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-   -   Canon R5 (https://forums.steves-digicams.com/what-camera-should-i-buy-80/canon-r5-227080/)

miami photographer Jul 10, 2020 8:54 AM

Canon R5
 
I am blown away. I am just wondering what would be the reason NOT to buy this camera...

Any camera shooting 4 or 8 K under $5000?

TCav Jul 11, 2020 8:50 PM

Quote:

Originally Posted by miami photographer (Post 1418354)
I am just wondering what would be the reason NOT to buy this camera...

It's mirrorless!

If that's not enough to dissuade you, allow me to elaborate.

Mirrorless cameras have shorter flange focal distances, so their lenses must bend light more in order to project an image over the entire image sensor. Bending light more has a number of consequences.
  1. It increases the propensity for field curvature (soft corners.)
  2. It increases the propensity for chromatic aberration.
  3. It increases vignetting.
  4. It increases the propensity for distortion.
Producing mirrorless lenses that overcome these shortcomings is possible, but it requires more advanced designs with their associate increased costs. It is true that the last three can be "compensated for" via in-camera processing, with varying degrees of success, but frequently by creating additional image flaws, especially the last two.
But there is no "compensation" for field curvature, and the "compensation" for distortion actually makes the soft corners worse.

Ozzie_Traveller Jul 13, 2020 1:00 AM

G'day TCav

While I look fwd to your posts for their technical content, I am a bit worried here and suspect that your sources of information may have given you some erronious information

May I post some images from my collection - the mirrorless m4/3 Panny G2, and the small sensor Panny FZ-200, each about a decade old. The G2 specifically does not have any (known to me) in-camera software to modify images to remove 'lens / lighting blemishes' and I do not expect the -200 to have any either. My thoughts here are that this technology is found in top-end dSLR bodies more than budget priced equipment

Sample-1 - standard image ... Panny G2 using commercial grade $300 / 14-140mm zoom lens
https://live.staticflickr.com/65535/...2d776a67_b.jpg
Notes- ex camera image, outback Oz, rich in colours but uniform toned sky

Sample-1A - the above image sliced and reversed Left to Right, putting the two outer corners together to view possible vignetting
https://live.staticflickr.com/65535/...6699658e_b.jpg
Notes- I cannot see any vignetting into the corners

Sample-2 - FZ-200 standard image - across back yard, houses and trees in foreground
https://live.staticflickr.com/65535/...8813475a_b.jpg

Sample-2A - the above image sliced and reversed Left to Right, putting the two outer corners together to view possible vignetting
https://live.staticflickr.com/65535/...b16823ce_b.jpg
Notes- I cannot see any vignetting into the corners

Sample-3 - FZ-200 stretched to max zoom (24x / 624mm FF Equiv) - at sporting oval floodlights some 200m distant
https://live.staticflickr.com/65535/...85e26fa1_b.jpg

Sample 3A - a 100% crop looking for Red / Blue CA lines alongside the verticals in the image
https://live.staticflickr.com/65535/...9f90905d_n.jpg
Notes- I am unable to see any Red / Blue lines edging the subject matter

While these cameras & lenses are 'bog standard + commercial grade + budget-priced' items, I would expect people contemplating anything like the R5, R6 or similar units would expect far better quality than shown here ... and yet the images shown here are, in my opinion, as good as any image taken using a traditional dSLR unit

Thoughts??
Phil

TCav Jul 13, 2020 11:26 AM

The 4/3 system was a new design, so there's no way a 1 to 1 comparison can be made the way that 'Full Frame' and APS-C systems permit. In those systems, SLR lenses either cost less or perform better, and frequently both, than equivalent mirrorless lenses.

The shorter flange focal distances, by their very nature, incur more severe chromatic aberration, more severe vignetting, more severe distortion, and more severe field curvature (soft corners). In the absence of better, more expensive lens designs to overcome some or all of these shortcomings, camera manufacturers have resorted to in-camera image processing. While automatic "compensation" for chromatic aberration is relatively straightforward, compensation for vignetting and distortion are not.

