Regular vs Full frame Cameras
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Fortkentdad
Senior Member
http://nikonites.com/d600-d610/27358-dx-auto-crop.html#post388018
for that "DX Crop Factor" discussion.
for that "DX Crop Factor" discussion.
It depends entirely what he's going to shoot. If he loves shooting birds, FX is fine when he loves a lot of sky too. I have to duct-tape a bird to the tree before I can have it fill my frame. For macro about the same is true, my FX is stuck at 1:1 while my DX goes beyond because of the crop.
For landscape and short range, I won't use anything but the FX.
For landscape and short range, I won't use anything but the FX.
Fairly certain the reproduction ratio of a lens will not change when switched between FX and DX bodies. The distance from mount to sensor would have to be different. We simply get a smaller image from smaller sensor, but still a 1:1 ratio.
Correct. Macro ratios are identical, regardless of the format. If a US quarter is projected onto the film plane/sensor and it measures 0.955" ø, it's 1:1. The format is not relevant.
Whiskeyman
Senior Member
Yes but 1:1 on a crop is magnified with the crop factor (in comparison) the moment you display the shot on a screen. The D3300 and D750 both have 4*6k resolution but 1:1 becomes very different because of the sensor size.
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It's not 'magnified with the crop factor'. It's merely cropped. A DX sensor cannot increase magnification.
Of course it is magnified in comparison. Smaller vs larger sensor at 1:1 using the same resolution. The lens is technically incapable of going beyond 1:1 yet the shot of the D3300 shows a larger subject than the D750. That's the small sensor's advantage when using the same resolution.
Once displayed on a screen, real world sizes no longer matter and are adjusted in relation to the pixel count.
The lens is 1:1, the image on the sensor is 1:1 but the moment the shot is taken, the dimensions of that shot are defined by the Mpix/sensor area. Roughly on my D3300 one millimeter is 250 pixels while on the D750 it is 166. If those are displayed on a computer screen, the millimeter of the D3300 is stretched in comparison and 1:1 becomes larger than the one of the D750.
It would require post-cropping the same area on the D750 and saving that using the same resolution as the D3300 to match both.
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Yes, but then you are not talking about reproduction ratio.
Indeed not. I assumed it was obvious I wasn't but maybe I should have been more specific.
As soon as the shutter closes, the mag/repro ratio is set. You can edit it until the cows come home. If it was 1:1 when it was shot, it's 1:1 forever.
It is 1:1, I don't argue that but 1:1 is meaningless in the world of pixels. It only has meaning until the shutter clicks. After that, size becomes relative. When I compare the shots of both formats, the smaller sensor shows the bigger bug even when they were exactly identical in size before the shutter clicked. In macro, that's the advantage of the DX.
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Yep. That's the 'crop factor' showing up.
Not sure if that would be considered an advantage, though.
Personally in macro I find it an advantage only when going very small. It's the same as with birding. My FX shot is exactly identical to my DX shot but since it uses a smaller portion at the same Mpix, I get more bird. I think that about every shot the FX takes and that requires cropping in post, the DX will do at least similar, if not better if it has the same pixels.
But every shot that is framed as such it doesn't require cropping, the advantage goes to the FX.
BackdoorArts
Senior Member
J-see does that to people.
It's a function of having to be right even when what you're saying is technically incorrect. Because we've gone over this ad nauseum in post after post about crop factors, and have documented until the cows come home that there is no "magnification" of images by a DX sensor. "Magnification" is an optical process that involves the enlarging of something, which does not happen in a DX body. What does happen is that the DX sensor packs more pixels into a smaller area, so while nothing is "magnified", there is a finer grain of light information being captured within the same space.Oh, dammit, let me do this one more time.
A sensor is made up of pixels which are spread out evenly over the entire area. An FX sensor is 36mm x 24mm, which is essentially the same size as a piece of 35mm film, hence the full frame designation. A Nikon DX sensor is 24mm x 16mm. This graphic shoes the relative sizes, with FX area being the full 36x24 box (each box represents 1mm), and the DX area being the white center 24x16 section...
When an images is projected through a full frame lens it covers the entire area.
A FX camera will capture the entire scene, though it does have the ability to shoot in DX Mode. Were it to do the latter it would simply crop out the darker shaded area in-camera. The resulting FX and DX mode images would have identical resolution and the DX image would be a pixel-for-pixel match to the FX image for the common areas. In other words, were you to take the 36x24 FX image and crop out the center portion in Photoshop you would wind up with the exact same image as you would get in DX mode. In plain numbers, a 24 megapixel FX camera uses all 24 million pixels in FX mode, but only around 10.667 million pixels in DX mode.
