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

"Who killed infinity focus"
Old 07-15-2014   #1
greyelm
Malcolm
 
greyelm's Avatar
 
greyelm is offline
Join Date: Feb 2010
Location: London, UK
Posts: 1,360
"Who killed infinity focus"

Here's an interesting article on infinity focus of modern lenses.


http://www.bhphotovideo.com/explora/...-focus?BI=4906
  Reply With Quote

Old 07-16-2014   #2
mfunnell
Shaken, so blurred
 
mfunnell's Avatar
 
mfunnell is offline
Join Date: Sep 2006
Location: Sydney, Australia
Posts: 2,460
Interesting reading. Thanks for posting the link.

...Miike
__________________
There is a very fine line between "hobby" and "mental illness." Dave Barry

My flickr photostream has day-to-day stuff and I've given up most everywhere else through lack of time or perhaps interest.
  Reply With Quote

Old 07-16-2014   #3
Tijmendal
Young photog
 
Tijmendal is offline
Join Date: Sep 2012
Location: Amsterdam, Netherlands
Age: 28
Posts: 506
I've wondered this in the past as well. Thanks for posting.
  Reply With Quote

Old 07-16-2014   #4
brbo
Registered User
 
brbo's Avatar
 
brbo is offline
Join Date: May 2011
Posts: 1,462
"One of the traditional hallmarks of a high-quality manual-focus lens was that the focus ring would stop precisely at the ∞ mark. This allowed photographers to set their lenses quickly so that everything past a known distance would be in focus. Photographers could do this on the run without looking at their lenses or doing hyper-focal calculations and adjustments."

Either me or author of this article don't quite understand 'infinity focus'...
__________________

  Reply With Quote

Old 07-16-2014   #5
uhoh7
Registered User
 
uhoh7 is offline
Join Date: Jan 2011
Posts: 2,810
"In optics and photography, infinity focus is the state where a lens or other optical system forms an image of an object an infinite distance away. This corresponds to the point of focus for parallel rays. The image is formed at the focal point of the lens.

In a simple, two lens system such as a refractor telescope, The object at infinity forms an image at the Focal Point of the objective lens, which is subsequently magnified by the eyepiece. The magnification is equal to the focal length of the objective lens divided by the focal length of the eyepiece. [1]"
wikipedia
  Reply With Quote

Old 07-16-2014   #6
Chris101
summicronia
 
Chris101's Avatar
 
Chris101 is offline
Join Date: Jun 2007
Location: Arizona
Posts: 4,365
An infinity focus stop only needs to be within the depth of focus of the largest aperture, as a matter of practical lens design.
  Reply With Quote

Old 07-16-2014   #7
Ko.Fe.
Kostya Fedot
 
Ko.Fe.'s Avatar
 
Ko.Fe. is offline
Join Date: Jul 2013
Location: MiltON.ONtario
Posts: 7,404
Quote:
Originally Posted by brbo View Post
"One of the traditional hallmarks of a high-quality manual-focus lens was that the focus ring would stop precisely at the ∞ mark. This allowed photographers to set their lenses quickly so that everything past a known distance would be in focus. Photographers could do this on the run without looking at their lenses or doing hyper-focal calculations and adjustments."

Either me or author of this article don't quite understand 'infinity focus'...
Wow, Thanks for saving my time from reading this nonsense.

My high-quality AF Canon L lenses wouldn't stop at infinity, but I feel it without looking at it.
And hyper-focal calculations has nothing to do with stop at infinity, but DoF, which you must look at.
This is the picture from B&H.
http://www.bhphotovideo.com/c/produc...mm_f_1_2L.html



And most of consumer grade DSLR(SLR) lenses do stop at infinity.

B&H dropped the plank so low with this one.
  Reply With Quote

Old 07-16-2014   #8
Roger Hicks
Registered User
 
Roger Hicks is offline
Join Date: Apr 2005
Location: Aquitaine
Posts: 23,947
Mostly twaddle. Then again, 1970s Vivitar "solid cats" focus "beyond" infinity to allow for thermal expansion: it can matter with very long focal lengths. Overall, with modern lenses, I can't help feeling "Serve you right for using autofocus".

