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Old Jul 17, 2020, 8:07 AM   #11
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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.
Actually, you're wrong, TCav. The light is bent LESS in mirrorless / RF lenses, than in DSLR / EF lenses. This IS the case, despite your repeated erroneous claims to the contrary.

As I wrote above, it's not just the throat diameter, there are a number of other aspects that come into play, e.g. the flange depth and so on. These all interact with each other. Simply quoting (as you do) "throat depth" shows you don't understand the intricacies of lens and mount design.

Did you view the video that I linked in my previous post? That video, and other resources clearly show that the larger rear optic elements possible with the RF mount now allow for straighter light transmission, compared to the EF mount.
Have you also researched other resources that point this fact out? (I can supply more, but you haven't engaged with the video or web page I referenced).

The cost increase of some RF lenses compared to their 'equivalent' EF is due to a number of aspects:
a) the shrinking market for photography demand and supply (several newer EF lenses are more expensive than their 'older / earlier version EF' counterparts, too!
b) recovery of new R&D costs on these new lenses (which means new lens types will be a premium for a while.. .the same occurred when e.g. Canon introduced EF - instead of FD lenses / mounts). In time the RF equivalents will reduce in time
c) inflation and other global market forces (again, recent / newer EF lenses are more expensive than their 'older / earlier version EF' counterparts, too!
d) each Canon RF lens has (at least!) 4 things in addition to their EF counterpart, 3 of these 4 are new 'in common' features to all RF lenses
i) common new RF feature #1 = a control ring
ii) common new RF feature/s #2 = newer and much faster electronics as well as communication protocol in the lens compared to any EF lens
iii) common new RF feature #3 is superior optics, sharpness in centre, at edges, colours are better in most cases and improved microcontrast, etc.
e.g. 1. the RF 24-70mm f/2.8 has IS (the EF 24-70mm f/2.8 doesn't have IS)
e.g. 2 the RF 70-200mm f/2.8 IS USM is much more compact design than the EF 70-200mm f/2.8 IS USM

I am hoping that my above information will help enlighten you. Regards. Peace.

PJ
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Old Jul 17, 2020, 3:18 PM   #12
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Simply quoting (as you do) "throat depth" shows you don't understand the intricacies of lens and mount design.
I didn't quote "throat depth". You did.

The entire lens gathers light for the entire sensor. That is, the left side of the lens doesn't just collect light for the right side of the sensor and the right side of the lens doesn't just collect light for the left side of the sensor. If you mask off the left side of the exit pupil, the entire image gets dimmer, not just some portion of it. So light from the extreme left edge of the exit pupil is just as necessary to properly illuminate the sensor as light from the extreme right edge. So:
  1. The farther apart the left and right edges of the exit pupil are, the more the lens must bend light in order to project light onto the entire sensor.
  2. The farther apart the left and right edges of the sensor are, the more the lens must bend light in order to project light onto the entire sensor.
  3. The closer the sensor is to to the exit pupil, the more the lens must bend light in order to project light onto the entire sensor.
Why Mirrorless is a bad idea by Tom, on FlickrSimple geometry.
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Last edited by TCav; Jul 17, 2020 at 10:30 PM. Reason: Add graphic
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Old Jul 17, 2020, 11:35 PM   #13
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I didn't quote "throat depth". You did.

The entire lens gathers light for the entire sensor. That is, the left side of the lens doesn't just collect light for the right side of the sensor and the right side of the lens doesn't just collect light for the left side of the sensor. If you mask off the left side of the exit pupil, the entire image gets dimmer, not just some portion of it. So light from the extreme left edge of the exit pupil is just as necessary to properly illuminate the sensor as light from the extreme right edge. So:
  1. The farther apart the left and right edges of the exit pupil are, the more the lens must bend light in order to project light onto the entire sensor.
  2. The farther apart the left and right edges of the sensor are, the more the lens must bend light in order to project light onto the entire sensor.
  3. The closer the sensor is to to the exit pupil, the more the lens must bend light in order to project light onto the entire sensor.

|Simple geometry.
Yes, it's simple geometry, but you have your geometry wrong.

