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How to Calibrate Your Zoom Lens To Capture What Your Eyes See

calibrate-1.jpgOne of my favorite lenses for journalism and street photography is the wide to telephoto zoom. Now we can shoot everything from landscapes to portraits with just one lens. However, there are times when you need a prime “normal” lens to capture exactly what your eyes are seeing. Most of us can adjust our zooms to approximate what were seeing but it usually leads to a less than desirable result.

We know that most modern cameras get the focal length from the electronics within the lens, however, most cameras do not display this information until after the shot. We also know that all lens manufacturers display some type of focal length information marked on the zoom ring. Most of these markings are only approximations of the true focal length and do not take into account the crop-factor of dx type sensors. So how can we be sure our lens is set to a “normal” focal length?

An easy solution is to calibrate your lens to your eye. You are probably thinking, “How is this possible”. We can do so using the same method we use to focus your fathers trusty pair of binoculars.

callibrate-2.jpgCalibrating your lens is simple. First, find a suitable static target to focus on. With both eyes open, adjust your camera so that one eye is looking through the viewfinder. Focus your lens at your target as you normally would.

Now, with both eyes open and focused on your target, slowly rotate your zoom ring until your image is sharp and your eyes no longer feel strained. Refocus your lens if necessary and repeat the procedure. You will get to a magic point where your focus and depth perception are “normal”.

At this point, you should be able to remove and replace your camera from your eye with no apparent change in your target. Your lens is now calibrated to your eye. You can optionally create a small mark on your zoom ring that corresponds to the mark on the body. Later on, when you need a “normal” lens, just rotate your zoom ring to that mark, and voila.

Gary C. Millwater has been a freelance photographer since 1976. Originally from New Jersey, he has traveled all around North America, Mexico, and the Bahamas looking for that next great shot. After moving to Florida in 1987, he was forced to trade in his lenses for a “real job”. He now shoots just for the fun of it. His non-published work can be seen at millwater-photography.com

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  • http://silverhalide.zenfolio.com Silverhalide

    I’ve had this thought too in the past, but I don’t think it works quite as described.

    Consider a Canon 1DsIII with a .78x viewfinder magnification, compared to a Canon 5DII with .71 viewfinder magnification. The 5D will need to zoom in closer to get an view in the viewfinder that matches what is seen with the naked eye, so the recorded image will be different. However, if we’re looking for something that matches what we see, given that they are both “full frame” cameras, we’d expect the same recorded image in both cases.

    Your process describes how to match the naked eye to the view in the viewfinder, but has nothing to do with matching the naked eye to the resultant image. I suspect, although I am not sure, matching to the resultant image would also involve how large the print is and distance from camera to subject and viewer to print, and several other factors.

    Also, your statement “Most of these markings …do not take into account the crop-factor of dx type sensors” is incorrect. Focal lengths are focal lengths and have nothing to do with crop. The focal length of a lens doesn’t change when you put it on a different camera. What does change is the apparent magnification of the image.

  • http://www.lightstalking.com Light Stalking

    Thanks for the wrap up, but I’d be interested to hear the author’s response to Silverhalide.

  • Mikel

    Wait…what? I’m not sure what this post is saying other than how to manually focus a lens…

  • http://blog.dcclark.net/ dcclark

    It’s not how to manually focus a lens — it’s how to adjust your zoom level to “normal”. But honestly, it’s really simple:

    1. Look at an object.
    2. Look at the same object through the viewfinder.
    3. Zoom until the object in the viewfinder looks like the object as you saw it with your own eyes.

    Alternative to step 3: Zoom until the object looks like you want it to look in a photo — whether wide, close, or “normal”.

    For reference, in 35mm film terms, a 50mm focal length is “normal”, meaning it has the same field of view as human eyes. On Nikon DX cameras, this is about 35mm. On Canon 1.6x crop cameras, this is about 30mm.

  • http://tianchad.blogspot.com Tian Chad

    This is a great tips and really useful for me :) Thanks~

  • PRH

    I’m not sure that field of view is correct because even full frame sensor/35mm film is a cropped version of what the human eye sees.

