Canon EOS R7 specifications [CR3]

Michael Clark

Now we see through a glass, darkly...
Apr 5, 2016
4,722
2,655
Correct me if I'm wrong with your conversions, but do crop sensors affect a lens Aperture??? would the 100-500mm just turn into a 160-800mm 4.5-7.1?? etc

For exposure you don't need to apply the conversion factor.
For depth of field you do need to apply the conversion factor.

There's no such thing as "true equivalency" when comparing differently sized sensors.
 
  • Like
Reactions: 1 user
Upvote 0

Michael Clark

Now we see through a glass, darkly...
Apr 5, 2016
4,722
2,655
No, they do not. The lens creates an image circle, regarless of what sensor (or if there is a sensor) behind it. That image circle includes the field of view as well as the depth of field.

A FF sensor 'crops' the image circle to a FF sized rectangle. The APSc sensor 'crops' it to an APSc sized rectangle (taking only the middle section of the full image circle of a FF lens). So you're getting a smaller FOV, as if the lens were longer in focal length. The image scale difference, or 'reach' as people like to call it, comes from the higher pixel density that is typical with APSc sensors vs FF sensors. So the Duck is the same physical size in the image circle whether the lens is on FF of APSc. The space around the duck is less on APSC, since it is not capturing as much of the image around the duck (Crop factor). The number of pixels per duck is higher on APSc (typically), meaning the resulting image of the duck when viewed at 300ppi (for example) is larger. This is 'reach' advantage of APSc.

Depth of field in the two images is the same. Where it would change is if you tried to match the FF field of view on an APSc sensor by going to a shorter focal length lens. For example, a 50mm FF image has about the same FOV as a 35mm APSc image. If both are taken at F2.8, the FF will have shallower depth of field, since the thickness of a focal plane at 50mm f/2.8 is thinner than a 35mm f/2.8 lens. If you are using the same lens at the same aperture, the DOF in the resulting image will be the same on both sensors (but the APSc sensor image will show a smaller FOV, as described above).

So on an R7, the effective FOV of the 100-500 is 160-800 (crop factor). The image scale difference ('reach') will be about 50% greater (more pixels per unit area) than an R5. And the DOF will not be affected.

Hopefully that helps.

Brian

DoF changes with increase in enlargement ratio/display size. Take the same exact negative and print both an 8x10 and a 16x20. When viewed from the same distance, the 8x10 will have greater DoF than the 16x20! When you enlarge by a greater factor you also enlarge blur by a greater factor and allow your eye to see blur that was too small to see as blurry at the lower enlargement ratio.

If you're cropping a FF sensor to match an APS-C sensor and display at the same size as you would with the other sensor, then the DoF field will be no different than if you used an APS-C sensor to begin with. But if you view an uncropped FF image at the same display size as an uncropped APS-C image shot with the same focal length from the same distance, the DoF will be different due to the difference in enlargement ratios.
 
  • Like
Reactions: 1 user
Upvote 0
Jul 21, 2010
31,023
12,777
Just an opinion, and we all have them. Everyone is free to disagree.

It seems to me that both Canon and Nikon let the 7DII and D500 replacements get lost in the shuffle in the rush to bring FF mirrorless to market earlier than either had planned because of the surge in Sony's share of the FF camera market from around 2015-2016 on.
Lost in the shuffle? Or an informed decision not to replace them? I suspect that if the 7DIII had merely been ‘lost’ or delayed, the R7 would have been a clear step up from the 7DII in all respects. The fact that it wasn’t suggests Canon‘s knowledge of the market let them to decide not to truly replace the 7DIII.
 
Upvote 0
Jul 21, 2010
31,023
12,777
But if you view an uncropped FF image at the same display size as an uncropped APS-C image shot with the same focal length from the same distance, the DoF will be different due to the difference in enlargement ratios.
More specifically, the DoF from the APS-C image will be shallower than that from the FF image under those conditions. That’s the opposite of the prevailing wisdom that DoF is deeper with APS-C. The latter results when you try to match the framing at a given focal length – to do so, the APS-C camera must be further from the subject and it’s that increased distance that results in deeper DoF.
 
Upvote 0

Michael Clark

Now we see through a glass, darkly...
Apr 5, 2016
4,722
2,655
Lost in the shuffle? Or an informed decision not to replace them? I suspect that if the 7DIII had merely been ‘lost’ or delayed, the R7 would have been a clear step up from the 7DII in all respects. The fact that it wasn’t suggests Canon‘s knowledge of the market let them to decide not to truly replace the 7DIII.

