5D III or 7D II?

[JoFT]

• 14mm f2.8 on 5D3 (Samyang) this lens becomes:
• 21mm f2.8 on 7D2
• 35mm f2.0 IS on 5D3 (Canon EF) this lens becomes
• 56mm f2.0 on 7D2
• 85mm f1.4 on 5D3 (Sigma) this lens becomes
• 136mm f1.4 on 7D2

This is not exactly correct. You also have to scale the f number with the crop factor to really get the lens that gives equivalent images. If you scale both the focal length and the f number you keep the absolute diameter of the aperture constant, which is what then gives you the same DOF and the same amount of light per pixel (assuming same pixel count).
This is also the main reason why you have higher noise on APS-C compared to FF at the same ISO. The ISO number is defined using the real (not the equivalent) f number. So what is called ISO 100 on APS-C is equivalent to ISO 100*1.6*1.6=250 on FF from a noise perspective. There might of course be some more differences resulting from more advanced technology in more expensive FF sensors compared to entry level APS-C sensors and better fill factor and less relative tolerances due to the bigger pixel sizes, but this is not the main contribution.
If you are limited by DOF (and shoot stopped down) you will not gain much with a FF sensor compared to APS-C, because you can use an f number which is 1.6 smaller on APS-C and consequently can reduce ISO by a factor of 1.6*1.6=2.5. The main advantage you get is in situations where you are not limited by DOF (or even want extremely shallow DOF) and can use low f numbers on FF which are not reachable equivalently on APS-C. And of course at the ultra ultra short end on APS-C you can get as low as 16mm equivalent (10mm) while on FF you can get to 11mm (canon lenses, non-fisheye), but the problem here is more lens design (and the distance of the back lens element from the sensor) and not so much caused by sensor size.

You are right, Beside the Angle of view there is an influence on the DOF, too. But this is another effect. The noise consideration was new to me. For me noise is related to pixel size: a pixel is a photon counter - and less size means less photons and more deviations and therefore noise....


But the effect is there.. I experienced it in sports photography when the 7D became the perfect solution shooting field hockey in summer outside - using the 28-300mm L-Lens... /Which is 44-480mm on the 7D....


For me this works, especially in combination with my zoom lenses...

 

[chrysoberyl]

• [/size]14mm f2.8 on 5D3 (Samyang) this lens becomes:
• [/size]21mm f2.8 on 7D2
• [/size]35mm f2.0 IS on 5D3 (Canon EF) this lens becomes
• [/size]56mm f2.0 on 7D2
• [/size]85mm f1.4 on 5D3 (Sigma) this lens becomes
• [/size]136mm f1.4 on 7D2

This is not exactly correct. You also have to scale the f number with the crop factor to really get the lens that gives equivalent images. If you scale both the focal length and the f number you keep the absolute diameter of the aperture constant, which is what then gives you the same DOF and the same amount of light per pixel (assuming same pixel count).
This is also the main reason why you have higher noise on APS-C compared to FF at the same ISO. The ISO number is defined using the real (not the equivalent) f number. So what is called ISO 100 on APS-C is equivalent to ISO 100*1.6*1.6=250 on FF from a noise perspective. There might of course be some more differences resulting from more advanced technology in more expensive FF sensors compared to entry level APS-C sensors and better fill factor and less relative tolerances due to the bigger pixel sizes, but this is not the main contribution.
If you are limited by DOF (and shoot stopped down) you will not gain much with a FF sensor compared to APS-C, because you can use an f number which is 1.6 smaller on APS-C and consequently can reduce ISO by a factor of 1.6*1.6=2.5. The main advantage you get is in situations where you are not limited by DOF (or even want extremely shallow DOF) and can use low f numbers on FF which are not reachable equivalently on APS-C. And of course at the ultra ultra short end on APS-C you can get as low as 16mm equivalent (10mm) while on FF you can get to 11mm (canon lenses, non-fisheye), but the problem here is more lens design (and the distance of the back lens element from the sensor) and not so much caused by sensor size.

Wait - what? Thank you; nicely explained. Now I am back to wanting a 5D III.