    I’ve always taken the “normal- as the human eye sees” to mean perspective. ie at wide angle the distances between objects appear greater than real life while telephoto everything appears stacked together.

    I’m probably wrong but I would have thought that 50mm would be “normal” on most dslr’s regardless of the crop factor. The distance between the sensor and the lens is basically the same as the 35mm film days. Someone with a knowledge of the physics of light might be able to either correct me or explain it better.

  • PRH

    Great tutorial by the way, I just tried it with my 18-55mm kit lens.

  • PJG

    I have to agree with dcclark above. The 50-55mm range will be “normal” for any lens. What the “sensor” sees brings into play the 1.6x factor (APS-C) as with my Canon 400D and 18-55mm lens. What the sensor sees absolutely must include the x factor and in those terms, normal is around 30mm. The 18-55mm lens is stated (at 55mm) to be moderate telephoto range of about 85mm in standard 35mm jargon. Only with a full-frame sensor can this process be used to approximate “normal”…I hope no one is totally confused now.

  • migs

    Before I was having trouble manually focusing the lens, thanks to this essay I know what to do now .

  • Richard Skoonberg

    I am curious to find out if what is normal is the same for everyone… I did this with DSLR and its APS sensor and my “normal” was 5omm which is about 70 mm when converted to 35mm format.. That seems long for “normal.”

  • C

    I also got 50mm on a 40D as “normal,” which translates to 80mm.

  • http://www.flickr.com/fababas fbo

    I think that perspective and field of view are 2 different things. The sensor size will affect the field of view, with the crop factor. The perspective is left intact, as far as I see it. Therefore, I would suppose that everybody should be getting results around 50mm regardless of sensor size.
    I just tried it with my 40D and it came around 55mm.

  • http://www.indiecentmusic.com Lirou

    That doesn’t work at all. I got 70mm as normal on a 18-135mm lens and a DX body. And I know by experience that normal is around 35mm on a DX.

    This may work if the viewfinder has no magnification. But that is not the case for most cameras.

  • http://www.millwater-photography.com Author

    Actually I’m not surprised that the responses to this article are way too analytical. The premise of the article was to give the user a way to capture an image close to what they are seeing, before they take their shot. Indeed, when we concentrate on something we humans tend to have tunnel vision. If that were to equate to a focal length, I would have to agree on the 70mm range. If we were to relax our vision our fov or aov would be much greater, probably around the “normal” range of around 43.3mm. However, the only way to know for sure would be to take an image after the calibration, enlarge it to life size, then compare that image side-by-side with the subject. But for those it may have helped for whatever reason, your welcome. That’s the whole point of this website…to share anything that may help others in their photographic endeavors. If optical physics is what your after, then there are websites for that too.

  • http://flickr.com/fredshome Fredshome

    My zoom lens is a 200-500 you insensitive clod !

    Apart from that, that’s one way to set the dioptric setting in the visor.

    OTOH, I don’t really see what the point is in geting the camera to see what the eye sees. I might be atypical but I can’t recall ever wanting to use any one of my cameras that way. I use them to capture something specific.

    Oh, and it seems to me that with APS sensors, the “magic number” is closer to 35-40mm than to 50.

  • http://www.tonyadoughty.com tonya

    Don’t know if this is the same thing, but this is also how I shoot fast moving sports (volleyball, hockey, soccer). I keep both eyes open, with my field of view calibrated to what I actually see (as described above) and then I can follow the action as its happening and I know before something enters the frame that it is about to. Much less panning around (“follow the ball”) this way. My “outside” eye sees everything happening outside the frame and as it transitions into the frame my “inside” eye (the TTL eye, if you will) picks it up. As the author describes above: “At this point, you should be able to remove and replace your camera from your eye with no apparent change in your target.” I know I have it exaclty right when I no longer feel like I am looking through a camera but that I am just watching the game. It kinda feels like being “in the zone” and I get the best photos in those moments.