Canon's tendency to split/combine model lines as market conditions evolve over the years (i.e. 50D → 60D + 7D, 1Ds III + 1D IV → 1D X) betrays your (lack of) logic here.

Market conditions, not to mention supply chain issues, in 2022 are not remotely the same as they were in 2016-17 when the decision to accelerate FF MILC development was made.
 
Last edited:
  • Like
Reactions: 1 user
Upvote 0
Jul 21, 2010
31,023
12,777
Canon's tendency to split/combine model lines as market conditions evolve over the years (i.e. 50D → 60D + 7D, 1Ds III + 1D IV → 1D X) betrays your (lack of) logic here.
There’s no lack of logic. Perhaps you merely fail to grasp it. When the 1D X came out, there was much wailing from some 1DsIII owners that the 1D X was not an upgrade for them, and many called for a true successor to the 1DsIII. Canon still hasn’t delivered one.

It certainly appears that the R7 combines the 90D and 7DII lines. That doesn’t mean it’s the successor to the 7DII.

Market conditions, not to mention supply chain issues, in 2022 are not remotely the same as they were in 2016-17 when the decision to accelerate FF MILC development was made.
Indeed. Before 2020, the supply chain constraints didn’t exist. Canon managed to develop and launch several camera bodies during the 5 years prior to 2020. They chose not to develop a 7DIII.
 
Upvote 0

Michael Clark

Now we see through a glass, darkly...
Apr 5, 2016
4,722
2,655
On the R5 (and R3) the UHS-II buffer clears significantly slower than the CF Express card and for those of us using the cameras at their maximum frame rate (20 fps and 30 fps respectively) using the CF Express card is basically mandatory. I use the CF Express as the primary and the camera is set to auto switch cards so the UHS-II slot is only used if CF Express is full. Lastly I use 625 GB CF Express cards so the chance of that is minimal.

Based on those who have held the shutter button down long enough to measure it, by all accounts buffer depth doesn't become a differentiator with the fastest writing UHS-II cards in the R5 until somewhere around 75 frames. YMMV. (Hint: not all UHS-II cards are as fast as the fastest UHS-II cards. Not even all V90 UHS-II cards write as fast as the fastest ones do.)
 
Upvote 0

Michael Clark

Now we see through a glass, darkly...
Apr 5, 2016
4,722
2,655
There’s no lack of logic. Perhaps you merely fail to grasp it. When the 1D X came out, there was much wailing from some 1DsIII owners that the 1D X was not an upgrade for them, and many called for a true successor to the 1DsIII. Canon still hasn’t delivered one.

Canon would not agree with you.

The official press release announcing the 1D X said it unequivocally:

"As the new leader in Canon’s arsenal of professional DSLRs, the EOS-1D X will be a high-speed multimedia juggernaut replacing both the EOS-1Ds Mark III and EOS-1D Mark IV models in Canon’s lineup."

I think Canon gets to decide if specific Canon cameras are replacements/successors of previous ones.
 
  • Like
Reactions: 1 users
Upvote 0

Michael Clark

Now we see through a glass, darkly...
Apr 5, 2016
4,722
2,655
Sorry but nope. Perhaps a bit of confusion on your part.

The aperture is not the image circle. The image circle is measured as the diameter of the circle illuminated by the lens at the image plane (sensor). Since an APS-C sensor is smaller than FF, lenses designed for crop sensors can have smaller image circles, meaning the lens can be designed smaller (but telephoto lens designs have large image circles, so there’s no real point in designing them specifically for a crop sensor).

Aperture is the diameter of the iris diaphragm, f/number is the ratio of the focal length to that diaphragm diameter. Focal length, aperture, and f/number are all intrinsic properties of a lens. They do not change regardless of the size of the sensor behind that lens. An 85mm f/1.2 lens has an iris diaphragm diameter of ~70 mm whether that lens is mounted on an APS-C or full frame camera.

You are correct that f/number is relative, but not that it changes with sensor size. It’s relative to focal length. A 50/1.2 lens will have a smaller Iris diaphragm diameter than an 85/1.2. A 500/7.1 will have about the same size iris diaphragm as an 85/1.2.

Aperture as discussed in camera terms is the relationship of the size of the opening of the aperture blades to the focal length of the lens.


The diameter of the physical iris is not the measurement used to calculate f-number. Entrance pupil size is the measurement used to calculate f-number.