 

[midluk]

You are right, Beside the Angle of view there is an influence on the DOF, too. But this is another effect.

What gives you the blurry out of focus area is the light that comes through the outer parts of the lens. The bigger the lens diameter, the blurrier it will be. What counts here is the absolute lens diameter not the relative f stop.

The noise consideration was new to me. For me noise is related to pixel size: a pixel is a photon counter - and less size means less photons and more deviations and therefore noise....

Less size means less photons if the illuminance (i.e. photons per area) on the sensor is the same. But if you shrink the sensor and at the same time increase the illuminance to compensate (which you effectively do if you also shrink the focal length by the same factor while keeping the area of the lens constant) you end up with the same number of photons. Assuming no transmission losses all light from the image-visible part of the "world" that reaches the lens area ends up on the sensor. This amount of light is independent of the size of the sensor (if you move the sensor closer to the lens, which you do by decreasing the focal length). If you do not keep the area of the lens constant but also shrink the lens diameter by the same factor (i.e. keep the f stop constant) then you will end up with less photons.
If you do long exposures where dark current becomes important, bigger pixels should even have more noise because the dark current scales with pixel area.

But the effect is there.. I experienced it in sports photography when the 7D became the perfect solution shooting field hockey in summer outside - using the 28-300mm L-Lens... /Which is 44-480mm on the 7D....

Yes, sure. The EF 28–300mm f/3.5–5.6L IS USM on the 7D corresponds to 45-480mm f/5.6-9 on a FF which would be a significantly bigger and heavier lens. On the tele end APS-C can show its advantage.

 

[candc]

• [/size]14mm f2.8 on 5D3 (Samyang) this lens becomes:
• [/size]21mm f2.8 on 7D2
• [/size]35mm f2.0 IS on 5D3 (Canon EF) this lens becomes
• [/size]56mm f2.0 on 7D2
• [/size]85mm f1.4 on 5D3 (Sigma) this lens becomes
• [/size]136mm f1.4 on 7D2

This is not exactly correct. You also have to scale the f number with the crop factor to really get the lens that gives equivalent images. If you scale both the focal length and the f number you keep the absolute diameter of the aperture constant, which is what then gives you the same DOF and the same amount of light per pixel (assuming same pixel count).
This is also the main reason why you have higher noise on APS-C compared to FF at the same ISO. The ISO number is defined using the real (not the equivalent) f number. So what is called ISO 100 on APS-C is equivalent to ISO 100*1.6*1.6=250 on FF from a noise perspective. There might of course be some more differences resulting from more advanced technology in more expensive FF sensors compared to entry level APS-C sensors and better fill factor and less relative tolerances due to the bigger pixel sizes, but this is not the main contribution.
If you are limited by DOF (and shoot stopped down) you will not gain much with a FF sensor compared to APS-C, because you can use an f number which is 1.6 smaller on APS-C and consequently can reduce ISO by a factor of 1.6*1.6=2.5. The main advantage you get is in situations where you are not limited by DOF (or even want extremely shallow DOF) and can use low f numbers on FF which are not reachable equivalently on APS-C. And of course at the ultra ultra short end on APS-C you can get as low as 16mm equivalent (10mm) while on FF you can get to 11mm (canon lenses, non-fisheye), but the problem here is more lens design (and the distance of the back lens element from the sensor) and not so much caused by sensor size.

Wait - what? Thank you; nicely explained. Now I am back to wanting a 5D III.

there is no such thing as iso equivalent. exposure and iso are not related to sensor size. there is equivalent aperture of lenses as they relate to different size sensors but that's only for dof

 

[jeffa4444]

The real difficulty is the burst rate the 5D MKIII is 6fps whereas the 7D MKII is 10. How significant this is only you can tell but aside from that the best compromise is actually the 5DS that has a 5FPS burst mode. It can be cropped to APS-H or APS-C and the noise at high ISO is slightly better than the 7D MKII. It also has a 1/2 stop more up to its maximum ISO although the 7D MKII has a higher maximum ISO rating (which is unsuable).
In all other respects the cameras are very similar with the same metering systems, similar focus points (5DS 61, 7D MKII 65) but the 7D MKII does add more cross type and does have GPS. The 5DS also has the mirror damping which is critical in my book for long exposure shots but not so for BIF.

