Go Back   Rangefinderforum.com > Cameras / Gear / Photography > Rangefinder Forum > Optics Theory -

Optics Theory - This forum is aimed towards the TECHNICAL side of photographic OPTICS THEORY. There will be some overlap by camera/manufacturer, but this forum is for the heavy duty tech discussions. This is NOT the place to discuss a specific lens or lens line, do that in the appropriate forum. This is the forum to discuss optics or lenses in general, to learn about the tech behind the lenses and images. IF you have a question about a specific lens, post it in the forum about that type of camera, NOT HERE.

Reply
 
Thread Tools Search this Thread Display Modes

21mm And Distortion
Old 02-16-2011   #1
wjlapier
Registered User
 
wjlapier's Avatar
 
wjlapier is offline
Join Date: Jan 2008
Posts: 1,263
21mm And Distortion

Something I never really paid much attention too, until I saw it in some of my pictures. Distortion. I'll include two pics below, but I'm now curious and wondering about something. Do all 21mm lenses display this much distortion? I don't shoot this wide usually. Any other 21's better at handling distortion? BTW, lens is CV 21/4 LTM. I was using my IF with CV 21/25 finder.
Attached Images
File Type: jpg 13730001.jpg (49.3 KB, 111 views)
File Type: jpg 13730003.jpg (67.7 KB, 101 views)
  Reply With Quote

Old 02-16-2011   #2
Sparrow
Registered User
 
Sparrow's Avatar
 
Sparrow is offline
Join Date: Feb 2006
Location: Perfidious Albion
Age: 64
Posts: 12,545
That isn't distortion, it's just the planar projection of the lens
__________________
Regards Stewart

Stewart McBride

RIP 2015



You’re only young once, but one can always be immature.

flickr stuff
  Reply With Quote

Old 02-16-2011   #3
ChrisN
Striving
 
ChrisN's Avatar
 
ChrisN is offline
Join Date: Apr 2005
Location: Canberra
Posts: 4,432
To avoid the converging verticals, try shooting with the camera exactly level - with the camera aimed at a point the same height as your eye. Do you have any samples like that? I'll bet they show the vertical lines standing true (but perhaps slightly curved). Even my Hasselblad SWC (famous for its lack of distortion) captures converging vertical lines if I point the camera upwards.
__________________
Chris


"The mission of photography is to explain man to man and each to himself. And that is the most complicated thing on earth."
Edward Steichen

RFF Gallery

Flickr
  Reply With Quote

Old 02-16-2011   #4
daveywaugh
Blah
 
daveywaugh's Avatar
 
daveywaugh is offline
Join Date: Apr 2008
Posts: 332
In 35mm, the best lens with regards to distortion (and almost everything else IMO!) has been the Contax G 21mm. Compared to SLR lenses or the Voigtlander lenses I have tried, it's in a different league.
__________________
www.davidwaugh.net
  Reply With Quote

Old 02-16-2011   #5
Roger Hicks
Registered User
 
Roger Hicks is offline
Join Date: Apr 2005
Location: Aquitaine
Posts: 21,858
There are three separate issues here.

First, true distortion ('pincushion' or 'barrel', according to whether straight lines near the edge of the frame are 'sucked in' or 'blown out'). Biogons (the f/4.5 models) are generally reckoned to be the winner. I don't really see this in your pics.

Second, converging/diverging verticals. These are caused by departures from holding the camera dead level. All suffer from this to the same extent. This is quite marked in your pics.

Third, something I was taught to refer to as 'true wide-angle distortion', where, for example, spheres are stretched into ovals. This is especially distressing when it happens to people's heads. As far as I know, most wide-angles suffer about equally from this, though optical designs may have some effect. Some people take exception to the term 'true wide angle distortion', but regardless of what you call it, it exists, and it 'stretches' things near the sides of the image. I don't really see this in your pics either.