Vignetting occurs gradually, but in-camera "compensation" for it occurs in steps, and while that may be adequate for some situations, it imposes a new image flaw for which there is no remedy.

"Compensation" for distortion requires the corners to be manipulated such that lines that should be straight but are curved because of the distortion, are artificially straightened by manipulating the pixels. The result is that the corners are softened even more than would occur from field curvature alone, and there is no compensation for field curvature.

As a result, dSLRs produce higher quality images at lower cost, than do mirrorless cameras.

I'm pleased to learn that you are satisfied with the results you're getting from your 4/3 mirrorless system, but it starts off with a handicap, albeit limited due to the smaller image sensor, that can't be compared with an equivalent dSLR system.

TCav Jul 13, 2020 11:33 AM

In all fairness, miami photographer was excited about the potential video capabilities of the Canon R5, and the handicaps I mentioned would scarcely affect the video quality the way that it would with still images.

TCav Jul 13, 2020 11:37 AM

Another factor in any decision to switch to a mirrorless system is that, while mirrorless cameras are smaller and lighter than equivalent dSLRs, their lenses are just as big and heavy. So the more gear you'll end up owning, the less that advantage will be.

Ozzie_Traveller Jul 13, 2020 5:50 PM

Quote:

Originally Posted by TCav (Post 1418367)
The 4/3 system was a new design, so there's no way a 1 to 1 comparison can be made the way that 'Full Frame' and APS-C systems permit. In those systems, SLR lenses either cost less or perform better, and frequently both, than equivalent mirrorless lenses.

The shorter flange focal distances, by their very nature, incur more severe chromatic aberration, more severe vignetting, more severe distortion, and more severe field curvature (soft corners). In the absence of better, more expensive lens designs to overcome some or all of these shortcomings, camera manufacturers have resorted to in-camera image processing. While automatic "compensation" for chromatic aberration is relatively straightforward, compensation for vignetting and distortion are not.

Vignetting occurs gradually, but in-camera "compensation" for it occurs in steps, and while that may be adequate for some situations, it imposes a new image flaw for which there is no remedy.

"Compensation" for distortion requires the corners to be manipulated such that lines that should be straight but are curved because of the distortion, are artificially straightened by manipulating the pixels. The result is that the corners are softened even more than would occur from field curvature alone, and there is no compensation for field curvature.

As a result, dSLRs produce higher quality images at lower cost, than do mirrorless cameras.

I'm pleased to learn that you are satisfied with the results you're getting from your 4/3 mirrorless system, but it starts off with a handicap, albeit limited due to the smaller image sensor, that can't be compared with an equivalent dSLR system.

G'day mate

I still have concerns regarding your presumptions - so I think we'll just remain friends by 'agreeing to disagree'
If
miamiphotographer wants to do video weddings, so be it :)

Phil

TCav Jul 13, 2020 9:41 PM

Because of the much shorter flange focal distance, mirrorless lenses must bend light more in order to project an image over the entire image sensor.

https://live.staticflickr.com/8575/1...a0b5d988_c.jpgA-Mount vs. E-Mount by Tom, on Flickr

Bending light more increases the propensity for chromatic aberration, vignetting, distortion and field curvature.
  1. Chromatic aberration results from different frequencies of light bending at different rates. If the optics bend light more, the difference at which different frequencies of light are bent will increase.
  2. Vignetting results from less light being projected at the edges and corners of a sensor than are projected in the center. If the optics bend light more, less light will be projected at the edges and corners.
  3. Distortion results from the optics not being able to project a rectilinear image. If the optics bend light more, the distortion will be greater.
  4. Field curvature results from the optics not projecting a flat, or planar image onto the sensor. If the optics bend light more, the field curvature will be greater.
These can all be remedied to a degree with better optics, but that means more complex and more expensive lens designs, but that could be significant. So manufacturers will often resort to the quick fix of compensating for the image flaws, but unfortunately, these compensations often introduce their own image flaws.

pj1974 Jul 14, 2020 5:36 AM

Hi TCav, G'day Ozzie_Traveller, and others! :)

There are many variables associated in the differences between the various "FF" DSLR lens mounts and their corresponding "FF" mirrorless mounts.
Unfortunately some of the arguments presented in this thread ignore a number of the crucial elements.

