Basic Statistics for Photographers

In statistical analysis, there are two fundamentally opposing forces at play, which one must, at all times, keep in balance in an attempt to suitably analyse a given set of data.

Suppose we have a new drug that we'd like to test for the treatment of runny noses.  We would design an experiment where some people get the drug and some people get a placebo ('sugar pill'), and then, over time, we'd see how many runny noses we observe in the two groups compared to when we started.  At the end, we'd analyse all the data and determine whether the drug works.

In this determination, we can conclude that the drug either does or does not cure runny noses.  And in so doing, we have two ways of being wrong; either we can conclude the drug does cure runny noses when it, in fact, does not (this is known as a 'false positive') or we can conclude  that the drug does not cure runny noses when, in fact, it does (not surprisingly, this is known as a 'false negative').

Minimizing false positives and false negatives is ALWAYS a trade-off.  The more you do to minimize one, the more the other becomes a problem.  In the end, the trade-off determines the accuracy of your experimental test (at this point, we go beyond what is commonly accepted as 'basic statistics', into the realm of receiver-operator curves and integral calculus...a realm into which I dare not - and some might say cannot - tread).

Whether you err on the side of false positives or of false negatives really depends on your specific question.  In some cases, it would be very much better to avoid false positives (e.g. Is this drug effective against breast cancer?), while in others, minimizing false negatives is preferred (e.g. Does this new food additive cause cancer?).

So what on Earth does this have to do with anything?

Well, consider this photo.

Two steps to the right, and this would have been great...

What's wrong with this (besides the blown highlights)?

Well, I don't know about you, but where I come from, people generally don't have poles sticking out of their heads.

I took this shot last November during my trip to London (...clearly).  It was about 9PM, and I was returning to my hotel after dinner.  It was misty and cold (...clearly), but that made for a very moody atmosphere, which I was trying to capture in the shot above.

It nearly worked.  By the time I saw this guy crossing the road and focused my Leica, he was two steps too far.  A potentially lovely photo of an interesting subject became a miss.  A false positive, if you will; an error of commission.

Now consider this photo, which I consider a false negative; an error of omission.

This was the greatest photograph in history.  Honest.

The photograph above was a false negative; it would have been an awe-inspiring photo for the ages, but I never took it.  Shame, really.

This highlights the key point I'd like to address: all other things being equal, should photographers err on the side of the false positive (i.e. shoot everything, and toss the crap later) or the false negative (i.e. take fewer - but hopefully better - photographs)?  And what is the appropriate balance between these two types of 'error'?

First, one might be tempted to argue that in this age of digital photography, which is more-or-less free after one has purchased the gear, the photographer should take as many photographs as possible, and then edit out the bad ones later.  After all, there's no additional cost to doing so, so why not?

This is essentially the 'spray and pray' method.  Undoubtedly, you'll end up with some nice photographs.  But you wont be learning anything in the process about how to actually make a good photograph; you'll just be a million monkeys on a million typewriters.

On the contrary, I'd like to advocate for taking fewer photographs; that is, for making more false negative errors.

Garry Winogrand was once asked whether he worried about all the pictures he was missing while he was reloading his Leica.  He famously replied "There are no pictures while I'm reloading."  The implication here is that the photographer is an integral part of the photo making process, and that "missed" photos were never actually photos in the first place.

As photographers approaching a scene, the first thing we should ask ourselves is not "How can I photograph this?" but rather "Should I photograph this?"  I would argue that, in the vast majority of cases, the answer to the latter question is "no!"

For example, consider the following photograph.

Utter crap.

I shouldn't have taken this photograph.  It's boring, cliché, and really has no redeeming value whatsoever.  And guess what?  I've taken thousands of photographs just like it, and so have you.  I should have kept right on walking, and aborted this awful attempt at street photography.

So how can we learn to walk away?  And if we walk away, how can we ever hope to learn about what works and what doesn't?  After all, we don't see the photos we never take, and thus we can't learn from them.

Well, therein lies the irony.  We need to take bad photographs in order to make good photographs.  We need to look at monstrosities like the shot above and recognize our faults, and try very hard not to make the same mistakes again.  As we progress as photographers, we need to learn to press the shutter button less, not more.  We need to learn what constitutes a good photograph, and have the confidence to say "No!  This scene in front of my does not pass muster."  We need to work harder to make good photographs, and a big part of this is taking fewer photographs.  FAR fewer.  Making more false negative errors.

