So You Wanna See the Difference Between Full Frame and Cropped Sensors?

[Robin Usagani]

Thank god.. i can sleep well now LOL.

 

[Carny]

Thank god.. i can sleep well now LOL.

We both will!

But not together. No matter what kind of dress you're wearing!

 

[WayneF]

....................................DX 50mm.....................................................................FX 50mm...........................

You did not compare them equally. For all things equal, these should be compared as they actually were. The DX image is cropped, specifically it should be shown only 2/3 the size of the FX (which then also makes the same subject be same size), because, the same lens would of course project exactly the same size subject. You did not show that same image projected by the same lens. The DX frame is already seriously cropped (to 2/3 dimensions), and should be shown that way, because the same lens at same distance obviously projects exactly the same image view, no matter which camera.

That is real world. However, you introduced additional magnification changes in one of them.

Here's what you paid admission for..............


....................................DX 35mm.....................................................................FX 50mm...........................

Right that shows it, but you don't mention what it shows (some won't otherwise get it. )
Here you are showing that for any two images showing the same subject at same size (at same aperture, but regardless of focal length or focused distance that is necessary to produce same subject size), then the depth of field is obviously the same. This is very old stuff that has been known for decades.

Format size (film size, like even large 8x10 inch film, or whatever) appears to vary depth of field only because they necessarily use a much longer lens to magnify image to cover the larger film size.


Normal lens focal length for:

Compact camera -varies, around 7 mm
DX - around 30mm.
FX - around 50mm.
8x10 inch film - around 300mm

This lens choice does of course affect depth of field. 300 mm has much less DOF than 7 mm (on any camera body). Sensor size of course typically requires the specific lens. Smaller images do require more enlargement (another factor). But the cropped sensor size itself does nothing - it simply reproduces the image the lens projects on it.

Newbies ought to read up, at Depth of field - Wikipedia, the free encyclopedia

It may be a bit obscure, but it speaks of magnification affecting DOF. Specifically,

"DOF is determined by subject magnification at the film / sensor plane and the selected lens aperture or f-number. For a given f-number, increasing the magnification, either by moving closer to the subject or using a lens of greater focal length, decreases the DOF; decreasing magnification increases DOF. For a given subject magnification, increasing the f-number (decreasing the aperture diameter) increases the DOF; decreasing f-number decreases DOF."

Note it points out that Magnification can be obtained by moving close to subject, or using a longer lens. These are the factors that affect DOF (and aperture).

 

[astroNikon]

This is very old stuff that has been known for decades.

It might have been known for decades
but people ask about it because they haven't known it for decades
it's a learning process for many, some people start without knowing much but only how to push the shutter button.

I found it very helpful myself when I read it last year.

 

[SCraig]

Four-year-old thread. Times have changed.

 

[astroNikon]

Four-year-old thread. Times have changed.

Yeah, my FF switches between Full Frame and Crop by the push of a button and click of a dial.
I can see this real time in seconds ... back and forth. How cool is that

 

[WayneF]

Four-year-old thread. Times have changed.

Oops! I missed that, but you're right, sorry. Something woke me up today, but somehow I managed to get into the wrong thread.

 

[runnah]

FF vs DX is like Quantum physics

If you think you understand quantum physics, you don't understand quantum physics.

 

[vintagesnaps]

Does having watched Quantum Leap count?

I see the difference when I take along a film camera and my digital that isn't FF and shoot the same scene from the same vantage point - I get more stuff in the frame with the film camera. (So I just have to adjust accordingly, plan on a larger field of view with one and smaller with the other.)

It's not rocket science (only quantum physics LOL).

 

[KmH]

Only if you know what the real Quantum Leap actually is?

 

[kundalini]

You did not compare them equally. For all things equal, these should be compared as they actually were. The DX image is cropped, specifically it should be shown only 2/3 the size of the FX (which then also makes the same subject be same size), because, the same lens would of course project exactly the same size subject. You did not show that same image projected by the same lens. The DX frame is already seriously cropped (to 2/3 dimensions), and should be shown that way, because the same lens at same distance obviously projects exactly the same image view, no matter which camera.

That is real world. However, you introduced additional magnification changes in one of them.

Prove it!

Right that shows it, but you don't mention what it shows (some won't otherwise get it. )
Here you are showing that for any two images showing the same subject at same size (at same aperture, but regardless of focal length or focused distance that is necessary to produce same subject size), then the depth of field is obviously the same. This is very old stuff that has been known for decades.

Format size (film size, like even large 8x10 inch film, or whatever) appears to vary depth of field only because they necessarily use a much longer lens to magnify image to cover the larger film size.


