[Mikesul]

I am always suspicious when a user with very few posts begins with what is notorious for being a contentious topic. Why would a new user assume that people on the new board are unaware of the issue?

[flaviopetrone]

I am always suspicious when a user with very few posts begins with what is notorious for being a contentious topic. Why would a new user assume that people on the new board are unaware of the issue?

I am absolutely agree with you.
Usually these kind of topics from new users are just created to create flames.

[redcat]

crop factors and other technical terms annoy me at first but now I really keep those out of my head and concentrate on shooting, pp and shooting more !

[normhead]

Right now, the highest resolution FF cameras are 36 MP, the highest APS-c are 24 MP. There is absolutely no value in promoting false apologies where you have to bend the real world to fit the analogy. The analogy fits, or you throw it out. If it doesn't fit it's not useful. There is simply more to small sensors verses big sensors than sensors with the same pixel pitch. Since one of the advantages of smaller size sensors is they almost always have a higher pixel counts, talking about different sensors as if that weren't true is completely misleading.

Now if you're talking about a 645z compared to a D810, or a D800 compared to a K-5 series camera you're talking pretty close. But even then you can't just say one is an effective crop of the other.

Other factors that are relevant
Lens size - if you shoot from the same spot, you're using a wider lens on the APS_c and you'll have more DoF.
Distance - If you use the same lens but back up, you will also have more DoF with the smaller sensor
Magnification - If you blow a smaller sensor up to the same size as the larger sensor you must magnify it more. The effects of such magnification are problematic, and the magnification will create different results depending on where the subject is within the DOF, and the size of the circles of confusion.

What leads to confusion is simplifying a very complex subject to one false analogy and trying to fool people into thinking that means something. The more informed person is going to be saying "that hardly tells the whole story, or sheds any light on how the crop factor applies to photography.

Essentially in your analogy, you're assuming same pixel density, same lens, you're just cutting out the middle of the Medium Format sensor to create a smaller image. In which case the crop sensor image would be a small subset of the total image of the Medium Format sensor. And the FF sensor is just as much a crop sensor as the APS_c sensor is. IN real life, no one shoots like that. One backs up, or uses a wider lens. If the Medium Format image is the perfect frame, then lenses and distances will be manipulated with APS-c or Full Frame, to create the same field of view.

That's why when you look at a D610 image or a K-3 image, they are essentially the same image with some variations of DoF and sometimes some different distortion from the different focal lengths of the lenses. There is no apparent "crop" to the image. But that's the real world. Not some analogy dreamed up to make a point.

D750 vs K-3, "where do I see the crop factor". Can you even tell which is which? Hint the best one with the best contrast and clearest focus is the K-3 (APS-c). Whatever advantages the larger sensor has, clearly are not apparent shooting at 100 ISO, where in this case the APS-c has a slight advantage. Despite all the hogwash about total light, cropped images, blah blah blah, the APS-c image is better. It can happen. Learn to live with it.

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Last edited by normhead; 11-04-2014 at 07:25 PM.

[drypenn]

Right now, the highest resolution FF cameras are 36 MP, the highest APS-c are 24 MP. There is absolutely no value in promoting false apologies where you have to bend the real world to fit the analogy. The analogy fits, or you throw it out. If it doesn't fit it's not useful. There is simply more to small sensors verses big sensors than sensors with the same pixel pitch. Since one of the advantages of smaller size sensors is they almost always have a higher pixel counts, talking about different sensors as if that weren't true is completely misleading.

Now if you're talking about a 645z compared to a D810, or a D800 compared to a K-5 series camera you're talking pretty close. But even then you can't just say one is an effective crop of the other.

Other factors that are relevant
Lens size - if you shoot from the same spot, you're using a wider lens on the APS_c and you'll have more DoF.
Distance - If you use the same lens but back up, you will also have more DoF with the smaller sensor
Magnification - If you blow a smaller sensor up to the same size as the larger sensor you must magnify it more. The effects of such magnification are problematic, and the magnification will create different results depending on where the subject is within the DOF, and the size of the circles of confusion.

