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07-04-2009, 02:32 PM   #46
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QuoteOriginally posted by ChrisPlatt Quote
I'm not sure if you meant to post that as a counterargument, but it is not. As the article in question explains, it is not focal length but rather subject distance (fro camera to subject) and viewing distance (from viewer to photograph) that creates the distortion, not focal length per se. And to the extent that the angle of view of the picture itself plays a role in this, that is also a separate issue from focal length. The perspective of an image taken with a 300mm lens is no different than that of a 28mm lens cropped to provide the same angle of view.

This distinction is important to the point nanok is making, which absolutely correct: if you *really* care about perspective, zooms are actually better than primes. That's because the only way to control perspective is to walk around until you get the perspective you like. With a prime, you are then forced into one particular framing for that image, but with a zoom, you can get control of the framing. That is, only a zoom (or an appropriately large collection of primes) gives you independent control of both perspective and framing.

07-04-2009, 03:12 PM   #47
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I have one AF Zoom lens that I got as a gift, which I never use any more.
All the rest of my lenses are manual K series fixed focal length. Compared to
my K series lenses, my FA zoom is plastic junk.

I only have manual film cameras, so all my picture taking is done this way.
I’ve been shooting fully manual since 1975, so see no reason to change.

It’s just my opinion but using a fully automatic digital camera and AF zoom lens, doesn’t look it would be any fun. Shooting manual is just what I’m used to, like driving a standard car as apposed to an automatic.

Yes I'm stuck in the 70's,
Phil.
07-04-2009, 03:13 PM   #48
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The second set of (four) photos illustrate the point I was trying to make.

Chris
07-04-2009, 05:36 PM   #49
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Like Marc I have little interest in manual zooms; besides his reasons I don't want to carry a heavy lens. Ever. Besides, on digital a lot of the focal length ranges no longer make much sense to me.

Where I want a zoom is in the super-wide end, since a small focal length change makes a big difference and I'm not going to carry primes for every number from 12 to 24, even if that were possible. And of course the whole "just move if you don't have everything in the frame" makes no sense if an inside wall is behind you. So that explains why I have the DA12-24mm.

I have the DA55-300mm because I have little dedicated interest in telephoto. This lens covers a big range well while staying light in the bag. I can't think of an old lens that would be any better.

That's it for zooms though; otherwise I prefer primes. (I do own other zooms but don't find myself using them.)

I must say that the inability of assigning a dial to ISO in manual mode often kills my enjoyment of using manual primes. I sure wish Pentax would notice me complaining about this and issue a simple firmware fix. I want the same dials to do the same thing no matter what mode I'm in and what type of lens is on the camera. Aperture control is on the lens so shutter and ISO should be on the dials.

The other thing that gets in the way of usability is the metering problem. It's one thing to press the green button before a shot. It's another to press the green button, then compensate for the exposure, then take the shot. That's tedious and too slow.

I think that besides price the main appeal of older lenses is in their solid metal build and smooth manual focusing. Digital-only lenses simply don't have that feeling; the focus must turn freely to allow the motor to drive the lens. However I think the FA Limiteds are on the good side of the MF fence.

MF lenses I use include the Vivitar 24/2, Vivitar 28/2, Vivitar Series 1 105/2.5 and smc Pentax 50/1.2.

Please, Pentax, fix the two problems noted above so I can enjoy MF and manual aperture lenses as much as I should.

Oh yeah, my last two blog articles are about choosing lenses.

07-04-2009, 09:08 PM   #50
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QuoteOriginally posted by ChrisPlatt Quote
The second set of (four) photos illustrate the point I was trying to make.
I'd say it nicely illustrates the point *I* am making, though - nothing about the perspective difference in those pictures is about focal length. It's about distance to subject, period. And it makes a great argument for the utility of zooms in exactly the way I was describing: they allow you to choose your framing and perspective independently. That is, you can decide you want the framing depicted in all four, but then walk forward or backward to change the perspective, and zoom in or out to keep the framing. With a prime, you're be stuck with one perspective for a given framing, because the only way to change framing is to change position. Of course, a big enough *set* of primes gives you the same sort of flexibility.
07-04-2009, 11:53 PM   #51
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So then why don't we shoot portraits with fisheye lenses?
And don't tell me it's because the working distance would be too close...