The entrance pupil is the size that the aperture diaphragm appears to be when viewed from along the lens' central optical axis from a distance sufficient to be considered "infinity" (which is based on focal length - the longer the focal length, the further the distance needed to make diverging rays from a point source of light indistinguishable from collimated light rays due to the limits of an optical system).

Any magnification between the physical diaphragm and the front of the lens will affect the size of the entrance pupil as compared to the actual physical size of the aperture diaphragm. For zoom lenses, as the amount of magnification between the iris and front of the lens increases or decreases so does the size of the entrance pupil, even though the actual physical aperture diaphragm is usually unchanged. (There are a few sophisticated designs that do slightly alter the physical diaphragm size, or even have a second diaphragm in the light path - usually to prevent optical aberrations from becoming too bad as the width of the entrance pupil would become to large for the amount of corrective optics incorporated into the lens.)

True constant aperture zoom lenses place all of the change in magnification between the physical aperture diaphragm and the front of the lens. Even most variable aperture lenses place the majority of the change in magnification between the iris and the front of the lens.

Consider a 70-300mm f/4-5.6 zoom lens. At 70mm and f/4 the entrance pupil has a diameter of 17.5mm. At 300mm and f/5.6 the entrance pupil has a diameter of 53.6mm. The physical iris does not enlarge by a factor of ≈3X as the lens is zoomed from 70mm to 300mm. Rather the amount of magnification that takes place between the physical iris and the front of the lens increases by ≈3X while the total magnification of the lens, including that magnification that takes place behind the aperture diaphragm, increases by a factor of ≈4.25X.

Consider an 18-55mm f/3.5-5.6 lens. At 18mm and f/3.5 the entrance pupil has a diameter of ≈5mm. At 55mm and f/5.6 the entrance pupil has a diameter of ≈9.8mm. The physical diaphragm does not expand to double in size between 18mm and 55mm. The size of the entrance pupil does, though, as roughly two-thirds of the ≈3X increase in magnification is applied between the physical diaphragm and the front of the lens.
 
Last edited:
Upvote 0
Jul 21, 2010
31,023
12,777
Based on those who have held the shutter button down long enough to measure it, by all accounts buffer depth doesn't become a differentiator with the fastest writing UHS-II cards in the R5 until somewhere around 75 frames. YMMV. (Hint: not all UHS-II cards are as fast as the fastest UHS-II cards. Not even all V90 UHS-II cards write as fast as the fastest ones do.)
You’re missing the point. The statement was about time to clear the buffer, meaning the lag period after releasing the shutter button following a burst, while the buffer is being written out to the memory card.
 
Upvote 0

Michael Clark

Now we see through a glass, darkly...
Apr 5, 2016
4,722
2,655
All a speed booster does is to put a magnifying glass at the end of your lens and reduce its focal length and f-number by the same amount. You are a nature photographer, so look at it this way. Suppose you take a photo of a square duck with your 400mm f/4 lens and it makes an image of the duck at say a 10mm x 10mm on the sensor, and the square contains say 10 Mpx and a 1000 photons hitting every second. Put a 0.71x speed booster on the lens to make it 284mm f/2.84 lens. The size of the image is now 7.1mm x 7.1mm, and contains only 5 Mpx, but still has 1000 photons/second hitting it. The image is now twice as bright and so you can increase the shutter speed 2x to get the same exposure as before. But, that's no advantage in the signal to noise of the image as you reduce the amount of light captured during the exposure two fold. If you take the speed doubler off you can also double the speed and double the iso and capture the same amount of light during the exposure. In this situation, all the speed doubler is doing for you is to give you a 5 Mpx image instead of a 10 Mpx without any gain of signal to noise. So, if you are reach limited, then the speed doubler is a true disadvantage.

On the other hand, if what you want is a wider field of view, then the speed doubler will do that for you. It is totally misleading to call these things speed doublers, they should be called field of view doublers.

Well, they do also allow one to use a shorter exposure time, which does have implications for moving subjects, especially if shooting straight to JPEG.

You are correct that in terms of "shot" noise caused by the Poisson distribution of photons there is no advantage. Depending on the camera design, though, there could be an advantage due to less "read" noise caused by thermal issues. With mirrorless cameras which keep the sensor powered pretty much all of the time this is moot. For cameras which do not energize the sensor when the shutter is closed this can be an advantage, particularly for long exposure photography.
 
Upvote 0

Michael Clark

Now we see through a glass, darkly...
Apr 5, 2016
4,722
2,655
You’re missing the point. The statement was about time to clear the buffer, meaning the lag period after releasing the shutter button following a burst, while the buffer is being written out to the memory card.

