Lens sizes equivalent 35mm film to digital lens sizes?

[crlewis]

Just purchased a Nikon D3100 fitted with the 18-55 lens, the camera data states that this equivalent to a 27-82.5 lens (35mm). I have a number of old lenses from my old nikon 35mm a 24mm, 35mm, 50mm and 105mm. So I presume that these lenses will be of a different value than the 35mm size? If so what sizes are they equivalent to digitally?

 

[Giulio Cengarle]

Hi, on your camera those lenses will correspond to their focal length multiplied by 1.5. This is because your sensor (DX size) is smaller than a 35mm film area (or an FX digital sensor), therefore only sees a smaller part of the image circle. In your specific case:

24mm > 36mm

35mm > 52mm

50mm > 75mm

105mm > circa 160mm




Enjoy those lenses!

Giulio

 

[Michael Benveniste]

crlewis wrote:

Just purchased a Nikon D3100 fitted with the 18-55 lens, the camera data states that this equivalent to a 27-82.5 lens (35mm). I have a number of old lenses from my old nikon 35mm a 24mm, 35mm, 50mm and 105mm. So I presume that these lenses will be of a different value than the 35mm size? If so what sizes are they equivalent to digitally?

The "crop factor" of your D3100 is 1.5, so for purposes of angle of view multiply the focal length by 1.5. So on you D3100:

• A 24mm lens will have the same angle of view as a 36mm lens on a 35mm film camera.
• A 35mm lens will have the same angle of view as a 52.5mmlens on a 35mm film camera.
• A 50mm lens will have the same angle of view as a 75mm lens on a 35mm film camera.
• A 105mm lens will have the same angle of view as a 157.5mmlens on a 35mm film camera.

 

[crlewis]

Thanks for the information.

Just one more thing to clarify, the old equivalent size of a Standard Lens was 50mm (35mm film). So with a digital camera the Standard Lens size is now approximately 34mm?

 

[Michael Benveniste]

crlewis wrote:

Thanks for the information.

Just one more thing to clarify, the old equivalent size of a Standard Lens was 50mm (35mm film). So with a digital camera the Standard Lens size is now approximately 34mm?

Yes. In fact, Nikon makes a 35mm f/1.8 DX, calling it a classic "normal" angle of view. For historical reasons, Nikon's 50mm lenses of the film era were actually 51.6mm.

--

I miss the days when I used to be nostalgic.

 

[Catallaxy]

The 50mm was supposed to be a "normal" lens for 35mm film cameras. A normal is defined as the diagonal of the sensor or of the film. For 35mm film and full frame the diagonal is really about 43mm. The reason they make 50mm "normals" (and 55mm before that in the early 60s) was that an f/1.4 aperture 45mm was very, very hard to make with 1960s and 1970s technology.

So our normals were really just very short telephotos because we wanted those f/1.4 and f/1.8 apertures. Over time, we just got used to that, even though modern technology can probably make a fast aperture 45mm now.

On a DX or crop sensor camera, 35mm equates to 53mm which is even more of a telephoto than the old 50mm on film. A true "normal" on DX is about 28 to 30mm.

So if you want a true normal, look to the Nikon 28 f/1.8 AFS or the Sigma 30 f/1.4. Both are good. I think the Sigma is a great lens with nice bokeh.

I am using a Voigtlander 40 f/2 on my full frame and a Voigtlander 28 f/2.8 on DX as my normals and love the very slightly WA look to them. They produce far more interesting images to my eye than a 50mm on FX or a 35mm on DX does.

 

[crlewis]

One of my favourite lenses that I used on my old Nikon 35mm Film camera was the 24mm. So according to the conversion this now equates to a 16mm lens.

The 16mm lens on the 35mm Film Camera resulted in a lot of distortion (fisheye type distortion).

So if a 16mm lens was used on a digital camera what would the distortion be like?

 

[Michael Benveniste]

crlewis wrote:

The 16mm lens on the 35mm Film Camera resulted in a lot of distortion (fisheye type distortion).

So if a 16mm lens was used on a digital camera what would the distortion be like?

Nikon's 16mm prime is a fisheye lens designed to provide a 180-degree angle of view diagonally on a 35mm film camera or FX-format dSLR. If used on your DX-format camera, it would still show exhibit some fisheye characteristics.

However, there's nothing about the 16mm focal length which requires it to be a fisheye, and Nikon makes four(?) different zooms which cover that focal length. Each has its own distortion signature, but all are roughly rectilinear.

 

[PHXAZCRAIG]

crlewis wrote:

The 16mm lens on the 35mm Film Camera resulted in a lot of distortion (fisheye type distortion).

So if a 16mm lens was used on a digital camera what would the distortion be like?

Depends on the lens, but wide-angle acts differently on film than digital, in ways not related to crop factor. An older design that was good on film tends not to be as good on digital, with worse corner distortion and more light falloff. (Has to do with light rays hitting the sensor at angles. Newer designs try to make the rays come straight into the sensor rather than hitting at such an angle).

That said, a DX camera with a full-frame 16mm lens won't see the corners of the lens to start with. The image projected on the sensor by the lens will be much larger than the sensor, and so the sensor effectively crops out the center of the image. (Therefore 'throwing away the corners'.) This often means you have better 'corners' when an FX lens is used on DX, because you only see the center of the lens, which is usually better than the corners.

It also means that DX wide angle lenses do not have to be nearly as big, heavy and expensive than FX lenses. You can get a 10-24 zoom that it probably better than the 16mm prime, at least stopped down a bit. Certainly it should be lighter and cheaper.

 

[Catallaxy]

Yes. You need a 16mm f/2 to get a similar look (DOF and angle of view) on DX as a 24mm f/2.8 of full frame (or 35mm film). However, I don't think they make such an animal.

There are several good WA lenses that cover that range, but all have smaller apertures.

Nikon 10-24

Nikon 12-24

Sigma 12-24 ( a dog of a lens)

Tamron 10-24 (soft)

Tokina 12-24 f/4

Tokina 11-16 f/2.8

Nikon 16-35 VR

Tokina 16-28 f/2.8

Sigma 8-16

Sigma 10-20 (variable aperture)

Sigma 10-20 f/3.5 constant

Nikon 14-24 f/2.8

Zeiss also makes a 15mm f/2.8 that is considered very, very good.



Some have terrible corners (see Sigma 12-24 above) and some have good corners. Some have terrible distortion (moustache and wave) and others have very little.

Oh, and then there are the fisheyes, which you can de-fish if you want.

Depends on what you want and how deep your pockets are.