Field of view and deceptive advertising
Jan 7, 2018 16:40:18 #
n3eg wrote:
EXCEPT since you're using a smaller portion of the image circle, vignetting will decrease along with corner sharpness being improved.
Yes indeed.
Jan 7, 2018 23:31:03 #
wdross
Loc: Castle Rock, Colorado
woodyd wrote:
Just joined the forum and i'd appreciate some view... (show quote)
The 300mm lense is just that - a 300mm lense. But the angle of view is dependent on sensor size. If I have a tripoded Canon or Nikon with a 300mm lense on it and next to it I have a tripoded Olympus or Panasonic with a 300mm lense on it, the Olympus or Panasonic will not have the same angle of view as the Canon or Nikon. The angle of view that the Canon and Nikon sees is 8° while inches away from their 300mm the Olympus or Panasonic sees an image of 4.1° with their 300mm lense.
Now to get the same angle of view that the Olympus or Panasonic sees (4.1°), what lense has to be mounted on the Canon or Nikon? The answer is a 600mm lense which will provide the same 4° that the 300mm lense is producing for the Olympus or Panasonic. Since 35mm is more or less the photographic standard for the industry, the phrases "equivalent in 35mm terms" and "angle of view equivalent in 35mm terms" were coined not for the focal lengths but for what was seen on the sensor and in the viewfinder.
Jan 7, 2018 23:35:10 #
woodyd wrote:
Just joined the forum and i'd appreciate some view... (show quote)
When I take a picture using a 300mm lens on my crop-sensor camera, then display the picture on my computer monitor, I see exactly what I would see if I had used a 450mm lens on a FF camera; you can describe that however you want to, but that final result is all that concerns me.
Jan 7, 2018 23:40:28 #
wdross
Loc: Castle Rock, Colorado
woodyd wrote:
So am I right or wrong in saying that a FX lens on a DX body gives a smaller field of view which gives the illusion of a bigger image but does not actually magnify the image? As focal length changes so do the characteristics of the lens. An FX lens on a DX body maintains the same characteristics pertaining to its focal length regardless of the size of the sensor?
The best lense for any sensor is the lense designed for that size sensor. And there will be lots of arguments as to how good lenses are that were not designed for that sensor size.
Jan 7, 2018 23:50:04 #
woodyd wrote:
Just joined the forum and i'd appreciate some view... (show quote)
I have always thought there was far too much emphasis put on this. But, it gives folks something to talk about. :-)
Jan 8, 2018 00:58:48 #
HarryBinNC
Loc: Blue Ridge Mtns, No.Carolina, USA
woodyd wrote:
Thank you all for replying to me so promptly. I very much appreciate it. I have read the articles in the links supplied and feel better about it :-)
I still maintain that its deceptive to say that a 300mm FX lens is equivalent to a 450mm on a DX body.
I still maintain that its deceptive to say that a 300mm FX lens is equivalent to a 450mm on a DX body.
I am thinking that you are still a little confused. It is not "deceptive" at all. It is simply a way to describe the RESULT of using a lense on a smaller camera than the lense was originally designed for. Consider a pair of prints of the same subject photographed with the same lens from the same location - one image from a 24Mpx (megapixel) "full frame" and another from a 24Mpx 1.5 "crop" camera. Now, since both cameras' sensors have the same number of pixels in the same 3:2 aspect ratio, you can print both resulting images at 250 dpi and get two same-sized 24" x 16" prints. And guess what? The subject in the print from the "crop" camera will be 1.5 times the size of the subject in the print from the ""full-frame" camera. In other words, the "full-frame" camera would need a lens with a focal length 1.5x times that of the lens on the "crop" camera to print the subject as large as it printed from the "crop" camera. That is why a lot of birders really like crop cameras - it is a lot easier to haul around a 400mm lens than the 600mm full-frame "equivalent"!
Jan 8, 2018 05:27:52 #
When I bought my D70 in 2006 (I think) I was also deceived by this, having used a Nikon F2 I was confused by this. I took a bunch of test photos and compared them and found that it was really field of view not "extra free reach".
Jan 8, 2018 05:32:32 #
HarryBinNC wrote:
I am thinking that you are still a little confused... (show quote)
So why wouldn't you just crop the FF photo in PP?
Jan 8, 2018 05:39:27 #
Hank Radt wrote:
So why wouldn't you just crop the FF photo in PP?
If you do the image came from the FF camera only have about 10MP and for the same size print it's only about 100ppi or so.
Jan 8, 2018 06:48:41 #
Jan 8, 2018 07:19:36 #
I have a Nikon P900 that Nikon advertises as 83x optical and max 2000mm equivalent. I see nothing deceptive about their description although the 35mm equivalent is 4.3-357mm. The DX lenses for my D300 are marked in 35mm equivalence which, I suppose, could be confusing due to the crop factor. I keep an image showing comparative sensor sizes on my iPad to remind me just how small the P900 sensor is but they do manage to pack 16 megapixels on it.
Jan 8, 2018 07:31:16 #
wdross wrote:
The best lense for any sensor is the lense designed for that size sensor. And there will be lots of arguments as to how good lenses are that were not designed for that sensor size.
FX lenses work well on both, but DX, or crop lenses generally only crop cameras. Nothing at all is lost when you use a full frame lens on a crop camera.
Jan 8, 2018 07:36:07 #
HarryBinNC wrote:
I am thinking that you are still a little confused... (show quote)
And, due to the fact that to get to 24x16 on the crop camera image you have to magnify the image 50% more you will see more noise, motion blur, softness and any other flaws in gear or technique than from the full frame image.
Jan 8, 2018 07:41:39 #
ToBoldlyGo
Loc: London U.K.
woodyd wrote:
Boberic I'm not sure I'm with you on this. From what I understand, the longer the focal length of a lens the more it magnifies the subject being viewed. A 35mm lens will not show the fine details of a bird's feathers at a distance whereas a 1000 mm lens will. Of course they also have very different field's of view but there is also a magnification factor involved and what I'm trying to get at is that a cropped sensor does not alter that magnification factor.
Hope this hasn't already been addressed and I missed it, but if you mount the same 1000mm lens on a 24mp full frame camera as a 24mp cropped camera, you will get more image detail of the feathers with the cropped camera. For a bird which is very far away, the cropped camera can be desirable over the full frame one. Many bird images are cropped anyway, and the cropped sensor has more translational information on the bird. This conversation can get interesting when you bring the 850 into it, which if I understand correctly, almost matches or even equals the pixel density of current crop sensor cameras. I stand to be corrected of course.
Jan 8, 2018 07:42:15 #
cdayton wrote:
...The DX lenses for my D300 are marked in 35mm equivalence which, I suppose, could be confusing due to the crop factor....
They aren’t specifically marked in 35mm equivalents, they are marked in actual focal length, as most lenses are.
If they were marked with the 35 equivalent focal length, your 35mm lens would say 52.5mm. (Or whatever you have). I think it would be very confusing if lenses were “dumbed down” and only had the full frame equivalent markings, especially since some people can use both full-frame and I think APS-C lenses on micro 4/3rds cameras.
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