengths within the same system/brand but also understanding the equivalent focal length between different systems/brands. So to “simplify,” the 36×24 format has been kept as a reference and even the various photography brands list it in the official specifications of their products. It helps us to quickly understand what kind of field of view a lens designed for a smaller sensor will reproduce.
With the basics above covered, let’s move forward and compare two camera systems.
On one hand we have a full-frame 36×24 camera and on the other, a Micro Four Thirds camera with a smaller sensor (crop factor is 2x). I am going to explain why the angle of view here is what matters more than the focal length written on the barrel. To do this, I will start with a classic example: the 50mm lens.
A 50mm lens on a 36×24 sensor gives an angle of view of 47°. We often refer to it as a “normal” or “standard” lens because it has an angle of view close to that of the human eye. Note that this association works only if we consider the central angle of view of our human eye which is around 40/60° and that mostly impacts our perception (meaning looking at something without turning our eye to the left, right, up or down). Because of this association, the 50mm lens has been very popular since the film days (it was also a common kit lens). We don’t really care about the actual physical focal length here but we do care about that 47° angle of view we like to shoot with. That’s the truly important specification.
If that standard angle of view is a “must-have” for the photographer who wants to use a Micro Four Thirds camera, the first thing he will check is which native m4/3 lens gives him the desired field of view and he will find out that it is the 25mm (that has the same 47° angle of view on Micro Four Thirds). If he wants to use a Fujifilm camera (APS-C format), he needs to look for a 35mm focal length.
Of course, this reasoning can be applied to every lens. My point here is that a photographer normally chooses a lens according to what he wants to photograph. Does he want a vast angle of view (wide angle) for architectural shots or something as narrow as possible to capture images of birds (telephoto)? The focal length is a common reference but the angle of view is what really matters for the photographer’s vision, especially if we compare lenses designed for different systems and sensors.
When I switched from my Nikon D700 to the E-M5 and subsequently the E-M1 for my work almost three years ago, I started to replace my lenses step-by-step, keeping the same or closest angles of view I had for my full-frame DSLR. I started with the M.Zuiko 12mm and 45mm because I had a Nikkor 24mm prime and an 85mm portrait lens. Then I added the Lumix 35-100mm f/2.8 because I was using a Nikkor 80-200mm f/2.8. I think you get my point.
So if I go back to the Olympus 300mm, it is correct to state that it gives the same angle of view as a 600mm lens on a full-frame camera for the two reasons I explained above:
- the angle of view is the same (approx 4.1°)
- because “full frame” (36×24) is the most common reference and the only system that has this kind of lens is the DSLR system right now.
But even more important is that this comparison is a starting point. It doesn’t imply that one is better or worse than the other. It gives a reference, nothing more.
Of course in this case it also highlights the advantage of the M4/3 version – namely, its smaller size, weight and price compared to the DSLR lens – but that has always been the case with Micro Four Thirds.
From this starting point, we can put other considerations on the table as well. For example a DSLR system has various telephoto prime lenses (from 300mm to 800mm) and two systems (APS-C and 36×24). If I add to the equation the various teleconverters (1.4x, 1.7x, 2x), it is clear that DSLRs still have more versatility for those in need of extreme telephoto lenses (and I could also mention the zoom lenses).
We could also talk about alternatives which in this case involves adapting a lens to a different camera system. For example, I recently saw some excellent shots posted to the MU-43 forum that were taken with a 300mm f/4 Sigma lens used on an OM-D camera. Of course you lose the autofocus as well as optical stabilisation, unless you buy an adapter with AF (but I don’t want to go off topic). If you can cope with manual focus, you can get excellent results. After all one of the advantages of a Micro Four Thirds system is the possibility to adapt lenses and get a narrower angle of view and more telephoto reach. Actually the Nikon or Canon 600mm on an OM-D E-M1 would give us a 1200mm equivalent focal length, but I wouldn’t use such a massive lens on such a small camera.
Finally I will add my two cents about a recurring argument concerning this topic:
A full frame DSLR with a 300mm and some cropping in post-production will give the same results. Well, let’s do some math to see if this is true.
