15 Replies Latest reply on Dec 8, 2011 7:37 PM by Jeff Schewe

    Camera Raw 6.5 - Lens Corrections

    M_L_R Level 1

      Hello: I know a 50mm lens is more commonly used for portrait shots but I like that I can be "POSITIONED CLOSER" to the subject when using a 35mm lens. Camera Raw 6.5 >Lens Corrections >Profile Make and Model and Profile, recognizes both of my lenses. My question is . . . can Camera Raw 6.5 "PROFESSIONALLY" eliminate the "distortion advantage" a 50mm lens has over a 35mm lens or am I still better off using the 50mm lens ? Thank-you, MLR

        • 1. Re: Camera Raw 6.5 - Lens Corrections
          Jeff Schewe Level 5

          M_L_R wrote:

           

          . . . can Camera Raw 6.5 "PROFESSIONALLY" eliminate the "distortion advantage" a 50mm lens has over a 35mm lens or am I still better off using the 50mm lens ?

           

          No...you are confusing lens distortion with the difference in perspective in a normal vs wide lens. The lens corrections fix spherical distortion, lateral chromatic aberration and lens vignetting. It has nothing to do with a wide angle perspective corruption.

          1 person found this helpful
          • 2. Re: Camera Raw 6.5 - Lens Corrections
            M_L_R Level 1

            Hello Jeff: Thank-you for your answer. To make sure I correctly perceived your answer, are you stating ? . . . "I'm better off using the 50mm lens because there will be less distortion, than if the 35mm lens is used, because, Camera Raw 6.5 can not correct this kind of distortion (barreling)". Thank-you, MLR

            • 3. Re: Camera Raw 6.5 - Lens Corrections
              Jeff Schewe Level 5

              I'm saying the lens correction tool in ACR has zero to do with the perspective of a lens...

              • 4. Re: Camera Raw 6.5 - Lens Corrections
                M_L_R Level 1

                Hello Jeff: I apologize, but . . . 1) I am under the impression that "Lens Corrections" attempts to remove the overall barreling (bulging) created by a lens. Am I wrong ? 2) "Lens Corrections" will need to un-distort (un-bulge) a 35mm lens picture more than a 50mm lens picture. Am I wrong ? I don't mind being wrong. I want to determine if I unclearly asked the original question or if I misinterpreted what "Lens Corrections" attempts to do. Also, My question does not concern the content the camera sees with either lens. Thank-you, MLR

                • 5. Re: Camera Raw 6.5 - Lens Corrections
                  Level 4

                  While I would never presume to speak for guru Schewe, perhaps I can offer a couple of comments that may aid communication here:

                   

                  1.— The perspective of a lens dictated by its focal length is not distortion in the sense of what is corrected by the ACR Lens Correction Tool—and that's what Jeff Schewe has been telling you;

                   

                  2.— Pin-cushion distortion and/or barrel distortion depend on the quality, optical design and construction of a lens; they do not necessarily or inherently have to be present in a lens and are not determined by the focal length of the lens alone.  Also, a zoom lens will in general be more prone to happen to have more barrel or pin-cushion distortion at any given focal length than a prime lens (i.e. a single-focal length lens) at the same focal length.

                   

                  If focal length were the determining factor for the (pin-cushion or barrel) distortion of a lens, there would be no need to have different distortion profile for each lens, just one for every focal length in the abstract.

                   

                  Thus, from my perspective, your question is  not artfully phrased and contributes to miscommunication.

                   

                   

                  ____________

                  Wo Tai Lao Le

                  我太老了

                  • 6. Re: Camera Raw 6.5 - Lens Corrections
                    M_L_R Level 1

                    Hello Tai: Thank-you for your answer. I don't have the ability to properly phrase my original question and this string seems to be heading off in a different direction. I appreciate the time you and Jeff contributed. I'll close this string. Thanks again. MLR

                    • 7. Re: Camera Raw 6.5 - Lens Corrections
                      Level 4

                      M_L_R wrote:

                       

                      …I'll close this string…

                       

                      Sorry, you can't. 

                       

                      The forum doesn't have that functionality. 

                      • 8. Re: Camera Raw 6.5 - Lens Corrections
                        Rick McCleary Level 3

                        The OP seems to be confusing two concepts: perspective and angle of view.

                         

                        A lens does not have perspective.

                        Perspective is a function of the distance from viewer to subject.

                        Perspective is completely independent of lens, camera, or the clothes you're wearing; it's determined only by the point in space from which a subject is viewed.

                         

                        What a lens DOES have is an angle of view.

                        The shorter the focal length, the wider the angle of view.

                        The longer the focal length, the narrower the angle of view.

                         

                        From the same perspective (i.e., the same point in space), a 50mm lens and a 35mm lens will give geometrically identical renderings of your portrait subject. The only difference is that the face of the portrait projected onto the camera sensor by the 35mm lens will be smaller than the one projected by the 50mm lens.

                         

                        Conversely, to get the same face size on the image with both the 50mm lens and the 35mm lens, you've got to move closer to the subject with the 35. This changes your perspective. It is this change in perspective that creates the distortion you're thinking about. It's not a function of the lens, it's a function of your perspective on the scene.

                         

                        For good quality lenses, my guess is that the distortion correction applied by ACR to both of your lenses will result in identical, albeit different sized, images. At that point, you're just dealing with the number of pixels used to render the image. For the same crop, the 35mm will use fewer pixels because the image on the sensor is smaller.