  • http://www.millwater-photography.com Author

    Tonya, it seems as though were on the same page. Someone finally got it… Like you, I’ve been using this routine for years shooting motor sports, cycling, and recently, extreme sports. Perhaps others will catch on and find this procedure useful.

  • iamunique127

    Mr. Millwater
    I have often thought about this and wasn’t aware of this quick and easy way to find the “normal” view. I have just used the zoom calibration of around 35mm. This works with any zoom in the “normal” range and with any camera. Thanks for the informative post.

  • Silverhalide

    Without getting into whether it’s useful to match what you see in the viewfinder with what you see with the naked eye, I thought I’d mention that dpreview has an interesting blog entry on normal lenses which touches on some of the issues discussed here such as whether normal lenses match viewing angle, and how viewing distance is related.

    http://blog.dpreview.com/editorial/2009/03/what-is-a-standard-lens.html

  • Fernando Tavares

    I’m late but this website is huge.
    Ok Gary, your article is perfect. To match the two views, we have to do it like you said. There is no other way.
    I’m a photographer but also a tv cameraman. Tv Lenses have big zoom ratios, 14x, 16x, 20. When i want to put on screen the same “perspective” relation of size distance, etc, of objects, I use this technic. People have to understand, that there are two different things we are talking about here. One is the relation between objects ( the notion we get of the distance between two trees distant apart 50 meters in our line of view, when we use a 50mm or a 300 mm, is huge – mostly the concept of perspective for photography). The other thing is how wide we can see without moving our eyes. I, have an angle of peripheral view, with detail, of about 120º horizontal. With no detail but still can see you move, 175º. Used to be 190 on my 20′s I’m 50 now). Meaning, I can see more wide than my canon 15mmf2.8 fish eye. But if i take picture with it, the relation of things in distance is diferent from how I see it.( strait line in front, not the optical distortion).
    This means, that to have the same notion of reality of my eyes, i use the two eyes method, to try to see as wide as my vision, i use a wide angle.

    Just one thing more, for those who didn’t understood it, this is not a technic to manually focus a lens.
    For that, you can do two things, first, just do it, manually. Second, also with auto focus of, press halfway, and rotate the focus ring at the same time. When your active focus square sensor( the one that illuminates red) lights, the object is in focus. This is a technic widely used by pros. And it is explaned in some user manuals of some cameras.

    BR
    Fernando

  • Emily

    This question is a bit off subject, but would you call the shots of yourself holding up a camera that covers one eye? i have been trying to find a term for these types of photos. im not talking about the silly teen girl shots in the mirror, but the ones that really artistic people take of themselves with one eye open and one eye covered with the camera. just like the photos in this article. if someone would help me out on this it would be soooo appreciated!
    thanks!

  • french71oz

    Better late than never!

    Being a serious amateur in photography, I was very interested by your informative post and after some difficulties to work it out, I finally understood and it worked well.
    Having my right eye feeling very stressed and sore after a session of shooting, I was always wandering how to avoid more damages to it, wearing glasses or without them, you have got me the very simple way to save it. My eye specialist only advised me to change eye when I am photographing, but I was not satisfied with this alternative.

    Very good info post, simple but effective solution indeed and thank you very much, you have saved me from stopping photography as an activity in my retirement days.

  • John Madden

    Gary,

    Cool tip…Nice article…

    I just tried this while reading the article on my flat screen tv. It’s kind of like focusing rangefinder with a split focus viewfinder. If you frame part of the tv (or any line for that matter) off the viewfinder when you hit the sweet spot the top and bottom of the screen make a perfect line with both eyes open. Allows binocular vision while shooting.

    Mine is at 62mm (just checked the exif data).

    What I think is really cool about this is that allows a completely different view when composing because with both eyes open you can view the entire scene with the viewfinder appearing as an overlay.

  • http://www.fotocomefare.com Alberto

    I’m really curious about how viewfinder maginfication affects this test.
    I tried it and found out that the best focal lenght for me was somewhat over 50mm on a D3000 (1.5 crop factor). Maybe my vision is too tunnelled.
    However I often noticed that my shots look a little different of what I saw in the viewfinder. So, how does my camera’s 0.8x viewfinder magnificaiton affect this test?

