Our discussion forums are a great resource for people looking to learn about photography, and it's therefore not surprising that certain topics are raised time after time. In many cases they are answered quickly and correctly, but certain topics are still subject to a great deal of confusion. One of these is the deceptively simple question of what the word 'standard' means in relation to lenses. It appears that there are certain misconceptions associated with this topic which reappear time after time, so in a bid to put the record straight, here's my attempt at an (almost) definitive answer.
At the simplest level, a standard lens is defined as one which produces images with a natural-looking perspective (the word 'normal' is often used synonymously in this context). This concept is perhaps best illustrated with regard to what it's not, that is to lenses which clearly don't meet this criterion. A telephoto lens, for example, renders distant objects larger in the frame, and has the effect of compressing the apparent spatial relationship between objects. A wideangle does precisely the opposite; in squeezing more content into the image, objects appear smaller and more distant. It's in the happy medium between these two extremes that the standard lens lies; the apparent sizes and spatial relationships between image elements appear natural, and much as they did in real life. So the question is, how de we define which lenses show these characteristics?
The answer lies in considering how we view images, and is perhaps easiest understood with respect to prints. Everything hinges on the fact that (with the exception of small prints) the most comfortable viewing distance is approximately equal to the print diagonal. For example, a 12" x 16" print has a diagonal of about 20", and it turns out that most viewers will choose to look at it from about 20". This allows them to take in the whole of the picture, while still being able to see fine detail.
So how does this relate to the focal length of a 'standard' lens? To understand this, let's conduct a thought experiment in which we take a picture, make a print on the spot, then see how it compares to the scene in front of us. Simple geometry (using the concept of similar triangles) states that a print viewed from a distance equal to it's diagonal will exactly match the subject in perspective when the focal length of the lens that was used to make the picture is equal to the diagonal of the sensor.
When we use this approach to calculate the focal lengths of 'theoretically correct' standard lenses for various sensor sizes, the results are slightly surprising. Full frame works out as 43mm, 1.5x APS-C as 29mm, and Four Thirds, 21mm. This flies in the face of received wisdom (and convention), which suggests 50mm, 35mm and 25mm respectively. How did that happen?
The answer goes all the way back to the earliest 35mm cameras, such as Oscar Barnack's Leica. For practical reasons of lens design as much as anything else, these were often fitted with 5cm lenses, and for various reasons this became a convention which firmly stuck. Oddly enough, the 35mm format counts as something of an outlier in this regard; the various 'medium' formats (such as 6 x 4.5cm) all stuck stubbornly to the 'frame diagonal' convention. Still even for 35mm there were honourable exceptions; many fixed-lens rangefinders (the progenitors of modern compacts) used lenses in the 40-45mm range, and Pentax famously launched its 'Limited' range of premium primes with a 43mm standard lens, which is still on sale today. And while it may sound like there's little difference between 43mm and 50mm, in reality it's the same as that between 28mm and 35mm, or 85mm and 100mm. There is, in fact, a fairly well-developed school of thought (which I must admit I personally subscribe to) that for a standard lens, that 40mm region is 'about right'.
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The Olympus 35RC ca. 1971, with its 42mm F2.8 standard lens |
Now that we've established what a standard lens really is, we can dispense with some of the misconceptions which continually reappear. A standard lens is not one which makes object appear the same size in the camera's viewfinder as they appear from the same position with the naked a eye; this is a function of both focal length and viewfinder magnification (indeed with a 50mm lens focused to infinity, it's used as the definition of viewfinder magnification). And a standard lens is not - quite - a lens with the same angle of view as the human eye; peripheral vision extends well beyond the angle of view occupied by the print at that 'comfortable' viewing distance.
So there we have it, the definition of a standard lens. Of course the punchline (and there always has to be one) follows on from my previous blog post, in which I decried the lack fast 'portrait' primes for APS-C, with the much-touted 50mm lens being a bit short for this role. Well to be honest, I wish manufacturers wouldn't build 50mm lenses for full frame either, but instead make their standard primes in that 43mm region instead (likewise rather than 35mm for Nikon's new DX prime, I'd have preferred 28mm). But at least for once I know this is an eccentricity, and I'm firmly in the minority in this regard.
ready for another "thought experiment"?
What if you looked at the iMac 24 inch screen in front of you...Would you sit 24 inches (60cm) away?
Would you still be comfortable reading the print?