Buffer clearing time is also directly related to the number of frames needing to be written, is it not? If an initial burst only half fills the buffer, it will clear in half the time as an initial burst that fills the buffer. I won't have to wait until those images that half filled the buffer are all written to the card before I can begin another burst.

If the buffer is never filled by not reaching the limits of the buffer, then clearing times are moot except on some very old designs that wouldn't allow one to begin another burst once the shutter button had been released until the buffer was completely clear.

Sure, beginning another burst when there are still images being written reduces how many frames one can add before the buffer is full. But if one never fills the buffer, then the buffer clear time is moot.

Say I have a camera/memory card combo I am using which allows me to shoot a burst of 75 images before the buffer is full and the burst rate bogs down.

Let's then say I shoot a burst of 40 images and release the shutter button. The buffer is a little over one-half full. I then wait a second or two, because of a lull in the action I am shooting, and the buffer is not yet clear but 20 of the 40 images have been written to the card and 20 remain to be written. At that point I can shoot another 55 images at full burst rate before the buffer is full. I won't be limited to only 35 additional images before the buffer is full.
 
Upvote 0

Michael Clark

Now we see through a glass, darkly...
Apr 5, 2016
4,722
2,655
Indeed. Before 2020, the supply chain constraints didn’t exist. Canon managed to develop and launch several camera bodies during the 5 years prior to 2020. They chose not to develop a 7DIII.

They did, however, divert internal human resources to the development of RF lenses and bodies. They even publicly announced doing so on the lens side of things.
 
Upvote 0

unfocused

Photos/Photo Book Reviews: www.thecuriouseye.com
Jul 20, 2010
7,184
5,483
70
Springfield, IL
www.thecuriouseye.com
There’s no lack of logic. Perhaps you merely fail to grasp it. When the 1D X came out, there was much wailing from some 1DsIII owners that the 1D X was not an upgrade for them, and many called for a true successor to the 1DsIII. Canon still hasn’t delivered one.

It certainly appears that the R7 combines the 90D and 7DII lines. That doesn’t mean it’s the successor to the 7DII.
This is one of the goofiest arguments I’ve heard. For months (probably more like years) you’ve argued that Canon would never make a successor to the 7D II. Right up until the day they announced the R7 you were absolutely insistent it wouldn’t happen. Well it happened and now you insist it’s not really a successor to the 7D and that you rather than Canon gets to decide what is and isn’t a successor. Sorry that your ego has been hurt. There is no shame in guessing wrong, but it’s embarrassing to pretend you won the election when you clearly lost.
 
Last edited:
  • Love
  • Haha
Reactions: 2 users
Upvote 0
Canon would not agree with you.

The official press release announcing the 1D X said it unequivocally:

"As the new leader in Canon’s arsenal of professional DSLRs, the EOS-1D X will be a high-speed multimedia juggernaut replacing both the EOS-1Ds Mark III and EOS-1D Mark IV models in Canon’s lineup."

I think Canon gets to decide if specific Canon cameras are replacements/successors of previous ones.
How dare you?! Mr. Neuromancer knows better about Toyotas and Canons lineup than the manufacturers themselves!
 
  • Like
Reactions: 1 users
Upvote 0
Jul 21, 2010
31,023
12,777
Buffer clearing time is also directly related to the number of frames needing to be written, is it not?
It’s mainly about max sustained card write speed, and CFe is faster than the fastest SD.

From the IR review, clearing a full buffer with SD ~3x longer than with CFe (6 vs. 18 s).
 
  • Like
Reactions: 1 user
Upvote 0
Jul 21, 2010
31,023
12,777
This is one of the goofiest arguments I’ve heard. For months (probably more like years) you’ve argued that Canon would never make a successor to the 7D II. Right up until the day they announced the R7 you were absolutely insistent it wouldn’t happen. Well it happened and now you insist it’s not really a successor to the 7D and that you rather than Canon gets to decide what is and isn’t a successor. Sorry that your fragile male ego has been hurt. There is no shame in guessing wrong, but it’s embarrassing to pretend you won the election when you clearly lost.
Thanks, that gave me almost as much of a laugh as your refusal to accept (or inability to grasp) the concept of equivalence.

The R7 looks like a great camera, and I’m pleased for those excited about it. Lower build quality, fewer control options, no grip, that’s not a true successor to the 7DII. It’s like saying the 2022 Corolla is the successor to the 2014 Corolla.

People will tell themselves it is, just like people told themselves the 7-series were baby 1-series bodies. Possibly because of their fragile egos. :ROFLMAO:
 
Upvote 0