Having said all of that, there is also a fundamental difference between the false positive posted immediately above and that at the top of this post.  The former is, in my opinion, a photograph that could have been a winner, were it not for my relative sloth in getting the shot taken.  It's a near-miss, and while I'm disappointed that it didn't work out as intended, it was worth the attempt.  On the other hand, the latter photograph is pure junk, and I should have known better.

What we need to do is teach ourselves to recognize crap photos before we take them.  A cursory glance at Flickr suggests we are far, far away from this ideal.

So what do you think?  Is it better to take more photographs and toss the junk, or to think more up front and take fewer, better photographs?

How to choose a film Leica M rangefinder

I'm often asked, "Which Leica M should I buy?".  My usual response is to run down the features of the various models and compare this to what the photographer is looking for in a camera.  At this point, it generally becomes clear which M is right.

Once you've made the decision to purchase a Leica M, you're confronted with a bewildering assortment of models released over the past 60 years.  In order to streamline the decision making process, I've summarized the decision making process into a handy dandy flow chart.  This chart includes all of the major Leica M models made since 1954, but excludes the Leica CL and Leitz Minolta CLE.  The chart also excludes non-Leica M compatible rangefinders such as the Zeiss Ikon, Konica RF, and the Voigtlander Bessa cameras; these are fine cameras, but for the purpose of this post, I'm assuming you're looking for a camera made by Leica.  Finally, I've not included more specialist M cameras, like the M1 and MDa, which lack a viewfinder, rangefinder, or both.

I've also not considered price as a factor.  For example, the Leica M6 and MP are very similar cameras with respect to their actual features, but the MP costs 2-3x what the M6 does on the used market.  That difference in price is more or less due to minor usability and aesthetic differences, and this is not captured in this chart.  Suffice it to say, you should decide on your budget before choosing an M camera (or any other camera, for that matter)

Finally, I should also point out that while I've tried to make it easy to select the hypothetically "best" camera for you, based on your needs, you should be aware that virtually any of these cameras are suitable for almost any user, with the possible exception of those cameras that lack certain framelines (e.g. the M3 lacks 35mm framelines, while the models with 0.85x viewfinders lack 28mm framelines).  All of these cameras are exceptional.

The first key decision to be made is: do you need a light meter?  If not, you essentially have five cameras to choose from: the M3, M2, M4, M4-2, and M4-P.  Which of these cameras will best suited to you comes down to what lenses you want to use, and whether you want a classic Leica M with brass top and components, or whether zinc and steel are sufficient.
 

The Unmetered Leica Ms

Leica M3

Used under Creative Commons license

The M3 was the first, and many say the best Leica M.  It's the M to choose if you only shoot with lenses of 50mm or longer, since it lacks framelines for anything wider than 50mm.  While this is a limitation of sorts, it's also a great feature, since the 0.91x viewfinder is the longest of any Leica M, and thus gives you the most accurate focusing of any Leica.

Leica M2

Photo by E. Wetzig, used under Creative Commons license

The M2 was the second M to be introduced, and was intended to be a low cost M3.  The major benefit of the M2 over the M3 is the addition of 35mm framelines.  The major downsides to the M2 over the M3 is the need to manually reset the frame counter every time you load a new roll of film.  The M2 introduced the standard 0.72x viewfinder, and thus offers slightly less accurate focusing of fast lenses than the M3, although whether this has any effect in practice is a matter of debate.

Leica M4

Used under Creative Commons license

The M4 is considered by many to be the best classic Leica M.  It introduced many of the features that are standard on film Leica Ms to this day, including a rapid loading system and a crank film rewind, both of which are vast improvements on the system used in the M3 and M2.  The M4 really is the classic M to choose if you want all of the modern amenities, but don't need a meter.

The M4 spawned two follow-up models (the sordid history of Leica is beyond the scope of this article, but suffice it to say that these follow-up models were absolutely crucial to the long-term success of the company): the M4-2 and the M4-P.

Image by Duc Ly, used under Creative Commons license

The M4-2 is very similar to the M4, but lacks the classic M design (note the 'Leica' and 'M4-2' on the front), and had a few internal modifications that lowered costs.

