Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-13-2008, 04:52 AM   #16
Veteran Member




Join Date: Aug 2007
Location: England
Posts: 309
QuoteOriginally posted by Photomaximum Quote
The 50mm on a normal film or FF digital camera is almost the same view as one human eye (not both)...
Actually, it is not the same field of view. You can see this with a FF camera. Stand in front of a window (or something else with defined edges) frame the object in the viewfinder so that its edges are just within the viewfinder (you may have to move away from or towards it to do this). Now quickly move the camera back and forth so you see the view with and without the camera. What you find is that the magnification is the same, but because there is some cropping, the field of view is less than you can see.

The greater field of view with your eyes is partly due to the fact that you have two eyes 6 or 7 cm apart, but even if you try the test above with one eye closed (obviously, not the one you use to look through the viewfinder ;-) ) you still get cropping. Just roughly, I reckon 50mm on a full frame camera crops to about 1/3 field of view. (But then I have had laser treatment on the edge of my retinas, so I have a more restrictive field of view than most people).

If I do the same thing with a 28mm lens the magnification is less than my eye, but the field of view is about half that I get with my eyes.

Richard

10-13-2008, 09:41 AM   #17
Veteran Member
simons-photography's Avatar

Join Date: Dec 2007
Location: Northamptonshire - England
Photos: Gallery
Posts: 497
so a "normal" 50 mm (in 135 format) is normal in the sense of perspective ? I'v always assumes that perhaps the huma eye was more like 35mm (in 135 format)
10-13-2008, 10:35 AM   #18
Veteran Member
tomtor's Avatar

Join Date: Apr 2008
Location: Netherlands
Posts: 382
QuoteOriginally posted by ChrisPlatt Quote
I have two eyes, with peripheral vision. A 35/40mm lens best approximates how I recall seeing a scene.

Chris
Yes, but when you looked through the viewfinder with ONE eye on a film SLR with 50mm mounted
the image just blended in, it was the same size. If you looked over the camera you saw the world in the same enlargement as through the viewfinder.
10-13-2008, 12:05 PM   #19
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by ChrisPlatt Quote
I have two eyes, with peripheral vision. A 35/40mm lens best approximates how I recall seeing a scene.
If you are referring to how 35-40mm looks on APS-C, I'd agree. I can clearly see *much* more than this, but much of that is peripheral. Somewhere around 35-40 is what I am most aware of in most situations. But what I can actually *see* is considerably more than 18mm on APS-C.

10-13-2008, 12:12 PM   #20
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by simons-photography Quote
so a "normal" 50 mm (in 135 format) is normal in the sense of perspective ? I'v always assumes that perhaps the huma eye was more like 35mm (in 135 format)
Once again, perspective has *absolutely nothing* to do with focal length. The perspective of a 35 lens is precisely the same as that of an 18mm lens or a 300mm lens - assuming you are using them all at the same distance from your subject.

The *only* thing that changes directly with focal length is angle of view. So that is the only thing we can talk about in terms of how it compares to the eye. And as mentioned in several posts above, that depends on whether we are talking abut one eye or two, and whether we are talking about peripheral vision or just hat we choose to "focus* on. If we are talking about everything we can see wioth both eyes, it's *much* wider than 35mm in 135 format - more like 24mm or so. If we are talking about what we are most *aware* of, that is subjective and varies from person o person and depending on the situation. But I'd personally say it's anywhere from around 40-70 in 135 format for me - and mostly right around 50-60.
10-13-2008, 01:55 PM   #21
Veteran Member
simons-photography's Avatar

Join Date: Dec 2007
Location: Northamptonshire - England
Photos: Gallery
Posts: 497
QuoteOriginally posted by Marc Sabatella Quote
Once again, perspective has *absolutely nothing* to do with focal length. The perspective of a 35 lens is precisely the same as that of an 18mm lens or a 300mm lens - assuming you are using them all at the same distance from your subject.
nope if you use length different lenses but keep your subject the same size in the frame by moving forward or back the apparant distantce of other things in the scene will change, so which lens gives the same apparant distances as the human eye sees ? often two objects are shot from further away with a longer lens to make them look closer ?
10-13-2008, 02:04 PM   #22
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by simons-photography Quote
if you use length different lenses but keep your subject the same size in the frame by moving forward or back the apparant distantce of other things in the scene will change
Well, yes - as I said, *distance to subject* is the key to persepctive. What caused the perspective to change was the fact that you *moved*, not the fact that you changed lenses. So it's meaningless to say that a given lens has the perspective as the human eye - no lens or eye has any perspective at all. It's all a matter of where you are standing.