Then there is the not so insignificant difference in price the 5DS is £ 2999 ($ 3699) whereas the 7D MKII is £ 1299 ($ 1599) over double the price.

The 7D MKII will always inhibit more noise than your 6D simply as a factor of the pixel size, it also has worse IQ at high ISOs but is far better at subject tracking, metering and reach.

 

[JoFT]

You are right, Beside the Angle of view there is an influence on the DOF, too. But this is another effect.

What gives you the blurry out of focus area is the light that comes through the outer parts of the lens. The bigger the lens diameter, the blurrier it will be. What counts here is the absolute lens diameter not the relative f stop.

Nicely explained.... I had to think about this.... Physically you are right - Isn´t that the definition of the f-number of the lens....

The noise consideration was new to me. For me noise is related to pixel size: a pixel is a photon counter - and less size means less photons and more deviations and therefore noise....

Less size means less photons if the illuminance (i.e. photons per area) on the sensor is the same. But if you shrink the sensor and at the same time increase the illuminance to compensate (which you effectively do if you also shrink the focal length by the same factor while keeping the area of the lens constant) you end up with the same number of photons. Assuming no transmission losses all light from the image-visible part of the "world" that reaches the lens area ends up on the sensor. This amount of light is independent of the size of the sensor (if you move the sensor closer to the lens, which you do by decreasing the focal length). If you do not keep the area of the lens constant but also shrink the lens diameter by the same factor (i.e. keep the f stop constant) then you will end up with less photons.
If you do long exposures where dark current becomes important, bigger pixels should even have more noise because the dark current scales with pixel area.

Here I disagree to some extend: I was not talking about sensor size but pixel pitch. My question is how many Photons a pixel can count:

• EOS 7D2: 4,1µ => 16,81µ2
• EOS 5D3: 6,25µ=> 39,06µ2
• This means that each pixel can count ca 2.32 more pixels in the 5D3 against the 7D2

The ISO itself for me is a kind of artificial factor in the game. It is well defined to match film and digital to come to comparable values f.i. on light meters camera settings etc. At the end it is a calibration value set by the camera manufacturer....

But the effect is there.. I experienced it in sports photography when the 7D became the perfect solution shooting field hockey in summer outside - using the 28-300mm L-Lens... /Which is 44-480mm on the 7D....

Yes, sure. The EF 28–300mm f/3.5–5.6L IS USM on the 7D corresponds to 45-480mm f/5.6-9 on a FF which would be a significantly bigger and heavier lens. On the tele end APS-C can show its advantage.

Thank you: this is why it makes sense to carry 2 bodies and 4 lenses instead of 1 body and 8 lenses.....

 

[midluk]

The noise consideration was new to me. For me noise is related to pixel size: a pixel is a photon counter - and less size means less photons and more deviations and therefore noise....

Less size means less photons if the illuminance (i.e. photons per area) on the sensor is the same. But if you shrink the sensor and at the same time increase the illuminance to compensate (which you effectively do if you also shrink the focal length by the same factor while keeping the area of the lens constant) you end up with the same number of photons. Assuming no transmission losses all light from the image-visible part of the "world" that reaches the lens area ends up on the sensor. This amount of light is independent of the size of the sensor (if you move the sensor closer to the lens, which you do by decreasing the focal length). If you do not keep the area of the lens constant but also shrink the lens diameter by the same factor (i.e. keep the f stop constant) then you will end up with less photons.
If you do long exposures where dark current becomes important, bigger pixels should even have more noise because the dark current scales with pixel area.

