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Sunday, 25 March 2012

Comments

I've never seen a wide angle lens with an internal filter drawer! Why don't more lense makers incorporate them?

Even if it added $500 to the cost, think of how many Nikkor 14-24mm users would kill for this feature.

Wow! That (rotating) filter drawer is ingenious! But doesn't it introduce a host of possible dust problems?

It's too bad there isn't a universal camera mount, I would love to use this on my Canon 5D or my Sony A77.

Dust problem? Maybe but then again it is an all-weather lens ( from the AW moniker) .

How does the polarising filter work with the wide field of view of this lens?

When I try to use a polarising filter on my 15mm APS-C lens, (22.5mm equivalent), I get nasty changes in saturation and brightness in the sky as you move across the image from one side of the frame to the other. My understanding was that this is because the influence of the polariser varies depending on the angle of the subject relative to the sun and that with an ultra-wide angle lens, one edge of the image frame might be nearly facing the sun, whereas the opposing edge might be facing 90° away from the sun. Thus changes in the influence of the polariser can be seen across the frame.

So how does this fancy new Pentax 645 super wide lens avoid this problem?

"When I try to use a polarising filter on my 15mm APS-C lens, (22.5mm equivalent), I get nasty changes in saturation and brightness in the sky as you move across the image"

That's only a problem if you want a uniformly dark blue sky over a wide field of view, which is a phenomen that I have never observed in the real world.

I have only ever used polarizing filters for photos of food, tabletop, architecture, paintings, plants, and other shiny things.

With digital, making multiple exposures with the filter at different angles, then compositing it in photoshop is pretty easy. With film, multiple exposures with different polarizer angles wasn't that big a deal.

David, most likely it still has that problem with skies that wide angle lenses have with polarizers, but there are other cases where it's nice to use a polarizer, like a flowing stream, perhaps, to cut reflection and provide lower shutter speed, or a wet forest scene with shiny leaves. And you could use other kinds of filters I'm sure. I'm wondering if you could have a gnd filter at the back end like this.

The new DA lens is simply a reduced coverage version of the initial D FA lens; perhaps by simple extension of the lens shade. There are a few troubling aspects of this change: The D FA version will continue to be available, but only in Japan, the rest of the world gets DA version. The reduced coverage DA lens cannot be used on film bodies or any future full frame 645DII. Pentax has reduced the coverage, but not the price. The only justification for the steep price tag is use on a full frame 645; for 5k, a Nikon D800 and 14-24mm seems like a good alternative.

David - It doesn't avoid the problem. Polarizers always have a problem with skies in wide angle shots.

So you can do things like lessen the polarization, or accept or hide the changes with your composition if possible.

But more importantly, polarizers don't have to be used on the sky; There are plenty of other uses. They work wonders on foliage and water. They can cut through glare on architectural shots. And they can help even out harsh shadows in some situations. I'm sure there are lots of others.

Oh my. Another nudge like this might put me on the MF digital side of the fence.

Mike only assumed it was for polarizers, but they would show what you described. It could be that the rotation is to allow for a grad filter or some such.

Keith:
A gradient filter wouldn't work that close to the arpeture, or rather it would effect the out of focus highlight areas but not the overall image.

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