Because NONE of the above 6 scenarios captures the situation I am talking about, i.e. the comparison between 2 systems where the newer throat diameter is larger, AND the flange distance is shorter for the SAME size sensor compared to the older system.

Why can't you see that, TCav? The above 6 scenarios you list do not depict the case that has been in discussion during this thread, i.e. EF mount to RF mount?
(My apologies I once mistyped 'throat depth' which you quoted above- when I meant "throat diameter" in that instance).

Light has to come from various angles in/ through and from the lens (from both sides of the lens to both sides of the sensor). The geometrical diagrams you have shown in this thread do not depict this accurately.

My point (and that of others) all along has been there is a complex interplay between lens design (including especially the max possible size of the rear element), and the aspects of the mount, particularly the throat diameters and then the flange distance as well as sensor size...
You are ignoring the interplay between these three, and erroneously simplifying the situation and thus coming to your wrong conclusions.

The majority of mirrorless (including Canon, especially Nikon, and most others) have INCREASED the possibility to make higher quality lenses, which we are seeing with the Canon RF lenses (as well as the Nikon Z mount lenses).
(again, I need to point out to you that the Sony is the odd one out - it is a shame they didn't use a larger mount/throat diameters, or they would have been able to produce even higher quality lenses than they already do (and their mirrorless lenses are already stunning).

Here is yet another resource that shows that mirrorless lenses and mounts allow higher quality lenses (which is especially true at the edge of the lens / edge of the sensor).
https://photographylife.com/what-is-lens-mount

Contained in the above article is a 9 minute video from a Nikon engineer (he also uses several diagrams to explain it to you.). If you want to argue the point, why not take it up with Nikon (or Canon, and others)?

In addition, here's a quote from the text in that above article too:
"Lastly, the throat diameter combined with flange distance determines the maximum possible angle of incidence of the marginal rays from the lens, which is important in designing lenses generally, the larger the angle of incidence, the easier it is to make high-performance lenses"

Then click the link I am providing below, to jump directly to the table in the article above, which compares the various lens mounts (both DSLR and mirrorless for most common manufacturers).
You can see that the max angle of incidence is higher in mirrorless lens/mount systems compared to DSLR lenses / mounts, so the mirrorless FF allows BETTER transmission of light.
https://photographylife.com/what-is-...unt-comparison

As I said above, the light is actually bent LESS in mirrorless systems (because of the interplay between the various aspects of lens design, throat diameter, flange distance and sensor size.

Again, I refer you to the 2 previous resources which say the same as the above. You have not engaged with neither of these articles.

https://petapixel.com/2019/06/17/can...e-outstanding/

Does the Lens Mount Matter? | Sans Mirror | Thom Hogan

i hope you will be able to learn something new through this discussion.

Regards

PJ
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Old Jul 18, 2020, 12:59 PM   #14
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A larger throat diameter permits a larger exit pupil.

A larger exit pupil means the lens has to bend light more. I covered that.

A shorter flange focal distance means the lens has to bend light more. I covered that.

So a larger throat diameter AND a shorter flange focal distance means the lens has to bend light A LOT MORE.

Bending light increases the propensity for field curvature, distortion, vignetting and chromatic aberration.

To overcome those propensities requires better, more complex, and more expensive lenses, in-camera cheating, or both.

Right?
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Old Jul 18, 2020, 8:08 PM   #15
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Meanwhile, in the real world, photographers are producing stunning images and videos using mirrorless cameras from a variety of manufacturers.

Mike
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Old Jul 19, 2020, 2:14 PM   #16
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Meanwhile, in the real world, photographers are producing stunning images and videos using mirrorless cameras from a variety of manufacturers.
Meanwhile, in the real world, photographers are producing stunning images and videos using smartphones. What's your point?
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Old Jul 19, 2020, 6:46 PM   #17
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Okay fellas - enough

I think that this debate has no easy solution and if we sit back for a moment we will realise that there are many types of camera out there along with many styles of photographer

I would suggest that we get back to our personal choice of equipment and go out and use it - esp as the weather is 'on-the-move' and 'times are a-changing'

Phil
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Old Jul 20, 2020, 8:30 AM   #18
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I'm still waiting for an answer to my question.

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Right?
That might be an easy solution to this debate.
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