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03-20-2013, 08:53 AM   #31
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QuoteOriginally posted by timo Quote
Hhhmmm - there have been long, laborious threads here and on dpreview demonstrating that neither focal length nor angle or view are related to perspective, strictly defined. Perspective depends entirely on the relative physical positioning of you (the photographer) and the various objects in front of you; that will not change no matter what lens you put on the front of the camera. (Distortion is something different.)
you are absolutely right about that, thanks for clarifying.

Consider the following:
(A) You want to fill the frame with head and shoulders from your subject.
(1) Using a 50mm eq. / 40° H-AoV. (Horizontal Angle of View)
(2) Using a 28mm equivalent / 65° H-AoV.

While keeping (A) premise, you will notice the the perspective difference becouse you changed lenses! (Ok, it is becouse you got closer to your subject to keep (A) but lets not be naive. This is what we think of, and not about distance or perpendicular plane to our subject).

Expanding the normal lens concept, it should have a focal length which allows the observer to view pretty similar through the camera as he sees with the naked eye.
This actually sounds quite lazy but it points out the "subjetive" matter in the definition of what is normal to someone.

Let me re-state:

"In 135 format (24x36mm), the diagonal of the sensor has 43mm. so, using a FL arround 43mm assures will produce an image with normal perspective; does not compress the edges or expand the center, while mantaining your relative position to the subject when seeing with your naked eye"

I think the 50mm design is fairly simple with great optical qualities. Maybe this is why almost every 28mm looks good on APS-C (it equals the sensor diagonal) but that´s another topic.

03-20-2013, 09:55 AM   #32
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I have to say, I made up my own definition years ago. Having gotten used to the technique using a telephoto where your off eye is open to find your subject and through the other eye you look to see what the camera saw, both at the same time (honest, you can train yourself to do this) ...I decided that the lens that was closest to having the same image in the viewfinder as I had through my open eye (in other words normal binocular vision) , was a "normal" lens. It's such a meaningless concept I've never even bothered to determine what a "normal lens is in the last 30 years... but I had a theory and at one point I could have told you what the most "normal" lens was.

These days I don't engage in such insanity.
03-20-2013, 10:07 AM   #33
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What we "see" is subject to interpretation by the brain. That is why tall buildings look as if they're falling down if the camera is tilted up, but seem fine when we look up at them.
03-20-2013, 05:13 PM   #34
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QuoteOriginally posted by normhead Quote
... I decided that the lens that was closest to having the same image in the viewfinder as I had through my open eye (in other words normal binocular vision) , was a "normal" lens. It's such a meaningless concept I've never even bothered to determine what a "normal lens is in the last 30 years... but I had a theory and at one point I could have told you what the most "normal" lens was.

....
A lot of people use that definition but it's meaningless because the image through the viewfinder is determined by viewfinder magnification as much by the lens!

I agree that debates about the definition of 'normal' lenses are pointless. The very concept seems entirely arbitrary to me. But I find it difficult not to respond to misleading definitions.

03-20-2013, 07:14 PM   #35
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QuoteOriginally posted by kristaps Quote
How do you explain the DA 21mm limited then? It's the same size as FA 43mm.
I really lack the expertise in optics to explain it as well as it deserves, but consider that the FA 43 is a 1.9 lens and the DA 21 is a 3.2 lens. If you do the math, that means that the aperture of the FA 43 wide open is 22.6mm, while the DA 21 is a scant 6.6mm. I think having a smaller max aperture means there is less aberration that needs to be corrected, and so it can be done with fewer elements. Had the DA 21 been created as a 2.8 lens or even an f/2 like the FA* 24, it would have been necessarily bigger. Just look at the DA 14 f/2.8 and the DA 15 f/4, that extra stop makes a huge difference.

On another note, have you considered a DA 35 f/2.4? I hear it is a gem of a lens, as long as you don't mind the lack of a distance or DoF scale.
03-20-2013, 07:18 PM   #36
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QuoteOriginally posted by timo Quote
A lot of people use that definition but it's meaningless because the image through the viewfinder is determined by viewfinder magnification as much by the lens!

I agree that debates about the definition of 'normal' lenses are pointless. The very concept seems entirely arbitrary to me. But I find it difficult not to respond to misleading definitions.
Hey, you two. Unlike you both I only started defining my normal lens 3 years ago when I decided I needed another lens for my AE-1 SLR.
Your input / corrections are much appreciated but no one is pushing you to be part of this thread.
I also know I can be mistaken but if I make a comment I try to be as carefull as possible. I do not mean to talk about this any further.

Last edited by carrrlangas; 03-20-2013 at 07:18 PM. Reason: english not my first lenguage
04-11-2013, 03:19 AM   #37
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QuoteOriginally posted by carrrlangas Quote
Hey, you two. Unlike you both I only started defining my normal lens 3 years ago when I decided I needed another lens for my AE-1 SLR.
Your input / corrections are much appreciated but no one is pushing you to be part of this thread.
I also know I can be mistaken but if I make a comment I try to be as carefull as possible. I do not mean to talk about this any further.