Cheers,

R.
__________________
Go to www.rogerandfrances.eu for a whole new website
  Reply With Quote

Old 02-16-2011   #6
wjlapier
Registered User
 
wjlapier's Avatar
 
wjlapier is offline
Join Date: Jan 2008
Posts: 1,263
Quote:
Originally Posted by ChrisN View Post
To avoid the converging verticals, try shooting with the camera exactly level - with the camera aimed at a point the same height as your eye. Do you have any samples like that? I'll bet they show the vertical lines standing true (but perhaps slightly curved). Even my Hasselblad SWC (famous for its lack of distortion) captures converging vertical lines if I point the camera upwards.
I was thinking it might be how I aimed the lens. I like this little lens alot. Colors are basically true to what I saw that day--see yellow painted winery.
Attached Images
File Type: jpg 13730012.jpg (66.7 KB, 51 views)
File Type: jpg 13730018.jpg (64.0 KB, 30 views)
  Reply With Quote

Old 02-16-2011   #7
helenhill
the click of a moment...
 
helenhill's Avatar
 
helenhill is offline
Join Date: May 2008
Location: New Yawk
Posts: 5,780
Oh hello William
its exactly that 'Look' that made Me fall for a 21 SA...the Exaggerated sense of Proportion
__________________
_____________________________________
Inspired Eye Link... 30 Questions, 14 Photos
https://www.flickr.com/photos/helena...in/dateposted/
______________
Leica M5 • X2

Last edited by helenhill : 02-16-2011 at 15:42.
  Reply With Quote

Old 02-16-2011   #8
helenhill
the click of a moment...
 
helenhill's Avatar
 
helenhill is offline
Join Date: May 2008
Location: New Yawk
Posts: 5,780
I guess I Love Imperfections....
__________________
_____________________________________
Inspired Eye Link... 30 Questions, 14 Photos
https://www.flickr.com/photos/helena...in/dateposted/
______________
Leica M5 • X2

Last edited by helenhill : 02-17-2011 at 02:58.
  Reply With Quote

Old 02-16-2011   #9
helenhill
the click of a moment...
 
helenhill's Avatar
 
helenhill is offline
Join Date: May 2008
Location: New Yawk
Posts: 5,780
the 21 SA again...
__________________
_____________________________________
Inspired Eye Link... 30 Questions, 14 Photos
https://www.flickr.com/photos/helena...in/dateposted/
______________
Leica M5 • X2

Last edited by helenhill : 02-17-2011 at 02:56.
  Reply With Quote

Old 02-16-2011   #10
wjlapier
Registered User
 
wjlapier's Avatar
 
wjlapier is offline
Join Date: Jan 2008
Posts: 1,263
Hi Helen,

Love them all, especially the first one.

Bill
  Reply With Quote

Old 02-16-2011   #11
Phil_F_NM
Camera hacker
 
Phil_F_NM's Avatar
 
Phil_F_NM is offline
Join Date: Jun 2004
Location: Philadelphia, PA
Age: 39
Posts: 2,934
The Super Angulon is technical wide angle perfection with regard to lack of distortion. You won't find any curved lines which are straight in real life as you would with lesser lenses. Aiming it so the planes aren't parallel with the film plane will cause the converging lines but that happens with all lenses. Wide angles just show it prominently.
I love my SA more than any other wide I've ever used. "It is so choice. If you have the means, I highly recommend picking one up." - Ferris Bueller

Phil Forrest
  Reply With Quote

Old 02-16-2011   #12
tlitody
Registered User
 
tlitody is offline
Join Date: May 2010
Location: Sceptred Isle
Posts: 1,773
Quote:
Originally Posted by wjlapier View Post
Something I never really paid much attention too, until I saw it in some of my pictures. Distortion. I'll include two pics below, but I'm now curious and wondering about something. Do all 21mm lenses display this much distortion? I don't shoot this wide usually. Any other 21's better at handling distortion? BTW, lens is CV 21/4 LTM. I was using my IF with CV 21/25 finder.
I can't detect any distortion there. Its just converging verticals from film plane not being vertical.
  Reply With Quote

Old 02-16-2011   #13
ChrisN
Striving
 
ChrisN's Avatar
 
ChrisN is offline
Join Date: Apr 2005
Location: Canberra
Posts: 4,432
Quote:
Originally Posted by wjlapier View Post
I was thinking it might be how I aimed the lens. I like this little lens alot. Colors are basically true to what I saw that day--see yellow painted winery.
That's it - excellent! I see why you like it.