What leads to confusion is simplifying a very complex subject to one false analogy and trying to fool people into thinking that means something. The more informed person is going to be saying "that hardly tells the whole story, or sheds any light on how the crop factor applies to photography.

Essentially in your analogy, you're assuming same pixel density, same lens, you're just cutting out the middle of the Medium Format sensor to create a smaller image. In which case the crop sensor image would be a small subset of the total image of the Medium Format sensor. And the FF sensor is just as much a crop sensor as the APS_c sensor is. IN real life, no one shoots like that. One backs up, or uses a wider lens. If the Medium Format image is the perfect frame, then lenses and distances will be manipulated with APS-c or Full Frame, to create the same field of view.

That's why when you look at a D610 image or a K-3 image, they are essentially the same image with some variations of DoF and sometimes some different distortion from the different focal lengths of the lenses. There is no apparent "crop" to the image. But that's the real world. Not some analogy dreamed up to make a point.

D750 vs K-3, "where do I see the crop factor". Can you even tell which is which? Hint the best one with the best contrast and clearest focus is the K-3 (APS-c). Whatever advantages the larger sensor has, clearly are not apparent shooting at 100 ISO, where in this case the APS-c has a slight advantage. Despite all the hogwash about total light, cropped images, blah blah blah, the APS-c image is better. It can happen. Learn to live with it.

@Normhead

This is a very informative lecture for a technical-dimwit like me!

Now I know how my audience feels when I talk about interest rates, compounding, and other financial subjects!

Liked!

[bossa]

I'm just trying to point out that a smaller sensor means a smaller field-of-view and not increased focal length. E.g. if you want to photograph birds, would you use a smaller sensor instead of a longer focal length lens ? Instantaneous reolution, which is equal to the pixel size divided by the focal length is not improved by having a smaller sensor (with less pixels). This is called IFOV and it is what determines the sharpness of the picture (in addition to lens quality).

Anyway, full frame sensors are becoming available and this discussion will become meaningless (I hope) !

---------- Post added 11-04-14 at 02:14 PM ----------


My apologies ! Think about it this way. Suppose you took the sensor in your DSLR and put tape over on half of it, so you only got half the field-of-view.
Is this the equivalent of doubling the focal length of your lens ? Could you double the distance from your subject and still get the same quality ?

No. Hope this helps.

You really do get extra reach, but it's not directly because of the camera or the lens, it's because of the output standards we use that are calibrated to the scale of the human body. We "always" magnify an APS-C camera output by exactly 1.5x more when compared to a full frame due to viewing conventions and/or printing standards.

[normhead]

You really do get extra reach, but it's not directly because of the camera or the lens, it's because of the output standards we use that are calibrated to the scale of the human body. We "always" magnify an APS-C camera output by exactly 1.5x more when compared to a full frame due to viewing conventions and/or printing standards.

Lets say the subject of the frame, a book page for example, fills the APS-crop area of a D800. It will be 15 MP. We have the 400 mm lens mounted on a tripod and the book is 30 or 40 feet away. At 15 MP the page as captured by the camera is approx. 5 thousand pixels across and has a lw/ph of approx. 2200. Take the FF camera off the back of the lens, put an APS-c 24 MP camera on it, and your image is now 6000 pixels wide and 2500 lw/ph. Your image is larger in that it has more pixels, and it has more resolution.

There really are more pixels and more resolution with the APS-c. And that's using a D800. With a 24 MP FF camera, you'd be looking at 4000 pixels wide and probably an extra 50% more resolution going to APS-c, within the area of the crop. The only way to match this resolution APS-c to FF is to go with a longer lens on the FF.

The extra "reach" is completely measurable, in both pixels, and lw/ph.

[audiobomber]

I do a lot of birding. A 24mp APS-C body is the best system for me, by far, because birding requires heavy cropping. The pixel density of a K-3 means I can crop really hard, and still have enough pixels left for a decent image. As Norm said, with a FF 36mp, my image will be much smaller (low megapixels) after cropping to the same FOV.