Chris
07-05-2009, 07:37 AM   #52
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QuoteOriginally posted by ChrisPlatt Quote
So then why don't we shoot portraits with fisheye lenses?
And don't tell me it's because the working distance would be too close...
That's a separate issue. A fisheye lens shoots a hemispherical image, in the perfect case with a 180░ angle of view. Other lenses shoot rectilinear images. This has nothing to do with perspective.

P.S. We do shoot portraits with fisheye lenses, especially if we are contracted by a punk band.
07-05-2009, 09:43 AM   #53
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So by extension one single focal length lens is all anyone would actually need.
Boy have we been duped by the interchangeable lens camera manufacturers!

Chris

07-05-2009, 01:12 PM   #54
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QuoteOriginally posted by ChrisPlatt Quote
So by extension one single focal length lens is all anyone would actually need.
Boy have we been duped by the interchangeable lens camera manufacturers!
No, I don't think that follows.

Though different focal lengths do not have different perspectives, they have different magnifying powers and different fields of view.

Of course different lenses might also render OOF areas differently and in focus areas likewise. Some might have greater resolution and some better control of various distortions. They also tend to have different close focus distances and optimal apertures.So I think there's lots of scope for LBA still!
07-05-2009, 01:34 PM   #55
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I stated the opinion "...one tends to zoom for framing, with little regard for the effect of focal length."

To which someone replied "...focal length has no effect whatsoever on anything else but framing."

In reply I posted a link to a Wikipedia page entitled "Perspective distortion in photography" because it includes a series
of the photos illustrating the different looks of the same (main) subject achieved using various focal length lenses.
In a followup post to clarify I stated this explicitly.

Now you admit "different focal lengths...have different magnifying powers and different fields of view"
and "might also render OOF areas differently and in focus areas likewise" etc.

Was it the inclusion of the word perspective in the author's title that bothers you?
I didn't write or title the darn Wikipedia page, I merely linked it.
FWIW I never even used the term perspective...

Chris

Last edited by ChrisPlatt; 07-05-2009 at 01:51 PM.
07-05-2009, 02:18 PM   #56
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Hey Chris, you seem to be getting a bit riled. All I did was respond to your question about fisheye lenses. Then I replied to the statement about all focal lengths being the same. I am trying to help. What have I said that makes you think I am "bothered"?

I have not read the wikipedia page, but I do know that "perspective distortion" is not distortion at all. It's a natural result of taking a picture from a given perspective.

And yes, perspective has nothing to do with focal length.
07-05-2009, 03:52 PM   #57
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I tried to refute the statement "focal length has no effect whatsoever on anything else but framing."
Curiously no one else took issue with it, and thererafter all criticism was directed at me.
Sorry if I seem to have overreacted. I will attempt to grow a little thicker skin for the future.

Chris
07-05-2009, 04:03 PM   #58
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QuoteOriginally posted by ChrisPlatt Quote
I tried to refute the statement "focal length has no effect whatsoever on anything else but framing."
Well, I'd have to agree with that!

Nothing I wrote previously was meant as criticism. Sorry if anything came across that way.
07-05-2009, 05:15 PM   #59
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QuoteOriginally posted by ChrisPlatt Quote
So by extension one single focal length lens is all anyone would actually need.
Huh? How does this follow? It *is* true that a 28mm lens cropped to yield the same FOV as a 300mm lens will yield exactly the same perspective (try it yourself if you still don't believe me), but of course, you'll have thrown away most of your pixels, and what's left won't be very high resolution.
07-05-2009, 05:17 PM   #60
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QuoteOriginally posted by ChrisPlatt Quote
I tried to refute the statement "focal length has no effect whatsoever on anything else but framing."
Curiously no one else took issue with it
That's because it is a true statement in the context of this discussion. I mean, it might effect DOF - and this was noted earlier - but not anything to do with perspective, which is what we were talking about. The only thing that affects perspective is your position relative to the subject. If this weren't true, we'd have to rewrite the last 500 years of art history. Perspective has been a well understood phenomenon for that long, and has nothing to do with lenses or focal length.

The idea that focal length relates somehow to perspective is a common myth, but as the article you linked to makes quite clear - just read the caption under the images you referenced - what affects perspective is distance to subject, period. It's just that different focal lengths tend to make us change distance to subject in order to achieve the same framing.
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