We have a Nikon D810 with its 36 Megapixel 36×24 sensor. The camera has a DX crop mode (APS-C) that outputs a 15.4 MP file. The Nikkor 300mm f/4 with the DX crop on the D810 gives us an angle of view of 5.20° (450mm equivalent). To match the same 4.10° angle of view of the Olympus lens used on the OM-D E-M1, I would need to crop further in post production for a final size of approximately 9MP. That is almost half the native 16MP I would get on my E-M1. Even taking into account the Canon 5Ds and its 50MP sensor, I would start from a 19MP file with the camera’s 1.6 crop and then I’d need to crop a second time. I am not sure there is a concrete advantage here. More important this comparison doesn’t hold water because it misses two crucial points.
First the Olympus 300mm will primarily interest those who already own a Micro Four Thirds camera. Those m4/3 users are not necessarily interested in considering a camera and a lens of a different system as an alternative to a native lens designed for the camera they already use. Second I know that cropping in post is a common solution in today’s digital era but if you buy a lens that gives you such a narrow angle of view, you usually do it because you like that kind of reach and you enjoy using it in the field rather than working in post production. I assume that when Canon releases its 120 MP camera, this will become an even bigger possibility but as far as I’m concerned, it takes away the fun.
I find it much more fascinating to photograph wild animals with the appropriate angle of view rather than relying on the megapixel count of my camera.
I had much more fun making my way slowly toward the seals and taking this shot rather than keeping my distance and cropping in post production.
I think that what bothers many people is that the new Olympus lens is larger and more expensive than the average m4/3 gear and I am sure that some even think that Micro Four Thirds is not worth such an investment.
Well, the only thing I can tell you is that I often see photographers at nature reserves with their large DSLR and lenses. Regardless of the focal length or camera used, the E-M1 with the 300mm feels smaller and lighter. More importantly, this type of lens wasn’t available before. It is an important step forward for the system and all mirrorless brands are working in the same direction. Panasonic just released a very interesting 100-400mm zoom, Fujifilm is preparing its own 100-400mm and I wouldn’t be surprised if we see something from Sony later on. Mirrorless systems are growing and that is what matters, for the users that have already invested in these systems and for those interested in using them in the future.
Of course this is my personal point of view and I am sure that other people will have their own. There are various angles of view but also different points of view. The important thing is to pick the one that suits your photography best!
At some point, I made up some formulas for ‘crop factor’ that was based on the fact that 90% of the time, I crop to 8X10. For example, the diagonal angle of view crop factor between m43 and FF is 2:1 (fairly precisely if I remember). With both formats cropped to 8X10 proportions, the multiplier was less.
Perhaps this incredible resolution of the 300mm Pro is the reason the bokeh suffers from busy-ness like my Oly 40-150mm does. It’s much better smooth. A lot of the newer super high resolution lenses suitable for the ever-higher-resolving sensors exhibit this quality, so the uber sharpness has a trade off. Guess that we can’t have it all?
You have that around backwards. It’s easier and cheaper to make a 300/4 for FF than for m4/3 because the smaller senor with smaller pixels requires the lens to have a higher resolution. FF also has the advantage of economies of scale which I mentioned. According to Olympus this lens is the highest resolving they have ever made, exceeding their renowned SHG lenses. You are not comparing like with like.
The 300/4 is designed to have a 4° field of view. Those made for FF are
designed to have an 8° field of view. They are just not the same
animal.
My old OM Zuiko 300mm f4.5 has 6 elements. The 300/4 has 17 elements, many of them made from exotic glasses, is weatherproof, has OIS and focus motors. The production costs of these two lenses are just not remotely comparable. It’s like comparing a Ford Focus to an EVO XIII RS and complaining the EVO costs more and you want it to cost the same as the Mondeo becase they are the same weight.
Thanks, nice to know. The point remains though that given the optical project is of the same “difficulty” to realize, so to speak, as a 300mm for full frame the price shouldn’t be so wildly different (unless it’s for marketing reasons, but that’s a different matter altogether).