Quote:
Originally Posted by helenhill View Post
Oh hello William
its exactly that 'Look' that made Me fall for a 21 SA...the Exaggerated sense of Proportion
And Helen - this is wonderful! LOVE this photo!
__________________
Chris


"The mission of photography is to explain man to man and each to himself. And that is the most complicated thing on earth."
Edward Steichen

RFF Gallery

Flickr
  Reply With Quote

Old 02-16-2011   #14
Rob-F
My Avatar Is Missing
 
Rob-F is offline
Join Date: Mar 2007
Location: The Show Me state
Age: 75
Posts: 4,400
Quote:
Originally Posted by Roger Hicks View Post
There are three separate issues here.

First, true distortion ('pincushion' or 'barrel', according to whether straight lines near the edge of the frame are 'sucked in' or 'blown out'). Biogons (the f/4.5 models) are generally reckoned to be the winner. I don't really see this in your pics.

Second, converging/diverging verticals. These are caused by departures from holding the camera dead level. All suffer from this to the same extent. This is quite marked in your pics.

Third, something I was taught to refer to as 'true wide-angle distortion', where, for example, spheres are stretched into ovals. This is especially distressing when it happens to people's heads. As far as I know, most wide-angles suffer about equally from this, though optical designs may have some effect. Some people take exception to the term 'true wide angle distortion', but regardless of what you call it, it exists, and it 'stretches' things near the sides of the image. I don't really see this in your pics either.

Cheers,

R.
My chance to teach the teacher. Roger, make a fairly large print of a shot you have taken with, say, a 21mm or wider lens. Well, OK, even a 24mm is wide enough to make the point. Then try viewing the print from a distance close enough so that your viewing angle across the print matches the angle of view of the taking lens. When you get the distance right,

VIOLA! The "distortion" will be gone.

The apparent distortion is caused by a mismatch between the angle at which the picture was photographed, and the viewing angle when viewing the print.

Try it! It works! Really!
__________________
May the light be with you.
-----------------------------------------------------
How could my avatar have just disappeared?
  Reply With Quote

Old 02-17-2011   #15
Roger Hicks
Registered User
 
Roger Hicks is offline
Join Date: Apr 2005
Location: Aquitaine
Posts: 21,858
Quote:
Originally Posted by Rob-F View Post
My chance to teach the teacher. Roger, make a fairly large print of a shot you have taken with, say, a 21mm or wider lens. Well, OK, even a 24mm is wide enough to make the point. Then try viewing the print from a distance close enough so that your viewing angle across the print matches the angle of view of the taking lens. When you get the distance right,

VIOLA! The "distortion" will be gone.

The apparent distortion is caused by a mismatch between the angle at which the picture was photographed, and the viewing angle when viewing the print.

Try it! It works! Really!
Dear Rob,

I'll almost completely agree, and the same argument appears on my site. From
http://www.rogerandfrances.com/subsc...ctive%201.html (Perspective):

Traditional 'standard' lenses and viewing distances are all well and good until you start to consider enlargements. Obviously, very few people are going to look at 24x36mm images from a distance of 43mm (the negative diagonal), except perhaps when they are going through contact sheets with a magnifying glass. So let's imagine we use a 43mm lens (the nearest we know of is the 42.5mm Biogon for the pre-war Contax) and blow it up 6x to 144 x 216mm, a bit under 6x9 inches. The optimum viewing distance for the 'magic distance' is now 6 x 43 = 258mm or a bit over 10 inches -- an ideal viewing distance for a print that size.

Now make a 40x50cm/16x20 inch print from the same negative: people do. You'll have to crop the negative a bit to make it fit, but for a borderless print this size you are looking at almost a 17x enlargement. Your optimum viewing distance is now 17 x 43 = 731mm or about 29 inches: probably a bit closer than most people would normally look at such a big picture unless they were examining it fairly closely, for example in a gallery.

Now change the focal length. Shoot the same scene, from the same spot, with both a 21mm lens and an 85mm lens. For the same size prints, we can establish the optimum viewing distances using our dear friends the similar triangles. For the 21mm, the viewing distance is 21/43 the distance for a 'standard' 43mm lens, and for the 85mm it is 85/43.

For the small print, the viewing distances go from 258mm/10 inches with the 'standard' lens to 126mm (near enough 5 inches) with the 21mm and 510mm, a bit over 20 inches, for the 85mm. With the big print (optimum viewing distance 731mm/29 inches for the 43mm lens) they are 357mm, 14 inches, for the 21mm shot and 1445mm, near enough 57 inches, for the 85mm. You will have noted that because we chose focal lengths that were roughly half the 'standard' and roughly double, the viewing distances in both cases are roughly halved and doubled. Similar arguments would apply to 14mm (about 1/3) and 135mm (about triple).