Here I disagree to some extend: I was not talking about sensor size but pixel pitch. My question is how many Photons a pixel can count:

• EOS 7D2: 4,1µ => 16,81µ2
• EOS 5D3: 6,25µ=> 39,06µ2
• This means that each pixel can count ca 2.32 more photons in the 5D3 against the 7D2

Yes, the full well capacity should indeed change with absolute pixel size. This helps you at low sensor sensitivities (i.e. low ISO). This is consistent with my statement that ISO 100 on APS-C corresponds to an equivalent ISO (the ISO that the light meter gives you when you use the equivalent f number) of 250 on FF. So FF can reach a factor of 2.5 lower ISO. Which of course if you can compensate for lower ISO with a longer exposure or a bigger aperture gives you lower Poisson noise on FF compared to APS-C. As soon as you are above ISO 250 it will give you no advantage, but higher pixel (electrical) capacity (proportional to area) should even increase read noise, because the same number of electrons (caused by photons) in the pixel area cause a voltage that is proportional to the inverse capacity. Bigger pixel size means less voltage and therefore more read noise (relative to the signal).

So to sum up all the points I have stated before:
An image taken with an APS-C camera with focal length f, f-stop N, and ISO s would look exactly the same (including noise level and DOF) as an image taken with a FF camera (same pixel count) and focal length 1.6*f, f-stop 1.6*N and ISO 2.5*s. This is as long as you do not take differences in the fill factor (possible advantage for FF) and differences in the read noise and dark current (disadvantage for FF) into account.

FF has an advantage in areas that APS-C can not reach:
- low (equivalent) ISO (below 250)
- low (equivalent) f-stops at the same equivalent focal lengths
- very low (equivalent) focal lengths
APS-C has an advantage mainly at long focal lengths where you do not have the equivalent focal length available on FF (lens weight, size and cost).
In all other situations where you can take the image at the corresponding equivalent values it does not make much of a difference whether you use APS-C or FF unless there is a significant difference in fill factor or dark current and read noise become important.

The ISO itself for me is a kind of artificial factor in the game. It is well defined to match film and digital to come to comparable values f.i. on light meters camera settings etc. At the end it is a calibration value set by the camera manufacturer....

We are comparing two cameras of the same manufacturer that do not have a huge age difference, so the ISO values should be roughly consistent between the 7D2 and the 5D3.

 

[JoFT]

The noise consideration was new to me. For me noise is related to pixel size: a pixel is a photon counter - and less size means less photons and more deviations and therefore noise....

Less size means less photons if the illuminance (i.e. photons per area) on the sensor is the same. But if you shrink the sensor and at the same time increase the illuminance to compensate (which you effectively do if you also shrink the focal length by the same factor while keeping the area of the lens constant) you end up with the same number of photons. Assuming no transmission losses all light from the image-visible part of the "world" that reaches the lens area ends up on the sensor. This amount of light is independent of the size of the sensor (if you move the sensor closer to the lens, which you do by decreasing the focal length). If you do not keep the area of the lens constant but also shrink the lens diameter by the same factor (i.e. keep the f stop constant) then you will end up with less photons.
If you do long exposures where dark current becomes important, bigger pixels should even have more noise because the dark current scales with pixel area.

Here I disagree to some extend: I was not talking about sensor size but pixel pitch. My question is how many Photons a pixel can count:

• EOS 7D2: 4,1µ => 16,81µ2
• EOS 5D3: 6,25µ=> 39,06µ2
• This means that each pixel can count ca 2.32 more photons in the 5D3 against the 7D2

Yes, the full well capacity should indeed change with absolute pixel size. This helps you at low sensor sensitivities (i.e. low ISO). This is consistent with my statement that ISO 100 on APS-C corresponds to an equivalent ISO (the ISO that the light meter gives you when you use the equivalent f number) of 250 on FF. So FF can reach a factor of 2.5 lower ISO. Which of course if you can compensate for lower ISO with a longer exposure or a bigger aperture gives you lower Poisson noise on FF compared to APS-C. As soon as you are above ISO 250 it will give you no advantage, but higher pixel (electrical) capacity (proportional to area) should even increase read noise, because the same number of electrons (caused by photons) in the pixel area cause a voltage that is proportional to the inverse capacity. Bigger pixel size means less voltage and therefore more read noise (relative to the signal).

So to sum up all the points I have stated before:
An image taken with an APS-C camera with focal length f, f-stop N, and ISO s would look exactly the same (including noise level and DOF) as an image taken with a FF camera (same pixel count) and focal length 1.6*f, f-stop 1.6*N and ISO 2.5*s. This is as long as you do not take differences in the fill factor (possible advantage for FF) and differences in the read noise and dark current (disadvantage for FF) into account.

