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05-06-2011, 01:29 PM   #31
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QuoteOriginally posted by geekette Quote
How well does the K-X meter with the Pentax-A lenses at all aperture settings? Because it doesn't meter well with the M & K lenses with the green button the more you close up the lens.
In my experience it the K-x meters as well with the A series as it does AF lenses. All settings are handled by the camera and there is no stopping down to meter.

05-06-2011, 07:19 PM   #32
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Looks like pentax-a is the way to go then. Pentax-A 50mm f1.4 (I can't afford f1.2). I might just get the 1.7
05-08-2011, 10:33 AM   #33
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QuoteOriginally posted by geekette Quote
I want a good 50mm full frame lens for use on my K2 and K-X (I understand it will be around 75mm on DSLR). I have the Pentax-M 50/f1.4 and Pentax K 55/f1.8 .. they are great but metering is a pain on the K-X with them. I'd like something that has auto aperture that is on par with the image quality of these lenses and that has a build quality better than the K-X kit lens... I know the old manual lens build quality can't be beat, but I am willing to sacrifice that if the optics in the auto-aperture lens are as good as the old lenses.
No, it will be 50mm, I recommend the A50mm F/1.4
05-08-2011, 03:30 PM   #34
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Keithlester, my Pentax-M 50mm/f1.4 is like putting a 75mm lens on my DSLR, that's why I said 75mm.

05-08-2011, 03:38 PM   #35
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QuoteOriginally posted by northcoastgreg Quote
The best auto aperture 50mm lens for Pentax is the A 50/1.2. It's in a league of it's own. The A 50/1.4 and A 50/1.7 are also very fine lenses capable of producing stellar results for a fraction of the cost of the 50/1.2.
Well, now, that depends on your deisres. the A50 f2.8 offers more resolution, both up close and at infinity. If you want a faster lens, then the A50 f1.2 is tops.
05-08-2011, 05:58 PM   #36
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QuoteOriginally posted by geekette Quote
Keithlester, my Pentax-M 50mm/f1.4 is like putting a 75mm lens on my DSLR, that's why I said 75mm.
Even if you are an old hand with FF, putting a 50mm lens on any camera means it's still a 50mm lens. Putting a lens on another camera does not change its focal length. The FOV will change because different size frames (film or sensor) will see different portions of the projected image, but the lens remains the same. It's the *camera* that changes.

My old story: Back in the day, I got a Spiratone 400mm lens. It had a T2 adapter for my half-frame (same size as APS-C) Olympus Pen-FT. I thought, OH WOW, IT'S LIKE A 600mm LENS! I quickly learned that no, it's not a 600mm lens, it's a 400mm lens with the image edges chopped off.

On a Pentax dSLR, the DA*55 and SuperTak55 are just the same: 55mm, no more nor less. Or do you think that mounting a DA*55 turns it into 77.5mm? If so, I have a bridge to sell you.

Last edited by RioRico; 05-08-2011 at 06:09 PM.
05-08-2011, 06:48 PM   #37
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Let me put it this way, you'd need a 75mm focal length DA lens to get approximately the same image on the ccd as you would a 50mm full frame lens. And at least the crop is in the optical stage, before the the medium.. huge difference than a crop of film or digital image.

Do zoom lenses do optical crops?

Anyways thanks for pointing that out and making me think.. Now I have questions lol.
05-08-2011, 07:48 PM   #38
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A lens does not crop. NO lens crops. The camera's frame crops. A smaller frame sees less of the projected image circle. That is, it chops-off part of the image. That's why the term "crop sensor" is used.

And this isn't limited to digital sensors. I've had a number of half-frame 35mm (135/HF) film cameras, whose frames are about the same size as an APS-C sensor. On my ICL (interchangeable lens) 135/HF SLR's and RF's, I could mount (via adapters) 100mm lenses originally intended for 6x9 MF cams, 135/FF SLRs, 135/HF cams, enlargers, projectors, whatever. What the lens was designed for is irrelevant. Any specific focal length mounted (correctly!) on a camera of any specific frame size, will have a certain FOV / AOV.

Back when I'd shoot 135/HF, 135/FF, 6x6 and 6x9 MF, and 9x12cm LF on the same day, I didn't think about crap.factors. The term didn't exist then. I just learned what any lens would do on any camera. All this marketing stuff about crap.factors and focal length equivalences only causes confusion.

I have a theory: P&S shooters buy a dSLR and a kit lens they think is 'equivalent' to their P&S zoom. Then they find their new kit lens has much thinner DOF than did the P&S, so pictures aren't sharp. Then they yell, MY KIT LENS SUCKS! and spend hundreds of bucks on an 'upgrade'. So the whole thing about 'equivalences' is just a sneaky marketing ploy to separate suckers from cash. And crap.factor feeds the phony equivalence meme. It's all a conspiracy!

[/me looks behind light switch plates for hidden microphones]

05-09-2011, 02:26 AM   #39
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not so

QuoteOriginally posted by geekette Quote
Keithlester, my Pentax-M 50mm/f1.4 is like putting a 75mm lens on my DSLR, that's why I said 75mm.
Not so, put a 75mm lens on your dslr and you will see that I am right.

it will give you a field of view like a 75mm lens on your 35mm film camera, but 50mm is 50mm, and 75 is 75
05-09-2011, 04:10 AM   #40
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QuoteOriginally posted by keithlester Quote
but 50mm is 50mm, and 75 is 75
I got that thanks
05-09-2011, 05:26 AM   #41
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QuoteOriginally posted by creampuff Quote
I believe the new Sigma 50mm f/1.4 as covers full frame.
It does, Though I really do not care for that lens's bokeh no matter what format it is used on - it just looks wrong to my eyes, there is too much spherical aberration.

the best Pentax 50mm lens ever made would have to be the K/A SMC 50mm f/1.2
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