Now, imagine that our 85mm shot is a portrait, and we make a 40x50cm/20x16 inch print from it. We often look at portraits of ths size from a distance of around 1.5 metres or 5 feet, so the perspective will be much more pleasing than it would have been with a 43mm portrait covering the same subject, but (necessarily) closer to the subject. Conversely, if we shot a landscape with our 21mm lens, and made a 40x50cm/20x16 inch print from that, we might well find a magical sense of being 'inside' the landscape if we stood close enough to it.


One reason I say 'almost' is that in reality, we very seldom do make such massive prints; or if we do, we seldom look at them from so close. The other is that I am reasonably confident that the 'spheres to ovals' phenomenon still applies. We normally turn our heads to look at things off to one side, and besides, the brain does an awful lot of post-processing, so we literally see what we expect to see.

I say only 'reasonably confident' on the basis of optical theory and the psychology of vision. I'm thinking in particular of a 21mm shot I took of the interior of a classroom in India where the headmistress is peeking through the door on one side. Her head is grotesquely distorted. Quite honestly, I'm not going to make a 20x16 inch print and stand REALLY close to it to see which of us is right. I think it's me, but it might be you.

Cheers,

R.
__________________
Go to www.rogerandfrances.eu for a whole new website
  Reply With Quote

Old 02-17-2011   #16
bigeye
Registered User
 
bigeye's Avatar
 
bigeye is offline
Join Date: Dec 2009
Location: New York
Posts: 1,185
The only way out of this is with movements - a view camera...

Rockwell has a pretty good primer on ultrawides.

Wonderful pics, Helen.
__________________
I bought a new camera. It's so advanced you don't even need it. - Steven Wright

Last edited by bigeye : 02-17-2011 at 03:55.
  Reply With Quote

Old 02-17-2011   #17
atlcruiser
Part Yeti
 
atlcruiser is offline
Join Date: Dec 2009
Location: atlanta
Posts: 1,211
This is from my CV 21/4 on the M8. I am sure there is some distorsion but I cant really see it. As long I I keep the lens level it works like a champ.
__________________
David

leica M6 ttl
Hassy X Pan
Big ass Fuji G690BL
Some really BIG ASS LF stuff

my flikr
http:[email protected]/

my website:
www.dearbornphoto.com

southeastern RFF flikr: Please look/join
http:[email protected]/?added=6
  Reply With Quote

Old 02-17-2011   #18
tlitody
Registered User
 
tlitody is offline
Join Date: May 2010
Location: Sceptred Isle
Posts: 1,773
Quote:
Originally Posted by bigeye View Post
The only way out of this is with movements - a view camera...
The best way out is to get your taking position right so that the camera can be level and the framing is correct. That way there is simply no need for a view camera. Of course that is not always feasible but is often overlooked when it is. It's just too easy to point the camera up or down rather than move yourself to the optimum position (which might include getting yourself into a middle floor of a building opposite).
  Reply With Quote

Old 02-17-2011   #19
wjlapier
Registered User
 
wjlapier's Avatar
 
wjlapier is offline
Join Date: Jan 2008
Posts: 1,263
Quote:
Originally Posted by tlitody View Post
I can't detect any distortion there. Its just converging verticals from film plane not being vertical.
I now see what distortion is ( not in my photos ) and what converging verticals are.

Anyway, this lens has me re-thinking CV lenses. Actually the build quality is very good.
  Reply With Quote

Old 02-17-2011   #20
barnwulf
Registered User
 
barnwulf's Avatar
 
barnwulf is offline
Join Date: Apr 2009
Location: Ankeny, Iowa
Age: 78
Posts: 1,336
Simply gorgeous shots Helen. Especially the first one. Jim
__________________
"Basically, I no longer work for anything but the sensation I have while working."
- Alberto Giacometti (sculptor)
  Reply With Quote

Old 02-17-2011   #21
MCTuomey
Registered User
 
MCTuomey's Avatar
 
MCTuomey is offline
Join Date: Nov 2004
Location: U.S.
Age: 62
Posts: 3,075
Quote:
Originally Posted by tlitody View Post
The best way out is to get your taking position right so that the camera can be level and the framing is correct. That way there is simply no need for a view camera. Of course that is not always feasible but is often overlooked when it is. It's just too easy to point the camera up or down rather than move yourself to the optimum position (which might include getting yourself into a middle floor of a building opposite).
Apologies if this is OT, but I found your post interesting.