Posted by: nugat | 7 Apr 2009 08:25:09
Thanks for breaking into yet another controversial can of worms! lol I do believe your point is very accurate, and we must keep in mind that the reference to "standard" is precisely that, a reference. From what I can gather through every resource I've investigated, this only means to serve the point as has already been discussed that the image is neither larger nor smaller than what the eye saw when composing the image in the first place. With this reference point in mind, wide angles give more image and telephotos less. We always try our best to nail down ideas with math and very seldom does it work out that way. Why? Because all images are subjective. Given the simplest of images and viewed by a multitude, when interviewed we find that few people saw the identical memorable points in the print. Our lives serve up different formats to view everything with, hence our different perspectives. And this kind of debate will go on and on while we are NOT out shooting! :)
Thanks, Andy, for a job well done and thanks Phil for giving us the information we need to make informed decisions. My Canon 5D MkII will be arriving shortly! ;)
Posted by: Dale | 9 Apr 2009 15:19:29
Tcav wrote: "That would put the preferred viewing distance of a 4x6 print at about 7 inches. NOBODY DOES THAT! That would put the preferred viewing distance of an 8x10 print at about 13 inches. That is about 50-75% too short, but something else I have noticed is that people will hold an 8x10 print further away than a 10x8 print."
I tend to disagree. I think the principle Andy brought out is generally true: the optimal distance for examination and enjoyment is indeed about equivalent to the diagonal-- sometimes practicality prevents us from employing this optimal distance....
A laptop computer sits on your LAP, whether it has a 10 inch screen or a 20 inch screen. But set it on a counter, and ask a friend to walk up and check out a slideshow of pictures that he's REALLY interested in, and that friend will position themselves ABOUT 20" from the 20" screen, and ABOUT 10" from the 10" screen.
The TV in my room here is 27" across, and the couch is about 160" away. But if I'm REALLY interested in viewing something, my face is ABOUT 27" from the screen. And I would be thrilled to be viewing a 160" screen from 160" away. But if you put a 300" screen in the same room, it would seem overwhelming from 160" away.
Not a very technical response, I know, but just pointing out some of my observations and experiences. Some people are also nearsighted and farsighted, which has an effect upon comfort levels of objects at various distances. But as a general rule, I agree with what Andy wrote.
Posted by: Paul Rahoi | 10 Apr 2009 20:02:16
May we simply agree that the 'normal' or 'standard' lens is one that would take pictures that would present the relative sizes of objects and distances of the scene exactly as seen by the human eye?
Posted by: Lim Teik Hock | 13 Apr 2009 17:20:29
Perhaps we need to do this experiment: Get people to stand at a place with good perspective lines as well as objects of varying distances. Then hand them a transparent pad to see through at their own comfortable arm's lenght and trace the outlines of every object in the frame with a marker.
Posted by: Lim Teik Hock | 13 Apr 2009 17:32:19
Then compare with photos taken from the same spot with prime lenses of different focal lengths. When the best fit is found-Eureka!
Posted by: Lim Teik Hock | 13 Apr 2009 17:38:01
Good. You discovered linear perspective, just like Brunelleschi in his 15th century "peepshow experiment".
http://www.dartmouth.edu/~matc/math5.geometry/unit11/unit11.html
But the second part of your experiment is wrong. When you put on different focal length lenses and DO NOT CHANGE position (POV), the perspective of objects (their relative sizes) on the registered image plane will not change. Only the angle of view will. So you cannot obtain a "normal" lens from this. Try it with your zoom (do not change position!) or read here:
http://www.cambridgeincolour.com/forums/thread266.htm
Perspective does not depend on lens . It is a geometrical relationship between objects' sizes and the position of the observer.
Posted by: nugat | 14 Apr 2009 14:42:13
Ah, yes! That's a good site to clear up some misconceptions. Thanks!
Posted by: Lim Teik Hock | 15 Apr 2009 17:40:16
We're used to thinking of perspective in 3 dimensional terms, and regularly have to convince newbies that FL does not affect perspective; only our shooting/viewing position affects perspective.
What about objects in two dimensions ? How much of our field of view do they occupy ? A wide angle lens records a wide field of view. If you print a WA image big and stand close to it, you mimic the wide field of view, but if you print an 8x10 and hold it in front of you, you've effectively shrunk a wide field of view down to something narrow.
