D7100

[Glenda]

I'm thinking of buying my husband a D7100. Now I've never fully understood the 1.5 crop factor and there always seems to be disagreements about what this means to the length of your lens. I noticed in the D7100 specs you can have a crop factor of 1.3 (I assume by means of a switch). One retailer is advertising this effectively changes your 70-300 to 140-600. In relation to shooting wildlife what changes would he notice?

[I @ M]

Have a read of the two linked pages in the library, they will help your understanding. :)

http://www.ausphotography.net.au/forum/showlibrary.php?title=New_To_Photography:Focal_Length_vs_Crop_Factor

http://www.ausphotography.net.au/forum/showlibrary.php?title=New_To_Photography:Full_Frame_vs_APS-C_DX_crop_factor_w_example

[arthurking83]

...... One retailer is advertising this effectively changes your 70-300 to 140-600. In relation to shooting wildlife what changes would he notice?


Damned! I needed a wife more like you! :th3:
(I think mine became defective over time, and way past the warranty period :p)

Effectively is the wrong choice of words I reckon.

Relatively is probably more accurate.

Relatively speaking, the 70-300mm lens will look more like a 140-600mm lens, but with a naturally deeper DOF for the same aperture used.

That is, because you're only cropping you don't actually get a 600mm lens, instead of a 300mm lens. A 600mm lens at f/5.6 is going to have much less DOF if shot from the same distance as the 300mm lens at f/5.6.

I say that relatively is more accurate a descriptor because while it looks similar, this similarity is really only in the field of view between the two focal lengths(on their respective formats .... 600mm on full frame, 300mm on cropped APS-C).

The difference in DOF is where it effectively looks different.

Another aspect of lenses and this equivalent focal length numbering system, is that of magnification.
The magnification of a 600mm lens(from the same shooting distance) as the 300mm lens is much higher. While not important to every photographer, this can be an important aspect of photography for some.

But while all this is technical related info, the reality is that YES, your 70-300 looks similar to how a 140-600mm lens does on a full frame camera.

FWIW: there should never be disagreement about what the crop factor of a camera means to the focal length of the lens.
There is only one answer and that answer is that the crop factor does nothing to the focal length of your lens.
This is the only answer, and again while it is a technical aspect, that many folks don't really care about, it doesn't remove the fact that this is simply how it is.

Both arguers 'are right' in this debate.
That is:
No, the focal length of the lens doesn't change if you switch from different format size cameras.
Yes, the focal length LOOKS like it increases as you switch to a cropped camera.

For wildlife, I think the D7100 is about as good as a camera body gets in Nikon circles at the moment .. good choice.

[Glenda]

Thanks Andrew and Arthur. I sort of understood the field of view changed but it helped to see the 2 bird photos in the second link Andrew posted to illustrate the effect.

Arthur I actually passed my D3100 on to hubby when I upgraded to the D7000. Ulterior motive - always felt a bit guilty dragging him out for night shoots because I didn't want to go alone. Now it's nice to have a hobby we can share and the same things that were frustrating me about the D3100 are now frustrating him.

[Tommo1965]

Thanks Andrew and Arthur. I sort of understood the field of view changed but it helped to see the 2 bird photos in the second link Andrew posted to illustrate the effect.

Arthur I actually passed my D3100 on to hubby when I upgraded to the D7000. Ulterior motive - always felt a bit guilty dragging him out for night shoots because I didn't want to go alone. Now it's nice to have a hobby we can share and the same things that were frustrating me about the D3100 are now frustrating him.

awesome post..its nearly always the other way round ( husband passes on a lesser model to the wife ).

im with Arthur... you're quite a catch :-)