What happens when you've got the camera level and the framing "correct" and you find yourself with a whole lot of street/parking lot/other in the foreground that's unwanted? You can change lenses. You can crop later. Or, if you have movements you can shift upward and eliminate the unwanted foreground in a few seconds.

Ok, one doesn't "need" a view camera. Just saying there's very often a lot of value in a view camera's movements which is why I like my 35mm T-S lenses a lot.
__________________
--Mike (confirmed midget imagist on stilts)

Bill Pierce's "photographer's proposition": I saw something wonderful, let me show it to you.


Fuji X
Leica M
Canon EOS
Hasselblad 503CW
Minolta Autocord


My Flickr
  Reply With Quote

Old 02-17-2011   #22
wjlapier
Registered User
 
wjlapier's Avatar
 
wjlapier is offline
Join Date: Jan 2008
Posts: 1,263
Quote:
Originally Posted by helenhill View Post
Oh hello William
its exactly that 'Look' that made Me fall for a 21 SA...the Exaggerated sense of Proportion
Interesting how the buildings are leaning to the left on the left side of the picture and as you look to the right the buildings by the park are leaning to the right.

Looking at my first photo the buildings in the foreground are falling inward.
  Reply With Quote

Old 02-17-2011   #23
MCTuomey
Registered User
 
MCTuomey's Avatar
 
MCTuomey is offline
Join Date: Nov 2004
Location: U.S.
Age: 62
Posts: 3,075
I think that's because your photo was taken with the camera leaning forward (lens' axis pointing down).
__________________
--Mike (confirmed midget imagist on stilts)

Bill Pierce's "photographer's proposition": I saw something wonderful, let me show it to you.


Fuji X
Leica M
Canon EOS
Hasselblad 503CW
Minolta Autocord


My Flickr

Last edited by MCTuomey : 02-17-2011 at 09:14. Reason: correction needed - got my direction backwards
  Reply With Quote

Old 02-17-2011   #24
ampguy
Registered User
 
ampguy's Avatar
 
ampguy is offline
Join Date: May 2006
Posts: 7,039
What I've found is that in nature, it's pretty easy to compose with the CV 21/4, (and, while harder, even the CV 15/4.5) even though some of the distortions mentioned are still present, if you compared with say a 35 cron asph or good 50 on a tripod. The photos can still look pleasing:



But, with square and rectangular architecture, with wider than some 35s, you sometimes have to pick 2 or 3 sides of the square or rectangle, that you wish to be parallel with your frameline edges. For this image, I bracketed, but ended up liking the street, and sky, and right hand side parallel to the print edges, while the left edge of the subject building is converging. I have other images that retained the left side's known vertical perspective, but at the expense of skewing the top, bottom, or right:



The CV lenses do have a bit of barrel distortion, noticeable at the edges, but not severe, and most lenses in the price range would exhibit the same, with the exceptions of some older '70s SLR glass that is not available anymore, and much larger in size.
__________________
My photo blog

  Reply With Quote

Old 02-17-2011   #25
helenhill
the click of a moment...
 
helenhill's Avatar
 
helenhill is offline
Join Date: May 2008
Location: New Yawk
Posts: 5,780
To My 'EYE' , All the shots here have a varying
Degree of Heightened Proportions.... thats why 21's are Stellar

Cheers & Thank You my Rff buddies /Bill, Chris, BigEye, Barnwulf
for the Kind Comments...
__________________
_____________________________________
Inspired Eye Link... 30 Questions, 14 Photos
https://www.flickr.com/photos/helena...in/dateposted/
______________
Leica M5 • X2
  Reply With Quote

Old 02-17-2011   #26
sepiareverb
aflutter.
 
sepiareverb's Avatar
 
sepiareverb is offline
Join Date: Feb 2007
Location: St Johnsbury VT
Posts: 6,856
Quote:
Originally Posted by helenhill View Post
I guess I Love Imperfections....
WOW! Such light. Delightful.
  Reply With Quote

Old 02-17-2011   #27
tlitody
Registered User
 
tlitody is offline
Join Date: May 2010
Location: Sceptred Isle
Posts: 1,773
Quote:
Originally Posted by wjlapier View Post
Interesting how the buildings are leaning to the left on the left side of the picture and as you look to the right the buildings by the park are leaning to the right.

