is 24mm prime the same as 24mm on a 18-105 lens

astroNikon

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Kinda a newbie question that I have not really run a test on this yet but I actually have 3 lenses that cover the same focal length.

I have a 24mm AF
a 24-85mm AF-D
and a 18-105 AF-S VR

and I use a Nikon D7000 DX camera

at 24mm (or 36 actually) is the 24mm prime, 24-85 @ 24mm and the 18-105 @ 24mm have the "exact" same coverage ?

Basically, If I took a picture of a brick wall at 24mm on all 3 would they all have to same amount of vertical and horizontal bricks in the photograph?
Thanks
 

Big Mike

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Yes, the focal length and thus the field of view should be the same.

The image quality however, may well be very different between the two lenses.
 

Dao

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In theory, they are suppose to be the same. However, in real life, it varies. 24mm focal length on one lens could be a little less or more while in the other one could be also a little more or less.


There is a old thread that a forum member took 2 photos at 70mm with the same camera. The first photo was from EF 24-70mm at 70mm while the other one was from EF 70-200mm at 70mm. Both photos field of view were totally different. You can tell by just looking at it.
 
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astroNikon

astroNikon

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think I'll test for myself too.

I'm assuming I'll have to move the position of the camera based on the length of the lens, ie, have the lens opening at the same distance from a wall versus having the sensor at the same location.
 

JacaRanda

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think I'll test for myself too.

I'm assuming I'll have to move the position of the camera based on the length of the lens, ie, have the lens opening at the same distance from a wall versus having the sensor at the same location.

Hmm, I was thinking the opposite and leaving the sensor in the same position.
 

table1349

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think I'll test for myself too.

I'm assuming I'll have to move the position of the camera based on the length of the lens, ie, have the lens opening at the same distance from a wall versus having the sensor at the same location.

FOV is going to be slightly different for all lenses. There is nothing that says 24mm lens has to be exactly 24mm and not 23.99mm or 24.01mm. If I can find it I have a chart of Canon and Nikon lenses and their exact measures specifications. I haven't looked at it for 4 or 5 years so it may take a while.
 

Solarflare

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As long as we only talk FOCAL LENGTH and FIELD OF VIEW, then yes, 24mm is 24mm is 24mm.

However, different lenses will have different errors - distortion, vignetting, sharpness, chromatic abberations, contrast etc. And of course also variances. Thus the images themselves will never be really equal, not even between two 24mm prime lenses of the same type.

And prime lenses will usually be brighter (can be opened a lot more, has less glass elements) than zooms, and typically offer better overall image quality, because there are less elements and less complexity. Of course if you have much less tolerances on the zoom and make the zoom lens really huge, you can compensate.



There is nothing that says 24mm lens has to be exactly 24mm and not 23.99mm or 24.01mm.
Reallife variations are a lot more drastic than that. A 28mm lens can be closer to 30mm or 26mm.
 

Dao

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From Juza photo, there is an article said the Tamron 18-270mm lens is only 230mm at the long side. While the 18-250mm, the long side is only 220mm actually.
 

AaronLLockhart

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24mm on DX is 24mm on FX.

Dragging up an old thread, but if you're talking about the distance of the back lens element to the sensor, yes, you're correct. However, if you're talking about rendered product, that is incorrect. A 50mm on a DX camera with a 1.5x crop factor produces the same framing equivalent of a full frame camera and a 75mm lens.

Distortion will be different, and you might have some visual differences such as perspective. However, the contents in the frame will be identical.
 

TCampbell

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As Big Mike points out... each lens will tend to have it's own personality.

One lens might have more aperture blades and may provide a well-rounded aperture and a better quality in the de-focused areas. Vignetting might be different. There are lots and lots of nuances.

The biggest "nuance" may well be that the focal ratios available on one lens may be much more versatile than the focal ratio range on the other lens.

But the focal length itself will be the same. Just know that camera companies round off everything. It is NOT, for example, unusual to test a 100mm lens and discover that it's really a 96mm lens. They do this with f-stops as well... they are typically rounded to the nearest 1/3rd stop value.
 
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astroNikon

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FYI, my 3 lens at 24mm were virtually identical. 24mm prime, 18-105 @24mm and 24-85 @24mm
on a close picture test of brick wall at about 8 feet.
 

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