  • Fernando T

    Alberto, the crop factor is just that, it has nothing to do with lenses but with Sensor size. The optics function the same way, the show the same thing, your smaller sensor(also your mirrow) lets you see less.
    The body you are using does not afect that.
    Prespective, compression efect of zooming, everithing is just the same.

    Hasselblad has masks to put over the glass, to conform your view in the viwefinder with the magazine you’re using (in film versions).

    Probably, the diference you notice in your pictures from what you see in the viewfinder, is because this one only shows 96% or so of the real frame.Look for this percentage in camera specs.

    For me is about 60 something mm. It tends to change slightly, with lenses special zooms, because of different elements number and groups in its construction.
    If you compare what you can see, lets say, at 50mm on a 35/70, on a 28/70, a 28/105, and a 50mm, there is a little difference in angle in all of them.
    keep shooting,

  • http://www.fotocomefare.com Alberto

    @fernando t, thank you for your answer. Crop factor for me is not a problem, I was wondering if I have to apply viewfinder magnification to this test results.
    I mean, after I determined that 50mm is the focal length closest to how my eyes see, should I multiply it for the viewfinder magnification, in order to have shots close to how my eyes see?

  • Fernando T

    Alberto,
    I think, that after we find the most similar angle, everything else is just talk about nothing.
    I think this because the moment we frame a scene, it no longer is surrounded by all we left out side the frame.
    So, it is now another thing, another view, and e can not compare it with the all place where it was located.
    Its like compare the clay mine with the final handmade pot.
    This is also why two photographers at the same spot just don’t make the same final picture.
    One example I usually give at my classes – I measure 1m64cm 6,38ft. When I first set my tripod, it is also based and conditioned by this factor. Even if I change it later(almost every time).
    You for sure have a starting point different from mine.
    Our ALL entire lives are lived from two different points of view. This simple.

    Well. at a coffe table we could continue this. But I’m in Cape Verde.

  • http://www.fotocomefare.com Alberto

    Fernando, you are completely right.
    For me, the best focal lengths are probably all above 100mm. What is important is the final image and if it works as you wished.
    However, I think every site I read suggests a 35mm lens as a normal lens on a cropped sensor and I really don’t get how they can do this while for my eye 35 always seemed too low and thanks to the method in this article I confirmed that.

  • Barry E.Warren

    Using a 18-55 mm lens on a Nikon D5000, it seems to me that 55mm is at the normal. I didn’t try my other lens but it most likely will remain at 55mm.

  • OK69foto

    Sound good … I try this in my future photo shooting in street! Thanks for ideea!

Some older comments

  • Barry E.Warren

    September 12, 2011 02:01 am

    Using a 18-55 mm lens on a Nikon D5000, it seems to me that 55mm is at the normal. I didn't try my other lens but it most likely will remain at 55mm.

  • Alberto

    September 10, 2011 12:26 am

    Fernando, you are completely right.
    For me, the best focal lengths are probably all above 100mm. What is important is the final image and if it works as you wished.
    However, I think every site I read suggests a 35mm lens as a normal lens on a cropped sensor and I really don't get how they can do this while for my eye 35 always seemed too low and thanks to the method in this article I confirmed that.

  • Fernando T

    September 10, 2011 12:15 am

    Alberto,
    I think, that after we find the most similar angle, everything else is just talk about nothing.
    I think this because the moment we frame a scene, it no longer is surrounded by all we left out side the frame.
    So, it is now another thing, another view, and e can not compare it with the all place where it was located.
    Its like compare the clay mine with the final handmade pot.
    This is also why two photographers at the same spot just don't make the same final picture.
    One example I usually give at my classes - I measure 1m64cm 6,38ft. When I first set my tripod, it is also based and conditioned by this factor. Even if I change it later(almost every time).
    You for sure have a starting point different from mine.
    Our ALL entire lives are lived from two different points of view. This simple.

