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12-03-2013, 09:30 AM   #1
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Full frame vs 1.5x Crop question at same distance

I was wondering, lets say you were comparing the same 35mm lens(Sigma 1.4 35mm for example) on both full frame(Nikon D600) and a 1.5x APS-C(Nikon D7000).

If you were to photograph a subject at the same distance with both camera bodies, would you be able to replicate the D7000 photo with the D600 by simply cropping the picture in post? If so would the D7000 be sharper then the photo cropped with the D600?



I apologized this being a bit of a loaded question.

12-03-2013, 09:42 AM   #2
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Yes, to both your questions. You'd need to use the D7000 and the D800, for example, which have the same pixel density, to get the exact same final photo.
12-03-2013, 11:17 AM   #3
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I'm curious as to the math behind that. The D600 has 24 mp to the D7000 which has 16 mp. When I was first thinking about this I thought logically since the D7000 has 1.5 crop to it, then it would equal the D600 since 24/16 = 1.5. I know this is a very simplified version and i'm not saying its correct by any means, but could you expand on how the cropping math would work between the different cameras?
12-03-2013, 12:00 PM   #4
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An FF sensor is 1.5 times larger than an APS-C sensor in linear dimension: Both width and height.

Thus, the FF sensor area is 1.5 X 1.5 = 2.25 times larger.

So, you will want to compare with an FF sensor that has 2.25 X 16 Mpx = 36 Mpx and that, as Giklab says, you wil find in a Nikon D800.

12-03-2013, 12:01 PM   #5
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It's about sensor area. (36*24)/(16*24)=2.25. You need to multiply the MP count with that. Don't worry. Been there, done that .
12-03-2013, 02:58 PM   #6
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QuoteOriginally posted by richmondthefish Quote
I was wondering, lets say you were comparing the same 35mm lens(Sigma 1.4 35mm for example) on both full frame(Nikon D600) and a 1.5x APS-C(Nikon D7000).

If you were to photograph a subject at the same distance with both camera bodies, would you be able to replicate the D7000 photo with the D600 by simply cropping the picture in post? If so would the D7000 be sharper then the photo cropped with the D600?


You can crop. The D7000 would be slightly better than the D600 but would be exactly the same as the D800.
01-14-2014, 06:21 PM   #7
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QuoteOriginally posted by richmondthefish Quote
I was wondering, lets say you were comparing the same 35mm lens(Sigma 1.4 35mm for example) on both full frame(Nikon D600) and a 1.5x APS-C(Nikon D7000).

I know your question has been answered. However, your thread title implies you actually want to compare two cameras used at equal distance, not with equal lenses.

And then, you would typically compare a D7100 with 35/1.4 Art with D610 with 50mm/1.8G as both are giving very similiar 24MP images. Same field of view, same noise (ISO set to 2x that of D7100), same depth of field. Both lenses fully resolve their sensor.

Both considerations (cropping from the same lens, using two comparable lenses) are usually combined when reasoning about differences coming from sensor size. Which us why I added this second thought to the discussion.
02-25-2014, 11:57 AM   #8
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QuoteOriginally posted by richmondthefish Quote
I was wondering, lets say you were comparing the same 35mm lens(Sigma 1.4 35mm for example) on both full frame(Nikon D600) and a 1.5x APS-C(Nikon D7000).

If you were to photograph a subject at the same distance with both camera bodies, would you be able to replicate the D7000 photo with the D600 by simply cropping the picture in post? If so would the D7000 be sharper then the photo cropped with the D600?



I apologized this being a bit of a loaded question.
Taking a photo with the same lens from the same spot will always generate the same image. The differnce is that a larger sensor put behind the lens will collect a wider angle of rays. The areas where smaller and larger sensor overlap show the same image.
No image will be sharper assuming that the lens defines sharpness. You may have higher resolution given on the pixel density that's all.

It is so easy to confuse people.

---------- Post added 25-02-14 at 08:00 PM ----------

QuoteOriginally posted by ElJamoquio Quote
You can crop. The D7000 would be slightly better than the D600 but would be exactly the same as the D800.

Wrong answer.

You may have more pixels covering the same area, but why is the image with more pixels any better? Pixel count / resolution and image sharpness are NOT related. This is a typical misconception. HIgher resolution, even the visibility of more details does not mean that the image is sharper!


Last edited by zapp; 02-25-2014 at 12:04 PM.
02-25-2014, 12:13 PM   #9
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QuoteOriginally posted by zapp Quote
Wrong answer.

You may have more pixels covering the same area, but why is the image with more pixels any better? Pixel count / resolution and image sharpness are NOT related. This is a typical misconception. HIgher resolution, even the visibility of more details does not mean that the image is sharper!
A rather old thread, but my answer was and is still correct.

The D800 cropped to the D7000 sensor size will produce the same picture as the D7000. It would be slightly better than the D600 cropped to the D7000 sensor size.
02-25-2014, 12:22 PM   #10
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QuoteOriginally posted by ElJamoquio Quote
A rather old thread, but my answer was and is still correct.

The D800 cropped to the D7000 sensor size will produce the same picture as the D7000. It would be slightly better than the D600 cropped to the D7000 sensor size.
+1

"Pixel count/resolution and sharpness are not related"

wat

Sharpness is the combined effect of contrast and resolution.
02-26-2014, 07:37 PM   #11
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QuoteOriginally posted by falconeye Quote
I know your question has been answered. However, your thread title implies you actually want to compare two cameras used at equal distance, not with equal lenses.

And then, you would typically compare a D7100 with 35/1.4 Art with D610 with 50mm/1.8G as both are giving very similiar 24MP images. Same field of view, same noise (ISO set to 2x that of D7100), same depth of field. Both lenses fully resolve their sensor.

