In future posts I’ll dive into detail on tripods and camera support. This post expands the reasons why I think it is so important to pay attention to camera supports.
Firstly, lets think about what we are trying do. Put simply, I want to exploit as much of the resolving powers of my camera’s sensor and lenses. Part of that is keep the camera rigidly fixed during the exposure. Now it’s pretty obvious that that might be important, but just how critical is it?
Well, consider a 24MP camera - in 3:2 format that would have 6000 pixels along the long axis of the sensor (6000x4000 = 24M). Now, if I fit a lens with a angle of view (AoV) typically used for landscapes, say 24mm equivalent, then the AoV along that same axis is around 74 degrees.
That means each pixel is covering an AoV of 74/6000 degrees, about 0.012 degrees - a tiny amount! Now, lets suppose the camera moves 0.012 degrees during the exposure. This would be imperceptible to the photographer, but vibration from wind, or sloppy technique could quite easily introduce this amount of movement and more.
But, let’s stick with just 0.012 degrees of movement to illustrate my point. That effectively means that the image data is now smeared between adjacent pixels. In affect the thin 0.012 degree slice of the image that each pixel should record is now one 0.024 degree slice with each pixel and it’s neighbour recording the same data.
So, with that tiny imperceptible amount of movement we have effectively reduced our linear resolution by half. In other words, instead of 6000x4000 resolving power, we now have 3000x2000. So, with that tiny, tiny movement, we have gone from 24MP to just 6MP. If we double that amount of movement, to 0.024 degrees (which again, would be completely undetectable by the user) we are down at just 1500x1000 or 1.5MP! Wow, 20 years of progress in digital camera resolution undone by a tiny fraction of degree of movement!
I have a theory that this is possibly why you see so many recent and high resolution cameras being sold in mint condition with very low shutter counts. I do wonder whether people upgrade, they see no dramatic improvement despite moving to a camera with double the resolution of their previous model. The camera takes the blame, not the user, who has simply neglected to consider their technique.
Now, I have no doubt some of you, if you have bothered to read this far, will be saying ‘this doesn’t matter to me because I have IS/VR/OIS’. Yes, image stabilisation (IS) is a useful technology (sometimes) and definately has it’s place. But, it’s place is not what many people think it is, or want it to be. Basically, IS serves a purpose to increase the probability of capturing an acceptable image at shutter speeds below that which most users could do this when hand-holding the camera. Yes, there are some more sophisticated systems in professional lenses that try to compensate or minimise the movement of, say, a boat, or the vibration of a (stationary) vehicle engine, but they tend to be the exception rather than the rule.
Note what I said above, an acceptable image, which means, using our 24MP example, may be an image with 18MP of detail, or 12 or 6 or even 3. Let’s face it, getting a an image that looks sharp on a webpage, or printed at A4 does not need anywhere near 24MP. The point is, you may get that sharp, but reduced effective resolution image with IS, as opposed to an un-usable blurry image without IS. We shouldn’t ignore as well that many cameras made in the last few years are capable of very good image quality at high ISOs, so the value of IS has, to my mind, declined dramatically from the days when shooting at anything above ISO 400 produced a muddy low contrast image.
Plus, professionals photographers have known for years how to maximise their chances of capturing usable images when hand-holding, by good technique (breathing tricks, bracing yourself and the camera, shooting at the ‘peak’ of the action etc) and knowledge (knowing what shutter speed works for a particular cameras/lens combination, in a particular situation). It’s all part of their craft. That’s not to say that they won’t take an extra insurance policy, like IS, it’s obvious they would, all else being equal.
Nikon for years got criticised for not putting VR into their excellent 24-70 f/2.8 lens. I would be willing to bet most of that criticism did not come from professionals. For decades photojournalists and others just got out with that lens and got the pictures they and their editors needed. Everyone who used the pre-VR version of this lens realises it’s a great tool that just delivers, and as the saying goes, bad workers blame the tools.
Anyway, I digress, this post was not meant to be about ‘acceptable’ images or a rant against IS, it’s about extracting the maximum detail out for landscapes shots, and as I hopefully showed above, it’s vital to keep that camera rigid during exposure, so as to record the most accurate data. In a future post, I’ll discuss what this means in practice, in terms of equipment and technique.
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