[bossa]

Stating that a K-3 has more resolution than a cropped D800 is not the point here as the original post referred to crop factor and FOV.

Obviously the ability to crop deeper into an image, and still retain enough information to satisfy IQ standards at a certain viewing distance, is dependant on pixel-density:noise ratios - I don't believe this was the subject of this discussion.

PS: The highest resolution APS-C is no longer 24MP but the 28MP Samsung which would come out at 63MP in a FF sensor.

[normhead]

When camera companies cite the equivalence of a camera with a small sensor as being euivalent to a 35 mm film camera with a longer focal length they are giving the impression that this is a good thing. It is not. You are NOT gaining resolution. You are simply losing field-of-view.
So the 35mm equvalent really refers to the field of view and not the resolution. For example, the K-3 has an "APS-C' sized sensor which is 23.5 x 15.6 mm. The 35mm film camera is 24 x 36 mm. This is a crop factor of 1.5. It is NOT the equivalent of a 1.5x increase in resolution. It is a 1.5x DECREASE in field-of-view. Take this to an extreme. Suppose a camera has a sensor that is 2.4 mm x 3.6 mm. Would this be the same as having a 10X longer focal length ? I don't think so !

Anyway, sorry for the rant. This is a great forum.

It is NOT the equivalent of a 1.5x increase in resolution.

Within the area of the crop sensor... well yes it is, if as mentioned, for birding where you end up cropping the APS-c image, and cropping a much higher percentage of the FF image, if shot with the same lens. In birding if you do a crop to 75% of the original image, on an FF with the same lens you'd have to crop 50% of the original image, to get the same image, to get the same FoV, and this would also cost 50% of the resolution. The original post is quite simply incorrect, in this instance.

This is so easy to see shooting a few mages and looking at the results, I'm not sure why it's a subject of theoretical discussion. Surely this type of discussion should be the result of someone shooting a few images and discussing their results. Not someone trying to comprehend the theory and throwing their deductions, unsupported by real world examples, right or wrong out for general discussion.

It is much better to use a theory to explain results, than it is to use a theory to predict results, especially if you never follow up and prove you are right in the real world. 99% of the misconception on this forum is from people mis-interpreting theory, and posting without a real world check.

All this dude had to do was set up a 400 mm lens, shoot with a D7100 and a D810 crop the images to the same FoV and compare results. There would have been no need for discussion, and no mis-information. the results would have been obvious. Instead we have pages of folks trying to figure out what he meant. And when you do figure out what he meant, it's misleading.

[BrianR]

A lot of professional photographers use APS-C sensors instead of Full Frame because of the longest focal (1.5 x).
I don't understand why it is supposed that we are "losing" something.

If you mount a FF lens on an APS-C body, every time you click the shutter you are murdering photons by sending them screaming into the side of the mirror box instead of letting them meet their destiny by striking your sensor or film. Sure, if you had no use for those photons anyway since you would have cropped a FF sensor/film afterwards with a piece of tape or scissors or photoshop then let the photonocide continue, it won't impact your photo since you had no use for those energetic little outliers. But let's be honest, a little part of your soul dies every time you do this until you are an empty shell of a photographer, callously discarding light without a shred of remorse. That's what you're losing. I shed a small tear every time I take a picture

[normhead]

If you mount a FF lens on an APS-C body, every time you click the shutter you are murdering photons by sending them screaming into the side of the mirror box instead of letting them meet their destiny by striking your sensor or film. Sure, if you had no use for those photons anyway since you would have cropped a FF sensor/film afterwards with a piece of tape or scissors or photoshop then let the photonocide continue, it won't impact your photo since you had no use for those energetic little outliers. But let's be honest, a little part of your soul dies every time you do this until you are an empty shell of a photographer, callously discarding light without a shred of remorse. That's what you're losing. I shed a small tear every time I take a picture

I feel your pain.... , cropping is like murder, the price of photography is expired photons..expiring in vain, they coulda been contendas

Photons who from the time they left the sun had their little photon hearts set on helping create a classic picture, cut down at the last minute, fractions of an inch from their goal by an oversize lens on a small sensor. Like salmon captured by hungry bears, just before they reach their spawning ground... oh, the injustice of it all.

