50mm lens=75mm on DX cameras? Confused!

[acoleman]

Okay, I'm confused now lol. I was just checking around on ebay and saw an AF-S Nikkor 50mm f/1.8G Lens but it said on a DX camera, (my d3100), the angle of view would be 75mm??? I'm very confused now lol. I don't want 75mm, I want 50... so am I looking at the wrong type of lenses for my camera or something? Or should I get the 35 so I'll actually be closer to the 50mm angle of view I want?

[RichardTaylor]

@ acoleman

That's correct - 35mm.

[acoleman]

So, an AF-S 35mm F/1.8 G DX lens is going to actually give me an angle of view of around 50mm? Or where it's a DX lens will it have an angle of view of 35?

[Tito87]

Originally Posted by acoleman

So, an AF-S 35mm F/1.8 G DX lens is going to actually give me an angle of view of around 50mm? Or where it's a DX lens will it have an angle of view of 35?

35 x1.5=52.5mm
50x1.5=75mm

[RichardTaylor]

Any 35mm lens will give you a real angle of view of 35mm, however it may have a different, depending on sensor size, equivalent of view compared to a full frame (24x36 mm) camera.

If you are using a 1.5 crop camera then 35mm will have a equivalent field of view, of 50mm.

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I own a 35mm lens (that will illuminate a 24x36mm sensor).
If I use it on my full fame camera the field of view is as per a 35mm lens.
If I use it on my 1.6 crop camera the field of view is approx that of a 56mm lens (That is the equivalent FOV to putting a 56mm lens on my full frame camera)

[Shokinen]

This is a concept that is not easy to understand without some visual explaination.
Full Frame Sensor vs Crop Sensor – Which is Right For You?

This thing with 50=75 or 35=50 is not because of the lens. It's in fact because of the sensor. A 35mm lens is a 35mm lens. Regardless if it's is DX or FX. It will distord like a 35mm lens. DX is only telling you the lens usable surface was design to cover the red area (from the link above) therefore much more affordable. An FX lens, will have a surface usable to cover the black area(from the link above). As you can see, much bigger surface therefore more expensive lens. You can put a DX lens on a FF body but you will either get vigneting or soft corners.

Having that said, 35mm or 50mm is a personal choice. As many people are recommending on this forums. If you have the kit lens (18-55mm), take some picture at 35mm, take picture of the same subject at 50mm. Move your feet to get the "same" image when you change focal lenght. Compare the picture and you will see there is a slight difference in term of distortion. You will also maybe notice that you can fit more in your frame at 35mm indoor as you cannot backup as much due to walls using 50mm.

Speaking for myself, I love my 35mm,
Hope this helps

[Digidave]

Personally, I think that people way over think this stuff. It's only confusing if you are comparing the difference between the same lens on a DX sensor & an FX sensor. If you only own 1 camera, whether it have a DX sensor or an FX sensor, you only need to compare the difference in focal length between 2 lenses. Put a 50mm lens on your camera. If you feel you need a wider angle or need to back up to get more in the scene but can't, then put a 35mm lens on.

Now, tell us why you feel you need a 50mm lens. Will you be taking shots in a crowded room where your space is limited? Is it for getting a more panoramic(wider view) sunset?

[acoleman]

I was thinking the 50mm would be good for me because I mainly shoot portrait shots... usually animals are my main subject. I'm also going to be getting into a lot of live band photography and I need the larger f stop for lighting purposes and the 50mm to get me close enough to the subject without having to be right up in their face when they're playing.

[acoleman]

Just to make sure I'm getting this right, is a 35mm DX lens still going to have me at around 50mm on my d3100? Or where it is a dx lens and I'm using it with my cropped sensor camera, will it give me the actual view of 35mm?

[ceremus]

Remember that the focal length is a constant physical property of the lens. It doesn't change and it's not different whether the lens is DX or FX or EF or EF-S. The only thing that changes is how the camera frames it on a full-frame body versus a crop-frame body. That difference being a crop body has a diminished field of view on the lens compared to a full-frame body (assuming the lens is compatible with both). A DX lens of 35mm still has a focal length of 35mm, just like a 35mm FX compatible lens does. It's just a difference of comparable field of view.

Look at the examples here for more visual examples of what we're talking about: Camera Lens Explained | DX & FX Format Lenses from Nikon

And pay attention to what was said previously about using your kit lens. A prime lens of 35mm or 50mm will frame exactly the same as your kit lens zoomed to those focal lengths, regardless of being a crop-sensor or full-frame lens. Your crop camera will frame it the same way. If 50mm is long enough for you to shoot your band members on stage then get a 50mm lens, although personally I doubt that's going to be long enough.