Canon EF and EFS lenses - silly question
Nov 5, 2016 11:22:49 #
Martino
Loc: Northwest Florida
Apologies for a dumb question, but my brain has gone into Saturday morning stupid mode.
I use a Canon 70D most of the time. I also have 400D back up body. For the 70D I have EFS lenses. I also still use EF lenses that I used to have with my EOS film bodies from way back. I have used a 1:6 crop sensor conversion to work out what the focal length will be on the 70D and 400D. No problem.
I'm assuming that if I acquired a used Canon EF 75-300mm F/4-5.6 II Lens, then I should use the same conversion ratio, so the extreme focal length would be around 480mm.
Is this correct, or should I go and lie down for a while?
I use a Canon 70D most of the time. I also have 400D back up body. For the 70D I have EFS lenses. I also still use EF lenses that I used to have with my EOS film bodies from way back. I have used a 1:6 crop sensor conversion to work out what the focal length will be on the 70D and 400D. No problem.
I'm assuming that if I acquired a used Canon EF 75-300mm F/4-5.6 II Lens, then I should use the same conversion ratio, so the extreme focal length would be around 480mm.
Is this correct, or should I go and lie down for a while?
Nov 5, 2016 11:24:47 #
Nov 5, 2016 11:24:59 #
The crop factor needs to be applied to ANY lens you mount on that camera to determine equivalent field of view.
Nov 5, 2016 11:30:28 #
MT Shooter wrote:
The crop factor needs to be applied to ANY lens you mount on that camera to determine equivalent field of view.
Nov 5, 2016 11:37:54 #
MT Shooter wrote:
The crop factor needs to be applied to ANY lens you mount on that camera to determine equivalent field of view.
That's correct.
Nov 5, 2016 11:41:03 #
Martino wrote:
The actual focal length depends on the lens, and is fixed. How the lens works, how its output is "interpreted", depends on the body. That is a fancy way of saying that you multiply every actual focal length by 1.6 to see what it will act like on your camera.Apologies for a dumb question, but my brain has go... (show quote)
Nov 5, 2016 11:43:14 #
Focal length does not change, no matter which body you mount the lens on. What changes is the field of view. The 1.6 conversion factor is correct for Canon APS-C bodies. If you shoot the same scene with the same focal length lens on both the APS-C and full frame bodies, there is no difference in magnification when the images are displayed at the correct ratio to each other. Since images are rarely displayed or printed in that manner, the APS-C image does appear to offer greater magnification. Not only that, the APS-C image will often have better IQ if you were to crop the full frame image to equal the APS-C image. My 7DII is 20.2mp. My 5DIV is 30mp. Even with the additional megapixels the 5DIV image, if cropped to match the same image from the 7DII, shows a distinct lack of IQ in comparison. These differences make the APS-C camera very handy for certain types of photography, such as BIF and sports.
Nov 5, 2016 11:48:40 #
As a side note. Canon adds a hard rubber extension to the back of this lenses to come up with "EF-S" designations. The mounts are exactly the same as EF lenses, but the extension hits a block inside the body and stops the bayonet from engaging. If you really wanted to, you could use a Dremel tool to remove the extension and the EF-S lenses would work on the full frame bodies. ALL third party crop sensor lenses mount on Canon full frame bodies and work just fine. The only downside is that crop sensor lenses will cause varying degrees of vignetting on the full frame sensors as they do not project an image large enough to cover the larger sensor. Crop sensor zoom lenses DO often cover the larger sensor at their longer zoom ranges though.
Canon is the ONLY camera manufacturer to intentionally prevent you from mounting their crop sensor lenses, don't ask me why. Maybe for the same reason they refuse to include the cameras shutter count in the image Exif data like ALL other manufacturers do. Canon always declines to directly answer these questions.
Canon is the ONLY camera manufacturer to intentionally prevent you from mounting their crop sensor lenses, don't ask me why. Maybe for the same reason they refuse to include the cameras shutter count in the image Exif data like ALL other manufacturers do. Canon always declines to directly answer these questions.
Nov 5, 2016 11:56:27 #
Martino
Loc: Northwest Florida
Thank you all very much for the rapid replies.
That all makes sense to me - I was doubting my own reasoning! That puts me straight and looks like I could relatively cheaply get worthwhile extra reach.
Many thanks again.
That all makes sense to me - I was doubting my own reasoning! That puts me straight and looks like I could relatively cheaply get worthwhile extra reach.
Many thanks again.
Nov 5, 2016 12:13:52 #
Nov 5, 2016 13:42:42 #
Martino wrote:
Apologies for a dumb question, but my brain has go... (show quote)
Your main question has been answered already, but are you sure that you want the EF 75-300 lens? A used EF 70-300 IS USM is a significantly better lens, and the stabilization is extremely useful for a lens with the equivalent field of view of a 480mm lens. There are a few on Ebay currently at quite reasonable prices.
The 75-300 EF lenses are widely regarded as some of worst lenses that Canon offers. They are however cheap.
Good luck
Nov 5, 2016 14:43:00 #
MT Shooter wrote:
The crop factor needs to be applied to ANY lens you mount on that camera to determine equivalent field of view.
That is not correct! The crop factor does not apply to EFS lenses (they are optimized lenses for the crop)!
Nov 5, 2016 15:18:38 #
speters wrote:
That is not correct! The crop factor does not apply to EFS lenses (they are optimized lenses for the crop)!
You had better research focal lengths!
Lens focal lengths never change, only the sensor size changes. CROP factor needs to be applied to EVERY lens mounted on a cropped sensor camera, period.
EF-S lenses are made to a smaller diameter, that's the only difference, their focal lengths are still stated in 35mm film format terms.
Nov 5, 2016 15:24:12 #
speters wrote:
You are confused. They may be optimized for APS-C, but they are all measured the same. Back when I was using a Canon Rebel, the EF 50mm lens I had {dating back to my Canon Elan daze} gave me exactly the same view that my 18-55mm kit lens when set at 50mm did.That is not correct! The crop factor does not apply to EFS lenses (they are optimized lenses for the crop)!
Nov 5, 2016 16:34:44 #
MT Shooter wrote:
You had better research focal lengths!
Lens focal lengths never change, only the sensor size changes. CROP factor needs to be applied to EVERY lens mounted on a cropped sensor camera, period.
EF-S lenses are made to a smaller diameter, that's the only difference, their focal lengths are still stated in 35mm film format terms.
Lens focal lengths never change, only the sensor size changes. CROP factor needs to be applied to EVERY lens mounted on a cropped sensor camera, period.
EF-S lenses are made to a smaller diameter, that's the only difference, their focal lengths are still stated in 35mm film format terms.
Are you really sure about that? Stated by whom?
What happens with a lens like the EF-S 10-22mm f/3.5-4.5 USM. Its focal length is exactly as it says, 10mm - 22mm. From a FOV perspective that is equivalent to a 16 -35 mm lens according to B&H and to the math (crop factor), but nowhere on the lens does it say 16 -35 mm which is the 35mm equivalent, nor to my knowledge does Canon include a 35mm equivalent length in the EXIF data of an image taken with this lens, at least I can't find it with EXIFtool.
What happens if you use a medium or large format lens on a crop factor camera? The focal length doesn't change, but surely 35mm is no longer the reference point from a stated focal range / FOV perspective?
I know I'm being a little picky here, but given your status as a professional dealer / retailer isn't accurate information important?
Perhaps there are different versions of lenses for sale in Montana!
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