DX Lenses

Derek_Teixeira

Derek_Teixeira

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Hey Guys,

Quick question for you. I currently have Nikon D60, and I am looking to get a prime fixed lens. I have been told though, that because the D60 uses a DX sensor, you should not buy a lens based off the mm listed on it, because the Nikon DX sensor has a 1.5 X difference. I sort of understand this and sort of don't.

Anotherwards, if I wish to have a lens that will give me a typical 50mm lens that I would find on a traditional film SLR, I would need to get a 35mm DX lens (because 50 x 1.5 = 3.33, which is close to 35mm). What if I do not use a DX lens though? What will the result be?

I'm sorry if that was confusing as hell, I guess I am just as confused as I sound :bang:
 
Simple. Same deal as with the DX lens. You multiple the lens focal length by 1.5. No difference. But you can't use DX lenses on FF cameras.
 
A little more information as to what I am looking for:

I am looking to get a lens for my D60, which would be equivalent to a 35mm lens on a standard SLR/FX ...
 
Well, any of the nikon 35mm lenses would work as a standard, as far as giving you the correct angle of view... but only the DX version 35mm f/1.8 has the AF-S motor in the lens for autofocus with your camera. (The 35mm f/2 AF-D lens will shoot and meter on your camera fine, but won't autofocus.)
-Brian
-Brian
 
If you go here

you will see that they state, "The 35mm focal length is roughly equivalent to 50mm on an FX camer"

I don't understand this. Because I am being told no one hand that there is no difference, but then I am reading that I won't have a 35mm view, but a 50mm, instead...
 
You usually buy the DX/EF-S lenses because they tend to be cheaper and lighter, as they're never intended to cover a FF sensor. My Tamron 17-50 is a digital only lens as it can only cover an AP-S sensor. It's the film equivalent of a 28-80/2.8, though much lighter
 
Nooooo. A 35mm DX lens will give you the 50mm field of view on your camera. A 35mm FF lens will give you the 50mm's field of view on your camera. It's the sensor size that makes the difference, not the lens.
 
Photon42 said:
Nikon has one which may suit you. See http://imaging.nikon.com/products/imaging/lineup/lens/af/dx/af-s_dx_35mmf_18g/index.htm

Rgds
Ivo
Click to expand...

Based on what you just sent me, the product description reads as follows:
"DX-format, normal single-focal-length lens with 35mm focal length (picture angle is equivalent to a focal length of 52.5mm in FX and 35mm formats)"

So this lens will give me the same view as a 35mm lens you may buy for a Leica, or any other older camera?
 
Pickett Wilson said:
Nooooo. A 35mm DX lens will give you the 50mm field of view on your camera. A 35mm FF lens will give you the 50mm's field of view on your camera. It's the sensor size that makes the difference, not the lens.
Click to expand...

Okay, now it is beginning to make sense to me. So if I would like a 35mm field of view, I would look to find a 24mm, if looking for a 50mm field of view, I would look for a 35mm. It does not matter whether the lens is DX or not though, because my camera can handle both, and will treat both the same?
 
The cropped bodies don't have a sensor a large as a 35mm film frame, but continue to use standard 35mm lenses (in terms of focal length etc) to avoid confusion. A 35mm lens does have the FOV you're used to, but only when shot on a full frame body. A crop body cuts off the outsides, leaving you with the center of the image you would have on a full frame body. You effectively lose 50% of the image area.

So, to put the FOV in terms we can understand, we apply the crop factor. A 35mm lens is still a 35mm lens, but the field of view on a APS-C crop body is roughly the same as that of a 50mm lens on a non crop body.
 
Derek_Teixeira said:
If you go here

you will see that they state, "The 35mm focal length is roughly equivalent to 50mm on an FX camer"

I don't understand this. Because I am being told no one hand that there is no difference, but then I am reading that I won't have a 35mm view, but a 50mm, instead...
Click to expand...