    Well. at a coffe table we could continue this. But I'm in Cape Verde.

  • Alberto

    September 9, 2011 07:56 pm

    @fernando t, thank you for your answer. Crop factor for me is not a problem, I was wondering if I have to apply viewfinder magnification to this test results.
    I mean, after I determined that 50mm is the focal length closest to how my eyes see, should I multiply it for the viewfinder magnification, in order to have shots close to how my eyes see?

  • Fernando T

    September 9, 2011 03:23 am

    Alberto, the crop factor is just that, it has nothing to do with lenses but with Sensor size. The optics function the same way, the show the same thing, your smaller sensor(also your mirrow) lets you see less.
    The body you are using does not afect that.
    Prespective, compression efect of zooming, everithing is just the same.

    Hasselblad has masks to put over the glass, to conform your view in the viwefinder with the magazine you're using (in film versions).

    Probably, the diference you notice in your pictures from what you see in the viewfinder, is because this one only shows 96% or so of the real frame.Look for this percentage in camera specs.

    For me is about 60 something mm. It tends to change slightly, with lenses special zooms, because of different elements number and groups in its construction.
    If you compare what you can see, lets say, at 50mm on a 35/70, on a 28/70, a 28/105, and a 50mm, there is a little difference in angle in all of them.
    keep shooting,

  • Alberto

    September 8, 2011 10:57 pm

    I'm really curious about how viewfinder maginfication affects this test.
    I tried it and found out that the best focal lenght for me was somewhat over 50mm on a D3000 (1.5 crop factor). Maybe my vision is too tunnelled.
    However I often noticed that my shots look a little different of what I saw in the viewfinder. So, how does my camera's 0.8x viewfinder magnificaiton affect this test?

  • John Madden

    September 5, 2011 02:00 am

    Gary,

    Cool tip...Nice article...

    I just tried this while reading the article on my flat screen tv. It's kind of like focusing rangefinder with a split focus viewfinder. If you frame part of the tv (or any line for that matter) off the viewfinder when you hit the sweet spot the top and bottom of the screen make a perfect line with both eyes open. Allows binocular vision while shooting.

    Mine is at 62mm (just checked the exif data).

    What I think is really cool about this is that allows a completely different view when composing because with both eyes open you can view the entire scene with the viewfinder appearing as an overlay.

  • french71oz

    September 3, 2011 12:34 pm

    Better late than never!

    Being a serious amateur in photography, I was very interested by your informative post and after some difficulties to work it out, I finally understood and it worked well.
    Having my right eye feeling very stressed and sore after a session of shooting, I was always wandering how to avoid more damages to it, wearing glasses or without them, you have got me the very simple way to save it. My eye specialist only advised me to change eye when I am photographing, but I was not satisfied with this alternative.

    Very good info post, simple but effective solution indeed and thank you very much, you have saved me from stopping photography as an activity in my retirement days.

  • Emily

    August 12, 2010 01:51 am

    This question is a bit off subject, but would you call the shots of yourself holding up a camera that covers one eye? i have been trying to find a term for these types of photos. im not talking about the silly teen girl shots in the mirror, but the ones that really artistic people take of themselves with one eye open and one eye covered with the camera. just like the photos in this article. if someone would help me out on this it would be soooo appreciated!
    thanks!

  • Fernando Tavares

    August 12, 2009 10:04 pm

    I'm late but this website is huge.
    Ok Gary, your article is perfect. To match the two views, we have to do it like you said. There is no other way.
    I'm a photographer but also a tv cameraman. Tv Lenses have big zoom ratios, 14x, 16x, 20. When i want to put on screen the same "perspective" relation of size distance, etc, of objects, I use this technic. People have to understand, that there are two different things we are talking about here. One is the relation between objects ( the notion we get of the distance between two trees distant apart 50 meters in our line of view, when we use a 50mm or a 300 mm, is huge - mostly the concept of perspective for photography). The other thing is how wide we can see without moving our eyes. I, have an angle of peripheral view, with detail, of about 120º horizontal. With no detail but still can see you move, 175º. Used to be 190 on my 20's I'm 50 now). Meaning, I can see more wide than my canon 15mmf2.8 fish eye. But if i take picture with it, the relation of things in distance is diferent from how I see it.( strait line in front, not the optical distortion).
    This means, that to have the same notion of reality of my eyes, i use the two eyes method, to try to see as wide as my vision, i use a wide angle.