The thing is that DX sensors are generally not packed full of pixels in the same manner. My D610 is a 24MP FX camera. My D7100 is a 24MP DX camera. Both sensors have 24 million pixels, so it stands to reason that if the DX sensor is that much smaller then those 24 million pixels must also be smaller in order to fit the same number of pixels in a much smaller area.
This is what confuses people like J-See and others. Because when I now use the exact same lens on the DX sensor, the area that would normally be captured by a full frame camera is simply ignored, while the center portion is now captured by 1.5X more pixels than it had been in DX mode on an FX camera...
Nothing is magnified!! If nothing else the opposite happens - pixels are shrunk!! But, the thing is that once the exposure happens, a pixel is a pixel is a pixel and 24 million pixels of light information are equivalent from an amount of information point of view - the fact that the DX sensors are smaller does not matter from an image size perspective (though it does matter in terms of the light information that theycapture - but that's another lecture). So when we compare the two images...
FX Capture:
DX Capture:
...it appears as if the lens used on the DX camera was 1.5x the focal length of the one used on the FX camera. This is where we get Focal Length Equivalence. If both images were shot with the exact same 50mm lens, on the DX camera it looks like it was shot by a 75mm lens - but it wasn't, and more importantly nothing was ever magnified!!
What happened is that the exact same number of pixels were just crammed into a smaller area, yielding a final image of equal resolution, but with a different overall field of view. So yes, the final DX image looks magnified, but absolutely no magnification occurs!!!
Yes, it seems trivial to pick on a term, but dammit, that's what language is about. When you say that "DX magnifies the image" that has a specific meaning in optics, that some sort of manipulation occurs with the bits of light projected from the back of the lens before it reaches the sensor. That's not what happens, so no, it's not magnified. It's merely a smaller portion of the image interpreted at a higher resolution.
So, for the love of God, stop saying it's magnified!!! Why?! Because it's wrong!!!
Now I know you don't care about being wrong when you think you're right - we've been through that before. And what bothers me is that more than that you don't care about misinforming people when you're wrong but think you're right. Well, I do care, because it perpetuates misinformation and ignorance, and God knows we have enough of that.
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That's what magnified means; increase the apparent size. That the original is identical is irrelevant, when compiled as a RAW file, my D3300 shot is magnified relative to my D750 shot since the smaller sensor has as many pixels.
If two would be taking the same shot with a DX and FX using the same lens, all sizes remain identical up to the sensor. If we could see the image projected on the sensor, both their sizes would be identical. Sizes meaning dimension to be clear. A real world meter is as large on my DX sensor as it is on my FX sensor if shooting the same lens at the same distance. That there's "more" shot is besides the point here. But once beyond the sensor, they become relative in size and the LCD on the one cam will show a bigger subject than the other.
That IS magnification.
It's not that different from what a zoom lens does compared to a prime. For both too the subject is identical in size and only by repositioning the one glass in relation to the other, we magnify. We don't magnify the subject, we magnify the image projected on the sensor. Mpix and sensor size fundamentally don't behave differently; the one in relation to the other defines the image projected.
If two would be taking the same shot with a DX and FX using the same lens, all sizes remain identical up to the sensor. If we could see the image projected on the sensor, both their sizes would be identical. Sizes meaning dimension to be clear. A real world meter is as large on my DX sensor as it is on my FX sensor if shooting the same lens at the same distance. That there's "more" shot is besides the point here. But once beyond the sensor, they become relative in size and the LCD on the one cam will show a bigger subject than the other.
That IS magnification.
It's not that different from what a zoom lens does compared to a prime. For both too the subject is identical in size and only by repositioning the one glass in relation to the other, we magnify. We don't magnify the subject, we magnify the image projected on the sensor. Mpix and sensor size fundamentally don't behave differently; the one in relation to the other defines the image projected.
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sonicbuffalo_RIP
Senior Member
Someone needs to see a Dr.
Maybe someone better read what I wrote.
The very reason people prefer DX over FX for birding and macro is that they show more subject in a shot with the same dimensions. If both shoot the same subject at the same distance; how would we call that difference in size of the one subject compared to the other? If not magnified, maybe we should say the duck looks larger, or the other smaller, compared to each other?
Would that be more accurate?
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