Both considerations (cropping from the same lens, using two comparable lenses) are usually combined when reasoning about differences coming from sensor size. Which us why I added this second thought to the discussion.
Based on the logic, then there is no advantage on FF virtually as the half/one stop low light ISO sensitivity is allievated by one stop higher ISO in FF. Is this true?
02-26-2014, 08:06 PM   #12
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QuoteOriginally posted by starjedi Quote
Based on the logic, then there is no advantage on FF virtually as the half/one stop low light ISO sensitivity is allievated by one stop higher ISO in FF. Is this true?
The SNR will be the same at the same DOF.

In reality there's other advantages to FF.

FF: Cheaper lens. Likely sharper, likely better colors. Possible DOF is narrower, and at that narrow DOF, SNR is better. Etc.
02-26-2014, 08:23 PM   #13
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QuoteOriginally posted by starjedi Quote
Based on the logic, then there is no advantage on FF virtually as the half/one stop low light ISO sensitivity is allievated by one stop higher ISO in FF. Is this true?
In effect: there is no noise advantage if you absolutely have to keep DOF, FOV, and shutter speed the same. (You're starting to understand some basics of equivalence by just asking this question, good job, a lot of folks don;t even get hat far )

Now, if you're willing to accept 1.3 stops less DOF for the same FOV - shutter speed the same - you can get that extra stop less noise. I say 'accept', but in many shooting situations most folks probably don't just accept it, they welcome it - it can bring better subject isolation. (example: 50mm f/2.8 ISO 800 FF vs. 33mm f/2.8 ISO 800 aps-c - same shutter speed and FOV, but the FF image has 1.3 stops less DOF and about a stop less noise (depending on the particular sensor QE.)

Note also that in the first example, where you've stopped down the FF shot to match the aps-c DOF - you've equalized the noise, but you may have another advantage in that you probably are getting a sharper image on FF because the lens is stopped down a bit more.

Example: 50mm f/2.8 ISO 200 on FF ~= 33mm f/1.8 ISO 100 on aps-c. They will have the same FOV, DOF, shutter speed, and noise - but the 50mm will likely be a tad sharper with less CA shown at f/2.8 than the 33 (or 35mm) at f/1.8, lens-dependent of course. In my personal shooting I saw this first hand - I moved from the Nikon 35mm f/1.8G on aps-c to the 50 f/1.8D to be my 'indoor normal' on FF, and when I wasn't taking advantage of the greater subject isolation + less noise (or when I needed more DOF) I was seeing a sharpness advantage - that 50 is just sharper at f/2.8 than the 35 was at f/1.8 (wide-open.)

A big reason I want a Pentax FF is to simply shoot the FA 43ltd on it. I think it would have the perfect FOV, and at f/2.8 & F4 it's just so blisteringly sharp that the images would just pop off the page, with that sharpness on the plane of focus with the slightly different FOV/DOF I was used to seeing with it on aps-c. People talk about 'updating the FA LImiteds' as if that were a necessity, but I'd be more than happy with my old copy of the 43ltd and a 36MP Pentax FF body.

.

Last edited by jsherman999; 02-26-2014 at 08:45 PM.
03-28-2014, 07:10 AM - 1 Like   #14
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This is the kind of thing a lot of people should look at before they get a camera. There are people on the site who should probably be FF shooters, but long story short, this is not the kind of question you should be asking. The goal of APS-c is not to mimic FF. If you want an FF camera, get an FF camera, you can do 90% of what FF does on APS-c, but for many photographers 90% of their work is within that 10%, so it really doesn't matter what APS-c can do, if it can't do what they want.

QuoteQuote:
You may have more pixels covering the same area, but why is the image with more pixels any better? Pixel count / resolution and image sharpness are NOT related. This is a typical misconception. HIgher resolution, even the visibility of more details does not mean that the image is sharper!
I would retract that statement myself unless you're going to post some example images. Unless you're talking about huge number of pixels on a very small sensor where the lens is out resolved by the sensor. On APS-c and FF sensors lenses are a long way from being out-resolved by sensor density, and the statement is completely false. Comparing APS-c and FF , every increase in sensor density has led to an increase in resolution, and every increase in resolution has lead to an increase in apparent sharpness, maybe not the pixel level. But if you take a D800 image and reduce it to K-3 size or D600 size, it will appear to be sharper. I know I argued with Jay on this point, did my test myself, and discovered Jay was right. You have to reduce a D800 image and K-5 image to less than 3800 pixels wide before they start to look similar. If you take a K-3 image and reduce it to K-5 size, it will still appear to be sharper. Many of us have done tests on images to see how this works.... so given that you could be talking about a very small sensor with very high pixel density, you might be right.. the statement is at best very misleading. Especially discussing APS-c and FF, where a D600 image is only marginally better than a D7100 or K-3 image if you aren't talking about control of DoF or noise. Talking APS-c and FF I think we can definitely say MP is the most important factor in the ability to create apparent sharpness.

Last edited by normhead; 03-28-2014 at 07:20 AM.
08-17-2014, 05:46 AM   #15
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QuoteOriginally posted by Giklab Quote
+1

"Pixel count/resolution and sharpness are not related"

wat

Sharpness is the combined effect of contrast and resolution.
No. In this example we only change the sensor. Smapling a signal with higher resolution does not necessarily mean that the results are sharper. We should hope that more MP results in more detail, but this is not a given.
The D800 was replaced by the D810. One improvement was reduction of vibrations. The more pixels you put on a sensor, the more important become camera vibrations. Signal to noise ratio gets worse. Refraction limitations kick in sooner for smaller pixels. The lens needs to be incredibly good.

Last edited by zapp; 08-17-2014 at 05:52 AM.
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