Different viewers will want to look at a print from different distances, but as Andy mentioned, all of this is based on the assumption that the diagonal of the print is the 'preferred' viewing distance. A 'normal' or 'standard' viewing distance. I've seen mention that this preference was known to painters before photography came along. It's likely an average or majority preference, but if (for whatever reason) you want to present an image in which the angle between objects matches that of the original scene, you have to make some assumptions about viewing position.
I'm not sure what all the fuss is about. Andy isn't proposing theory here; he's explaining why the 43mm lens was developed as a 'normal' lens. If you like 'normal' better than 'standard'; if you think the word 'standard' should apply to 50mm kit lenses because they're cheap; if you want to argue that one viewers normal isn't quite the same as another ... that's all fine. But none if it conflicts with the information Andy presented.
It's a simple matter of fact. If you shoot with a lens with a FL equal to the diagonal of the film/sensor then if you view the resulting uncropped print at a distance equal to the diagonal of the print, you'll see objects separated by the same angle of view. Use that info or don't as you see fit.
(You could also use the mathematics to figure a viewing distance for large prints taken at wide angles to mimic the original viewing conditions; i.e. to avoid compressing a vista into a narrow image held at arms length and instead present it as something that occupies your peripheral vision).
I'm using a 28mm lens on APS-C as a 'normal' ... I tried a 35mm and found it a little "claustrophibic" :) I'd previously used a 50mm on film (liked it) but also a compact rangefinder with a 40mm (loved it). There's a natural quality to pictures from these lenses explained by the mathematics. That said, I don't hesitate to use other FLs; a natural look is nice & all, but it's frequently not the right FL for what I'm shooting.
Posted by: Dennis | 16 Apr 2009 14:59:01
In the mid-20th century legal text "Photographic Evidence" by Charles Scott (sadly long out of print, and I don't have a copy handy to quote precisely) I recall a "normal" lens being defined as a lens with a focal length within the range of 0.5x the film diagonal to 2x the film diagonal.
This is perhaps overly broad, but it is obviously intended to center on a 1:1 correspondence between the film diagonal and the lens focal length.
Posted by: David Martin | 16 Apr 2009 17:37:45
I found the blog items on “What is a standard lens” and “What are the portrait lenses” very useful. It is certainly a complex area. I would welcome comments on the following summary just in case I have misunderstood some items:
The two key parameters are picture angle and perspective.
The picture angle is determined by the focal length of the lens, the perspective is determined by the camera to subject distance.
If you take a shot with say a 50mm lens the picture angle is 46 degrees using a full frame (35mm) sensor. If you switch to a smaller sensor (say Nikon DX format which I use) then the picture angle decreases to 31.5 degrees so you are effectively cropping your picture. The perspective stays the same. If you move backwards to take in the original subject then the perspective changes.
This is where I become confused in that we now move on to discussing the effect of the optics (physics) and the effect of framing subjects in the viewfinder (art) and the relationships between them.
If, for example, your subject is fixed such as a group of people and you fill the viewfinder with the group then I will often select a perspective that renders distant objects larger in the frame and hence use a telephoto lens and remain some distance away from the group to give the required perspective. I do this because in this type of image both people and location are important. Similarly if I photograph a tree I will often go close and use a wide-angle lens so that the subject is clear and you are not distracted by distant objects.
Regarding portraits my understanding is that the critical parameter is perspective and that the most flattering picture comes from using focal lengths between 85mm and 135mm on full frame sensors where the viewfinder is filled with the full head and shoulders. For this discussion let us assume we use a 100mm lens which has a 24.7 degree picture angle. The implication is that the camera to subject distance (and hence perspective) is now defined. From this point on the choice of sensor size and lens is almost irrelevant (assuming satisfactory resolving power). You could for example use a 50mm lens on a full frame sensor and crop the image for an identical result. This implies using a 65-70mm lens on a DX format sensor etc. I personally use the Nikon 85mm f1.8 (128mm full frame equivalent), which gives better results than my 50mm f1.4 although I must try standing at the correct distance and crop my 50mm images to compare results properly.
I would welcome any comments on the above. Perhaps I have got it completely wrong.
I have also posted this under the “What are the portrait lenses” blog.
Posted by: David MacInnes | 17 Apr 2009 05:37:24
I reckon the natural perspective is that which reflects intimacy: a few millimeters for lovers and our buddies from India (who have no notion of personal space), two feet for friends and family, three feet for aquaintances.
