18-55mm Kit Lens / 50mm Question

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Sandpatch

Senior Member
I have a question about DX lens cropping and I hardly know how to ask it.

For 40 years I shot 35mm film and recognized that a 50mm prime offered the best real life reproduction of what my eyes saw, without the "distortion" that a wide angle lens or telephoto lens brings.

With my D5100 I often use my 18-55mm kit lens. If I wish to achieve the same "real life", distortion-free view with my kit lens, what would I set it at? 33mm in view of its 1.5 crop factor? Leave it at 50mm?

I'm thinking that perhaps the crop factor has nothing to do with the distortion-free realism of an image and that the 50mm setting continues to reign. It looks that way in my photos.

(For the record, I enjoy wide angle and telephoto shots too!) I apologize for my poor wording here. Thanks y'all.

Sandpatch
 
Horoscope Fish

Horoscope Fish

Senior Member
Sandpatch said:
I have a question about DX lens cropping and I hardly know how to ask it.

For 40 years I shot 35mm film and recognized that a 50mm prime offered the best real life reproduction of what my eyes saw, without the "distortion" that a wide angle lens or telephoto lens brings.

With my D5100 I often use my 18-55mm kit lens. If I wish to achieve the same "real life", distortion-free view with my kit lens, what would I set it at? 33mm in view of its 1.5 crop factor? Leave it at 50mm?

I'm thinking that perhaps the crop factor has nothing to do with the distortion-free realism of an image and that the 50mm setting continues to reign. It looks that way in my photos.

(For the record, I enjoy wide angle and telephoto shots too!) I apologize for my poor wording here. Thanks y'all.

Sandpatch
Click to expand...
The DX crop factor is 1.5 "magnification" basically speaking. On your D5100's 18-55mm you have to multiply by this factor at all focal lengths. So what you have, effectively, in your 18-55mm lens is a 27-83mm lens. To get the 50mm perspective you want you'll need to set your focal length to just under 35mm since 35 x 1.5 = 52.6.

And just to clarify, before someone jumps all over me, the DX crop factor gives the appearance of a magnification but it's not *really* a magnification per se, it is in fact, a crop when compared to the full size FX sensor; hence the quote marks.
 
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Rexer John

Senior Member
My undersanding is that you would need to set the DX to 33mm to get the same angle of view as your 50mm on a 35mm film.

So you should be shooting at the same distance, for the same image with DX at 33mm vs 35mm film at 50mm focal length.

The bigger the sensor (or film), the more depth of field you can show at any given aperture but the crop conversion should work out well.
 
nikonpup

nikonpup

Senior Member
for dx, yes 33mm is the new 50mm. But. If i shoot at 18mm or 50mm and get a shot that makes me all warm and fuzzy, i am a happy camper.
 
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Sandpatch

Senior Member
Thank you everyone -- I think I understand now. This explains why I have to step waaay back from the subject when I mount my old Nikkor 50mm to by D5100.
 
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