It's called 'crop factor' and it applies to any lens used on a camera with a different-sized sensor (or film) than the one it was originally designed for.

http://en.wikipedia.org/wiki/Crop_factor

Imagine a 35mm frame of film. Imagine your 35mm lens focused on that frame of film, and you take away the outer edges of that 35mm frame of film, so that it is reduced in size considerably. Now where do the edges of the image produced by the 35mm lens fall? Outside the new smaller sensor.

Therefore, a (smaller) DX sensor (compared to a 35mm frame of film) is just like cutting the middle out of a 35mm frame of film. You get the center, and the rest of the light cast by the 35mm frame just does not get recorded.

If you took a photo with your 35mm lens on a film camera, and the same photo with the same lens on a DX sensor, and then cropped the 35mm sensor down (the same as what 'digital zoom' does), you'd have two identical images.

So take whatever is written on the lens if it is intended for 35mm cameras and multiple that by 1.5, and that is how it will behave on your DX sensor camera.
 
Derek_Teixeira said:
I don't understand this. Because I am being told no one hand that there is no difference, but then I am reading that I won't have a 35mm view, but a 50mm, instead...
Click to expand...

It's actually quite easy. Your lens has a focal length. That is a physical characteristic of the optical system of the lens, no matter what size of sensor you put behind it. A 35mm lens is a 35mm lens and stays one. Strapping a differently-sized sensor behind the lens changes nothing about the lens.

However, your lens has a field of view. We talk about wideangles, normal lenses, telephoto lenses etc. Telephoto lenses are lenses with a smaller field of view, wideangles those with a bigger field of view. These are basically notions about field of view. The field of view does depend on the size of the sensor - a smaller sensor only looks at a smaller portion of the image.

People are so used to thinking in terms of 24x36 sensors ("FX", "full-frame") that they say a 50mm lens "is" a normal lens. In fact it's not - it's only normal on a 24x36 recording medium. (For example, on medium format the 50mm is a strong wideangle because the recording medium is bigger, so that a 50mm lens that covers all of that bigger "sensor" also has a bigger field of view). Your camera, however, has a smaller sensor than 24x36. So when you put a 50mm lens on it, the small sensor sees only a smaller field of view. That's why suddenly the 50mm lens becomes a telephoto lens. As everybody is so used to talk in terms of 24x36-equivalent pseudo-focal-lengths, you get these statements like "on a DX sensor my 50mm is now a 75mm". In fact it's not. It's still a 50mm, only the narrower field of view from the smaller sensor makes it appear as a 75mm lens would appear on a larger sensor. This is why newbies tend to get confused.

As everybody is so used to 24x36, people have invented the term "format factor" or "crop factor" to speak about these differences in field of view. Your DX sensor has a crop factor of 1.5, meaning that the sensor is 1.5 times smaller, and hence the field of view of all lenses is also 1.5 times smaller, because the sensor only looks at the center part of the image from the lens.

What you want is apparently a lens that looks on DX like a 35mm lens would look on 24x36. So you take the crop factor (1.5), and divide these 35mm by the crop factor. You get 24mm. This is the physical focal length of the lens you need. On 24x36, a 24mm lens would be a strong wideangle; but since the DX sensor only looks at the center section of the image, the smaller sensor makes it appear longer.
 
Unfortunately, Nikon does not make a 24mm prime that will autofocus on the d60. Your best option is to get the autofocus 24mm f2.8, even though you will have to focus manually. In the event that you ever get a full frame dslr, or any film nikon slr, the 24mm will work on it. Since you are looking at getting in to rangefinders, there is no time like the present to start getting used to manual focusing. there is a manual focus 24mm f2, but it is twice as expensive used as the 24mm 2.8 AF lens. my next statement is one that is generally pretty hotly contested, but i am of the opinion that it is a good thing to avoid dx lenses, as lenses are purchases that are meant to last decades, and i am not convinced that the dx format will last that long.
 
Bottom Line:
If you want a prime lens with an field of view of a 35mm lens on your D60, you'll need a 24mm lens.
Since Nikon does not offer a 24mm lens with the AF-S designation, and since your camers needs those lenses to auto focus, there are no Nikkor/Nikon options.

May be an aftermarket option?

Kiu
 
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