200mm 200mm???

JustJazzie

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Like every junkie who gets a new toy, I decided I should compare my new 70-200 lens, to my old 18-200 amount lens. I am SHOCKED at the results. My test was entirely scientific (read the sarcasm here.) I sat down without moving and set each camera to the same settings (iso 800, 1/200, f 6.3) and fired away. I was expecting to find a difference in image quality, color rendering etc, but instead what I found was two enterily Different field of views, on 2 crop sensors?! Both lens's are practically the same length when the lens's are fully extended (≤.5 inch) So is sony lying about it being an 18-200? Is nikon? Am I missing something entirely regarding the labeling of focal length? This looks like a pretty significant difference to me! $14175047388_6aa0bd3c51_o.jpg $14338574536_d753f608e0_o.jpg
 
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Which exact camera bodies?
Different makers crop sensors are different multiples/

For instance Nikon is 1.5x, and Canon is 1.6x from everything I've read
So if SOny uses a different sized "crop"ed sensor it's going to have a different multiple of the focal length

a 200 on a Nikon dslr is going to be 300
on a 1.6x canon it's going to be 320 equivalent

on a smaller sensor it's going to have a larger multiple
Image sensor format - Wikipedia, the free encyclopedia
or
http://www.gizmag.com/camera-sensor-size-guide/26684/
 
Thanks Astro!! You're right. Apparently the 7100 comes default in 1.3 crop mode and only 16mpx. WEIRD! I fixed my settings, and now they are both at 1.5! Thanks a bunch!

Had to edit to add: this explains so much. I didn't understand why I had a 125% viewfinder, which kept throwing me off so badly, or why my pictures were so grainy compared to the nex7! Hahah. I'm excited to see what happens with that fixed!
 
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Well, after switching the crop factor to dx mode I am STILL seeing a major fov difference between the two, which are both supposedly 1.5..... Any other reasons this might happen?
 
.......... Any other reasons this might happen?

Focus breathing
..... the change in focal length as the lens is focused at different distances.
 
The partial answer is actually in your photos. If you look at the EXIF, the Sony picture @200mm is at 300mm 35mm eq. Look at the Nikon picture, (1.33 digital zoom) and you have a 400mm equivalent.
:D
 
.......... Any other reasons this might happen?

Focus breathing
..... the change in focal length as the lens is focused at different distances.

Yeah, loss of effective focal length at close ranges is VERY common with many lenses, both primes and zooms. The fact that many lenses lose focal length is one of the major reasons that the testing websites often report the maximum close-up magnification a lens can achieve, as a way to give people a good idea of "how big an image" can be had with a lens. The lens manufacturers usually mention maximum magnification ratio in their most-detailed information pages, and in the lens instruction manuals or pamphlets.

A sensor that is physically smaller will produce a more frame-filling image when the same lens is mounted on the smaller-sensor body instead of the larger-sensor body. But with this specific set-up, an 18-200 and a 70-200, you have two different lenses, on two different cameras, so you cannot do a head-to-head test. I know that Nikon's 18-200 zoom loses a lot of focal length as it is focused closer...I mean a LOT of focal length is lost on that lens; perhaps trhe one for the NEX system also loses a lot of F.L.?
 
Thanks for all the help guys! I learn something new everyday!
 
The partial answer is actually in your photos. If you look at the EXIF, the Sony picture @200mm is at 300mm 35mm eq. Look at the Nikon picture, (1.33 digital zoom) and you have a 400mm equivalent. :D

Digital zoom? Isn't thar only on point and shoots? :headscratch:
 
The 1.33 'digital zoom' that Rick mentioned is the D7100 operating in what Nikon used to call "High-Speed Crop Mode", back when that feature was first introduced on the D2x in late 2004. The D2x offered an APS-C sized sensor, but it also had High-Speed Crop Mode that boosted the firing rate from 5 frames per second up to 8.2 frames per second, while capturing a much smaller area, with an effective focal length multiplier of 2.0x, as opposed to the full-sensor capture, which was 1.5x.

The D7100 is continuing the same Nikon tradition of allowing the user to capture the FULL area of the sensor, OR, to capture a lesser area of the sensor. With a really pixel-dense sensor like the 24MP one in the D7100, using less of the sensor still results in a capture with ample pixel count and of good quality.
 

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