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10-25-2010, 12:22 PM   #31
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lens because this particular 50mm measures closer to 80mm on aps-c.But I'm getting such amazing pictures that I'm not coming close to on DA.The pictures are nice. They're easy on DA.I can pop them out faster than a bunny can breed but none are magical. I'm


Last edited by troglodyte; 10-25-2010 at 12:29 PM.
10-25-2010, 12:25 PM   #32
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seriously considering switching to all manual for what I do. This was before I knew the magic of A glass and everyone touted 'designed and optimized for digital DA is BETTER!'.
10-25-2010, 12:27 PM   #33
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it's calibration check time

It's time to check your metering calibration.

Take each lens and find a nice uniformly lit block wall (one color only), or paved road/sidewalk

with each lens (make sure each field of view is only the control surface nothing else, or alternatively use spot metering) take a series of shots in AV mode with each lens at each aperture from wide open to stopped down fully/

With each set of shots measure the central 10% greyscale value, and one corner 10% value. Most image editors allow you to do histograms on the selection, just make a box with the select tool, and then record the center and corner histogram.

plot the measured values against aperture,

Ideally you shouldhave the peak of the histogram (median value) at about 110, and each 40-50 greyscale is 1 stop.

You will then understand exactly how each lens meters on your camera.
10-25-2010, 12:37 PM   #34
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Good idea Lowell.

I would like to add that you are comparing two very different focal lengths. The optical properties of a wide angle (21mm) and 50mm are very different.I would agree that 50mm renders very nicely... it's a classic focal length for a reason. But I think you are mistaking the magic of 50mm for the magic for the A series. I doubt that you would feel the same way about the 28mm 2.8, which has some of the "deficits" of a wider angle lens. Wide angle lenses bend light more, and introduce all sorts of interesting changes to rendering that you do not see in a more natural focal length like the 50mm.

Now if you want all metal and tiny, manual Pentax lenses are a good way to go... I just hope you realize WHY you like the 50mm over the 21mm... and I don't think it's DA vs. A.

Also, the advantage of "designed for digital" has to do with the coatings, rejecting flare better for digital sensors. May or may not be a real issue for you, but that is what the whole designed for digital thing is about. I'm not sure that changing to manual focus glass will help with the whole wide-angle vs, normal IQ issue.

Also, remember that tiny and aperture do not play well together. Larger apertures require larger lenses. The A 50 1.7 is nice and tiny, the 1.4 is larger, and the 1.2 is even larger. This is one of the reasons the limiteds are so damn tiny, they aren't super-fast. In my book, this is not really a big deal, thanks to ISO and the fact that these lenses tend to look good wide open. You can't get that performance from the 50mm 1.7 wide open... it usually goes to 2.8 anyways!

You might want to consider this lens as a compromise between 50mm and 21mm. I would personally go for the FA version but you want metal, so

https://www.pentaxforums.com/lensreviews/SMC-Pentax-A-35mm-F2-Lens.html

And there is always the 31mm LTD.

10-25-2010, 12:51 PM   #35
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Lowell,
That's not the problem. I'm complaining about color 'pop'. The DA just don't got it in low light. It's a I want more light whore.
I compensate for metering by taking a few test shots and knowing if I'm in backlit, frontlit, low light, even light,
10-25-2010, 12:53 PM   #36
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etc and then I take mental note of what to set those to.
10-25-2010, 01:02 PM   #37
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QuoteOriginally posted by troglodyte Quote
Lowell,
That's not the problem. I'm complaining about color 'pop'. The DA just don't got it in low light. It's a I want more light whore.
I compensate for metering by taking a few test shots and knowing if I'm in backlit, frontlit, low light, even light,
I don't understand

you started by asking if the lenses were some-how rated differently and that the 50mm was brighter at any stop.

to me, that suggests you start with the exposure of the two, and how accurate the camera is. That is where you have to start

then, when you go on to discuss "pop" you have to recognize part of the "pop" is not related to lighting but to focal length, depth of field and isolation of foreground and background with depth of field. In that area the 50mm will win every time because longer focal lengths have less depth of field, and as a result, the subject seems to "pop" because it is not just lighting that attracts your eye, but focus.

with good foreground / bakground separation, and some depth of field on the subject you can have subjects that seem to be 3 dimensional and look almost as if they were pasted onto the background. This is depth of field and your 21mm won't have this attribute because it has too much depth of field.
10-25-2010, 01:06 PM   #38
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Lowell,
So maybe the pictures are really equally bright but are attributes of DOf, focal length and isolation fooling me?

10-25-2010, 01:31 PM   #39
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So would getting a medium format camera allow me to use a 50mm lens with the light properties ie DOF, isolation, etc but gain the angle of view I want? 21mm on aps-c and 35mm on FF?
10-25-2010, 01:41 PM   #40
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Well... maybe. You are also talking about spending at least 10 X the amount on this sort of technology, and IMHO, not really for the right reasons. Besides, those cameras are massive, and their lenses are massive. You were complaining that the 24mm 2.0 was too big and now you want a medium format camera??

You need to re-read this thread and realize that you are really all over the place here. The simplest solution, I think, would be a 35mm 2.0 lens on a DSLR. Good compromise between 21mm and 50mm, without spending 10, 000 + dollars. Or, seriously consider the FA 31, if you are willing to buy full frame or MF...
10-25-2010, 01:42 PM   #41
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Not saying I'll do it, just curious.
10-25-2010, 01:51 PM   #42
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Considering you want a fast-as-possible wide angle, increasing the sensor size will help, but is becoming less necessary as technology improves. You will get thinner DOF's because you will be able to stand closer to your subjects with the same focal length.

I'm not 100% convinced that this will really solve your problem though. You simply state that colours so not pop with the 21 as much as the 50... you did not comment on depth of field until Lowell suggested that it might be a problem. I would look to make sure you are exposing those two images correctly, looking at the histograms. Don't just match the apertures and shutter speeds, because these are different focal lengths.

The other thing... simple thing... that might help you is changing the JPEG settings, if you are shooting JPEG. I don't have to worry much about colour because I work in RAW, but the JPEG settings out of camera can be very blah if you have something specific in mind. Every lens (especially older lenses) add their own flavor to the colour, so that might account for the difference. Have you tried fooling with the JPEG setting on your camera?
10-25-2010, 01:52 PM   #43
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Paperbag,
I'm trying to figure out why I'm getting the results I am. The easiest solution would be to extent the view of my A 50? Right? I only know how to take the pics, not why they turn out how they do. Dumb physics. I wish I could post some examples.
10-25-2010, 01:53 PM   #44
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QuoteOriginally posted by troglodyte Quote
.Even with the 50mm at f4 and the 21mm at f3.2, the 50mm is brighter and more colorful. With very bright lights or the sun
See what you did here? f4 at 21mm does not equal f4 at 50mm. Thats why you should do the test that Lowell suggested to figure out how each lens exposes.
10-25-2010, 01:54 PM   #45
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I shoot RAW.
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