For what I can understand the problem is not in making exceptional lenses for smaller formats (i.e. going from a 300mm made for full format to a 300mm made for m4/3), but the opposite (making a 300mm for full format that performs as well as a 300mm made for m4/3).
Otherwise compact camera and smartphone lenses (the smallest sensors around) should be prohibitively expensive!
Actually that’s exactly my point: the 300/4 has been for years the “cheap” or at least affordable super-tele alternative.
A 300mm is a 300mm no matter what sensor you’re putting behind it, coverage of the format aside. And if anything else it should be more difficult to build one for a full frame camera (larger area to cover with good quality), so if CaNikon (and Pentax, that certainly didn’t have the same economies of scale) managed for years to sell one at a rather affordable price Olympus shouldn’t have troubles either, unless they want to cash in but that’s another matter.
Not so sure about that. I’ve got a Contax 100-300 and a 180/4 Leica that are 30 to 40 years old, but still beat the crap of anything else I’ve tried on the E-M10 sensor.
And according to LensCore.org (they tested a lot of lenses on 200Mp sensors) basically any decent lens made in the last 50 years should be able to deliver plenty of resolution (at least 50Mp for the worst of the bunch), at least when stopped down.
It would interesting to see Lenstip try out some of the highest performing lenses on the newer 16MP or even 20MP sensors to see if they are able to cope as well with the higher pixel densities, and what lp/mm figures they can achieve.
I would expect they are, as the 20mm/1.7 and old Olympus HG 11-22 that I have are able to quite easily resolve single pixel detail in the center (though not the corners).
I think magnification is actually a really interesting discussion, because it has a very specific technical meaning (the physical size of the object reproduced at the film/sensor plane), but you really do need to take into account pixel density in order to form a practical working definition. I say pixel density specifically, because if the smaller sensor has the same pixel density (i.e. 12MP Oly E-P1 vs. 50MP Canon 5DS), the “equivalent magnification” is no better with the cropped sensor – you’ve effectively just cropped a smaller image out of the larger image at the same level of quality. That said, it’s no worse, either (unless you’re photographing a subject at 1:1 that is larger than the 17.3x13mm sensor size with M4/3), but the advantage you get from M4/3 for macro is really in getting greater DoF with the same field of view, or having more pixels per tiny bug / coin / flower with the same focal length.
People that need this lens for their needs will buy it. Forum warriors that wanted an incredible pro lens for under 1k will complain till cows get home. Direct comparisons almost always leave out the fact that optical stab + ibis combo gives amazing flexibility and freedom to shoot hand held.
Have you ever tried GX8 + Metabones Canon EF to MFT Smart Adapter + Canon 300mm f/4 or similar setup?
There is no standard how to measure the angle of view.
For still it is typically (but not always) is the diagonal angle (covers whole image circle). But cine/video use exclusively the horizontal angle (cuts the corners). And I heard that there are some fields where vertical angle is used instead.
This actually brings us to another problem. FF and APS-C are 3:2 while 43 is 4:3, meaning that diagonal on 3:2 is somewhat longer (making the calculated angle narrower) than on 4:3 format. Recall the older 6×6, 7×6 and 6×4.5 formats – and the angle of view measure becomes even harder to compare.
You don’t frame or compose a photo with the focal length of a lens, you use the Angle Of View. The Angle Of View required to capture a given scene is a constant – it doesn’t change. The focal length required to deliver a particular AOV is a variable and changes depending on the sensor being used.
Referencing focal length and implying it can be considered as something independent of sensor size is disingenuous and illogical.
Lenses, cars, watches, phones clothes,and houses are not priced and sold by the Kg, but by the costs of the required manufacturing processes, the materials used and very importantly – by the economies of scale.
I think it should be interesting to compare E-M1 + 300mm f4 vs GX8 + Metabones Canon EF to MFT Smart Adapter + Canon 300mm f/4. Let’s start…
Price comparison:
Lens $ 1349.00
Adapter $ 399.00
Total $ 1748.00
Oly lens $ 2500.00
WINNER: Canon + Adapter
* In addition to the Adapter you can buy Metabones Canon EF SpeedBooster without spending more than $2500 and obtaining a more versatile solution with a 210mm f2.8 (0,71x).
