GF 30 vs 32-64

Started 5 months ago | Discussions thread
norjens
norjens Regular Member • Posts: 392
Re: curves

left eye wrote:

norjens wrote:

left eye wrote:

The 32-64 has a major curved plane of focus.

[snipped]

I still don't see how this is a negative in general.

Generally a flat plane of focus is preferable - as then the plane of focus is predictable, flat is flat. A curved plane is somewhat of a irresolvable case - as to where the curve is.

They're both regular and familiar shapes that we see all around us, so I doubt I'm the only one not having a greater problem predicting where a curved plane will be as soon as I'm familiar with the lens. Just looking outside without a camera, it's not hard to visualize some curve on the ground. If it were a zigzag or saddle shape I'd agree.

Jim's tests while thorough, tested the 32-64mm sides and corners by focusing on them - rather then on the centre and then inspecting the sides and corners. Focusing on the sides/corners gives a best case scenario for the lens, but doesn't match up in my experience to real-world scenario.

Lens testing is always done in the best case, removing bottlenecks like motion blur, pixelation (where possible) and misfocus, obviously Jim doesn't test misfocused areas because that is meaningless. He tests with correct focus for each part of the frame, and where that is depends primarily on where those objects happen to be.

I've actually been very disappointed with the performance of the sides of this lens - due to the curved plane of focus. Sure when I focus at distance (near infinity) the corners render really close ground to be in focus - that's nice, but the sides at the same central near infinity distance are totally out of focus - disappointing.

If your subjects are always on a perfect line, like a head-on shot of a wall, then I understand. But most subjects are randomly distributed, no? Especially in street and hiking, which is the use cases in question here.

I realise, and as I said, for environmental portraits some extra de-focus outside of your subject can be ok, but I'd rather just control this with aperture than a curved plane of focus.

The 30mm is far better in this regard than the 32mm end of the zoom - a fact that is hidden by Jim's test. In this regard I do think the 30mm has significant optical advantages over the 32mm end of the zoom. In fact for landscapes (horizons at middle to long distances) the 32mm end of the zoom is poor - due to the curved plane of focus, for closer subject - where an obvious horizon isn't present, the curved plane of focus becomes more integrated into the depth a scene.

Horizons are in general curved, because the earth is curved. Variations due to elevation are common, but completely straight ones are not. At middle to long distances the depth of field becomes less and less limiting, so it doesn't matter as much as for mid to short.

As a landscape lens - I'd pick the 30mm every time, and the 23mm. For environmental portraits I'd pick the 32-64 zoom - due to FL flexibility - but I still wish it's plane of focus was flatter.

[snipped]

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