FF has an advantage in areas that APS-C can not reach:
- low (equivalent) ISO (below 250)
- low (equivalent) f-stops at the same equivalent focal lengths
- very low (equivalent) focal lengths
APS-C has an advantage mainly at long focal lengths where you do not have the equivalent focal length available on FF (lens weight, size and cost).
In all other situations where you can take the image at the corresponding equivalent values it does not make much of a difference whether you use APS-C or FF unless there is a significant difference in fill factor or dark current and read noise become important.

The ISO itself for me is a kind of artificial factor in the game. It is well defined to match film and digital to come to comparable values f.i. on light meters camera settings etc. At the end it is a calibration value set by the camera manufacturer....

We are comparing two cameras of the same manufacturer that do not have a huge age difference, so the ISO values should be roughly consistent between the 7D2 and the 5D3.

Wow, thank you a lot. Are You in the business? from where do you know this??? I could not find this....


What wonders me: I shoot both, and -especially at ISO100 there is no difference in noise visible to me. I can mix both cameras easily - as long as I am below ISO 200....


But pixel size will have an effect on diffraction limits, too, or???

 

[midluk]

Wow, thank you a lot. Are You in the business? from where do you know this??? I could not find this....

No, I'm not in the business, but as an experimental particle physicist I have some experience with light detection. It's mainly a combination of facts I read somewhere in the past. The rest I deduced myself. I'm pretty sure I did not make any big mistakes, but I might have missed something or made some simplifications. So feel free to point to problematic areas in my argumentation. After all I also want to learn something from thinking about it.

What wonders me: I shoot both, and -especially at ISO100 there is no difference in noise visible to me. I can mix both cameras easily - as long as I am below ISO 200....

At ISO 100 (real not equivalent) the main limitation is likely read noise, which might indeed be comparable on both cameras. Absolute read noise (in ADC counts) should be identical for different sized sensors using similar technology. Of course the relation of ADC counts to photon counts will be different for different pixel sizes (and different ISO settings).

But pixel size will have an effect on diffraction limits, too, or???

The diffraction is caused by the edges of the aperture. It's worse the bigger the ratio of edges to total area becomes. So it depends on the absolute size of the aperture. Which again means that equivalent images (everything scaled as above) will also be affected identically by diffraction on APS-C and FF. You are mainly enlarging the diffraction by choosing a larger focal length but compensating for that by the bigger pixels. Of course for a constant sensor size bigger pixels (which means a lower pixel count) will be affected less by diffraction (or more pixels like in the 5DS means diffraction becomes more evident), but this is just the general loss of resolution where at some point the additional loss by diffraction becomes negligible. And of course it you scale only the focal length but not the f number you get less diffraction for FF but this is not caused by the pixel size but by the fact that you change the absolute aperture.

 

[chrysoberyl]

midluk and JoFT: You have made this one of the most education and interesting threads. I cannot express thanks enough.

 

[tomscott]

Having both is a killer combination. My 7DMKII arrives on Friday. ;D

 

[JoFT]

Having both is a killer combination. My 7DMKII arrives on Friday. ;D

Congrats!!! 100% agree!!! killer combo nails it!

 

[JoFT]

midluk and JoFT: You have made this one of the most education and interesting threads. I cannot express thanks enough.

Thank you: I must say: midluk´s explanation have blown me away, positively. and challenged as well. I do not call me an expert in this matter - but same motivation - i want to learn and understand.


Maybe that my demands on "expertness" are a bit higher working with lasers and having a friend who is developing optics since years...

 

[jeffa4444]

The way the pricing has gone on the 7D MKII so quickly I can see Canon canning it in the future and retaining APS-C for consumer DSLRs only. They may well expand the FF cameras that have crop modes and try & retain the higher pricing. The 7D MKII pricing is very similar to the 6D with way more functionality (except wi-fi) and with a 5DS currently 2.5X more expensive with very similar spec except for frame rate & GPS to the 7D MKII and FF sensor to the 5DS.