Posted by: Greg Lorriman | 17 Apr 2009 11:37:43
thanks for the great review and some excellent comments.
Posted by: camera digital lenses guy | 18 Apr 2009 01:43:49
Just want to add my 2 cents. People refer to these 'normal' lenses as those which closely match what the eye 'sees'. Many people say that this is achieved with a 50mm, however technically that only captures what a single 'eye' sees when taking the shot. So, when you review your printed out image, the picture never has that sensation 'what i saw'. I think a 'normal' lens would be slightly wider somewhere between 28-39mm to compensate for the other missing 'eye'.
I've noticed some photographers tell me that with the fixed 24 or 35mm lens, they 'step into the shot' and many 50mm users backup when taking pictures. Just a thought.
Posted by: jojo | 18 Apr 2009 04:11:28
This thread that was started with the noble goal of ending the confusion over what "standard/normal" lens is only perpetuates the chaos.
The notion of "perspective" should not be used here at all, as perspective does not depend on lens focal length . This is surprising to many but it's simply a fact. The basis of "persepective" called "foreshortening", where closer objects seem bigger and the more distant ones smaller, depends only on the position of the observer and the objects' dimensions.
Another claim made to the "normal" lens is connected with the film/sensor/print diagonal.
Supposedly lens of f-length equal to the diagonal will render the image "natural looking" when printed and looked upon from the distance equal to the print's diagonal.
It is totally unclear what "natural looking" might mean, if perspective cannot be a factor here.
The only presumption left here is that the phenomenon of Angle of View (AOV) is a factor.
Maybe the "diagonal distance" assumption replicates the human AOV and hence we see such pictures as "natural"?
Diagonal of a 3:2 rectangle is always c=1.8a (approx.) where "a" is the shorter side (vertical). When looked upon from 1.8a the horizontal AOV for such a rectangle is 45 degrees (53deg diagonal AOV) which corresponds to a 43mm f-length lens producing an acceptable image circle for the 24x36 frame.
Is human horizontal AOV 45deg?
Or maybe 40 deg delivered by the 50mm lens?
Or maybe 60deg produced by the 31mm lens?
Do people always look at objects with one "normal/standard" AOV?
The answer is yes, yes yes and no.
Posted by: nugat | 18 Apr 2009 11:37:17
Part deux
Perimetry measures that the field of vision in humans can extend to 180 degrees (usually less), 120-140 of which is two-eye overlap binocular (depth perception). The peripheral 40 degrees is one eye only due to eg. nose getting in the way and lack of overlap. The central part of retina called fovea is responsible for acute vision, when detail is necessary eg reading, examining something, watching movies. Foveal vision has 2 degrees AOV (two degrees).
To use it effectively one often shifts the gaze from detail to detail, eg when reading, or looking at actors faces on a movie screen.
To replicate human physiology a "normal" (human vision like ) lens would need to cover horizontal AOV 2-180 degrees. For 35mm frame that's from extreme fisheye to 1000mm telephoto .( ImaxDome offers a 180 degrees projection).
They are not very practical proposals. When you look at people in an art (photo) gallery they gather the interesting visual information via movements. They walk. If something catches their attention , often from peripheral vision, they'll stop and look at it directly. Then they close in. Finally they close up for detail scrutiny. Then they often back off. They will use most available AOV to get "the full picture".
In film we replicate the vision mechanism via camera moves, lens choice and editing. Wide shot, medium shot, close up.
As an arbitrary compromise one might consider horizontal AOV of 15-85 degrees as the most common .
That corresponds to f 20-135mm on the 35mm film. Or if one prefers 0.5 to almost 3 of that film diagonal.
It also covers conveniently most of portrait lenses and wideangles without getting too much of distortion.
Portrait lenses. What good would be a definition of the "normal" lens that excludes glass depicting human faces in an acceptable way?
With a 43mm lens one has to get so close to the subject to fill the frame that foreshortening effect between eg nose and ears becomes visible and distracting.
A bit wider and the portrait can become a caricature.
One can agree or not whether 20-135mm is a reasonable f-length of an every-day, normal, standard lens. You can extend it down to 14 or up to 300, whatever. But fixing it at the diagonal of the frame just does not make any sense.
On the other hand if the choice was limited to one f-length, manufacturers and buyers would settle around the frame diagonal. Building lens with the image circle diameter around it's f-length is simple and cheap. And as such fairly standard.