Cheers,

R.
  Reply With Quote

Old 07-16-2014   #9
judsonzhao
Registered User
 
judsonzhao is offline
Join Date: Jul 2013
Posts: 267
I don't quite get the point of the article, probably I'm so mean, lol.
Are there anyone killing infinity focus? Has it been killed yet?
  Reply With Quote

Old 07-16-2014   #10
Ranchu
-
 
Ranchu is offline
Join Date: Sep 2009
Posts: 2,695
Good info, thank you.
  Reply With Quote

Old 07-16-2014   #11
JoeV
Thin Air, Bright Sun
 
JoeV's Avatar
 
JoeV is offline
Join Date: Sep 2006
Location: Albuquerque, NM, USA
Posts: 1,703
Well, there's no point in attempting to focus at infinity, because with the inverse-square law by the time light from infinity reaches your camera there's very little left with which to make an exposure.

~Joe
__________________
"If your eye is clear, your whole body will be full of light"

Inventor of the Light Pipe Array
My Blog
My latest book
  Reply With Quote

Old 07-18-2014   #12
David Hughes
David Hughes
 
David Hughes's Avatar
 
David Hughes is offline
Join Date: Dec 2007
Posts: 7,475
Quote:
Originally Posted by brbo View Post
"One of the traditional hallmarks of a high-quality manual-focus lens was that the focus ring would stop precisely at the ∞ mark. This allowed photographers to set their lenses quickly so that everything past a known distance would be in focus. Photographers could do this on the run without looking at their lenses or doing hyper-focal calculations and adjustments."

Either me or author of this article don't quite understand 'infinity focus'...
Add me to the list of doubters, please. This intro makes you suspect what follows.

Regards, David
  Reply With Quote

Old 07-23-2014   #13
cosmonaut
Registered User
 
cosmonaut's Avatar
 
cosmonaut is offline
Join Date: Nov 2006
Location: North Georgia
Posts: 1,207
Infinity died when Carl Sagan did.
__________________
Cosmo
  Reply With Quote

Old 03-12-2015   #14
kossi008
Photon Counter
 
kossi008's Avatar
 
kossi008 is offline
Join Date: May 2008
Location: Dresden, Germany
Age: 53
Posts: 927
Well they did not make their point very well, and they did not mention that you actually give half of your DOF away if you focus to infinity (instead of the hyperfocal distance).

But then, focusing to infiinity via hardstop is really the only thing to do if it's really dark and you cannot see the scale anymore.

This used to annoy me greatly when trying to do night shots with my Canon EOS gear (all of which has been sold in the meantime)... it would be too dark for the AF to find its mark, and I would not be able to focus manually either. Very frustrating. And yes, it did serve me right for using AF.
__________________
Photon Counter
My flickr: http://www.flickr.com/photos/[email protected]/
  Reply With Quote

Old 03-12-2015   #15
TXForester
Registered User
 
TXForester's Avatar
 
TXForester is offline
Join Date: Sep 2009
Location: Alba, Texas
Posts: 1,244
I'm more concerned about the other distance marks and aperture marks. If a lens doesn't have these, like many entry level lenses, then you have to measure the distance to the focal point, and consult a chart or app in you smart phone. Assuming you can do both. Old way gave you an aperture setting at approximately the DoF you want in seconds.
__________________
Bender: I support and oppose many things, but not strongly enough to pick up a pen.

Democracy is the art and science of running the circus from the monkey-cage.” ― H.L. Mencken
  Reply With Quote

Old 03-12-2015   #16
Huss
Registered User
 
Huss is offline
Join Date: Sep 2014
Location: Venice, CA
Posts: 7,701
I thought this was about infinity focus locks. Like on my Summicron V1.
  Reply With Quote

Old 03-12-2015   #17
John E Earley
Tuol Sleng S21-0174
 
John E Earley's Avatar
 
John E Earley is offline
Join Date: Jul 2012
Location: Virginia
Age: 72
Posts: 1,750
Quote:
Originally Posted by Roger Hicks View Post
Mostly twaddle. Then again, 1970s Vivitar "solid cats" focus "beyond" infinity to allow for thermal expansion: it can matter with very long focal lengths. Overall, with modern lenses, I can't help feeling "Serve you right for using autofocus".