For example, the comparisons between Sony A-mount vs Sony E-mount does NOT apply to the Canon EF-mount vs Canon RF-mount, because the Canon RF-mount has a larger diameter than the EF-mount (and even moreso for Nikon, which had an even smaller DSLR FX-mount)

So in fact, the exact opposite of the following sentence (from TCav) is true when it comes to the Canon RF mount (which the original post in this thread is about).
"Mirrorless cameras have shorter flange focal distances, so their lenses must bend light more in order to project an image over the entire image sensor. "

That is, Canon mirrorless lenses need to bend LESS light to project over the same (36mm x 24mm) surface area of a "FF" sensor (due to differences in throat size, flange depth, etc.

See this page (text and video) which give a description why RF lenses have some properties that allow them to be better than their EF counterparts.
https://petapixel.com/2019/06/17/can...e-outstanding/

I could go into more detail - e.g. the interplay between the various front, middle and rear lens elements, as well as how the lens-mount throat, the sensor flange distance and sensor technology (light wells, micro-lenses, materials used, sensor coatings, etc) all also play a part.
Here's some more reading - that does indicate that the newer FF mirrorless lenses have more capability than the older FF DSLR lenses.
Does the Lens Mount Matter? | Sans Mirror | Thom Hogan

Regards

PJ

TCav Jul 14, 2020 7:27 AM

Quote:

Originally Posted by pj1974 (Post 1418372)
For example, the comparisons between Sony A-mount vs Sony E-mount does NOT apply to the Canon EF-mount vs Canon RF-mount, because the Canon RF-mount has a larger diameter than the EF-mount (and even moreso for Nikon, which had an even smaller DSLR FX-mount)

So in fact, the exact opposite of the following sentence (from TCav) is true when it comes to the Canon RF mount (which the original post in this thread is about).
"Mirrorless cameras have shorter flange focal distances, so their lenses must bend light more in order to project an image over the entire image sensor. "

That is, Canon mirrorless lenses need to bend LESS light to project over the same (36mm x 24mm) surface area of a "FF" sensor (due to differences in throat size, flange depth, etc.

In fact, the larger throat diameter means that those mirrorless lenses must actually bend light MORE. Light is projected onto the sensor from all directions from the extreme left edge to the extreme right edge. A larger throat meas that the the extreme left edge and the extreme right edge are farther away from each other, so the angle at which light mus bend in order to cover the entire sensor is greater.

This has always been true throughout the history of photography. More primitive optics couldn't project a planar image onto the film, so the lens was kept farther from the film. As optics progressed, and as film became better, imaging surfaces became smaller and smaller, field curvature became less and less significant, so cameras got smaller and smaller.

I freely concede that there are some excellent mirrorless lenses available, but their excellence comes at a significant additional cost. Canon's EF 24-70/2.8 costs $1,600, while their RF 24-70/2.8 costs $2,300. Similarly, Canon's EF 70-200/2.8 costs $1,800 while the RF 70-200/2.8 costs $2,700. Clearly, Canon has made some excellent mirrorless lenses, but they cost significantly more than the dSLR counterparts, in order to produce similar image quality.

My argument is that, in order to satisfy the much higher demands of the shorter flange focal distance, the lenses must overcome the barriers I mentioned in my earlier posts, and correspondingly be much more expensive, or the cameras must do some cheating on their behalf, and often both.

Mirrorless cameras, as a class, require us to, on one hand, pay more, or on the other hand, accept lower image quality. We usually end up somewhere in the middle of that spectrum.


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