Weight comparison:
Lens g 1190.00
Adapter g 160.00
Total g 1350.00
Oly Lens g 1270.00
WINNER: Olympus (-80g)
* Not a huge difference here
Dimension comparison:
Canon + Adapter
Max. diameter 90 mm
Length 246 mm (221+25)
Filter 77 mm
Olympus
Max. diameter 93 mm
Length 227 mm
Filter 77 mm
WINNER: Olympus (-19mm in Length) Canon (-3mm in diameter)
* No clear winner here, differences are negligible
Angle of view comparison:
Autofocus comparison:
Resolution comparison:
… comparison:
It’s up to you Mat! 😉
I think an article like this could attract lot of traffic from the web.
Noted 😉
I agree. Too bad they make my head hurt!
Depth of field is so small with fields of view this small, what difference does it make? If anything, I think the MFT 300 mm f/4 would have an advantage – easier to keep both eyes in focus!
Others have responded too, but remember that this has to have huge resolution (come on LensRentals, run your Olaf!) to make it worthwhile as a rival to the CaNikon 600’s. 16 MP in the area of the EM1’s sensor would be 64 MP on a CaNikon. That means you need some awesome glass.
Indeed – you can go to lenstip.com and see that m43 lens resolutions are generally much higher than full frame equivelants (from a angle of view point of view). A Canon 85mm 1.8 reaches about 40 lines / mm at 5.6 (http://www.lenstip.com/291.4-Lens_review-Canon_EF_85_mm_f_1.8_USM_Image_resolution.html) vs. over 75 lines / mm for an Olympus 45mm 1.8 which peaks at a lower 2.8 (http://www.lenstip.com/316.4-Lens_review-Olympus_M.Zuiko_Digital_45_mm_f_1.8_Image_resolution.html).
So, here is the case where the m43 lens virtually doubles the resolution to counter the sensor being half as tall or wide. Furthermore, the peak resolution of the m43 lens is 2 stops faster than that of the Canon.
So full frame sensors tend to have less noise at a given ISO. But, with my m43 system, I can lower the ISO and shoot wider than a full frame camera to attain peak resolution (even ignoring the fantastic stabilizer in my Olympus). So, many of the m43 low light noise arguments go away.
Understanding that you would like to keep this discussion focussed on depth of field, I won’t ask a question per se but rather ask that you talk about magnification equivalence in a later article as well.
Be careful not to make assumptions about the physics here. For supertelephotos like this, the image circle is almost never the limiting factor in the lens design, rather the objective lens and the physical aperture required to produce the f-number.
This generally will hold true in any case where the effective aperture (300/4=75mm) is much larger than the image circle, which holds true for both M4/3 and FF/135 in this case. In fact, you will find that even a Pentax 67 300mm/f4 that needs to cover a negative more than 4x larger than FF will be approximately the same size as one designed for FF, M4/3, or even 16mm film.
The tl;dr here is that image circle is basically irrelevant to the element size with this focal length until you get up to, say, 4×5″ sheet film.
Hehe, I guess you have a point here. I was never a big fan myself at school 🙂
The Olympus 4/3 300mm f/2.8 is massive. I tried once and that really felt like a 600mm full frame lens! 🙂
I use f/11 sometimes with my m4/3 lenses and honestly I never got any problems. If we pixel peep we can see some slight difference in comparison to faster apertures (depending on the lens as well) but it is not drastic. Actually I find the new Oly 300mm acceptable up to f/16.
Thanks David. Quoting your sentence:
“I suspect how we see all this depends on what we started with and for most of us we ‘understand’ this in our own way.”
I agree. Actually I remember when working at the Cannes Film Festival as an assistant: the photographer was using a Nikon D200 then switched to a D700 and she was ever so happy about it because her 50mm “was a 50mm again”. She was so used to 35mm film that she always struggled somehow to get used to the APS-C crop.
In the next article take size (and price) into consideration also.