Cheers,

R.
I use modern autofocus lenses half the time. Does that mean it serves me half right or half serves me right?
__________________
Creation stands with neck outstretched....
  Reply With Quote

Old 03-12-2015   #18
Samouraï
Registered User
 
Samouraï's Avatar
 
Samouraï is offline
Join Date: Jun 2011
Posts: 498
Quote:
Originally Posted by Ko.Fe. View Post
Wow, Thanks for saving my time from reading this nonsense.

My high-quality AF Canon L lenses wouldn't stop at infinity, but I feel it without looking at it.
And hyper-focal calculations has nothing to do with stop at infinity, but DoF, which you must look at.
This is the picture from B&H.
http://www.bhphotovideo.com/c/produc...mm_f_1_2L.html



And most of consumer grade DSLR(SLR) lenses do stop at infinity.

B&H dropped the plank so low with this one.
I used to have some Canon glass (including this one), and hitting infinity was always a pain. Not much of an issue in practice on a DSLR because I never shot manual (as I couldn't really gauge it without a split prism or a rangefinder).
  Reply With Quote

Old 03-12-2015   #19
mdarnton
Registered User
 
mdarnton is offline
Join Date: Mar 2008
Location: Chicago
Posts: 1,262
I sent a Nikon AI lens in for cleaning a couple of years ago and it came back focusing past infinity at the infinity setting. I called to complain, and the (Nikon authorized and trained) repair service put on the (Nikon trained) technician who explained that some AF systems won't give a green dot unless you go past the point of focus and back, which you can't at infinity if it stops there. He said the official word from Nikon was to set them to go past infinity for that reason, mainly, he thought, to keep people from complaining that they couldn't focus at infinity. :-)

He did set mine back to the way it was after I asked. My complaint was that I focus by scale quite often, and it didn't work to be setting seven feet and getting fifteen. He warned me, however, to specify what I wanted on future repairs, so it would come back right.
__________________
Thanks, but I'd rather just watch:
Mostly 35mm: http://www.flickr.com/photos/mdarnton
Large format: http://www.flickr.com/photos/michaeldarnton
What? You want digital, color, etc?: http://www.flickr.com/photos/stradofear
  Reply With Quote

Old 03-12-2015   #20
raid
Dad Photographer
 
raid's Avatar
 
raid is offline
Join Date: Nov 2005
Location: Florida
Posts: 30,762
I still have not accepted AF lenses. Manually focusing is more fun.
__________________
- Raid

________________


http://raid.smugmug.com/
  Reply With Quote

Old 03-13-2015   #21
ph.
Registered User
 
ph. is offline
Join Date: Sep 2014
Posts: 83
AND not to speak of the many inaccurate mount adapters which for wide-angles can make you wish for even greater inaccuracies. At least one maker sticks to actual mount dimensions. One whom one may perhaps not name or fall foul of advertising rules (new flexibility in English -slightly translated).

p.
  Reply With Quote

Old 03-13-2015   #22
charjohncarter
Registered User
 
charjohncarter's Avatar
 
charjohncarter is offline
Join Date: Dec 2006
Location: Danville, CA, USA
Posts: 8,775
Quote:
Originally Posted by TXForester View Post
I'm more concerned about the other distance marks and aperture marks. If a lens doesn't have these, like many entry level lenses, then you have to measure the distance to the focal point, and consult a chart or app in you smart phone. Assuming you can do both. Old way gave you an aperture setting at approximately the DoF you want in seconds.
Yeah, how do you set your flash strobe if the lens doesn't give you a proper distance.
  Reply With Quote

Old 03-20-2015   #23
1joel1
Registered User
 
1joel1's Avatar
 
1joel1 is offline
Join Date: Sep 2006
Location: San Diego, CA
Posts: 234
Part of the deal with the old FD mount "L" lenses was that they would focus past infinity to allow for thermal expansion of the fluorite elements.