Posted by: nugat | 18 Apr 2009 15:53:52
I tried a 28mm lens (which I borrowed from a friend) on my D50 a couple of years back now. I remember that it was very easy to shot with compared to the 35mm lens (which seems a little long). So yes Nikon should have released a 28mm f/1.8 DX. Better still maybe we can convince them to release a 28mm f/1.4 DX.
Posted by: James Clarke | 23 Apr 2009 02:40:33
One statement in this article reminded me of something that I find really annoying with digital SLRs--the measurement of viewfinder magnification.
For 35mm SLRs for many years, viewfinder magnification was defined as stated--"indeed with a 50mm lens focused to infinity, it's used as the definition of viewfinder magnification." This was fine, since the image size at the focal plane produced by full-frame film SLRs was the same for all of them.
In the transition to digital, however, I think it was a mistake to continue using this definition. It allows camera makers to overstate the actual magnification of their finders. I would have preferred that viewfinder magnification be defined as the relative size of an object as viewed through the finder, _when an objective with a field of view equivalent to that of a 50mm lens on full-frame 35mm film is attached_. Given that on APS-C sized DSLRs the field of view of a 50mm lens is roughly equivalent to that of a 75mm lens on full-frame 35mm, measuring viewfinder magnification with a 50mm lens on those cameras is like measuring it with a 75mm moderate tele on full-frame. This means that, for example, if one looks through the finder of a Nikon D90, with its "95% finder magnification", with a 35mm lens mounted, giving a field of view similar to that of a 50mm on full frame, one will see a finder image that is far less than life sized. If a manufacturer _really_ wanted to overstate their finder magnification, they could just use an even smaller sensor.
I have not paid attention but I imagine this happens with 4/3 system cameras, for example. I bet that there are cameras for that system with "near 100% finder magnifications" which actually have half-life-size finder images when a 25mm lens is mounted, giving a field of view roughly equivalent to "standard" on full frame 35mm.
Posted by: Ross Alford | 23 Apr 2009 05:10:06
Most interchangeable 35mm cameras had a "standard" lens of 50mm, although some manufacturers increased the focal length of their large aperture lens to 55mm. Almost all of the fixed lens 35mm cameras, and this by no means meant they were second rate, had a focal length of 45mm. Many of these cameras were reliant on the focusing scale for focusing and most of them focused by moving the front element(elements) relationship to the rest of the lens. I wonder whether the fact the interchangeable lens cameras were also rangefinder cameras, and therefore capable of being more accurate in focusing, played any part in the manufacturers using the slightly longer focal length as a sort of cachet?
Posted by: Brett | 25 Apr 2009 14:37:59
There's a little problem with the comment about how 645 "all stuck stubbornly to the 'frame diagonal' convention". The format is 56x42mm, the diagonal is 70mm, and no 645 system that I know of uses a 70mm normal. They all use 80mm, 1.14x the diagonal, for a normal.
Exactly the same ratio as 50mm/43.3mm, and for pretty much exactly the same reasons.
Posted by: Joseph S. Wisniewski | 29 Apr 2009 15:30:13
Since I am newbie in learning photography, At present I still looking for a lens for my need [Journalism]. At least, I don't give up to explore this site finding what I need to know about how to take a good picture using the right camera. May I have bless from God
Posted by: dboedax | 30 Apr 2009 12:30:37
Thank you
Posted by: dboedax | 30 Apr 2009 18:45:11
Thank you. I'm so sorry. Your posting is very interesting.
Posted by: dboedax | 30 Apr 2009 19:52:27
I've read a really interesting article on Introducing Dynamic Pictures. Check it out here: https://www.blogger.com/comment.g?blogID=1483721464786678472&postID=1519087178296145110&page=1
Posted by: Katty Wayar | 30 Apr 2009 21:39:56
A Standard Lense: look through the camera viewfinder with your non-dominant eye and don't block your domiinant eye with the camera. Look at and point the camera at a far enough away spot. Then pick a focal length that closes matches the size and angle of the view.
Posted by: cesar ramos | 1 May 2009 00:45:21
Put your right eye to the viewfinder. Keep your left eye open. Zoom your lens so that it matches what your left eye sees. Your lens is now set for "normal." It should be in the 45-50mm range.
