Some thoughts about testing longer lenses...

The long end of the Panasonic FZ2500... Stage lighting.

I always feel a bit disingenuous when I describe myself as a neophyte with long and very long lenses because over the years I've dabbled in long lenses across many systems. I've never owned any of the ultra-nose-bleed-expensive super telephotos. No 600mm f4.0s or 300mm f2.8s. But I will say that the introduction of semi-super long lenses in several one inch sensor cameras did much to whet my appetite to try longer and longer zooms in the m4:3 and APS-C systems. I shy away from using fast, long lenses on full frame or medium format cameras as I value my lower back and really don't want to flirt with herniation anywhere on my body. It might hamper my swimming....

But if you are hankering for a taste of the long stuff I would say (emphatically) that a good way to get your feet wet is with a Sony RX10; model three or four, or a Panasonic FZ2500. The FZ2500 has the equivalent angle of view of a 400mm full frame lens. The RX10.4 goes all the way out to an equivalent of 600mm. If that's not enough reach then you are heading for specialist territory and a quick wallet draining.

Whichever system you choose and whichever long lens (let's consider long to be anything with a field of view smaller than that of a 200mm equivalent = the long end of everyone's 70-200mm vanilla zooms) I think you need to really test it; not just to see how much potential and sharpness it delivers, but to see how much you might need to work on your chops in order to squeeze out the goodness designed into the modern, long lenses. 

Why am I suggesting this? Because a cursory review of long lens reviews on YouTube and many blogs shows that nearly every reviewer is telling you how sharp ( or more frequently; unsharp) the lens you've been thinking about actually is. There are a few reviewers like Thom Hogan who understand that they're not going to see the whole potential of a lens unless they have it secured to a good tripod and, further, that they must practice good shooting techniques. 

The realization that a tripod is essential for lens testing comes to me after reading in 90% of the reviews that, a. they are only shooting handheld, but with image stabilization and at fast shutter speeds (you know---the shutter speeds that don't seem to work well with I.S.) and, b. the lenses they test always tend to get worse and worse, performance-wise, as the reviewer progresses to longer and longer focal lengths. 

Are we actually to believe that all our caffeine besotted web-reviewers are like demi-gods in that they are able to securely, and without shake, handhold a 600mm lens so well that there is no degradation of imaging performance due to camera movement? I'd be amazed to find one who can pull it off. 

Here's another aspect that might not occur to testers in mild climes, when the atmosphere heats up you get heat waves that reduce resolution and contrast in longer lenses. Oh, and while we're talking about atmospheric effects, let's also consider that smog, smoke, fog and other airborne diffusion filters (atmospheric haze, yikes) profoundly limit the sharpness of an image that was focused on a distant subject. Is it any wonder that a reviewer who is handling a loaner lens for a week consistently finds all the distant subjects, taken at long focal lengths, handheld, to be less sharp and snappy than the review photos taken of said reviewer's cat from five feet away, in daylight, with a 50mm prime lens at f5.6?

I thought about all this as I read through plus and minus reviews of the Fujifilm 100-400mm XF lens I bought for my Fuji cameras last week. I want to see for myself what I might expect from the new lens and so I'll be testing it as time allows throughout the rest of the week, culminating in its use at a dress rehearsal for a new play at Zach Theatre on Sunday. 

Here are some of my essential practices for testing long lenses: 

1. If you live somewhere hot get up early on a sunny day before heat waves act like a soft focus filter for your lens. 

2. Put the damn camera and lens on a tripod. I know, I know, tripods are not sexy + God forced people to make image stabilization because he/she hates tripods. Whatever. Your test is meaningless if you don't at least establish a baseline with the camera and lens mounted on a tripod. After the tests are done you can throw away the tripod, if you like, but at least you'll come to know that the lens might be sharper than you think while you may be less sharp than you imagine. 

3. Don't confuse a camera's inability to perform good continuous AF tracking with lens softness or "a lower performance at the longest focal lengths. Yes, you should eventually test the total system performance but putting a new 100-400mm on a older XT1 body which has not had any firmware updates and then blaming the lens when the focus is less than stellar is unfair. Which brings me to point #4....

4. Update both the lens and the body firmware before you do your tests. Even systems that don't always tout their latest upgrades will almost certainly have improved what they can with each new rev. Even if they don't announce the improvements, incremental or otherwise. I've purchased several new lenses which had firmware that dated back years. I update them before I test them. 

5. I've had enough Nikon 800 series cameras to know that many times a "soft" lens is really just a symptom of a camera body that needs a bunch of focus adjusting to work right. If every other person who owns the lens you are testing is getting good results, and you don't, you might need to change bodies just to be sure a lame body is not the culprit. Especially if a normally well regarded lens isn't sharp anywhere in its focal range.

6. Speaking of focus, while you have the big lens on a tripod you might want to find a non-moving target and compare your manual focusing skills against the camera's autofocusing skills. Many times the little AF boxes that litter camera finders aren't as accurately lined up with the actual focusing sensors as we might want to believe. Putting your system on an immovable tripod and then using focusing magnification to go in as tight as you can and manually focus will let you fine tune the exact point of focus better. Then you can test in AF and see what gets you closest. Remember, you want to know what the lens is capable of without covert interference from a camera. 

7. Evaluation of your testing is the last step. I know a lot of people who shoot their "test" shots and then chimp on the rear camera screen in order to evaluate how "sharp" their shots are or how sharp their lens might be. Of course that's an information deficient environment for good evaluation. Maybe wait until you get home, brew a nice cup of coffee, and settle into you favorite office chair first and then pop that memory card into your computer with the calibrated Retina screen, convert your raw files and then have a peek. You'll quickly see where your new lens shines and where it might fall down on the job. 

If your litmus test is the screen on your phone then, don't worry, all your lenses are already good enough.

Once you've figured out that your lens really is sharp when it's on a tripod and nicely focused you can start peering into the weak points of your technique, your support gear, your focusing precision and much more. I normally test lenses the way I use them. I put them on a known good body and head out the door to shoot mostly stuff that doesn't move, which allows me to hand hold shorter lenses and to take time to ensure focusing precision, but, as I've said, the longer focal lengths constitute a smaller percentage of my overall experience and I am more methodical when I test them. If you see me around Austin this week you'll probably see me toting my Gitzo tripod. It's not the biggest tripod I own but it's rock steady while still being small enough to still carry around for a few hours at a time. 

Below are a whole mess of photographs I've done in recent years using the long zooms on the aforementioned Sony and Panasonic one inch cameras as well as a random collection from other lenses and camera systems. With good technique a so-so lens can return better images than a $12,000 lens in the hands of a lazy, incurious person.
OMG. Shot with the FZ2500 from a long way away....

Sony RX10 IV does corporate event. Near the 600mm limit....

Shot from the very top of the graffiti wall about 200 feet away.

shot across four lanes of traffic on Congress Ave.