There are a lot of opinions around about lenses and many of them are based on the same opinions we have had for ages, perpetuated by the makers and some purchasers through ignorance or sometimes deliberately.
Lets look at some of these myths.
1) Fast lenses are better than slower ones.
This is patently not true, in fact in the past slower lenses were considered stable, faster ones had to go to extreme measures just to be as good, while delivering the special feature they were bought for.
Hollywood set-like light captured buy the kit 40-150 Olympus. At f8, which was needed for the correct depth of field, no other 40-150 I own would have made the image any better.
If you need a fast lens, then got one, but don’t buy a usually big, usually expensive fast lens to get your landscape passion off and running. Most lenses are near identical at smaller apertures and once you are over the uber-blur look, you may rarely use the very wide aperture that cost you so much.
An early image taken on the Sigma 30 f1.4, a lens known to produce super sharp images wide open. Since purchasing it, I have rarely used it, possibly responding to the flat, very modern sharp-soft rendering it is prone to or maybe the large (for MFT) form factor? The reality is, I like context in my images, something this lens is designed to blur away.
2) Bigger and more expensive lenses are inherently better than smaller ones.
Another myth. A lens if made to the needs of its design concept, does not need to be any bigger than it needs to be, which is to say, that monster chunk of glass up front, might not be an image improver, it may simply need to be there, just equalise the lens with it’s lesser stable mates.
Designers go to great lengths to make their flag ship designs their best lenses, something they may find challenging as lesser lenses pretty much come together effortlessly.
Large lenses also mean bigger filters and they require better flare controls.
The lens that took this (17 f1.8 Oly mk1) is not overly special on the test bench, it has soft corners wide open (often a field curvature thing, that means nothing in the field), average overall measured sharpness (not visual sharpness), a very small front element and a small overall form factor, mediocre Bokeh with a modest aperture, but it consistently takes some of my favourite images. The designers wanted a good street photography lens and made just that.
3) The lens mount does not matter (do we even think about it?).
The lens mount determines the stress placed on the lenses design. The Sony mount for example is quite small, the sensor is as bigger than the mount itself, meaning the effort made to make wide lenses for it has to be both clever and extreme resulting in some massive, complicated and heavy glass.
Nikon on the other hand have made their new mount so big, they could almost accommodate a larger format with it. This makes some aspects of lens design like super fast and fast-wide lenses significantly easier. The larger mount also results in about one stop less perceived depth of field, so a modest f4 lens acts like an f2.8 version.
4) Lots of (often exotic) glass makes better lenses.
Again, like points one and two, more glass and more glass with indecipherable lettering (LD, SLD, Asph etc) is not there to make a lens better, but more likely just to make a lens possible*. If you make a lens faster, longer, wider, a zoom, it gets harder to achieve good results so exteme designs become the norm. Lots of special glass, lots of glass and lens coatings generally become mandatory, resulting in that heavily corrected look.
A common theory floating around is that lots of highly corrected glass tends to render a “flatter” image, an image that has a more 2D look, that looks less realistic and satisfying to the eye. Whether that is true or not, there is a look some modern super lenses have that to be honest I am not a huge fan of.
I am reminded of the three tilt/shift lenses Canon made in the EF range. Two were not hard to make so got no exotic glass and no red “L” ring, the more difficult 24mm needed extreme effort (and two models) so it got the works. Perception was the non-L lenses were inferior, which was erroneous as they were all identical, they just suffered from Canons odd “L” class segregation policy.
Ironically, more glass increases the chance of lens miss-alignment, introducing flaws. This is less common these days, but as Lens Rentals revealed in their testing, not completely solved.
5) Sharper is better than softer.
Aa any cinematographer will tell you, there are types of sharpness, sometimes down-sides to too much sharpness or contrast and selection of a lens needs to match the needs of the job. I have personally come to class lenses as hard, simple, or micro-contrast sharp.
None is better than the other, but each does it’s intended job.
Super sharp corners wide open or perfect field flatness for example are basically a waste unless you shoot perfectly flat subjects wide open all the time.
Taken on a $100 plastic fantastic kit lens, this is not only sharp enough, but “perfectly” sharp to match the subject and look I was after. I have three 40-150 lenses used as the light requires, the biggest and heaviest being the fastest, but in this situation would it have taken a better image? I am often grateful that I had that lens on that day in Japan as it captured a dozen of my favourite images without unnecessary weight, bulk or speed.
6) Test charts are needed to determine quality.
Lens tests are a basic form of categorising a lens in direct comparison to other lenses using the same test processes and the user needs to be aware of the process and it’s limitations.
No more, no less.
The lens test has always been a good place to seek justification for a purchase or feed the lust for a future one, but they must be taken in specific context to their process and the reader needs to be aware that there is a lot more to a lens than test data.
Examples of confusion I have witnessed are different cameras being used in different formats then the results compared, or the top 20% of an MTF chart compared to another, ignoring the reality that both lenses filled the first 80% effortlessly.