Now, if one lens makes you *want* to move closer or further away to approximate the same view you get with your eyes, that's just another way of saying that the *angle of view* of that lens is wider or narrow than that of your eyes. We 8can* talk about the angle of view of our eyes. Al;though as I've said, the *actual* angle of view of our eyes is *very* wide - wider than an 18mm lens on APS-C (which is wide as I can go to test it with). But much of that is peripheral. The portion of the view we really notice is considerably less, but it's also very subjective - meaning it is also kind of silly to say that 50mm (or 35mm, or any other specific focal length) is the same as our eyes. The standardization of 50mm as the "normal" lens was quite arbitrary, really.
10-13-2008, 02:10 PM   #23
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by ChrisPlatt Quote
No, a 35-40mm lens on 35mm film.
That's what life looks like to me.
I agree, it's all very subjective...
Interestingly, I am *learning* to "see" with a 28mm lens on APS-C, which is only just narrower of a view than the 35-40 on film. I am always at first taken aback at how much I can see, although to be perfectly honest, the fact that it is also small in the viewfinder contributes to my momentary disorientation - and yes, I do realize that this is a red herring. Anyhow, I can indeed see the sense in which the 28 does pretty accurately what I portray something about the scene for me, but it's an interesting point between "everything I can see" and "just what I care about". Maybe, "what I care about together with what I can't help but notice".

10-13-2008, 06:50 PM   #24
Veteran Member




Join Date: Sep 2006
Location: Melbourne, Australia
Posts: 423
QuoteQuote:
@ 28mm - We don't have a DA 17.5 and would the DA12-24/4 be a good alternative?
If you don't mind manual focus, there is a Tokin 17/3.5 or you can get the upcoming DA15mm. I have DA14 myself.

QuoteQuote:
@ 50mm - FA31/1.8 comes close to 50mm
31mm/1.8 is a little too rich for me. I use my FA28/2.8. I heard that Sigma 28/1.8 isn't bad either.

QuoteQuote:
@ 135mm - FA85/1.4 comes close but the FA77/1.8 is smaller and cheaper
I use either FA50/1.4 and/or Tamron 90/2.8 to cover this range.

cheers
Kenny
10-14-2008, 11:38 AM   #25
Site Supporter
Site Supporter




Join Date: Feb 2008
Location: MT
Posts: 1,082
Just to add to the discussion...there are those who claim the 50mm "normal" lens is based on it being the closest to the 43mm diagonal dimension of 35mm film. I never really understood this approach any more than I understand that 50mm lenses do not show me the same angle of view my eyes can see.
Note that some of this discussion was popular when the 43mm Limited first came out and proponents claimed it to be the "true" normal lens by matching the diagonal frame dimensions--this was before the digital boom...I never bought the theory stuff, but I did buy the lens within about a month of its introduction.

Regarding perspective, gosh, I thought perspective was simply the new rage in pornos? Or maybe it was the cover of a Pink Floyd album?

There are advocates out there who encourage the "doubler" effect for building a prime kit: 24, 50, 100, 200. This approach is actually quite common in the medium format world where zooms are fairly uncommon and where most photogs don't want to carry very many big heavy lenses in a kit. Even the fairly recent Hasselblad Xpan panorama cross-overs (35mm and medium format in one body) were offered only with 45mm and 90mm lenses as the "common" kit before they came out with a superwide that didn't fit the "doubler" theory.

In '90's Pentax lens brochures and early website listings, our manufacturer of choice specified categories rather than direct lens sizes and actually the choices are fairly intuitive for me: ultra wide, wide, normal, telephoto and supertelephoto were the categories as I recall (plus specialty lenses like Macro and Soft Focus in their own category). I you build a kit with each of these categories represented you'd have most everything covered for most photographers.
10-15-2008, 09:07 AM   #26
Site Supporter
Site Supporter




Join Date: Feb 2008
Location: MT
Posts: 1,082
Tripped over an old PZ1-p marketing brochure yesterday...Pentax also had a category--medium telephoto which includes the "portrait" lenses. At that time mainly the FA*85, but currently the DA70 and FA77 Limited lenses would be in this range.
10-15-2008, 05:12 PM   #27
Forum Member
ariahspam's Avatar

Join Date: May 2008
Location: Lima, Peru
Posts: 69
QuoteOriginally posted by Ron Boggs Quote
Tripped over an old PZ1-p marketing brochure yesterday...Pentax also had a category--medium telephoto which includes the "portrait" lenses. At that time mainly the FA*85, but currently the DA70 and FA77 Limited lenses would be in this range.
Wouldn't it be DA*55's job?
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
50mm, da12-24/4, fa31/1.8, fa77/1.8, k-mount, k1000, kit, lengths, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
focal length ewig Troubleshooting and Beginner Help 11 07-23-2010 09:32 PM
focal length landscaped1 Troubleshooting and Beginner Help 48 05-05-2010 03:04 PM
K7 is 1.5 x focal length? rdrum76 Pentax DSLR Discussion 18 06-30-2009 08:30 AM
What is Focal Length Ole Photography Articles 2 05-15-2009 12:20 PM
Focal Length ? deludel Photographic Technique 14 01-30-2008 06:58 PM



All times are GMT -7. The time now is 06:20 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top