mborn Loc: Massachusetts

I do not worry about crop factor just go out and shoot and enjoy

mas24 Loc: Southern CA

Interesting information given so far. Some of which I already knew. I have a friend who owns a Canon crop sensor camera. And his crop factor is 1.6X, rather than 1.5X on the Nikon. Certain lenses are designed for Nikon DX cameras, such as one I own. Nikon 35mm f18G. And Canon has lenses formatted for their crop sensor cameras. Nikon's DX 35mm f1.8G, which I own, is a superb, inexpensive lens you can purchase for only $197. Photographers on this forum even use it on the Nikon D500. So, it must be acceptable.

alfeng Loc: Out where the West commences ...

Yes ...

While the multiplication factor is obviously something to be aware of with "normal" and telephoto lens focal lengths, it may-or-may-not become more relevant for your consideration if-or-when you decide you want WIDER fields of view AND if you are aware of the equivalent fields of view produced by a particular focal length on a Full Frame (35mm) film camera ...

For example, I have a 17mm rectilinear ultra wide angle lens which becomes the FF equivalent of a ~24mm lens on a DX camera body, and ~35mm on an m4/3 camera body ...

... A person would need an 8mm lens to achieve the same field of view with an m4/3 camera body -- I'm under the impression that ALL (?) of the 8mm lenses are "fisheye" types.

There are ZOOM lenses which have the equivalent of ultra wide fields of view for most cameras AND alternatively many people like to stitch multiple images together to achieve wide angle images; so, capturing wide angle images mostly becomes an issue for your wallet and/or how you may want to achieve a wide angle image ... if that ever occurs.

rmalarz Loc: Tempe, Arizona

Focal length is what it is. A 50mm lens is going to be a 50mm lens regardless of the camera on which one mounts it. The 1.5 is an optical illusion caused by using a smaller portion of the images circle projected by the lens.
--Bob

selmslie Loc: Fernandina Beach, FL, USA

It's not an optical illusion. It is simply a crop.

You get exactly the same effect if you use a 50mm lens on a full frame camera and then crop 1/3 from each dimension of the resulting image.

The end result is as if you had used a 75mm lens in the first place.

When you crop an image you also reduce the effective DOF.

rmalarz Loc: Tempe, Arizona

Well, then, more like an optional delusion.
--Bob

camerapapi Loc: Miami, Fl.

"Is the multiplication factor only applied if I mount an FX lens on the camera?"

Regardless of the lens you mount in your camera that multiplication factor applies.

burkphoto Loc: High Point, NC

There two fisheyes at 8mm in the Micro 4/3 world, and one is by Panasonic, while the other is by Olympus.

Leica engineered an 8-18mm f/2.8-f/4 zoom for Micro 4/3. *It isn't a fisheye at the wide end.* If you need the rough equivalent of a Canon 16-35mm, that's it. Oly has a 7-14mm f/2.8 zoom, and Panasonic has a 7-14mm f/4 zoom, too. None of the zooms is a fisheye.

So whether you come to Micro 4/3 from Canon or Nikon full frame gear, you can find an equivalent for most of your lenses. Equivalent focal lengths exist from 14 to 800mm.

http://hazeghi.org/mft-lenses.html

mflowe Loc: Port Deposit, MD

It is the focal length stated on the lens. The focal length does'nt change

CatMarley Loc: North Carolina

The focal length of the lens is what is written on the barrel. The "multiplication factor" applies because the small sensor of the DX camera intercepts only the central part of the cone of light emerging from the rear of the lens and striking the sensor. In essence, the small sensor is cropping the image and enlarging the central portion.

Woodworm65 Loc: Lombard, IL

dcampbell52 Loc: Clearwater Fl

A DX 300mm lens mounted on ANY Nikon camera will the rough equivalent to a 450 mm FX lens on an FX camera (note that 450 mm FX lens on a DX camera would have similar results to a 650mm lens on a DX camera). Now to put things into perspective... if that 300mm lens was a FX lens, it would appear as a 300mm on the FX camera but a 450 on the DX. NOW, one other thing about the DX lens on an FX camera... many (most) Nikon FX camera have a DX setting making the camera crop the sensor /image area to make it the same as that of a DX camera... some settings on the camera will do it automatically and others will have an image exposed in the center 2/3rds of the sensor/frame. So, a Nikon FX camera can emulate a DX camera or use DX lenses but will have the DX strengths and weaknesses. A DX camera will use FX lenses but will only use the center 2/3rds of the optical area (the DX view finder and sensor will automatically throw out the extra exposed area (since the sensor is 2/3rds the size of an FX sensor). Personally, I love my DX camera for birding and telephoto shots.. I love my FX camera for normal to wide angle shots.. the trick is to use each to it's best and be aware of each's limitations.

jeep_daddy Loc: Prescott AZ

You needn't add the multiplication factor at all. This factor only lets you know what the difference between a full frame and APS-C in focal length is. So if you had been used to using your 35mm film camera with a 100mm lens, you could figure that by using that same 100mm lens (focal length) on your D5200 would be like using a 150mm lens.

Polock

if a person were to take a lens for a full frame camera, point it up to the ceiling so their ceiling light was projected on the table.
now have two pieces of paper, one the size of a ff sensor the other aps-c.
now slide each paper under the image. your picture is what's on the paper
the lens didn't change, only the paper/image size/ sensor size
notice the light didn't get bigger, you just saw more of it (fov)
now lets all go get our scissors

the numbers on a lens are there because some guy measured it with a yardstick.
he didn't know if you were putting it on a ford or chevy

berchman Loc: South Central PA

People here are saying that a 50mm lens on a DX sensor camera would be the same as a 75mm lens on an FX camera. Yes, it would be the same field of view, but how could it be the same perspective which depends on how far away you are from the subject. So if you are filling the frame with 75mm on an FX camera, wouldn't you have to step backwards when using a 50mm lens on a DX camera in order for a person's face to look the same?