Posted by: henderpete | 2 May 2009 14:16:57
First, the issue of terminology. "Normal" vs. "Standard" - who will win? Who cares? Just go take good pics. I personally like the term someone used in the first couple of days of posting to this thread - "neutral". I take that to mean that when a print is viewed from a particular lens and no one can detect any telephoto or wideangle attributes in the photo, the lens used was in the "neutral range". And that is certainly not to say that it has to refer to one specific focal length for each format size or ratio. It's much more subjective and a matter of perception.
Second, viewing distance. Now I didn't read every single post so I'm hoping someone else has already addressed this in some way. Here, it's several issues and you can't base a focal length preference on it. Right off, no one will be viewing an image with any great seriousness at a distance too close for their eyes to focus (unless they are REALLY into abstract images). Most people tend to hold books and read them within their arms reach. Does that prove anything about optics? Well, perhaps our eyes have developed a preference for this distance for critical focussing but for taking in most information, it's another matter. Forget just how wide of an angle of view the human eye is capable of taking in, the question needs to be what angle of view do most people care about for viewing a scene (to get the big picture, as it were). When I watch people look at photos and paintings in a museum, I don't really see much of an average (other than they will stand somewhere in front of that which they are observing, 2 to 20 feet perhaps). What I often see instead is a process take place. They usually start at a distance that lets them get an impression of the whole image. They will then move around to study it further, sometimes moving in closer to become more immersed or see more detail, sometimes stepping further back to compress the "story" or image elements. The time they spend at any distance depends entirely on what they find of interest there. There are no averages that hold any relevance.
Third, I think most of you have WAY overanalized this subject. I appreciate the effort to use a formula of some kind to create a rule of thumb. But remember, you are creating that to give you a black and white anchor in a very gray subject. Find the lens and camera combination that pleases you and protrays your subject in the way, perspective, DOF, angle of view that you feel represents your way of seeing best. Then just go to work and capture, capture, capture. Stop spending time making sure every hair gets sufficiently split. They don't need to be. Look for info that helps you find your photographic voice and cut the rest loose. Make it all more about the product and process and less about the calculations. There is only occassionally satisfaction found there and rarely any real beauty.
Sorry for the rant. I don't post often enough I guess. So it all comes out at once. I'm just saddened when I see so many losing sight of the art being your goal. Few of us are in this to be some kind of technical photographer.
Posted by: Piqued | 3 May 2009 18:11:03
hi
this is Shreya I read your blog regularly...your post are really useful. I'm trying to learn photography and have a query I would be happy if you give me your valuable inputs on the same. I have digital camera canon powershot S2 IS which is no longer available in market but there higher versions of the same one available which are canon S3 and S5 I want to buy an extra lens for the same so which is going fit the one and do i buy a zoom lens or a telephoto?
Posted by: Shreya | 6 May 2009 07:33:26
Hi
This is Shreya, I read your blog regularly...your post are really useful. I’m trying to learn photography and have a query I would be happy if you give me your valuable inputs on the same. I have digital camera Canon Powershot S2 IS which is no longer available in market but there higher versions of the same one available, which are canon S3 and S5. I want to buy an extra lens for my camera so, which is going fit the one and do I buy a zoom lens or a telephoto?
Posted by: Shreya | 6 May 2009 07:46:14
hi
nice post...i would like to know that, ealier the camera used to be japan made now we don't get it. they are mostly china made or it is written japan INC. so are these cameras original and after this change is their any difference in there in their performance
Posted by: Pradnya | 6 May 2009 08:11:03
When I learned what I know about photography...
a 'standard lens' gave accurate prespective on a full length human figure.
A 90mm lens gave accurate pespective on a head and shoulders portrait.
A 135mm lens gave accurate perspective on a headshot.
By accurate I mean the face looked normal without an exaggerated or flattened nose....
Posted by: mac | 6 May 2009 10:48:13
Thank goodness the Sigma DP2 has a 41mm lens.
Posted by: rob | 6 May 2009 22:24:48
It's a shame (to me) how manufactures keep marketing 50s as the portrait lens of today, of the APS-C format sensors. As mentioned before in some comment, they only make such success because are cheap. To me, the Pentax 77 mm seems to be the best of all mencioned. I think that most people prefer pay more for a convinced portrait than buy these options, these crap options.
About bokeh, Sony has just the best lens in the world. It's its 135 mm STF. It's an awsome lens. Just perfect for portraits. Of course that for APS-C it should downfocal a little bit, and its maximum aperture also is not the ideal, but in terms of bokeh I can't see other better until now. Dream with a 60 mm (93) and a 90 mm (140) with the bokeh technology of that Sony STF. Just perfect, wouldn't it?
