[Anvh]

Uhmmm you're the first to come with personal attacks so dont come with me that i cant read, besides you kept mixing things up with our last conversation so if i did read something wrong then don't lay the blame with me.

Repeating yourself won't help because that's what you're doing now since i can simply repeat myself as well so it will become an endless loop.
And you didn't give me a book, you gave me a quote out of a book and to that quote i simply said it was bullocks. Since you say you've a degree in biology then it would be quite simple for you to dismiss my claim why it's bullocks, since you haven't can i presume i'm correct?

Very funny you come with a link that doesnt explain anything or add something, how meaningless.
Well for fun shall we actually discuss it.

This is roughly the same as the angle that the human eye can comfortably view, which is why it gives a natural-looking perspective .

Okay since you've a biological degree please explain to me what the definition of "comfortable view" is, if it even means something....
Now the second part "natural-looking perspective", well here we go the definition of perspective.

the appearance of objects, buildings, etc., relative to each other, as determined by their distance from the viewer, or the effects of this distance on their appearance

Great actually nothing concrete about field of view in that so how does the word "perspective" works in that sentence?

[Blue]

Uhmmm you're the first to come with personal attacks so dont come with me that i cant read, besides you kept mixing things up with our last conversation so if i did read something wrong then don't lay the blame with me.

Repeating yourself won't help because that's what you're doing now since i can simply repeat myself as well so it will become an endless loop.
And you didn't give me a book, you gave me a quote out of a book and to that quote i simply said it was bullocks. Since you say you've a degree in biology then it would be quite simple for you to dismiss my claim why it's bullocks, since you haven't can i presume i'm correct?

Very funny you come with a link that doesnt explain anything or add something, how meaningless.
Well for fun shall we actually discuss it.

Okay since you've a biological degree please explain to me what the definition of "comfortable view" is, if it even means something....
Now the second part "natural-looking perspective", well here we go the definition of perspective.
Great actually nothing concrete about field of view in that so how does the word "perspective" works in that sentence?

I wrote the book title, year and author in that post. Go to a bookstore or library or Amazon. I also posted the article about the FA 43. I have discussed normal and standard lens in the context of the FA 43 and DA 40 all I intend to for now. As a matter of fact, I have 3 biology degrees. However, if you want biology tutoring, Tallahassee is probably way out of your way. However, if you are ever in town, I can probably get you a discount. In the mean time you are back on the Ignore List.

[Anvh]

As far as biology stuff goes,the foveal region is surrounded by the parafoveal region while the 1 to 2 degrees of the foveal region is the sharpest. However, the parafoveal can go up to 30 degrees into the near periphery. It is about the perspective created. If you look, you will see that Hedgecoe said eyes and not eye. However, this is the reason a numerical definition or rule was adopted by some to describe a normal or standard lens. The point is that a standard lens will give closer to a natural view of a subject than wide angles or telephoto lenses.

Wow you're improving, you go from an insult to actually explain yourself when you edited your comment.
But isnt the parafoveal belt part of the periphial vision and since the quote clearly say nonperiphery i'm missing the connection...

[Anvh]

I wrote the book title, year and author in that post. Go to a bookstore or library or Amazon. I also posted the article about the FA 43. I have discussed normal and standard lens in the context of the FA 43 and DA 40 all I intend to for now. As a matter of fact, I have 3 biology degrees. However, if you want biology tutoring, Tallahassee is probably way out of your way. However, if you are ever in town, I can probably get you a discount. In the mean time you are back on the Ignore List.

Thanks for explaining nothing, i wonder why i even bothered.
Every time i asked you to explain yourself you can't and when i press on you put me on the ignore list, is it so hard to explain something for you or are there other problems?

Well i can see why you're giving away discounts if you also teach like this...

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Last edited by Anvh; 06-25-2012 at 11:25 PM.

[glasbak]

Well, this 'discussion' started probably because of Anvh reply to my message.
Anvh wants probably to show his wiki knowledge, but for photography, his message boils down to what I stated in the first place, take the diagonal.
I replied to 'builttospill', because he threw in '100% viewfinder magnification'.
And that is generally defined when using a certain focal length, usually close to the 'normal', except for APS-C, where camera builders specify it at 50mm, so it looks better on the spec sheet.

So can we stop throwing mud ?

[Anvh]

Wiki knowledge, then you don't know me well enough i almost never quote them or actual use them for meaningful information so don't pretend like you know me.
Besides i never said that taking the diagonal of the formatt was wrong, i only make a point that that isn't a true definition because it doesn't explain what a normal lens actually is and why it's called normal and i haven't seen or heard anything to change my mind on this.
It just happen to be the diagonal of the formatt for general use at least because if we get situations where the photo isnt viewed normally then we need to take that into account to get a natural looking perspective.

if you want my own words what normal lens is then a normal lens is the lens that gives you a normal perspective with your final image so it isnt a fix value really.

[Virginia Bill]

I think that you guys slinging mud at each other should get off my thread. The question I asked was answered, clearly and with documentation, several posts ago. Thanks to those who posted constructively.

[Ben_Edict]

...
if you want my own words what normal lens is then a normal lens is the lens that gives you a normal perspective with your final image so it isnt a fix value really.

Apart from the Wiki-related discussion: NO lens gives you a perspective. That is only common misconception. Perspective is a result of distances (from photographer to subject - to other parts in the image).

What you might mean is the "normal angle of view". But what is that? The discussion about the sharpest regions of vision in the eye is going in the right direction, I think, because it doesn't lead to a real conclusion and surely not to a sharply defined rule. I find the definition of a "normal" field of view highly individual. In 35mm film days, my personal "normal lenses" where the 35mm and the 80mm. The 35mm lens would roughly put on film, what I see and perceive when I look at a wide scene. But the moment I concentrate on something interesting, my brain blends out all the lesser important stuff and my angle of view (or of perception) is then represented best by the 80mm lens.

