mimbu said:

I recommend you stop with the corporate bootlicking before the boot polish gives you cancer.

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You have reached a new low. Cancer kills millions of people each year.

nadroj said:

You bet! Happy to hear you're experiencing the same. I'm over the moon with Sigma lenses on Canon bodies and I am excited for the R7 Mark II because of it. Should be a stunner with the 17-40mm f/1.8 which I adore.

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I'm a bit jealous. I was so excited when the 18-50 f2.8 was announced that I pre-ordered it. I rarely do that, preferring to see what the critics say first. But I had confidence in Sigma, having had several of their DSLR APS-C lenses in the past. But ... I had no inkling that a 17-40mm f1.8 was in the pipeline! I'll spring for one eventually I'm sure. But the R7ii is the first priority.

neuroanatomist said:

I'm not sure that many people really care about equivalence. I certainly don't take a picture with my R1 then try to set up a completely equivalent shot with my M6II.

It's a useful concept to understand, if only to avoid sounding foolish when making comparative statements about different cameras. I've seen many people buy into the idea that there is a free lunch, and that a smaller sensor delivers a smaller, cheaper system with no tradeoffs. For some reason, people stop that line of thought at APS-C (or m4/3 on other forums), but no one seems to carry it forward and believe that an ILC with a P&S-sized sensor would be even better than their APS-C camera body, if their logic was reasonable.

On the flip side, I've seen some FF users treat equivalence as a bludgeon to claim FF cameras are superior, when of course there are good reasons for both formats (and for medium format and P&S cameras, too). As I mentioned above, a system that's smaller, lighter and/or cheaper has meaningful advantages. When packing a carryon for an overnight business trip, it's far easier to pack the M6II, M11-22 and M18-150 in the suitcase than the packing lenses with the corresponding coverage along with the R8. But the shallow DoF you can get with a fast lens, or the wider FoV with a lens like the RF 10-20/4, can't be replicated on a Canon APS-C MILC (at least, I don't think there is a rectilinear 6mm lens for RF-S).

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I think the value of equivalence is to understand the range of capabilities of a given set of equipment, and the relative compromises one makes.

My first FF DSLR was the 5Dii, and I spent a lot of money on a f2.8 trinity. I quickly discovered that unless photography was my one and only objective for the day, I hated carrying it. I much preferred to carry the APS-C DSLRs that I had before and after the 5Dii for everything other than totally dedicated photography. But what's the compromise? Well, a f2.8 lens on an APS-C body gives you about the range of capabilities as shooting no faster than f4.5 on the FF body. You give up that first f-stop and a third for a kit that's easier to carry. That's the type of tradeoff that equivalence helps to clarify.

I've since had a FF mirrorless system with f4 lenses, and don't hate it. That's about my happy place for size vs capability.

In the case of the lens that's the topic of this thread, you give up another stop of light. If you can imagine shooting no faster than f6.3 on FF, it will be about the same as that.

neuroanatomist said:

It doesn’t scale like that, as @AlanF stated. For example, my RF 100-400mm f/8 has a front element of ~50 mm in diameter. 400 mm / 8 = 50 mm. So far so good.

If that relationship scaled across all focal lengths, my RF 10-20mm f/4 would have a front element of ~5 mm in diameter. In fact, its front element is ~60 mm in diameter, larger than that of the 100-400/8.

Lens design matters. The takeaway is that the entrance pupil is at the front element for long telephoto designs, so that becomes the limiting factor in lens diameter. At shorter focal lengths, other factors are limiting.

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Yes. For complex lenses, the entrance pupil may be very different than the front element size. I'm fuzzy on the relationship; this is what Google tells me: "The entrance pupil in a complex lens is determined by imaging the physical aperture stop through all preceding optical elements into object space. It is the virtual or real image of the diaphragm as seen from the front of the lens, defining the cone of light that enters the system."

neuroanatomist said:

For equivalent framing. Focal length is an intrinsic property of a lens, independent of the sensor behind it.