                        • 9. Re: Camera Raw 6.5 - Lens Corrections
                          M_L_R Level 1

                          Hello Jeff: I appreciate your answer. My original question (I am intending to ask) has nothing to do with "perspective" or "angle of view" or "number of pixels" (I say this with respect) . . . My original question (I am intending to ask) concerns "lens distortion" only. I will again attempt to rephrase my original question. AFTER applying "Lens Corrections" (properly) to a picture shot by a 35mm lens and a picture shot by a 50mm lens, is the RESULTING quality of lens distortion (in the two pictures) the same ? Or, will a 50mm lens always have a noticeably less amount of lens distortion ?

                           

                          The following is information and not part of my question . . . I am deciding weather to purchase a "Canon f/1.4L 35mm" lens or "Canon f/1.2L 50mm" lens. My camera has a full sized sensor. Please read my original question at the top of this string.

                           

                          Thank-you MLR

                           

                          also in a post above, I wrote "I'll close this string". I meant I was considering my question "no longer a request", but I changed my mind.

                          • 10. Re: Camera Raw 6.5 - Lens Corrections
                            Rick McCleary Level 3

                            I have re-read your original post.

                             

                            In it you say:

                            "...I know a 50mm lens is more commonly used for portrait shots but I like that I can be "POSITIONED CLOSER" to the subject when using a 35mm lens..."

                             

                            Then you ask:

                            "...can Camera Raw 6.5 "PROFESSIONALLY" eliminate the "distortion advantage" a 50mm lens has over a 35mm lens or am I still better off using the 50mm lens?"

                             

                            I don't know what you mean by "distortion advantage". I'm taking a guess that you are referring to the "big nose" effect of sticking a lens too close to someone's face. Is that what you mean? If so, the short answer to your question is no.

                            1 person found this helpful
                            • 11. Re: Camera Raw 6.5 - Lens Corrections
                              M_L_R Level 1

                              Hello Rick: Sorry. In my last post I referred to you as Jeff (a previous responder). Yes, I was referring to the "big nose" effect. Your reply "no", answers my question. Thank-you very much. I will purchase the "Canon f/1.2L 50mm" lens (and choose higher "distortion quality" over "standing a little closer to the photo-shoot subject") Thanks again, MLR

                              • 12. Re: Camera Raw 6.5 - Lens Corrections
                                Bo LeBeau Level 4

                                I think you are going about this backwards.

                                You say you are trying to decide between a Canon f/1.4L 35 mm and a Canin f/1.2L 35 mm

                                 

                                You should be reading reviews on the web about these lenses. There is so much information regarding these lenses.

                                Some sites will do strict optical testing and report the results. Users will also report their experiences.

                                 

                                Just remember that even under strict quality controls there can be slight variances between lenses for the same batch.Good testing sites usually mention this.

                                WIth so many people being online around the world there will always be some people who hate the lens and others that love the exact same lens.

                                 

                                Just do some research (strict optical tests or user experiences or both) to help you decide.

                                After reading enough you should be able to get enough info to make a purchase decision that you will feel comfortable with.

                                 

                                In short, make the decision on the lenses as the actually are in the real world, rather than worrying about correcting any possible lens distortion by using Photoshop or whatever after the fact.

                                Good Luck!

                                • 13. Re: Camera Raw 6.5 - Lens Corrections
                                  Noel Carboni Level 7

                                  You really haven't given enough information for anyone to be able to advise you on specifics.  Nor can anyone make your decisions for you.  Only you can choose what you like best.

                                   

                                  Maybe you might want to rent each of the lenses you're considering buying and do some testing.  Then, once you've gotten a feel for how the images look, perspective-wise, buy the large aperture lens of your choice.

                                   

                                  It seems to me a bit silly to think about plunking down a grand on a lens without looking at pictures in the context of the work you want to do!

                                   

                                  -Noel

                                  • 14. Re: Camera Raw 6.5 - Lens Corrections
                                    M_L_R Level 1

                                    Hello Bo and Noel: Thank-you for you help.

                                    This forum post was the last piece if information I needed to complete my lens comparisons (at this point).

                                    I wanted to see if Camera Raw >Lens Corrections could influence my purchase decision.

                                     

                                    (above post) type error correction . . . "Canon f/1.4L 35mm" lens . . . "Canon f/1.2L 50mm" lens

                                     

                                    Thanks again, MLR

                                    • 15. Re: Camera Raw 6.5 - Lens Corrections
                                      Jeff Schewe Level 5

                                      Rick McCleary wrote:

                                       

                                      A lens does not have perspective.

                                      Perspective is a function of the distance from viewer to subject.

                                      Perspective is completely independent of lens, camera, or the clothes you're wearing; it's determined only by the point in space from which a subject is viewed.

                                       

                                      Perhaps technically correct but not practically relevent...

                                       

                                      While it's true that the "perspective" is dictated on the distance from camera to subject, in practical terms if you fill the frame with the exact same subject size, the viewpoint (and hence the "perspective") will be different...

                                       

                                      As a result a full frame face shot with a 35MM vs a 50MM lens will indeed have a different perspective. As indicated by the OP, a face will elongate with a full frame shot of a face taken with a 35MM lens vs a longer lens. This is the practical impact of focal length. The longer the lens the more confessed the perspective.

                                       

                                      And this has zero to do with "lens distortions" which are a technical defect  of the optical properties of a lens such as barrel distortion, CS and vignetting.

                                       

                                      The lens dictates the point of view of the image…a wide angle lens will have a forced perspective while a longer lens congresses the perspective. ACR can correct for barrel distortion, CS and vignetting but nothing relating to perspective.