Looking at my first photo the buildings in the foreground are falling inward.
if film plane is tilted forward from vertical the result is diverging verticals. If film plane is tilted backwards from vertical the result is converging verticals. In this case camera is tilted forwards. Everything to left of centre leans left and everything to right of centre leans right. The reverse is the case if camera is tilting upwards. You can play with that knowledge to get some really extreme effects.
  Reply With Quote

Old 02-17-2011   #28
Chris101
Lazy Lytro Shooter
 
Chris101's Avatar
 
Chris101 is offline
Join Date: Jun 2007
Location: Arizona
Posts: 4,135
Quote:
Originally Posted by atlcruiser View Post
This is from my CV 21/4 on the M8. I am sure there is some distorsion but I cant really see it. As long I I keep the lens level it works like a champ.
http://farm5.static.flickr.com/4146/...7bc74335_b.jpg
I'm tempted to say that I can't see the distortion for the trees.
__________________
101-365
  Reply With Quote

Old 02-17-2011   #29
tlitody
Registered User
 
tlitody is offline
Join Date: May 2010
Location: Sceptred Isle
Posts: 1,773
Quote:
Originally Posted by MCTuomey View Post
Apologies if this is OT, but I found your post interesting.

What happens when you've got the camera level and the framing "correct" and you find yourself with a whole lot of street/parking lot/other in the foreground that's unwanted? You can change lenses. You can crop later. Or, if you have movements you can shift upward and eliminate the unwanted foreground in a few seconds.

Ok, one doesn't "need" a view camera. Just saying there's very often a lot of value in a view camera's movements which is why I like my 35mm T-S lenses a lot.
If your framing is correct you can't shift the lens without changing the framing. So what you are suggesting is taking a different picture without the distractions in it. But you can't have it both ways.
Yes crop out what you don't want. And a lot of photographers will put their tripod on top of their car to remove that close up foreground. And there are telescopic poles you can mount your camera on to get some height to give a better viewpoint. Or use a step ladder. Or yes you can buy a view camera if you want the additional level of difficulty. All I'm saying is that there is often a simpler way of resolving compositional problems which don't involve going to a view camera. Or you can just tilt the camera and enjoy the converging/diverging verticals for their effect.
  Reply With Quote

Hi Chris
Old 02-18-2011   #30
ampguy
Registered User
 
ampguy's Avatar
 
ampguy is offline
Join Date: May 2006
Posts: 7,039
Hi Chris

In nature shots, it's hard to know if a tree is really straight or not.

But with buildings and window frames, sometimes chairs or rectangular desks and tables, we assume they might be straight, and can often see the slight effects of barrel distortion.

A common explanation, usually from owners with a bunch of barrel distorted lenses, is that if you are going to shoot architecture, you shouldn't be using a rangefinder or cheap glass. But in the 21st century we live in, it's hard to find a lot of scenes without some known straight lines ...

Quote:
Originally Posted by Chris101 View Post
I'm tempted to say that I can't see the distortion for the trees.
__________________
My photo blog

  Reply With Quote

Old 02-18-2011   #31
tlitody
Registered User
 
tlitody is offline
Join Date: May 2010
Location: Sceptred Isle
Posts: 1,773
Quote:
Originally Posted by ampguy View Post
In nature shots, it's hard to know if a tree is really straight or not.

But with buildings and window frames, sometimes chairs or rectangular desks and tables, we assume they might be straight, and can often see the slight effects of barrel distortion.