This individuality is one reason, why a simple technical definition of the "normal lens" as having a fl app. the length of the film format diagonal is useful and meaningful. By the way, I did not quote the full length of the Encyclopedia of Photography entry, it is longer and also refers to the 52 deg field of view, associated with a normal lens etc.

Ofcourse there is a relationship (historically) between the normal lens and human vision, but if you just look up the in-depth discussion of this relationship (as given for example on page 201 in Ray's "Applied Photographic Optics") it is quite clear that the "natural" look a "normal" or "standard" lens is expected to provide is mostly a heresay wisdom. It certainly does not apply to the 35mm format, but derives from old and obsolete "whole plate" prints at the time, when prints would not be enlarged, but contact printed. For 35mm and other "small" film formats (129 or whatever) you also need to account for enlargement factor etc. That is, why I think, that any perception-based definition of a normal lens is arbitrary.

Ben

[Ben_Edict]

I think that you guys slinging mud at each other should get off my thread. The question I asked was answered, clearly and with documentation, several posts ago. Thanks to those who posted constructively.

I understand your feelings, but openly posted threads often evolve like that. I do not quite understand, why personal insults need to be written down, but some people seem to have a need for that.

Nevertheless going back to your initial question: You are coming from Nikon. Nikon had a famous "normal" lens in its portfolio back in the 70s/80s: The Noct-Nikkor 58mm/1.2. 58mm was quite a bit long for a normal lens, but today we have 60mm macro lenses on the market, which is not far off. Also, you should also take into account, that real focal lengthes are often somewhat different from what is engraved or printed on the lens barrel. Even the very first 50mm standard lens for the first Leica had 52mm fl in reality. So, Pentax could have sold the FA 77mm Ltd, easily as an "80mm" lens, if they had wished to do so, without any complaints from customers.

Ben

[Neville Holmes]

I think that the 105 and 135mm lenses were standard focal lengths from pre film days when glass plates were used. So use them and be grateful that your Butler is not now required to carry your gear.

[zapp]

Nope, normal focal length is generally defined as the diagonal of the sensor format

sqrt( 24^2 + 36^2 ) = 43mm




If you look at the field of view differences between these lenses, you wil see a significant difference !
Personally I think that lenses are better specified by the angle they cover, than their focal length, then all those confusing conversionfactors for different sensor sizes would not exist.

About the weird focal lengts, they are mainly marketing or historical.

The only thing that is constant for a given lens is the focal length, not the angle of coverage.
Assuming that one sensor format is the base has always been wrong.

[pepperberry farm]

talk about a resurrection...

[Wheatfield]

A true normal replicates what the eye sees. When I hold the viewfinder of a film camera with 100% magnification, with the 43 mounted, to my eye it shouldn't look any different from when I remove it from my eye. This means the subject should appear to be the same distance behind the lens and to my eyes by themselves.

There's nothing arbitrary about the focal lengths selected. No company; Pentax, Nikon or Canon would pull a focal length number out of a hat for their next lens. Research is done. Lenses are designed. Your statement seems random and arbitrary and doesn't make sense. Lens design is not random, nor is marketing, and never has been. Picking a lucky number can't be called marketing. If marketing was involved a number of analyses would have been conducted, and may have included focus groups consisting of photographers discussing preferred focal lengths while marketers took notes. Marketing includes research and evaluation of data to meet a target audience. I can tell you with confidence the marketing team from Pentax never approached the FA Limited lens designer and informed him he had to create a 77mm lens because it's a lucky arbitrary number. Sounds silly doesn't it? It should.



Obviously the difference is enough because Pentax currently produces the DA 15 Limited and DA 21 Limited; members of this very forum own both.

Interestingly enough, the human eye is also "square" at a focal length of ~20mm, and a "sensor" (retina) diameter of ~20mm. I expect this is why standard lenses focal length so closely matches the diagonal of the format. It mimics the geometry of the human eye, and therefore gives a fairly natural looking rendition.

[Lord Lucan]

talk about a resurrection...

I hope it does not resurrect the acrimony

[Digitalis]

A lot of people here are forgetting that a lot of the "standard" focal lengths we see these days still conform to what was common in the days of rangefinders, which had fixed frame lines that followed a range like this: 28/50 35/90 75/135* - every manufacturer had to conform to the framelines to even have a shot in the market at that time. The SLR gave manufacturers the freedom to produce lenses that had non-standard** focal lengths but very few manufacturers really took advantage of it....well at least until Jun Hirakawa got bored.

Are you absolutely sure of this? I have never heard of any of the Pentax 40mm lenses having any aspherical elements.

For the record, none of them do. The rumor of the FA43 having an aspherical element was just that - a rumor, possibly as an unscrupulous effort to increase the resale value of early versions of the lenses. The DA40 and M40 are basically the same lens, many performance characteristics are mirrored in the two lenses*** that it would be perverse to say otherwise in my opinion.

That is why it is called "normal"

Normality is typically defined by whatever occupies the middle of a bell curve. As a collector of 50mm lenses, there are some lenses I have that are labelled as "normal" and are distinctly abnormal when compared to other lenses in the same class. There is a lot of variation in 50mm lenses.


* Some rangefinders had 21/35 24/50 75/90 framelines, though focal lengths wider than 21mm often required an accessory viewfinder that fitted into the cameras cold shoe. These lenses were often very slow and DOF was so great with such lenses that precise focusing was hardly required. Most photographers "shot from the hip" with such lenses.
** Pentax never made a rangefinder, so this is probably where all the weird focal lengths came from - pentax was never in the rangefinder straitjacket to begin with.
*** taking copy variation into account.