 

[turbo1168]

The way the pricing has gone on the 7D MKII so quickly I can see Canon canning it in the future and retaining APS-C for consumer DSLRs only. They may well expand the FF cameras that have crop modes and try & retain the higher pricing. The 7D MKII pricing is very similar to the 6D with way more functionality (except wi-fi) and with a 5DS currently 2.5X more expensive with very similar spec except for frame rate & GPS to the 7D MKII and FF sensor to the 5DS.

I don't see much difference in the pricing drop over the first year or 2 in other Canon cameras. 70D, $100 drop first year, another $100 second year. 6D, $250 drop first year, another $100 second year, etc. After the initial big push when released, the pricing gets adjusted to what the market will bear.

 

[unfocused]

The way the pricing has gone on the 7D MKII so quickly I can see Canon canning it in the future and retaining APS-C for consumer DSLRs only. They may well expand the FF cameras that have crop modes and try & retain the higher pricing. The 7D MKII pricing is very similar to the 6D with way more functionality (except wi-fi) and with a 5DS currently 2.5X more expensive with very similar spec except for frame rate & GPS to the 7D MKII and FF sensor to the 5DS.

I don't see much difference in the pricing drop over the first year or 2 in other Canon cameras. 70D, $100 drop first year, another $100 second year. 6D, $250 drop first year, another $100 second year, etc. After the initial big push when released, the pricing gets adjusted to what the market will bear.

I think people get confused over grey market pricing, retailer street pricing and Canon's pricing. The only one that matters to Canon is their own pricing to retailers and we don't know what that is.

If you look at MAP pricing however, the real drop has been in the 6D, which is selling for about 60% of its introductory price. The 7DII is selling for about 80% of its introductory price. Another way to look at it: the 6D began life more expensive than the 7DII and it's now selling for less than the 7DII. Granted the 6D is an older camera, but the key point is that the 7DII has not dropped any more quickly than other cameras. Actually, the 5Ds seems to have fallen further, faster.

People who predict the demise of the 7DII fail to understand how significantly Canon changed the target for this body. The 7DI was a top of the line general purpose camera at a time when the cost of entry into the full frame world was much higher.

With lower cost full-frame cameras (like the 6D) Canon decided to make the 7DII into a niche market camera. It is called the APS-C version of a 1D for a reason. It is very much targeted to sports, wildlife and bird shooters and does that very well. Many buyers of the 7DII are using it as a second body (which is my case) and it is clearly designed to complement the 5D. That doesn't mean it can't be used as one's sole or primary body, just that it also fills a niche that no other body can.

 

[Andreas]

I have a 5Ds for underwater photography, high resolution is great, low fps no issue. 7DM2 for topside for wildlife, where higher speed is advantage paired with a 100-400 lens the crop sensor gives you extra reach and my 5DM3 use more for landscape and underwater too when i wnat to have high resolution topside....advante is that all 3 cameras use the same batteries, same grips, same metering system, very easy and fast to switch from one to another...

 

[turbo1168]

I think people get confused over grey market pricing, retailer street pricing and Canon's pricing. The only one that matters to Canon is their own pricing to retailers and we don't know what that is.

Kind of the point I was trying to make. Market MSRP (USA for example) shows a steady price drop on most any camera body as time goes on. 6D prices dropping so drastically was probably due to the fact that the consumer's didn't purchase them in as high of numbers as Canon projected. Pricing was too high that many could justify purchasing the 5D bodies instead or purchased a crop frame such as the 70D at a lower price point. Simple supply and demand.

 

[Hjalmarg1]

For BIF the 7D2 is hard to beat both for its AF and its crop factor. I would get the 7D2. Plus the 5D3 has a problem with AF illumination in AI servo mode that the 7D2 does not.

+1, this is a terrific combination for BIF

 

[Big_Ant_TV_Media]

WHY DO PEOPLE KEEP PUTTING THE 7D2 AS A SOLELY A SPORTs,WILDLIFE CAMERA IT CAN DO EVERYTHING U NEED IT TOO DO AND MORE ESPECIALLY IF U HAVE THE RIGHT GLASS