Reviews > Ramblings of the Fierce Bear of the North

The fallacy of using long lens technique (LLT) at slow shutter speeds

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Bjørn Rørslett:
[ Posted 03 November 2007 - 23:40 Modified and reposted by agreement  ]

What is "long lens technique" ?

It simply is putting one hand on top of the lens, at the tripod collar position and pushing down, whilst you press your face against the finder of the camera, then gently trip the shutter release. Claimed by many people to be the panacea to obtain sharp images with long lenses [some even assert  you can make do with flexing and poorly designed  tripod mounts because of the LLT], but as evidenced here, will actually do the opposite if shutter speeds are slow.

The problem with advocating proper long lens technique (LLT) as the solution to all stability issues with long lenses, is that it ignores the need for shooting at really slow speeds. I don't doubt LLT can secure a sharp image at 1/125 sec, so can any decent tripod collar/tripod combination do equally well. But what happens when you go slower, say approaching 1 sec or even longer? Many times you need to use such speeds for nature photography. I consider 1/15 sec "fast" for long periods of the year and in winter, 1/4 sec to 6 sec are normal.

The following setup was used: a very long and heavy lens with a very sturdy tripod mount  (180-600/8 Nikkor ED, weight 3.2 kg), a very stable tripod (Sachtler ENG 2 CF HD, weight 4 kg), a very stable tripod head (Burzynski), and a very lightweight DSLR (D40). I ran comparisons of a test target of speeds ranging from 1/4 sec to 6 secs, using either proper LLT or no LLT. The camera was on all occasions triggered by a remote control (ML-L3)  to eliminate any influence from manually tripping the shutter release. D40 has no mirror lockup and I did not use a self timer. For a LLT/no LLT comparison, the conditions should be ideal. The lens and tripod are so heavy and stable that you can't see any sign of vibrations when looking through the finder and the lens is tapped. Surely adding more stabilisation by LLT should do nothing to upset this?

I did repeated sequences but all A/B comparisons showed a result similar to the one shown below.

It is readily apparent that even under this set of "optimal" conditions, LLT will deprive the image of detail sharpness. You simply CANNOT touch the lens during a [long] exposure and still have optimal sharpness. This underscores the need for having stable tripod mounts on a long lens. For fast shutter speeds, LLT is OK, but a good tripod mount is better.

So, can a solid support help reduce the vibration caused by the mirror slap between the shutter speeds 1/15 to 1 second without mirror lockup?

Certainly. But even the best support can be inadequate if the tripod mount is poor enough, precisely around say 1/15 sec or so. That is the underlying reason why I complain so much about the long Nikkor mounts. My usage is geared towards slow shutter speeds. I don't do birds in flight or quickly-moving animals. Details and landscapes at dusk or dawn or in the "half-light" period of the year are my speciality.

Of my long lenses, the 200/2 VR is most prone to issues because of its bad tripod collar. It doesn't look that bad but real-life experience shows otherwise. The 300/4.5 ED follows next in terms of poor mount. Usually I can get by in the critical range with MLU with both lenses, though. On the other hand, lenses such as 300/4.5 ED-IF, 300/2.8, 400/3.5, 400/5.6 ED, 500/4, 500/5.6, 500/8, 800/5.6, 800/8, 1000/11, 1200/11, plus the 200-400/4 AIS and 180-600/8 ED all go well even in the critical range, so with any of these, I just shoot away and don't think too much about the actual shutter speed. Thus, I have earlier shown really sharp images taken with the super telephoto 1200/11 at speeds down to around 1/5 sec.

Makes sense to me.  The human body is essentially unstable, so is unlikely to add stability to anything.

Bjørn Rørslett:
That is an excellent way of stating this obvious yet so frequently overlooked fact, Anthony.

Do have a look at the way birders and wildlife photographers handle their long lenses if the opportunity arises. Most do put their hand on top of the lens.

What result would you expect if, instead of your hand, a passive weight were draped over the lens where the hand might be? (like a wide cloth strap with small sandbag at either end.)

Bjørn Rørslett:
You mean, compared to not touching the lens?

With a decent tripod/head, adding weight actually influences the image sharpness much less than one might expect. The important factor is torsional rigidity and coupling between lens and tripod, not weight of the supporting structure as such. You can prove the last point simply by putting camera + lens directly on the ground. The support now is the mass of the entire planet. Yet you can easily get unsharp images.


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