Normal lens focal length for:

Compact camera -varies, around 7 mm
DX - around 30mm.
FX - around 50mm.
8x10 inch film - around 300mm

This lens choice does of course affect depth of field. 300 mm has much less DOF than 7 mm (on any camera body). Sensor size of course typically requires the specific lens. Smaller images do require more enlargement (another factor). But the cropped sensor size itself does nothing - it simply reproduces the image the lens projects on it.

Newbies ought to read up, at Depth of field - Wikipedia, the free encyclopedia

It may be a bit obscure, but it speaks of magnification affecting DOF. Specifically,

"DOF is determined by subject magnification at the film / sensor plane and the selected lens aperture or f-number. For a given f-number, increasing the magnification, either by moving closer to the subject or using a lens of greater focal length, decreases the DOF; decreasing magnification increases DOF. For a given subject magnification, increasing the f-number (decreasing the aperture diameter) increases the DOF; decreasing f-number decreases DOF."

Note it points out that Magnification can be obtained by moving close to subject, or using a longer lens. These are the factors that affect DOF (and aperture).

At the time of this post, there was much chatter about DX vs FX and nobody had the balls to demonstrate. The consensus of questions was centered around the most common focal length..... 35mm vs 50mm of each format. If you had read the original post of that thread, there were a couple of coded references that should have been paid attention to. Specifically, "This is a v-e-r-y non-scientific lab results test. " and "(T)his made sense and I did a reshoot..... on a Sunday afternoon, I had nowhere to go, and no chance of driving.......... getting the picture? " . If you can't understand the inferences, then shame on you. The afternoon started like this.....

By the time the post processing was done, there is no doubt I was completely soused. But I will bet a dollar to a doughnut there was very little difference in any re-sizing, because I have a process.

Now I am the first to admit that aberrations are extremely possible, but on that particular day, a decent effort was put forward.


So here's my challenge to you WayneF, do your own bloody study of the DX versus FX with the most common lens choices and post your results to enlighten the masses (or the unwashed multitude, if that is your preference) to prove me wrong. Otherwise, STFU.

This is very old stuff that has been known for decades

Really? Then why is the question still being asked four years on? You can bow your chest out all you like, but until you attempt to fail with examples, your words have very little significance. I look forward to your results.

 

[Braineack]

You did not compare them equally. For all things equal, these should be compared as they actually were. ...That is real world. However, you introduced additional magnification changes in one of them.

Are you looking at the same two pictures as the rest of us?



This is the DX image resized by 1.5x and placed directly over the FX shot. Why would you expect the DX shot taken at the same position as the FX to be the same size? The image size of the FX is 1.5x larger than the DX, so the image size must be scaled to show the effect.

This lens choice does of course affect depth of field. 300 mm has much less DOF than 7 mm (on any camera body). Sensor size of course typically requires the specific lens. Smaller images do require more enlargement (another factor). But the cropped sensor size itself does nothing - it simply reproduces the image the lens projects on it.

If he shot the monkey from 5 feet away at f/.6 with a 50mm lens, he'd have DOF of .67ft.
If he shot the monkey from 20 feet away (4x further) at f/5.6 with a 200mm lens (4x longer), he'd have a DOF of .67ft.

Note it points out that Magnification can be obtained by moving close to subject, or using a longer lens. These are the factors that affect DOF (and aperture).

yes, and this is why people will always say the FX will achieve better DOF--you can stand closer with a longer lens (narrower DOF), and compared to a crop you will get better background magnification coupled with narrower DOF for better bokeh.

It's pretty clear the see the background on the 50mm FX shot has much better bokeh compared to the 35mm DX shot.

 

[astroNikon]

The LENS nor the IMAGE PROJECTION itself does not change on a FF lens (DX specific lenses, which are smaller glass project a smaller image). It's the size of the camera sensor whether it takes a smaller portion of the image, or larger, as demonstrated above .. from what I understand. Thus the small sensor "crops" the FF image.

If he shocked the monkey from 5 feet away at f/.6 with a 50mm lens, he'd have DOF of .67ft.
If he shocked the monkey from 20 feet away (4x further) at f/5.6 with a 200mm lens (4x longer), he'd have a DOF of .67ft.

I think this thread needs to be locked before it really derails

oops, too late

 

[runnah]

Only if you know what the real Quantum Leap actually is?

I just hope the next leap is the leap home.

 

[astroNikon]

Here's another perspective/view to see

This is through a Viewfinder of a d600, which allows one to change between "crop" mode and FullFrame mode.

To the left is the CROP version.
Notice the rectangular square box (drops the entire grid in FX mode). Anything outside of that box will not be in the photo, where as in FF mode then entire image is captured.

Versus on the right the normal look through the viewfinder as FullFrame - I use the grid turned on.

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