    Just one thing more, for those who didn't understood it, this is not a technic to manually focus a lens.
    For that, you can do two things, first, just do it, manually. Second, also with auto focus of, press halfway, and rotate the focus ring at the same time. When your active focus square sensor( the one that illuminates red) lights, the object is in focus. This is a technic widely used by pros. And it is explaned in some user manuals of some cameras.

    BR
    Fernando

  • Silverhalide

    March 22, 2009 02:10 pm

    Without getting into whether it's useful to match what you see in the viewfinder with what you see with the naked eye, I thought I'd mention that dpreview has an interesting blog entry on normal lenses which touches on some of the issues discussed here such as whether normal lenses match viewing angle, and how viewing distance is related.

    http://blog.dpreview.com/editorial/2009/03/what-is-a-standard-lens.html

  • iamunique127

    March 17, 2009 09:49 pm

    Mr. Millwater
    I have often thought about this and wasn't aware of this quick and easy way to find the "normal" view. I have just used the zoom calibration of around 35mm. This works with any zoom in the "normal" range and with any camera. Thanks for the informative post.

  • Author

    March 13, 2009 01:43 pm

    Tonya, it seems as though were on the same page. Someone finally got it... Like you, I've been using this routine for years shooting motor sports, cycling, and recently, extreme sports. Perhaps others will catch on and find this procedure useful.

  • tonya

    March 13, 2009 02:00 am

    Don't know if this is the same thing, but this is also how I shoot fast moving sports (volleyball, hockey, soccer). I keep both eyes open, with my field of view calibrated to what I actually see (as described above) and then I can follow the action as its happening and I know before something enters the frame that it is about to. Much less panning around ("follow the ball") this way. My "outside" eye sees everything happening outside the frame and as it transitions into the frame my "inside" eye (the TTL eye, if you will) picks it up. As the author describes above: "At this point, you should be able to remove and replace your camera from your eye with no apparent change in your target." I know I have it exaclty right when I no longer feel like I am looking through a camera but that I am just watching the game. It kinda feels like being "in the zone" and I get the best photos in those moments.

  • Fredshome

    March 13, 2009 01:11 am

    My zoom lens is a 200-500 you insensitive clod !

    Apart from that, that's one way to set the dioptric setting in the visor.

    OTOH, I don't really see what the point is in geting the camera to see what the eye sees. I might be atypical but I can't recall ever wanting to use any one of my cameras that way. I use them to capture something specific.

    Oh, and it seems to me that with APS sensors, the "magic number" is closer to 35-40mm than to 50.

  • Author

    March 11, 2009 08:20 am

    Actually I'm not surprised that the responses to this article are way too analytical. The premise of the article was to give the user a way to capture an image close to what they are seeing, before they take their shot. Indeed, when we concentrate on something we humans tend to have tunnel vision. If that were to equate to a focal length, I would have to agree on the 70mm range. If we were to relax our vision our fov or aov would be much greater, probably around the "normal" range of around 43.3mm. However, the only way to know for sure would be to take an image after the calibration, enlarge it to life size, then compare that image side-by-side with the subject. But for those it may have helped for whatever reason, your welcome. That's the whole point of this website...to share anything that may help others in their photographic endeavors. If optical physics is what your after, then there are websites for that too.

  • Lirou

    March 10, 2009 01:06 pm

    That doesn't work at all. I got 70mm as normal on a 18-135mm lens and a DX body. And I know by experience that normal is around 35mm on a DX.

    This may work if the viewfinder has no magnification. But that is not the case for most cameras.

