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Old Apr 19, 2007, 11:23 PM   #11
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robar wrote:
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a 28mm will be the same as 28mm on the kit lens. which would be a 42mm.
Well not entirely true....

A DA is going to be different if only because the entire image is focused on the sensor vs cropped.

But then comes the flipside question....

A few years down the road when near everything WILL be Full Frame (and given tech changes I doublt it will be much longer than that).... what are you going to do with all these then relative unsaleable DA lenses??? (VS the classic.. even 40+ year old Pentax lenses still perfectly usable today.)

The KD10 now sells for less than what the original (infinately less capable) Canon Rebel 300D did just ~3 years ago.


But to answer the OP ?

Yes 28mm is about the min affordable wide.

Below that the otic complexities, especially to keep them rectalinear (undistorted) gets very complex/expensive to make.



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Old Apr 20, 2007, 2:55 PM   #12
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I happen to have the M24mm 2.8, bought in 1980. I hardly ever used it because on a film camera it is just a bit too wide for my tastes, and does have a bit of fish-eye barrel distortion. I've used it much more with the digital cameras - there's still some barrelling, but not that much. When I first got the K100, I posted some pictures taken at night in Las Vegas with it. It might be a cheaper alternative, if you can find one. I haven't used it much since I got the K10 - I have had some exposure problems with it and have gone back to using the kit lens for wide angle pictures.
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Old Apr 20, 2007, 4:11 PM   #13
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Hayward wrote:
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robar wrote:
Quote:
a 28mm will be the same as 28mm on the kit lens. which would be a 42mm.
Well not entirely true....

A DA is going to be different if only because the entire image is focused on the sensor vs cropped.

don't pay attention to this BS. you are entirely wrong hayward. 28mm is 28mm. sheesh. the DA 28mm has the same crop factor as the old FF lens. there is no magnification factor
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Old Apr 21, 2007, 1:23 PM   #14
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Hayward mentioned the DA lenses being brigther before and I doubted it, but I'm not one to just say something has to be wrong without knowing for sure so I went ahead and tested it myself. I put the camera on a tripod, set it to aperture priority at f/8 and shot a DVD case with an SMC A 50mm f/1.7 and the kit lens set to 50mm.

The first thing I noticed was that at 50mm, the kit lens was wider angle than the A lens. I had to set it to 55mm to be about the same. I'm not sure if there would have been a visible difference when shooting something farther away.

Secondly, the kit lens was at least a half stop brighter. By default it was trying to shoot at a 50% faster shutter speed. I then set the camera to M and shot them at the same speed, and the shot from the kit lens was very noticeably brighter.

I've always assumed the DA lenses were just smaller and lighter, and never read (and still can't find) anything that suggested they focused the light on a smaller area, but it appears very possible.

Of course, Hayward's prediction that all cameras will be Full Frame in a few years is just silly. If anything, there will be more smaller sensored cameras like the Olympus because new sensors will be more sensitive and making lenses and bodies for them will be so much cheaper.
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Old Apr 21, 2007, 4:12 PM   #15
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i didn't say anything at all about brightness. hayward stated that with a DA lens that the whole image would be captured by the sensor and this is nothing but disinformation. the DAs have the identical crop factor as any other lens.
28mm is 28mm !

roy
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Old Apr 21, 2007, 7:13 PM   #16
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robar wrote:
Quote:
i didn't say anything at all about brightness. hayward stated that with a DA lens that the whole image would be captured by the sensor and this is nothing but disinformation. the DAs have the identical crop factor as any other lens.
28mm is 28mm !

roy
My post wasn't specifically addressed to you or anything you said. I actually agree with both of you (except for where each of you disagree with each other).

A 28mm lens, whether it's FF or DA, is indeed 28mm. And the crop factor is always there, so either 28mm lens will become 42mm equivalent.

However, Hayward is also correct in pointing out that while there is a crop factor, DA lenses aren't really cropped in terms of cropping out light information. If you manage to mount a DA lens onto a camera with a FF sensor, it'll capture roughly the same field of view but with a black border because the image circle is designed to match the smaller sensor size.

The main reason for my post was pertaining to Hayward's point about the lens focusing the light more directly into a smaller area. When he first said this I doubted it, but then tried the experiment and it seemed to support what he was saying. I was kind of hoping someone could shed some more light on the subject by either confirming what Hayward is saying, or providing an alternative explanation as to why f/8 on a DA lens is noticeably brighter than f/8 on an A lens.
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Old Apr 21, 2007, 7:33 PM   #17
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Hayward wrote:
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Well not entirely true....

A DA is going to be different if only because the entire image is focused on the sensor vs cropped.

case rested
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Old Apr 23, 2007, 1:00 AM   #18
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robar wrote:
Quote:
i didn't say anything at all about brightness. hayward stated that with a DA lens that the whole image would be captured by the sensor and this is nothing but disinformation. the DAs have the identical crop factor as any other lens.
28mm is 28mm !

roy
Sorry for the misunderstanding, no I meant just what Cropsy ended up testing I hadn't... but just made sense in a optical physics sense. A FF lens you are spilling 1/3 the light and image.

And no image size will be no different as FL is FL, but ALL of a DA lens's light is concentrated on the sensor (and will be vignetted on a FF) so the image is likely to be different, being more concentrated/dense light rays (vs cropped, spilled/lost more spread light) covering just the sensor area.

As to how much there will be a move to FF.... I've been called wrong in the past about stuff (like there will never be a 10MP P&S or as inexpensive as now) but ended up right. I think only the bottom end SLR's will be crop in the not too distant future.

We shall see.


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