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Of course. And field of view depends on the focal length and the sensor size.

nadroj said:

It does seem like there's something like this going on -- but have you found evidence for it being 30%? I think we're all curious what the backroom deals really are, but I haven't seen any proof yet.

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Someone on YouTube said it. I mean, that's proof, right?

DocInfoSci said:

With the understanding and respect that people who shoot both FF and CF cameras care about equivalency, I think many of the people who purchase a camera will own one at a time.

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I'm not sure that many people really care about equivalence. I certainly don't take a picture with my R1 then try to set up a completely equivalent shot with my M6II.

It's a useful concept to understand, if only to avoid sounding foolish when making comparative statements about different cameras. I've seen many people buy into the idea that there is a free lunch, and that a smaller sensor delivers a smaller, cheaper system with no tradeoffs. For some reason, people stop that line of thought at APS-C (or m4/3 on other forums), but no one seems to carry it forward and believe that an ILC with a P&S-sized sensor would be even better than their APS-C camera body, if their logic was reasonable.

On the flip side, I've seen some FF users treat equivalence as a bludgeon to claim FF cameras are superior, when of course there are good reasons for both formats (and for medium format and P&S cameras, too). As I mentioned above, a system that's smaller, lighter and/or cheaper has meaningful advantages. When packing a carryon for an overnight business trip, it's far easier to pack the M6II, M11-22 and M18-150 in the suitcase than the packing lenses with the corresponding coverage along with the R8. But the shallow DoF you can get with a fast lens, or the wider FoV with a lens like the RF 10-20/4, can't be replicated on a Canon APS-C MILC (at least, I don't think there is a rectilinear 6mm lens for RF-S).

DocInfoSci said:

And if a CF edition is their camera, then this constant aperture zoom (among some of the others available for RF CF) is a rather excellent option as compared to the EF era. I think that this lens will make a lot of CF shooters happy if it can be priced less than $1,500. And obviously (but worth stating anyhow) it would pair well with bookend lenses such as the 14-30 and 55-210. That coverage would make an excellent kit for a new shooter, school teacher, junior park warden, soccer mom, limited income retiree, etc.

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Absolutely. I think more choice is good. But I can also see some reasons why it might not happen.

DocInfoSci said:

If Canon could release a similarly inexpensive CF UWA constant f/4 zoom (same build quality as the 15-70) then coupled with a 70-200 f/4 FF lens Canon will basically have said, relative to the EF era, they're taking these customers seriously. It's certainly better than just the 17-55, which was an almost-nice thought that didn't line up with anything equally serious.

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That may be true. Certainly things trended the other way in DSLR days. The EF-S 17-55/2.8 was a great lens for crop cameras, and never updated. The EF-S 10-22/3.5-4.5 was another excellent lens that was downgraded to the slower EF-S 10-18mm. The 90D was essentially the successor to the 7DII. All of those show that APS-C DSLRs were trending downmarket.

The MILC market is trending up overall, but I'm not sure that fully applies to the APS-C segment. By the numbers, that segment is shrinking pretty substantially. From around 90% in the heyday of DSLRs, last year APS-C MILCs were 63% of the market. So Canon may prefer to avoid making 'too good' a range of lenses and bodies with APS-C sensors, to further drive sales of FF MILCs.

DocInfoSci said:

That stated, the lesson I learned was buy as little CF gear as possible if there's the slightest chance of an upgrade path to FF. Fortunately, I had some smart elders clue me in early into my lens journey.

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My first DSLR was a Rebel T1i/500D, that I replaced with a 7D. I subsequently added a 5DII, and used both side by side until the 1D X delivered both FF and speed, and since then my only APS-C cameras have been M-series for the portability.