Size has to be compared with same Angle of View and same Depth of Field, I think. But I don’t know any 600mm f/8 (without mirror) and even no 300mm f/2 in m43.
The sole comparable lens is 4/3 Olympus 300mm f/2.8.
My only gripe with the Oly (and with Panasonic about their 100-400) is that they’re trying to sell a 300/4 (absolute focal length is independent from sensor size), besides made for a smaller format (= no large glass elements needed to cover a large format) at an insanely expensive price. Just check how much Canon charges for their 300/4 IS made for full format.
I think if OVFs and DSLR autofocus sensors could properly deal with an f/8 lens, there would be a ton of people interested in a lightweight, high quality, affordable 600mm/f8 lens. But an OVF would be too dim, and the autofocus sensor would be too slow, and it would still need to be an extremely long lens (regardless of the reduced weight and diameter), to make such a thing practical.
I shoot with manual lenses on M4/3 and APS-C, and regularly stop down to f/8, f/9, or even f/11 (so f/22 in FF terms!) at 300mm to get sufficient depth of field. Modern sensors, especially full-frame ones coupled with image stabilization, can easily cope with 600mm/f8 while still giving remarkable quality. Its the rest of the system that falls apart…
And before someone brings up how I’m ruining my images with diffraction by stopping them down so far, I guess I’ll let you judge for yourself what f/11 looks like on M4/3 and how terrible it is. 🙂
https://c2.staticflickr.com/8/7573/16296860565_a85302cb62_h.jpg
As someone who ‘grew up’ in photographic terms with 35mm film, I keep those ‘conversions’ in my head. I then get an idea of what I’m liable to get in the frame. I even did that working with 645 MF. For example a 45mm lens on that type of camera has the ‘equivalent’ angle of view of a 28mm ‘FF’ lens but the DOF of a 45mm. So basically I’d stop down a bit more to get what I wanted.
These days I use a 14mm on m4/3 and use wider apertures. I find it difficult to see a m4/3 or APS-C lens for what it is. So what I’m saying is I suspect how we see all this depends on what we started with and for most of us we ‘understand’ this in our own way.
I do have to start doing a few ‘mental gymnastics’ these days however because I’m using a lot of adapters. 0.68x, 0.71x and 2x on m4/3 for example. Using a 14mm Samyang ‘FF’ lens with those three adapters I get approximately 18mm, 21mm and 28mm but all with the DOF characteristics of a 14mm. It works for me and I get what I want.
Finally, I agree very much with the point of the article. That the way to deal with this is work out your own way to cope with it. There are many posts on this on the photographic Internet and most seem to confuse and create confrontation, which is as pointless as it is a waste of time. Mathieu’s post is certainly one of the most sensible I’ve read and I applaud that. These days everything from smartphones to large format digital backs are used for photography and we all seem to be able to cope with focal lengths, angles of view and DOF and create the images we want in terms of the numbers. We can then get on with the business of making what we capture with our lenses and sensors, of whatever size, meaningful and interesting. Which is of course the real tricky part.
My point of view is there will be many users that shall enjoy this new long lenses. I very much like the devellopment of this lenses for mFT.
Personally I don’t need them but I didn’t needed the longest lenses for the OM Zuiko’s and FT DZuiko’s as well.
But I know my angle of view is very standard!
I wanted to keep the article focused on the angle of view here. Depth of field would have involved a different chapter (because there is some confusion regarding this as well) so that could be the topic for another article 🙂
Uhm… maybe the comparison isn’t unfair but to me is not totally fair as well. Angle of view (so the focal lenght) is the same, but you know that aperture equivalent is not the same. You have a f/4 FF vs a f/8 MFT aperture equivalent.
So you wouldn’t get “this same shot with both system and their respective focal length” in terms of bokeh. Full frame shot will have a shallower depth of field.
So a fair comparison would be between a MFT 300mm f/4 and a FF 600 f/8.
It would definitely help to keep the angle of view as a reference more often.
Things would be easier if we ignored the focal length and just used angle of view. It would save a lot of arguments on forums …