Image by Daniel Petrzelka, used under Creative Commons license

The M4-P was the forerunner to the metered Ms, and introduced the 28mm framelines that are standard on most Ms today.  It's a great choice if you don't want to pay the premium for an M6, which is essentially the same camera with the addition of a meter.

The Metered Ms

Leica M5

Used under Creative Commons license

Most people will tell you that the M6 (see below) was the first M body with a light meter; and they'd be wrong.  In fact, the M5, which actually predates the meterless M4-2 and M4-P, was the first metered M.  Unfortunately, the M5 gets a bad rap from a lot of people, owing to its unorthodox design and its quirky metering system.  However, the M5 is actually a great camera, and because it gets overlooked, it can generally be had for very little money.  The meter was designed to run with a battery that contains mercury, which no longer be purchased.  This means that you either have to recalibrate the meter to work with modern alkaline batteries or go meterless.  Alternatively, these batteries are supposed to give the appropriate voltage for these types of cameras.

Leica M6

Used under Creative Commons license

Now we come to first of the truly "modern" M cameras.  The M6 offers reliable TTL metering, a good variety of framelines from 28mm to 135mm, and its meter runs on batteries that can be purchased at any local drug store.  This is the M that I recommend to most people, and it was my first M as well.

The M6 gave rise to an enormous number of special editions, which are beyond the scope of this article, as well as the later M6 TTL models.  These models differ only in their inclusion of TTL flash metering (IMPORTANT: both the M6 and M6 TTL offer TTL ambient light metering), and some other cosmetic changes.  The M6 TTL was also offered in three viewfinder magnifications: standard 0.72x, a 0.58x model, which is great for those who wear eyeglasses (as it provides a little more space around the outer framelines), and a 0.85x model, which provides a little higher magnification (and thus a little more accurate focusing), at the expense of the 28mm framelines.

Leica M7

Used under Creative Commons license

With the exception of the digital M bodies (not discussed here), the M7 is the only Leica M that requires batteries to function (the M5, M6, and MP use batteries strictly to power their light meters, but the operation of these cameras is fully mechanical).  Actually, that's somewhat misleading; the M7 can operate without batteries, but you are limited to two shutter speeds: 1/60 and 1/125.  This may not seem to be that much of a limitation, but if you're stuck somewhere without a spare set of batteries, you're in trouble.  However, the benefit of this is that the M7 is the only film M that offers an auto exposure setting.  In this mode, you set your f/stop and the camera selects the appropriate shutter speed (you can also use traditional manual exposure control).  Whether this is a benefit is a personal choice.  The M7 is a current model, and is offered in the same three viewfinder magnifications as the M6 TTL: 0.72x, 0.58x, and 0.85x.

Leica MP

Used under Creative Commons license

Now we come to the big boy; the ultimate (and probably final) film M: yes, it's the MP.

'MP' stands for 'Mechanical Perfection', and was Leica's attempt to put everything they learned about making film rangefinders into a single camera.  While the MP and M6 offer very similar feature sets, the MP really is a more refined camera.  First, the MP returns to brass construction (which produces a noticeably smoother operation over the M6), a vastly improved viewfinder window (which lacks the tendency to 'white out' due to flare when pointed toward a light source, as is common on some M6s, including the one I owned), and a return to the classic M aesthetic.  As with the M6 TTL and M7, the MP is offered in three viewfinder magnifications: 0.72x, 0.58x, and 0.85x, and in black paint (I own a black paint 0.72x model) or silver chrome.  The MP truly is the finest M available, but of course there is a downside: price.  If you can live with the aesthetics and slightly-less-than-absolutely-silky operation, then the M6 is a better choice (it should be noted that the operation of the M6 is more refined than virtually every other camera on the market...it's just that the MP is that much better).  But if price is no object and you want the best of the best, in a camera that will last your lifetime (and probably that of your offspring), then the MP is the clear winner.

 

I hope this guide is useful to you.  I'll say it again: any of these cameras are a wonderful choice, and are capable of making stellar images, when coupled to a great lens and (most importantly) a great photographer.  This guide is merely my attempt to help steer you in the right direction when it comes to picking a Leica M that best suits your needs.

Happy shooting!