A common explanation, usually from owners with a bunch of barrel distorted lenses, is that if you are going to shoot architecture, you shouldn't be using a rangefinder or cheap glass. But in the 21st century we live in, it's hard to find a lot of scenes without some known straight lines ...
funny thing is that some biogons such as the Zeiss ZM C Biogon 21 F4.5 or 35 F2 exhibit virtually zero distortion which is less than most other lenses.
  Reply With Quote

right
Old 02-18-2011   #32
ampguy
Registered User
 
ampguy's Avatar
 
ampguy is offline
Join Date: May 2006
Posts: 7,039
right

but those are costlier than say a cv 35/2.5 which has very low distortion, and don't have hipster qualities like the hexar af lens

Quote:
Originally Posted by tlitody View Post
funny thing is that some biogons such as the Zeiss ZM C Biogon 21 F4.5 or 35 F2 exhibit virtually zero distortion which is less than most other lenses.
__________________
My photo blog

  Reply With Quote

Old 02-18-2011   #33
MCTuomey
Registered User
 
MCTuomey's Avatar
 
MCTuomey is offline
Join Date: Nov 2004
Location: U.S.
Age: 62
Posts: 3,075
Quote:
Originally Posted by tlitody View Post
If your framing is correct you can't shift the lens without changing the framing. So what you are suggesting is taking a different picture without the distractions in it. But you can't have it both ways.
Yes crop out what you don't want. And a lot of photographers will put their tripod on top of their car to remove that close up foreground. And there are telescopic poles you can mount your camera on to get some height to give a better viewpoint. Or use a step ladder. Or yes you can buy a view camera if you want the additional level of difficulty. All I'm saying is that there is often a simpler way of resolving compositional problems which don't involve going to a view camera. Or you can just tilt the camera and enjoy the converging/diverging verticals for their effect.
I applied quotation marks to the term correct in my earlier post to indicate that, hypothetically, the framing wasn't actually correct but had problems needing correction. I should have been clearer, sorry.

I guess I think it's safer & simpler to carry a tilt-shift lens (or even a view camera) than resorting to telescopic poles, step ladders, upper floors in nearby buildings, stilts, stage heels, what-have-you. How do you fit that stuff in your domke anyway?

Anyway, imho, converging/diverging verticals and distortion can work really well - Helen's pics are wunnerful - but they aren't always pleasing.
__________________
--Mike (confirmed midget imagist on stilts)

Bill Pierce's "photographer's proposition": I saw something wonderful, let me show it to you.


Fuji X
Leica M
Canon EOS
Hasselblad 503CW
Minolta Autocord


My Flickr
  Reply With Quote

Old 02-18-2011   #34
PKR
Registered User
 
PKR is offline
Join Date: Jul 2010
Posts: 1,373
This is what I use when necessary.
http://www.kirkphoto.com/Bubble_Level.html

pkr
  Reply With Quote

Old 02-18-2011   #35
tlitody
Registered User
 
tlitody is offline
Join Date: May 2010
Location: Sceptred Isle
Posts: 1,773
Quote:
Originally Posted by MCTuomey View Post
I guess I think it's safer & simpler to carry a tilt-shift lens (or even a view camera) than resorting to telescopic poles, step ladders, upper floors in nearby buildings, stilts, stage heels, what-have-you. How do you fit that stuff in your domke anyway?
A tilt shift lens is an easy option for 35mm photography like tilting the camera up or down is. A view camera is not an easy option and requires a whole new system with lenses, a means to develop and scan/print.
Then if you have ever looked at the MTF charts for lens you find that distortion kicks in the further from the lens axis you move meaning there is usually very limited shift without distortion unless you have long focal length lenses with much bigger image circles than your film format. But that means longer focal lengths which means being further from sibject which introduces more foreground which can be problematic. And shift introduces abberations such as coma. With a TS lens for a 35mm camera how much shift do you get without introducing distortion. The (now old) contax 35mm F2.8 shift lens gave 2% distortion in the corners before any shift. I suspect the even shorter lenses available give even more. So use your TS lens to stop converging / diveging verticals but introduce more distortion.
I still say the optimum is to place yourself in the optimum position with a distortion free lens. But that is for absolute optimum which architectural photographers may want. Most of us don't need that level of correction as no one really worries about a tad of distortion or converging verticals unless it contains people/faces.

p.s. It's all fairly academic now that you can easily correct distortion and perspective digitally. Only if you are wet printing does it still bear some consideration.