Joel
  Reply With Quote

Old 03-20-2015   #24
TXForester
Registered User
 
TXForester's Avatar
 
TXForester is offline
Join Date: Sep 2009
Location: Alba, Texas
Posts: 1,244
Quote:
Originally Posted by charjohncarter View Post
Yeah, how do you set your flash strobe if the lens doesn't give you a proper distance.
Yep. Not like I carry a tape measure or a laser distance measurer in my pocket when I go out to take photos.

Why can't a modern digital have the ability to measure the focus distance, then put a screen up on the LCD that is a chart for aperture and DoF for that distance. Essentially doing what an app in your phone can do without the extra burden.

Alternatively you could have a program where you focus on the near side of the desired DoF, then focus on the far side of the DoF and the camera automatically calculates a focus distance and aperture that gives you what you want and sets both. You might have a third focus point for the subject to insure it is sharply focused.
__________________
Bender: I support and oppose many things, but not strongly enough to pick up a pen.

Democracy is the art and science of running the circus from the monkey-cage.” ― H.L. Mencken
  Reply With Quote

Old 03-21-2015   #25
dct
Registered User
 
dct's Avatar
 
dct is offline
Join Date: Jan 2011
Location: Zurich
Posts: 1,178
Quote:
Originally Posted by TXForester View Post
Yep. Not like I carry a tape measure or a laser distance measurer in my pocket when I go out to take photos.

Why can't a modern digital have the ability to measure the focus distance, then put a screen up on the LCD that is a chart for aperture and DoF for that distance. Essentially doing what an app in your phone can do without the extra burden.
Exactly this.
What I see in my Fuji X series is this approach, having a meter (or feet) bar with an in-focus-field depending on the aperture and a mark where the lens focus is actually set manually or by AF. I try to utilize it when I need true hyper focal focus, but also for zone focus of course.

The implementation in the Fujis is not bad, but for sure it could me optimized widely with the capability of personal configuration functionalities as your suggestion below.
Quote:
Originally Posted by TXForester View Post
Alternatively you could have a program where you focus on the near side of the desired DoF, then focus on the far side of the DoF and the camera automatically calculates a focus distance and aperture that gives you what you want and sets both. You might have a third focus point for the subject to insure it is sharply focused.
I would add the functionality of broadening and limiting the DoF area depending on the purpose of your image (print small, print big, for pixel peepers...) and the lens in use.

Would all of this solve the whole problem of infinity focus for AF lenses without mechanical coupling to the focus ring?
__________________
photos
RFF gallery
  Reply With Quote

Old 03-21-2015   #26
Sparrow
Registered User
 
Sparrow's Avatar
 
Sparrow is offline
Join Date: Feb 2006
Location: Perfidious Albion
Age: 67
Posts: 12,451
Quote:
Originally Posted by cosmonaut View Post
Infinity died when Carl Sagan did.
with ... Buzz Lightyear, surely
__________________
Regards Stewart

Stewart McBride

RIP 2015



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

flickr stuff
  Reply With Quote

Old 03-21-2015   #27
Ronald M
Registered User
 
Ronald M is offline
Join Date: Aug 2005
Posts: 4,513
Quote:
Originally Posted by Roger Hicks View Post
Mostly twaddle. Then again, 1970s Vivitar "solid cats" focus "beyond" infinity to allow for thermal expansion: it can matter with very long focal lengths. Overall, with modern lenses, I can't help feeling "Serve you right for using autofocus".

Cheers,

R.
Because it is very helpful in fast moving situations. Unfortunately they have ruined the lenses for the more useful manual focus.
  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 06:18.


vBulletin skin developed by: eXtremepixels
Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2019, 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.