  • fbo

    March 10, 2009 06:45 am

    I think that perspective and field of view are 2 different things. The sensor size will affect the field of view, with the crop factor. The perspective is left intact, as far as I see it. Therefore, I would suppose that everybody should be getting results around 50mm regardless of sensor size.
    I just tried it with my 40D and it came around 55mm.

  • C

    March 9, 2009 03:30 am

    I also got 50mm on a 40D as "normal," which translates to 80mm.

  • Richard Skoonberg

    March 9, 2009 01:49 am

    I am curious to find out if what is normal is the same for everyone... I did this with DSLR and its APS sensor and my "normal" was 5omm which is about 70 mm when converted to 35mm format.. That seems long for "normal."

  • migs

    March 8, 2009 07:04 am

    Before I was having trouble manually focusing the lens, thanks to this essay I know what to do now .

  • PJG

    March 8, 2009 06:12 am

    I have to agree with dcclark above. The 50-55mm range will be "normal" for any lens. What the "sensor" sees brings into play the 1.6x factor (APS-C) as with my Canon 400D and 18-55mm lens. What the sensor sees absolutely must include the x factor and in those terms, normal is around 30mm. The 18-55mm lens is stated (at 55mm) to be moderate telephoto range of about 85mm in standard 35mm jargon. Only with a full-frame sensor can this process be used to approximate "normal"...I hope no one is totally confused now.

  • PRH

    March 8, 2009 12:06 am

    Great tutorial by the way, I just tried it with my 18-55mm kit lens.

  • PRH

    March 8, 2009 12:05 am

    I'm not sure that field of view is correct because even full frame sensor/35mm film is a cropped version of what the human eye sees.

    I've always taken the "normal- as the human eye sees" to mean perspective. ie at wide angle the distances between objects appear greater than real life while telephoto everything appears stacked together.

    I'm probably wrong but I would have thought that 50mm would be "normal" on most dslr's regardless of the crop factor. The distance between the sensor and the lens is basically the same as the 35mm film days. Someone with a knowledge of the physics of light might be able to either correct me or explain it better.

  • Tian Chad

    March 7, 2009 04:47 pm

    This is a great tips and really useful for me :) Thanks~

  • dcclark

    March 7, 2009 02:10 pm

    It's not how to manually focus a lens -- it's how to adjust your zoom level to "normal". But honestly, it's really simple:

    1. Look at an object.
    2. Look at the same object through the viewfinder.
    3. Zoom until the object in the viewfinder looks like the object as you saw it with your own eyes.

    Alternative to step 3: Zoom until the object looks like you want it to look in a photo -- whether wide, close, or "normal".

    For reference, in 35mm film terms, a 50mm focal length is "normal", meaning it has the same field of view as human eyes. On Nikon DX cameras, this is about 35mm. On Canon 1.6x crop cameras, this is about 30mm.

  • Mikel

    March 7, 2009 01:32 pm

    Wait...what? I'm not sure what this post is saying other than how to manually focus a lens...

  • Light Stalking

    March 7, 2009 10:42 am

    Thanks for the wrap up, but I'd be interested to hear the author's response to Silverhalide.

  • Silverhalide

    March 7, 2009 09:40 am

    I've had this thought too in the past, but I don't think it works quite as described.

    Consider a Canon 1DsIII with a .78x viewfinder magnification, compared to a Canon 5DII with .71 viewfinder magnification. The 5D will need to zoom in closer to get an view in the viewfinder that matches what is seen with the naked eye, so the recorded image will be different. However, if we're looking for something that matches what we see, given that they are both "full frame" cameras, we'd expect the same recorded image in both cases.

    Your process describes how to match the naked eye to the view in the viewfinder, but has nothing to do with matching the naked eye to the resultant image. I suspect, although I am not sure, matching to the resultant image would also involve how large the print is and distance from camera to subject and viewer to print, and several other factors.

    Also, your statement "Most of these markings ...do not take into account the crop-factor of dx type sensors" is incorrect. Focal lengths are focal lengths and have nothing to do with crop. The focal length of a lens doesn't change when you put it on a different camera. What does change is the apparent magnification of the image.

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