Email: brqyvn@gmail.com
Hi Photographer friends,
For years now, we have been buying lenses that are designed to a certain focal length, (say a 50mm lens) but when used on a digital camera, with a smaller sensor than the old 35mm film camera standard (24mm x 36mm), we are told that with a multiplying factor our new lens will have a different equivalent in 135 /35mm format. i.e. a 50mm lens attached to an APS-C digital camera with a sensor having a 1.5 multiplier will be equivalent to a 75mm lens.
A 50mm lens is always a 50mm lens in terms of focal length, and the perspective is always that of a 50mm lens no matter what camera it is attached to. I think it's time to drop the equivalency to the old 35mm film cameras and stop confusing entry-level photographers.
Assuming that you are already aware of the crop factor and 35mm format equivalency, and without going to a lot of explanation about it, (learn about the crop factor here and here if you are not familiar with it or just Google it), the final true result is really the angle of view.
Hi Photographer friends,
For years now, we have been buying lenses that are designed to a certain focal length, (say a 50mm lens) but when used on a digital camera, with a smaller sensor than the old 35mm film camera standard (24mm x 36mm), we are told that with a multiplying factor our new lens will have a different equivalent in 135 /35mm format. i.e. a 50mm lens attached to an APS-C digital camera with a sensor having a 1.5 multiplier will be equivalent to a 75mm lens.
A 50mm lens is always a 50mm lens in terms of focal length, and the perspective is always that of a 50mm lens no matter what camera it is attached to. I think it's time to drop the equivalency to the old 35mm film cameras and stop confusing entry-level photographers.
Assuming that you are already aware of the crop factor and 35mm format equivalency, and without going to a lot of explanation about it, (learn about the crop factor here and here if you are not familiar with it or just Google it), the final true result is really the angle of view.
During the film era, various format existed. There were the 35mm cameras, the medium formats (6 x 6, 6 x 4.5, view cameras in 4 x 5, 5 x 7, 8 x 10, etc. Nobody ever used conversion factors to describe what a medium format lens would be equal to in 35mm cameras.
When the first Digital SLR cameras began to appear, manufacturer opted to use 35mm bodies and lenses, ( good economic decision but stupid photographic decision). The problem was that technology of the time only had developed sensors were much smaller than a 35mm film plane, hence the birth of the crop factor and equivalency to 35mm film cameras format.
Most young photographers don't know much about the old 35mm film cameras and they don't care. All they know, or need to know, is what a particular lens of a particular focal length looks like when viewed through their own digital camera viewfinder. That comes with minimal usage and experience. Once they know, they will be able to understand and pre-visualize what and when to use a particular lens on their camera.
Most young photographers don't know much about the old 35mm film cameras and they don't care. All they know, or need to know, is what a particular lens of a particular focal length looks like when viewed through their own digital camera viewfinder. That comes with minimal usage and experience. Once they know, they will be able to understand and pre-visualize what and when to use a particular lens on their camera.
It becomes even more ridiculous when describing a digital camera, having a sensor of the same size of the old 35mm film camera (24mm x 36mm), as a full frame camera. Hello! All camera are really full frame in their own format. Think about the Pentax 645D or the Leica s2. Should we call them super full frame or describe their lenses as a equivalent in 35mm format?
So I say... just continue making and sell lenses with their correct focal length stamped on but let the users figure out what they will be like on their particular cameras. It would be a short transition, but this equivalency is nuts. Lens are indeed labelled correctly, but described as equivalent to 35mm in magazines, camera manuals, advertisement, on the internet, etc. Please just stop the conversion factor. It all about what you see in your viewfinder.
When you look at an object, you likely can tell its size fairly accurately. For example, If you live in the U.S. you could visualize an object and recognize it as being about 1" inch long. You wouldn't have to know its metric equivalent, would you? The opposite is true if you live in a region that uses the metric system. Why using an equivalency with lenses and cameras?
Thanks for reading,
When you look at an object, you likely can tell its size fairly accurately. For example, If you live in the U.S. you could visualize an object and recognize it as being about 1" inch long. You wouldn't have to know its metric equivalent, would you? The opposite is true if you live in a region that uses the metric system. Why using an equivalency with lenses and cameras?
Thanks for reading,
May the good lighting be with you,
Yvon Bourque
7 comments:
Yvon, isn't this already what manufacturers do? I believe all my lenses all have actual focal length printed on them.
I don't think most manufacturers describe their lenses in terms of 'equivalency', though a few might mention it in addition to the actual length on the spec sheet. Cameras with fixed (non-interchangeable) lenses are more likely to use 35mm equivalence but still usually in-addition-to actual focal length, not instead-of. Perhaps that's a little more reasonable since the owner/buyer of such a camera is much less likely to know what the meaning of a 6.2mm lens is in terms of angle-of-view.
Which brings us to what the more sensible unit of measure to describe the usage for a lens on a given camera--angle-of-view. Unfortunately getting people to think in terms of angle-of-view is probably a lost cause -- too much tradition.
Andrew,
You are correct about what the lens manufacturers do. I meant to write camera makers. I will change that. As for the angle of view, it is really what I started writing this blog about, but changed my mind when trying to explain the formulas and that the angle of view is taking the width, height and diagonal measurements in consideration. I still think lens should be labelled in terms of angle of view, using only the horizontal angle.
Great post, I get tired of all of the talk on forums discussing the proper multiplier to convert a lens from "full frame". People spend time making charts to carry with them to "convert" their lenses to size sensor they are using. Who cares? You are right, it's all about what's in your viewfinder, get out there and shoot. I would also like to see the terms "full frame" and "crop sensor" go away. One of the first photographers that inspired me used a camera that produced 8x10 negatives, that is what I would call "full frame", everything smaller than that is "cropped". Thanks for the great blog.
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Yvon, you are right on target with your post. When I first developed an interest in digital photgraphy after some years absence from using film I was confused with the conversion of the crop factors. Really no merit to entire process and definetly no apparent benefit.
G;Day
This item has a good diagram explaining focal length vs crop factor.
http://www.ausphotography.net.au/forum/showlibrary.php?title=New_To_Photography:Focal_Length_vs_Crop_Factor
Kim,
Thanks for the diagram, but the issue at hand is not so much about what is the crop factor and focal length equivalent. It about why keep referring to the old 35mm film format, and using the 35mm film format at the "Full Frame" camera. They are all full frame in relation to their sensor. You don't take pictures by calculating what the crop factor is, you look in your viewfinder and compose the image. Sometimes you need a wide angle field of view, sometimes a telephoto, etc. The best way to learn what a particular lens will do is by installing it on your camera and look in the viewfinder. It becomes what you want or it doesn't. After a while you will know intuitively what a certain focal length will be like in your camera viewfinder. You don't go and say my car has a four cylinder engine, equivalent to xxx on a six cylinder, and xxx on a 8 cylinder engine. You don't label an 8 cylinder engine as a full size engine. They are all full size engines, depending on their own unique design.
Yvon I think it's really an issue with comparing digital to (if you will) old school cameras, I am still a fan of digital but lets be honest it's turned everyone into a photographer these days, even camera phones have the power to take a decent photo these days but it takes a photographer to produce a great picture, NOT the camera on it's own, what do you think?
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