Posted by: Richard de Andrade | 6 May 2009 23:00:31
Sorry, wrong entry
Posted by: Richard de Andrade | 6 May 2009 23:02:31
I agree that 'normal' is better placed than 'standard' for this matter. I think normal should be normal, 43, 29 and 21. Those 25, 35 and 50 convenctioned have no reason to be if not by costs reasons. Longer focals needs less retrofocal power (resulting in less optical engineering and glass material etc.), and also match the low magnified viewfinders. If an FF have a 43 mm lens attached and its VF is 1 x magnified, the image observed throught it will match in size the image viewed by your other eye outside (that can see the scene directly). If do the same viewing but now through a VF 0.9 x magnified, you'll need a 48 mm lens to simulate the same effect. So they produce a 50 mm to simulate that normality (of course I'm speaking of FF). But in terms of smaller sensors, something similar occurs.
Even worse. Notice that manufacturers indicate the magnification of its APS-C sensor dSLRs considering a "normal" (50 crép of always) focalised at infinity. This really makes difficult to any person evaluate what the hello is a 'normal' lens. The era of conventions because of technical difficulties in manufacturing should be buried. Today they have technology and means to make this type of lens just as it should be since a long time ago. The shortening of the excess of flange by removing the pre-historic mirror box should definetively take out the barriers to make real 'normal' lenses (without retrofocus elements), and EVF should leave room to work on full magnification (1 x) eyepieces.
Why manufacturers insist in using "normal" instead of 'normal' in these days is problably a question to be answered by anyone that doesn't understand of photography like we do. Sometimes I just wonder what the 'porra' we do here (and you, editors, there). Such profissional websites, such experts visitors. In the end, besides all the same conclusions between us, it seems that only the ignorant wealthy consumer wins. They buy advanced and semipros and don't worry about these things :(
Posted by: Richard de Andrade | 7 May 2009 15:07:53
As I recall, "normal" focal length approximates the diameter of the captured image circle. Ideally, the viewfinder also is constructed so that the scene has approximately the same magnification with a normal lens as when directly viewed.
I believe the propensity toward longer normal lenses really comes from yet another issue: the focal length of a simple lens is the distance from lens center to the image plane at infinity focus, and this distance is too long on SLRs thanks to the thickness of the mirror box. Thus, one could argue that lens makers tended toward the long side for SLR normals to simplify lens design, but on the short side for non-SLR cameras in order to increase depth-of-focus and capture slightly more than the viewfinder in order to hide minor focus and viewfinder alignment errors.
Posted by: ProfHankD | 14 May 2009 15:54:25
It's amusing listening to a bunch of arguments that attempt to provide recise answers based on an assumption for which no evidence whatsoever was advanced : the claim that 1) al humans view a scene with such and such a field of view, and 2) that this supposed field of view is precisely the PREFERRED
perspective. Obviously neither of these claims has the slightest morsel of evidence to back them up, nor to answer the obvious counterclaim that NOTHING that can be sai about any human would apply exectly to all humans. And THAT is where all of the troubles began. It reminds me of those early lobotomists who would fiecely argue whether their totally
worthless and misunderstood lobotomies should be executed at this degree of rotation of the scalpal or some other.
Posted by: Biker | 16 May 2009 02:26:45
Call it Diagonal Equivalent if it suits that description. Normal or Standard on 35 mm is 50-55mm as it became that standard in time. On a 6x6 camera Diagonal Equivalent is 79mm and the variation in standard is between 75-85mm. On a 6x9 it is much harder to set as the 9 can represent 82 to 88 mm, 100 to 105 mm is the standard though where the diagonal on a 56x88mm frame measures 104mm and on the 56x82mm frame it is 99mm. In short, with larger film frames the Standard gets closer to Diagonal Equivalent.
Prints hardly ever represent the right view angle at viewing distances and often are not intended to represent them. Bill Brandt's wide angle shots are a nice but extreme example of that. So forget calculations based on paintings or prints.
Posted by: Ernst Dinkla | 18 May 2009 10:32:09
I remember my leica cl with a standard 40 mm, I tested it vs my leica iiic 50 mm, and I preferred the perspective of the 40
Posted by: fabio | 18 May 2009 14:39:28
at what event we use standard lens?
Posted by: fanino maynardo | 20 May 2009 17:10:54