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Post by drako on Jul 25, 2010 11:09:23 GMT -5
Can anyone direct me to chart or calculator that shows 35mm focal lenghth equivalents for digital?
For example, I love the field of view I get with a 21mm lens in 35 format. What focal length would I need to get this on a digital?
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daveh
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Post by daveh on Jul 25, 2010 11:35:56 GMT -5
The trouble is, it depends on the size of the chip. The multiplier on many digital SLRs is around 1.6 e.g. an 18mm lens on a Canon 30D is about the same as a 29mm lens on a 35mm camera. The multiplier the other way round is about 5/8, or 0.625. A 21 mm lens on a 35mm camera would equate to about 14mm for a digital SLR.
I have just had a look at the Panasonic FZ20 - a six times multiplier on that: a 6-72mm lens, equivalent to 36-432mm on a 35mm camera.
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Post by nikonbob on Jul 25, 2010 11:44:10 GMT -5
Johnny
Dave hit the nail on the head when he said you must know the sensor size. I had a good conversion chart but I can't find it. For DSLRs the multiplier fact can be 2X, 1.4X, 1.5X, 1.6X and of course virtually none on a camera with a full frame sensor. If I find the chart I will post a link.
Bob
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mickeyobe
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Post by mickeyobe on Jul 25, 2010 12:30:42 GMT -5
My owner's manual says the conversion factor is 1.5. It might be something else for a different digital camera. As I understand it that applies to any lens I put on the camera. Therefore a 35mm film camera lens of 50mm focal length would be 75mm on my Pentax K100d.
Instead of constantly having to refer to a chart why not put the converted focal length on a tiny adhesive label and attach one to each lens or inside of a lens cap.
Mickey
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SidW
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Post by SidW on Jul 25, 2010 16:59:13 GMT -5
Make life easier. If it's 1.6 pretend it's 1.5. Then just add on half. Or roughly half. 13.5+7 is around 210
The focal length doesn't actually change, of course. It' just the way a 35mm full frame lens seems to behave on a smaller sensor DSLR.
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Post by Rachel on Jul 26, 2010 4:54:50 GMT -5
I guess that the 35mm equivalent sizes are of little interest to many (most?) digital camera users who have never owned 35mm cameras.
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daveh
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Post by daveh on Jul 26, 2010 9:20:10 GMT -5
Rachel, too true.
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Post by drako on Jul 26, 2010 14:05:12 GMT -5
Thanks all. My reason for asking is that I'm considering my first DSLR purchase but, before doing the deed, want to be sure the appropriate size lenses will be available.
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keith
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Post by keith on Jun 9, 2011 23:50:30 GMT -5
There is a very full description of sensor sizes on Wikipesia under "APS-C"
What we are really talking about is the angle of view. an 18mm lens on an APS-C sensor is 76 degrees which equates with the FOV of a 28mm lens on a 35mm SLR (75 degrees)
A 50mm prime lens on a 35mm SLR has a Field of View of 47 Degrees, the same 50mm lens on a Sony Alpha series D-SLR has a Field of View of 32 degrees which is almost the same as a 70mm lens on a 35mm camera (34 degrees)
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Post by barbarian on Jul 17, 2011 16:32:46 GMT -5
My wife's four thirds sensor gives a 2X magnification. With an adaptor, my 55mm 1.2 Nikkor becomes the equivalent of a 110mm 1.2 portrait lens. Not bad.
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Post by keith201 on Mar 18, 2012 23:50:28 GMT -5
Nikon and Sony use identical APS-C sensors, 23.6x15.8mm, the 'crop factor' is 1.5 so a 18mm - 70mm kit zoom will have the same field of view as a 27mm - 105mm lens on a 35mm camera. Canon sensors are very slightly smaller, their crop factor is 1.6. The focal length remains the same, it is just that the image is cropped smaller on APS-C compared with the 35mm so it seems more telephoto.
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daveh
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Post by daveh on Mar 19, 2012 1:16:08 GMT -5
(From memory) Canon have three sensor sizes in its SLR range, giving crop factors of 1.6, 1.3 and 1. Most of the cameras have the 1.6 crop factor.
Another important thing with the lens is, of course, its coverage. Canon has EF and EF-S lenses. Put an EF-S lens on a full size sensor or film camera and the result is severe vignetting.
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Post by nikonbob on Mar 19, 2012 11:19:36 GMT -5
Dave
That is a real can of worms when you look at backward compatibility. I don't know why Canon did that as most of the other camera makers avoided that issue to a greater extent. OTOH you can modify or adapt more other makers lenses to Canon than seemingly any other DSLR make. What you make on the beer you loose on the peanuts, I suppose.
Bob
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Post by andys93integra on Mar 19, 2012 11:39:51 GMT -5
You can not physically put an EF-S lens on a FF Canon body, just wont work.
You can, however, put a DX lens on a FF Nikon body but the camera will recognize it and adjust the sensor accordingly.
Andy
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daveh
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Post by daveh on Mar 19, 2012 12:29:45 GMT -5
Andy, yes, I know that, but I was just illustrating the point. The problem is mainly one of the back focus distance. In certain focussing positions the rear element will foul the mirror of a full frame camera. Canon themselves put a stop on the EF-S to prevent them being inadvertently mounted on a FF body. The stop can be removed. Nikon's system if "better" in that an APS-C lens can be used, but to prevent vignetting the image is cropped. What was a FF 12mp sensor (or whatever) becomes an APS-C sensor of 5mp or so. The image used is that which is inside the vignetted area.
I can use my EF-S sized Sigma lens on the Canon EOS 35mm film SLR, but there really isn't any point because of the vignetting. I don't know if the Sigma would work on a FF digital Canon. Perhaps the rear element doesn't protrude as much as the Canon EF-S lenses.
Anyway I'm not sure why I would want to spend £1500 or so on a FF body and then put a "cheap" EF-S lens on that won't cover all the sensor.
Incidentally, I have previously found that a Prakticar Pentax bayonet zoom lens will not mount on a Pentax body (or is it the other way round?) even though both are FF sized coverage and apparently compatible.
Dave.
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