The lesson I remembered from shooting film was glass >> body. I skipped the EF-S 18-55mm kit and 50/1.8 that were commonly recommended, and got just the T1i body only. I bought the EF-S 17-55/2.8 and EF 85/1.8 as my starter lenses. The only other EF-S lens that I bought was the EF-S 10-22. I kept both EF-S lenses until I sold the 7D.

rombe3jr said:

Canon wants 30% of the sale price as a fee for anyone using the RF mount. Pay or get sued.

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It does seem like there's something like this going on -- but have you found evidence for it being 30%? I think we're all curious what the backroom deals really are, but I haven't seen any proof yet.

zapper said:

Thanks for the clarification - this helps a lot. I've noticed that the lens corrections appeared to be working despite what I thought the menu was saying. I know that the Sigma Contemporary lenses lean heavily on digital corrections, and the embedded jpegs don't show noticible distortion. It makes sense that the distortion correction is forced on, because it's an integral part of the design of these lenses.

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You bet! Happy to hear you're experiencing the same. I'm over the moon with Sigma lenses on Canon bodies and I am excited for the R7 Mark II because of it. Should be a stunner with the 17-40mm f/1.8 which I adore.

I think if I bought into tele primes at this point I'd switch to RF, but since I have enough nice EF gear as it is I am actually tempted to grab one of these at the end of the year. Just to have one for walk-abouts in the wet autumn weather along the beaches. It does seem well loved by all who speak of it.

Oddly, I don't know anyone in arms reach who owns one for which I could borrow to play with; they have other tele options that I get to play with (and that's also nice). Just a weird wrinkle of circumstance I guess.

I have to laugh at people's aversion to removable tripod collars, though. Yeah, I've heard the horror stories. That's never happened to me or anyone I know, and I really appreciate that I can yank the collars off my 70-200, 300, and 100 macro. When I put the collars on, I tighten the knob...

(Yes. I know. Those who have dumped thousands of dollars onto the ground thanks to a loose collar will flame me. I feel for them. That would truly be terrible. But I still like my removable collars for hand-held parties.)

neuroanatomist said:

Yeah, but that lens only has an 86x zoom ratio, 9.3-800mm (18.6-1600mm with extender). A better 'deal' is the UHD DIGISUPER 122x 4K box lens that is 8.2-1000mm (16.4-2000mm with extender). That one sells for $213K (and @becceric it's 400 g lighter, weighing in at only 26.6 kg).

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Ahh... GAS. And weight savings!
I used to be that way about bicycles.
That lens does make my EF 11-24mm feel like the RF 40mm pancake!

With the understanding and respect that people who shoot both FF and CF cameras care about equivalency, I think many of the people who purchase a camera will own one at a time. And if a CF edition is their camera, then this constant aperture zoom (among some of the others available for RF CF) is a rather excellent option as compared to the EF era. I think that this lens will make a lot of CF shooters happy if it can be priced less than $1,500. And obviously (but worth stating anyhow) it would pair well with bookend lenses such as the 14-30 and 55-210. That coverage would make an excellent kit for a new shooter, school teacher, junior park warden, soccer mom, limited income retiree, etc.

If Canon could release a similarly inexpensive CF UWA constant f/4 zoom (same build quality as the 15-70) then coupled with a 70-200 f/4 FF lens Canon will basically have said, relative to the EF era, they're taking these customers seriously. It's certainly better than just the 17-55, which was an almost-nice thought that didn't line up with anything equally serious.

That stated, the lesson I learned was buy as little CF gear as possible if there's the slightest chance of an upgrade path to FF. Fortunately, I had some smart elders clue me in early into my lens journey.

*IF* this lens has any degree of weather sealing it would solve the lens dilemma I've been struggling with and will be an insta-buy for me. But this is RF-S so I'm fully expecting that it will continue the budget build quality tradition. It will definitely cause me to wait and see whether it pans out before going with another option, though.