Last edited by tlitody : 02-18-2011 at 21:29.
  Reply With Quote

Old 02-19-2011   #36
wjlapier
Registered User
 
wjlapier's Avatar
 
wjlapier is offline
Join Date: Jan 2008
Posts: 1,263
Quote:
Originally Posted by PKR View Post
This is what I use when necessary.
http://www.kirkphoto.com/Bubble_Level.html

pkr
I have one of those but wouldn't think to use it on a RFer. Though, I have to admit I did mount it next to the 21/25 VFer on my IF. But didn't go out shooting with it.
  Reply With Quote

Old 02-19-2011   #37
Rob-F
My Avatar Is Missing
 
Rob-F is offline
Join Date: Mar 2007
Location: The Show Me state
Age: 75
Posts: 4,400
Quote:
Originally Posted by ampguy View Post
What I've found is that in nature, it's pretty easy to compose with the CV 21/4, (and, while harder, even the CV 15/4.5) even though some of the distortions mentioned are still present, if you compared with say a 35 cron asph or good 50 on a tripod. The photos can still look pleasing:



But, with square and rectangular architecture, with wider than some 35s, you sometimes have to pick 2 or 3 sides of the square or rectangle, that you wish to be parallel with your frameline edges. For this image, I bracketed, but ended up liking the street, and sky, and right hand side parallel to the print edges, while the left edge of the subject building is converging. I have other images that retained the left side's known vertical perspective, but at the expense of skewing the top, bottom, or right:



The CV lenses do have a bit of barrel distortion, noticeable at the edges, but not severe, and most lenses in the price range would exhibit the same, with the exceptions of some older '70s SLR glass that is not available anymore, and much larger in size.
Ampguy: I wanted to show a method of fixing this problem that I use frequently. I use the perspective correction feature of Photoshop Elements. I'm using PSE 6 currently, since it runs on the iMac.

To do this, I first brought the picture into PSE 6. Then I clicked "new layer from background." Next, I used the perspective feature to widen out the top of the building, straightening the verticals in the process. I rotated the picture slightly clockwise, as the camera was not quite level. Finally, I used the clone stamp to fix blank areas that were created by the rotation.

I'm a stickler for correct verticals, so I also use 28mm and 35mm PC lenses on film and digital Nikons.

Another good trick is to use a wider lens, and hold it in portrait position so as to be able to include the top of the building, while keeping the back (film or sensor plane) vertical. Then you can either crop out the excess foreground, or keep it if it is interesting. I'm finding that a photo of a tall structure often needs some extra foreground; it seems to visually "balance" the height of the building. (This might just be me, though.)

I had to reduce the file size to make it upload, so it will not really be useable to print, but I hope it's good enough to show the basic idea.

Hope this gives you a useful idea or two.

Best, Rob
Attached Images
File Type: jpg Ted's picture corrected.jpg (47.3 KB, 7 views)
__________________
May the light be with you.
-----------------------------------------------------
How could my avatar have just disappeared?
  Reply With Quote

Old 02-19-2011   #38
ferider
Registered User
 
ferider's Avatar
 
ferider is online now
Join Date: May 2005
Posts: 10,889
Quote:
Originally Posted by wjlapier View Post
Something I never really paid much attention too, until I saw it in some of my pictures. Distortion. I'll include two pics below, but I'm now curious and wondering about something. Do all 21mm lenses display this much distortion? I don't shoot this wide usually. Any other 21's better at handling distortion? BTW, lens is CV 21/4 LTM. I was using my IF with CV 21/25 finder.
You can test for optical/rectilinear distortion by overlaying straight lines in PS. Like this:



Basically, in your pics, there is none. You don't need another lens

Roland.
  Reply With Quote

Old 02-19-2011   #39
ferider
Registered User
 
ferider's Avatar
 
ferider is online now
Join Date: May 2005
Posts: 10,889
Here is an example of barrel distortion (Summilux 50/1.4 v2):



Easy to correct in PS though:

  Reply With Quote

Old 02-19-2011   #40
ferider
Registered User
 
ferider's Avatar
 
ferider is online now
Join Date: May 2005
Posts: 10,889
Here you see what Roger calls "true wide-angle distortion" (using a 15mm, a fairly rectilinear lens).



Look at the guy on the right (my father in law). This photo made me stop using anything wider than 28.

Roland.
  Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -8. The time now is 10:07.


vBulletin skin developed by: eXtremepixels
Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2016, Jelsoft Enterprises Ltd.

All content on this site is Copyright Protected and owned by its respective owner. You may link to content on this site but you may not reproduce any of it in whole or part without written consent from its owner.