A question that I get, and see very frequently on forums that I moderate, is the one about the super telephoto zoom. The flavour of the month in these critters is the 150mm - 600mm variant, with most of the discussion around the different Sigma and Tamron lenses. As always there is plenty of back and forth on which one is better. I’m not going there. They are both fine lenses, I have shot them both, and like any lens with this wide an angle of view variance, they are a compromise to some extent. This means that primes will typically outperform them optically. Not a big surprise, there is no alignment between a 150-600 and a 600 prime when it comes to cost of acquisition. Since there is no such thing as a free lunch, anyone who complains about their new 150-600 not being as sharp or having the contrast of a 600 prime is what the doctors like to refer to as cuckoo for cocoa puffs.
Frankly the challenge is not the optics. The challenge is the load of sheep dung wrought by sellers and writers who suggest that these things are usable handheld by normal humans for more than a few shots.
I constantly hear the 1/focal length guideline applied to lenses. It’s a guideline, not a rule and does nothing to take into account the weight and physical size of the lens in question. So the assumption that you are going to be good at 1/600th of a second has a high probability of being wrong when shooting handheld with such a lens.
Contrary to many forum rants, the issue is not the lens at all, the challenge is the critter trying to hold a sixteen inch long tube of metal and glass steady for an angle of view (FF) of 4.13 degrees or about 2.69 degrees on a crop sensor. What’s going to shake more? You or everything else? Here’s a hint, it’s you.
So in this scenario, applying that 1/focal length guidance is as some would say, a big sack of hooey. M43 users will be laughing happily because of course they get the same angle of view with a 300mm lens that is lighter and smaller. And since most of us cannot see a difference between images from different camera sensors, they’re right and we should move on.
Want to learn something? Call up your local photo expert, be that person Uncle Bob, or the seller in your local camera store and ask “what’s the minimum safe handheld shutter speed with a 150mm-600mm lens” If the answer is anything other than to ask you a bunch of questions in return, you are talking to someone who actually has no idea what he or she is talking about, in which case, ask the cat. The answer will be as accurate, and you will at least get to see live disdain for the question.
The other problem that you will have if you can get past the need for extremely high shutter speeds to counter your shake - and forget all the blah blah about lens stabilization systems - I will come to that in a moment. you now have to get enough light to the sensor. People don’t buy big zooms to shoot them at their shortest focal length, they buy them to shoot them at their longest, otherwise why spend the money in the first place? Let’s all keep moving and assume that no one reading this is concerned about how large their equipment looks to others ok?
At 600mm, most of the lenses top out at a maximum aperture of f/6.3 Let’s do some quick math assuming that it is a bright sunny day and you want the best contrast and dynamic range so you choose ISO 100. That means that with the lens wide open, your shutter speed on a bright sunny day is going to be 1/800th of a second. Want more shutter speed, start bumping the ISO. That’s not a bad thing but lots of folks freak out about noise because they determine if there is too much noise by looking at a blown up image on a 27” display from 6 inches away. This behaviour is a widely spread disease medically referred to as photographic related nasal compression, because noses are crushed against the glass. It’s fundamentally dumb, and you all know better, yet it happens every day.
Ok so to get a safe handholdable shutter speed you’ve now moved to ISO 400 on our bright sunny day. But wait! What if there isn’t bright sun where the subject is, or you are photographing against a bright sky and therefore need to overexpose to prevent your subject from falling into silhouette? Now you are more likely in the ISO 1600 to ISO 3200 range. For many folks this is the no go zone, and that is a personal decision. Moreover shooting a number of frames is going to result in muscle fatigue and that’s going to result in, yup you got it, more shake and the need for more shutter speed.
Now about that vaunted image stabilization or whatever set of miasmic buzzwords are used. The reality is that IS in lenses works most effectively with vibration under 5 Hertz and over 10000 Hertz. This means, it’s not doing very much of anything at common shutter speeds. If you choose to believe the mcmarketing, that’s your choice, but there is no whining allowed when things don’t work out.
At this point you may be thinking that my point is not to buy one of these lenses. Nope, my point is that if you are going to practically use one of these lenses, you are going to need a stable mount for it. And that means a tripod, or at least a monopod, coupled with well practiced technique. Yes there are photographers who can shoot massive lenses handheld, but they practice all the time, manage their breathing and create bone bridges in their positioning for maximum stability. You may be able to do these things as well with sufficient effort and if you are diligent and practice for some months, good for you.
Also consider where your support is planted. A tripod standing on wood, may be more stable than handheld, but wood is an excellent resonator (why it is used so much in music) and transmits shake from one place to another with gusto and aplomb. I have had long exposures made on the first floor of a wood framed building ruined by kids jumping on the second floor. Metal resonates as well but not as badly. Concrete not so much. Rock is also good. General earth is good too but you should be using ground spikes to dig in and prevent minor shifting that is normal for those rubber feet found on most stability devices. I use Really Right Stuff kit myself, and have both ground spike kits and rock claws for my tripods and monopod.
I was asked many times if a tripod would help when photographing from a boat. Think about it. Does the boat move? If yes, and the answer IS yes, so does the tripod and one should expect camera shake. Also tripods on boats are a hazard where someone or something often ends up swimming. If you have to shoot from a boat, rent the fastest lens you can for the subject and crank that ISO up. And shoot a lot because you will have a bunch of discards. Such is reality. Obviously this is considerably less a problem with short focal length, wide angle of view lenses, but those are not what we are talking about here.
Super telephoto zoom lenses can help you get shots that you would otherwise not be able to achieve. However they are not the panacea that they are often presented as and some critical thinking about your specific use cases BEFORE the credit card comes out, could save you both money and frustration. If you assume going in that the lens is going to spend its life on a tripod, you will be far better off and less likely to be horribly disappointed.
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I'm Ross Chevalier, thanks for reading, watching and listening and until next time, peace.