The real question is what does the image look like? I was once told by a Leica technician that lens test procedures are important to some extent, but the only way to find out if a lens suits your needs is to use it for two years. The modern equivalent is to look at images taken with a lens in situations similar to your ideal.
Are the images it makes all same-ish, do they look flat or two dimensional, are they boringly too perfect, lacking life or character? That lens may test very well, but is that enough?
Designers always have a goal in mind, but more recently that goal seems to be to make the “perfect” test bench lens, no matter the cost in other areas.
The only way to really get to know a lens is to use it doing what you do, how you do it.
7) More Bokeh is better.
For a start that is a mis-use of the term.
Bokeh just is, it is not a measurement. You can have different Bokeh, more or fewer out of focus elements in your image and the effect can be exaggerated or avoided as needed, but more is not fundamentally a measurement of better.
This is an often very real reason for buying a super fast lens, the ability to loose a background to soft and beautiful blur, but it is only one photographic option and assumes that the subject in context to their environment is not wanted. You don’t tell a story with a super shallow depth of field image, only take a portrait and you do not need a fast full frame lens to do that either. If you intend to tell stories, you will find that the lenses ability to render harmonious semi-soft backgrounds is more important than it’s silky soft blurring of everything.
Any image, unless taken of a flat surface will have an element of Bokeh because depth of field is a measurable thing, so when buying a lens, look at it’s rendering and how you react to it in all circumstances, not just up close-wide open.
Taken with the 17mm lens mentioned above, a lens that has such expanded and coherent Bokeh transition that I call it my “never miss” lens for street photography. It can be shot at f2.8 with manual focus set to 5ft and is sharp-seeming from front to back of the image. I can even safely use it wide open with similar results in low light. This image that could be called “Arrows of confusion” is also a good example of one that requires more depth to tell the whole story.
Lenses I have come to respect, even love over the years are a mix of those known to be spectacular and some very modest lenses. The right lens for the job is all you need.
The Olympus 17mm f1.8, featured a couple of times above is one of my most used lenses over the last twelve or so years. A staple of ten trips to Japan (possibly the only lens that has made every trip), it and the more impressive 75mm f1.8 are responsible for many of my favourite images. They are an example of two very different specialist lenses, complimenting each other perfectly.
I appreciate it’s forgiving elongated Bokeh rendering (not usually a modern Bokeh enthusiasts go-to, but ideal for street imaging), resistance to flare and handling of strong light, it’s tiny form factor, super reliable AF, manual focus clutch (basic but workable), perceived micro-contrast sharpness and organic colour. It has become an unlikely landscape favourite, a street champion and I even like it’s shallow depth Bokeh-when I need it. My 15mm Pana-Leica is similar in many ways, seems to be better at dull day brilliance and snappier shallow depth images, so they can act as a the perfect pairing.
The more fragile-sharp, lighter, brighter and more modern Bokeh rendering of the 15mm Pan-Leica is a nice foil to the 17mm, justifying both in my kit.
If I owned the f1.2 version I would probably appreciate it for paid work when stresses not of my choosing come into play, but when stopping it down to f2.8 or 4 for street and general travel, it’s images would likely be no different.
I am not saying the 17 f1.2 is not a very special lens, but for my needs, it is over kill and provides nothing my more pedestrian Panasonic 35 f1.8 on a full frame body cannot (similar depth of field, better low light performance, lighter weight), but neither are ideal for travel.
For my more recent trips, the 9mm Pana-Leica, basic 17, 45 and kit 40-150 Oly and kit 12-60 Panasonic lenses have been more than enough for my needs and in total weigh less than my Oly 40-150 f2.8 or Sigma 28-70 f2.8 while adding depth and options.
Very often an f4 version of a professional zoom matches a f2.8 one at shared apertures, but costing and weighing half as much. Which would you take on a long hike for landscapes? Cheap f1.8 primes are often excellent and stable (and enough), low glass count lenses can have a very good 3D rendering and low flare.
Some past favourites include the 180 and 28 f2.8, 50 and 90 f2 macro OM Olympus, Canon FD 24 f2.8 SSC and 100 f4 SC, EF 135 f2L, 200 f2.8L, 400 f5.6L, 35 f2 and 50 f2.5 (old models), 28 and 85 f1.8 USM’s, Olympus 17, 45 and 75 f1.8’s, all three 40-150’s from the kit to the f2.8, 75-300 kit tele and 300 f4. A mix of premium and more ordinary lenses.
*There are many cases if lens spec creep over the years that have not bettered the optical quality of a lens, only added a feature and compensated for the feature with improved design. An example is the Canon 100mm Macro lens. The very first FD lens was not AF, internal focussing, stabilised or overly fast at f4. By the time Canon had improved it over 3-4 models until the EF 100 f2.8L IS, with internal focus, was made it was no sharper, but it was also not less sharp or prone to flare. All the special glass and clever design had managed to make a better, heavier, dearer adn more complicated lens that was the visual equal of the much easier to design original.