Sorry teacher.
04-11-2013, 03:29 AM   #38
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QuoteOriginally posted by twitch Quote
The FA31 is not a bad stop gap measure while we are waiting for a true normal
...you can certainly do worse.

04-11-2013, 07:44 AM   #39
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I just bought a Pentax-A 28mm f/2.8 to be my "normal" lens, there are plenty of choices in legacy glass that don't cost much.

Just figure out what you want to spend, look and see what lenses are in your range, and use the reviews to help you narrow it down. Someday I may upgrade to an F series instead to have autofocus, but right now I can get the Pentax-A for about a third the cost and I feel like I'll learn more from doing more of the work myself. Even that isn't new though I don't know if I'll ever buy a new-generation lens unless it's got a Limited or * in the name or it's just a great deal in the marketplace/eBay.
04-11-2013, 10:03 AM   #40
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The Sigma 28mm f/1.8 works great on my K-5... but it is kind of big and heavy for a prime. I usually default to my other Sigma - the 30mm f/1.4. If I don't mind a slightly tighter field of view, the DA 35mm f/2.8 Limited can't be beat. Don't ask me why I have all three of these lenses (plus the DA 40mm f/2.8 Limited). It's a long story.
04-11-2013, 10:34 AM   #41
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I'm in the same boat Biro. I have an Image A 28mm f2.8, Kiron 28mm f2, FA 28mm f2.8, FA 35mm f2, DA 40mm Ltd and XS 40. I also have a Kalimar 28mm f2.8 for reversed lens macro.

I like 28mm on APS-C for indoor use, because it's the widest you can go without introducing wide angle weirdness. OTOH, it's hard to ignore the FA 35's combination of auto-focus, fast aperture and extreme sharpness when packing my kit bag for the day.

I am most comfortable with the 40mm FOV, but it's a bit too tight indoors.The colour and contrast from the DA 40 is remarkable for landscapes. You gotta love a pancake for its size, especially the DA 40 with hood. I only bought the XS 40 for its crazy price in the K-01 kit. I will be selling it, whenever I finally get around to it.

Kristaps, I think you're on the right track with the FA 35 f2.0. B&H shows them in stock at $399, that's as good a price as you'll get.
04-11-2013, 11:02 AM   #42
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QuoteOriginally posted by normhead Quote
Maybe I'm missing something here, but on a 1.5 crop, would not 35 be a "normal" lens? 1.5 x 35 is 52.5, half way between a 50 and 55. How does it get better than that?
It doesn't get better than that.
At some point somebody decided that because the 50-55 lenses were close to the diagonal of the film that surely a 43mm lens must be the ideal "normal" FL. The 43 is the 1:1 match, but "normal"?

nor·mal
/ˈnôrməl/
Adjective
Conforming to a standard; usual, typical, or expected.
Noun
The usual, average, or typical state or condition.
Synonyms
adjective. regular - standard - ordinary - common - usual
noun. normality - normalcy - perpendicular

It seems to me that by definition 50-55 is "normal" in the 35mm format. Cameras traditionally, and normally, came with lenses in that focal length range; not 43mm.
04-11-2013, 11:29 AM   #43
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QuoteOriginally posted by Parallax Quote
It doesn't get better than that.
At some point somebody decided that because the 50-55 lenses were close to the diagonal of the film that surely a 43mm lens must be the ideal "normal" FL. The 43 is the 1:1 match, but "normal"?

nor·mal
/ˈnôrməl/
Adjective
Conforming to a standard; usual, typical, or expected.
Noun
The usual, average, or typical state or condition.
Synonyms
adjective. regular - standard - ordinary - common - usual
noun. normality - normalcy - perpendicular

It seems to me that by definition 50-55 is "normal" in the 35mm format. Cameras traditionally, and normally, came with lenses in that focal length range; not 43mm.
Never used a 50mm on my 35mm film SLRs, always used a 35mm.... guess I'm abnormal (or A. B. Normal to quote Marty Feldman)
These days for APS-C I use a combination of 24mm (Sigma 24mm f2.8AF) 30mm (Sigma 30mm f1.4) and the DA40XS. I did have the DA-L 35mm F2.4 for a while but didn't like this focal length at all on my K20
04-11-2013, 11:41 AM   #44
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QuoteOriginally posted by StephenHampshire Quote
I use a combination of 24mm
My dream lens would be a 24mm f2(ish) Ltd.
04-12-2013, 09:15 AM   #45
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QuoteOriginally posted by Parallax Quote
My dream lens would be a 24mm f2(ish) Ltd.
24ish mm, OK, but not f/2 - make it an f/1.2, and it'd be a winner!
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