[audiobomber]

Stating that a K-3 has more resolution than a cropped D800 is not the point here as the original post referred to crop factor and FOV.

Obviously the ability to crop deeper into an image, and still retain enough information to satisfy IQ standards at a certain viewing distance, is dependant on pixel-density:noise ratios - I don't believe this was the subject of this discussion.

It is necessary to consider pixel density in format comparisons, just as it is necessary to consider aperture equivalence. M4/3 shooters always yack about focal length, but many refuse to acknowledge aperture, so they end up ridiculously comparing an m4/3 300mm f4 to a FF 600mm f4.

Incomplete information leads to poor understanding. All parameters must be considered when comparing sensor formats; AOV, DOF, noise, perspective, resolution, technology. Only then can a cogent comparison be made.

If you re-read the original post, the thread starter has no real understanding of resolution. He is confusing resolution with magnification.

[normhead]

It is necessary to consider pixel density in format comparisons, just as it is necessary to consider aperture equivalence. M4/3 shooters always yack about focal length, but many refuse to acknowledge aperture, so they end up ridiculously comparing an m4/3 300mm f4 to a FF 600mm f4.

Incomplete information leads to poor understanding. All parameters must be considered when comparing sensor formats; AOV, DOF, noise, perspective, resolution, technology. Only then can a cogent comparison be made.

Exactly... and for most of us, by the time we understand the topic we study last, we'll have forgotten what we learned about the topic we studied first. Just shoot pictures.

[wizzster]

I feel your pain.... , cropping is like murder, the price of photography is expired photons..expiring in vain, they coulda been contendas

Photons who from the time they left the sun had their little photon hearts set on helping create a classic picture, cut down at the last minute, fractions of an inch from their goal by an oversize lens on a small sensor. Like salmon captured by hungry bears, just before they reach their spawning ground... oh, the injustice of it all.

You are breaking my heart !! Especially for the ones in super dim light that are on a first name basis with the sensor.

---------- Post added 11-05-14 at 10:11 AM ----------

Within the area of the crop sensor... well yes it is, if as mentioned, for birding where you end up cropping the APS-c image, and cropping a much higher percentage of the FF image, if shot with the same lens. In birding if you do a crop to 75% of the original image, on an FF with the same lens you'd have to crop 50% of the original image, to get the same image, to get the same FoV, and this would also cost 50% of the resolution. The original post is quite simply incorrect, in this instance.

This is so easy to see shooting a few mages and looking at the results, I'm not sure why it's a subject of theoretical discussion. Surely this type of discussion should be the result of someone shooting a few images and discussing their results. Not someone trying to comprehend the theory and throwing their deductions, unsupported by real world examples, right or wrong out for general discussion.

It is much better to use a theory to explain results, than it is to use a theory to predict results, especially if you never follow up and prove you are right in the real world. 99% of the misconception on this forum is from people mis-interpreting theory, and posting without a real world check.

All this dude had to do was set up a 400 mm lens, shoot with a D7100 and a D810 crop the images to the same FoV and compare results. There would have been no need for discussion, and no mis-information. the results would have been obvious. Instead we have pages of folks trying to figure out what he meant. And when you do figure out what he meant, it's misleading.

Hi. OK I give up ! I was only trying to say that IMHO, camera and lens manufacturers are misleading people by saying e.g. 50mm lens is euivalent to a 75 mm lens. Tha's all I was trying to say. I was wondering if I am the only bothered by this. You are correct in your statements about needing to consider everything, including pixel density, pixel size, CCD vs CMOS, lens MTF, distoriton, aberrations, etc etc etc.

This is a great forum ! I will now shut up.

BTW, I love my K-3 !!