Olympus 300 mm options Photo comparision - Cheating Cheetah

Started 2 months ago | Discussions thread
Tech Head Regular Member • Posts: 132
Re: Not useful

Samuel Dilworth wrote:

Like practically all of these casual lens tests, this one is worse than useless.

I say that not to be unkind but because, at best, no firm conclusions can be arrived at. And, at worst and much more likely, viewers will draw the wrong conclusions. The latter has already happened above.

I stand by my conclusion, and I believe the results will be substantially similar if the OP repeats the test.  It may not be perfect, but the differences were substantial enough that I don't think any repeat tests will alter the ranking of the lenses.

Take the comparison between the 40-150 mm f/2.8 with teleconverter and the 300 mm f/4 prime. The focus is different. In the centre, the wooden background around the cup is sharper with the zoom (compare the wood grain to the immediate left of the cup). The cup itself is sharper with the prime (compare the hash pattern of the cup texture above the cheetah’s back). Who knows if either of these is best focus: there isn’t enough information in the frame to tell.

Meanwhile, the field curvature of the two lenses, being different, combines with the non-perpendicular camera axis to give a confused picture. The knot in the wood at the extreme top-left corner is sharper with the zoom, whereas the right edge of the frame generally is much sharper with the prime, but mainly – we’re left to assume – because it’s out of focus with the zoom.

Although there are literally dozens of pitfalls with this kind of testing that I cannot exhaustively preempt others from making with a few paragraphs of text, an easy first step is to test at infinity. That makes the scene effectively perpendicular to the camera without the need for difficult alignment.

Take a landscape-type picture from some height so that the entire scene or at least key areas of the frame of interest – the left and right extreme edges near the middle, for example – are at infinity. Then do your best to focus accurately, taking many pictures and using the sharpest ones for the comparison. I hope it goes without saying that you need a sturdy tripod, good tripod technique (self-timer, etc.), stabilisation off, a largely windless day, and so on. That goes double for 600 mm-e lenses.

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