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Fx and DX
#1
What happens when you use DX lenses on ff cameras? What is 300mm f4 performance on ff? I mean is it fx



What is the difference between ff camera and not ff cameras?



Sorry for my ignorance



Thanks
#2
[quote name='Walid' timestamp='1331025877' post='16434']

What happens when you use DX lenses on ff cameras? What is 300mm f4 performance on ff? I mean is it fx



What is the difference between ff camera and not ff cameras?



Sorry for my ignorance



Thanks

[/quote]

There are 135 format (otherwise known as 35mm film, which is actually 36mm wide <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='Wink' /> ) sensors, they are called "full frame". Then there are cameras with a bit smaller sensor, they are called "APS-C" size. APS was a smaller film type introduced in the 1990's.



SLR lens makers, obviously, used to make lenses which have a big enough image circle to work well with the FF sensor and film size.

But in the digital age, making big sensors is difficult and expensive, that is why smaller sensors started to appear, the APS-C size sensors.

Lens makers responded to that by making lighter, cheaper lenses with a smaller image circle.



To differentiate between full size and smaller size image circle lenses, they use different codes in the lens names.



Nikon adds "DX" to APS-C lenses.

Canon uses "EF-S" instead of "EF" for APS-C lenses

Sony adds "DT".

Pentax just makes a mess of the naming.

Tokina uses "DX", like Nikon.

SIgma uses "DC" for APS-C, "DG" for FF.

Tamron uses "Di II" for APS-C, "Di" for FF.



Nikon started relatively late with full frame sensors. Confusingly, Nikon felt it necessary to think of an equivalent name like DX....

So now, instead of normally talking about APS-C, Nikon likes to say "DX", and instead of talking about FF, nikon likes to say "FX".



Any Nikon F-mount lens which has no "DX" in its name is a full frame lens. In that sense it is "FX".

If you use an APS-C lens on full frame, you get dark (black) corners, which is called vignetting. If you use an APS-C zoom lens, it may be that on the widest settings, you can actually use it without getting dark corners.



Examples for that are the Nikon 12-24mm f4 DX and Tokina 12-24mm f4 DX which work without vignetting from about 18mm to 24mm on full frame. And the Tokina 11-16mm f2.8 DX, which works without vignetting at 16mm on full frame.



The 300mm f4 from Nikon is not an APS-C lens, so works as designed on a FF camera.
#3
Thanks for thorough explanation, much appreciated
#4
I have been told that Nikon 300mm f4 on FF camera will not be 300mm it will be less, is this correct?
#5
[quote name='Walid' timestamp='1331034620' post='16439']

I have been told that Nikon 300mm f4 on FF camera will not be 300mm it will be less, is this correct?

[/quote]

No, that is not correct. The FL (Focal Length) will always stay the same, regardless of the camera a lens is mounted on.



And AFAIK, the Nikkor 300 F/4 is an FX lens, so will work both on APS-C and FF.



The difference or confusion if you like, comes in from that fact that a smaller sensor based camera only sees part of the image a FF sensor sees, a crop of the full image circle, hence the alternative name of cropcameras and of the term crop factor. This crop factor is the measure by which a FL needs to be multiplied with in order to get a FF equivalent FL. IOW, a 300 mm on a Nikon APS-C body, which has a crop factor of 1.5, provides the same angle of view, due to the camera sensor only seeing part of the FF image, of a 1.5 X 300 mm = 450 mm lens. And when mounted on a FF camera, you will get the view it would normally have. The latter people sometimes also refer to as a crop factor of 1 <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='Big Grin' />.



As BC notes higher up, a lens specifically designed for a "crop camera" will have a smaller image circle, tailored to the APS-C sensor format, and therefore when used with a FF sensor camera, the image will vignette heavily.



HTH, kind regards, Wim
Gear: Canon EOS R with 3 primes and 1 zoom, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, extension tubes, an accessory plague, and an Olympus OM-D 1 Mk II and Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ...
#6
Brightcolours & wim



You ahev both been brilliant



cheers for that
#7
To illustrate the effect of a smaller (or bigger) sensor with the same lens, this Tamron tool is helpful. It will help you get a better idea.

http://www.tamron.eu/en/lenses/focal-len...rison.html



You see "35mm Film", and "Digital". The 1st is full frame, the 2nd is APS-C.
  


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