Coming from the M43 world I didn't entirely realize how spoiled they are for hiking/travel lenses. All sorts of 24-xx (equivalent) options many with robust build and weather sealing at a range of aperture/size/cost. I'm trying to find 'that lens' for my R7. Maybe I'm over-valuing weather resistance, but being in the dusty SW and having been caught in weather when traveling far too frequently I'm far more comfortable having it. (we got drenched several times on a trip to NZ and the E-M1.2/12-100 came through with aplomb)

The only RF-S lens with any advertisement of splash/dust resistance is the Sigma 17-40 which is probably the most logical choice, but I'm unreasonably annoyed that it's 17 rather than 15 on the wide end. And general hiking/travel really doesn't need F/1.8 so there's a size penalty. I find myself very seriously considering the RF 14-35/4 as it seems the best fit - 22-56 equivalent (maybe even a bit wider if you manually tweak the corrections), L build quality, reportedly great optically even with the corrections (and APS-C avoids the worst of the corrections in the first place); just evaluating whether paying the premium for an FF ultra-wide (albeit a fairly reasonably priced one) is worth it.

A Painted Lady found its way to my garden today.
R5II + 100-500 + 1.4x extender.

InternalRevenue said:

I somewhat feel the same but 17mm ends up just a little too tight often enough for my video projects that I still kept and use the 15-85 after buying the 17-40, despite the EF-S's many, many quirks and deficiencies for video use. The closeup IQ and MFD isn't that great on the Sigma either, and if Canon manages to get as good a MFD/magnification ratio on this thing like they did with the RF-S 18-150, I might just spring for this 15-70 (or buy it bundled with the R7ii if offered).

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Yeah, even on in the 10D says, 17 was tight. But the standard "kit" lens 18 was even tighter. And for all the concerns about deficiencies, its f/4 aperture was pretty useful. F/2.8 would have been better, but the 16-35 f/2.8 at the time was really not quite as good a lens. it had some really crazy flare issues.

Canon wants 30% of the sale price as a fee for anyone using the RF mount. Pay or get sued.

phree_ed said:

How I would have liked a replacement to the 15-85 for my R7 but sorry Canon - too late. I got tired of waiting and just three days ago picked up a Sigma 17-40 f1.8.

Yeah I know it's only 40mm at the long end but I've got it and I won't be stuffing around selling it and purchasing another lens.

But never say never I guess

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I somewhat feel the same but 17mm ends up just a little too tight often enough for my video projects that I still kept and use the 15-85 after buying the 17-40, despite the EF-S's many, many quirks and deficiencies for video use. The closeup IQ and MFD isn't that great on the Sigma either, and if Canon manages to get as good a MFD/magnification ratio on this thing like they did with the RF-S 18-150, I might just spring for this 15-70 (or buy it bundled with the R7ii if offered).

phree_ed said:

How I would have liked a replacement to the 15-85 for my R7 but sorry Canon - too late. I got tired of waiting and just three days ago picked up a Sigma 17-40 f1.8.

Yeah I know it's only 40mm at the long end but I've got it and I won't be stuffing around selling it and purchasing another lens.

But never say never I guess

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I used the Canon 17-40 f/4L on my 10D and 30D cameras back in the day. At the time, it was about the sharpest ultra-wide Canon had, with some very rich colors and great contrast. 40 is a little bit short, but that Sigma f/1.8 has the potential to be a real gem.

This supposed RF-s 15-70 F4 is a lens I would have gladly bought to upgrade from the EF-s 18-135 and update the EF-s 15-85.

Both are variable apertures of 3.5 - 5.6 so a constant aperture at 4 is nice.
I don't find realistic to expect such a wide range of focal length to offer F2.8 unless it's a L lens and totally not the same package of size and price (and ultimately audience)

The lack of such a lens made me upgrade to FF format but I'm glad some stuff is finally happening to the APSC side

zapper said:

Right, if D = f/N, (D=entrance pupil, f=focal length, N=f number) and f and N both are scaled by the same crop factor for an equivalent focal length and aperture, then D is the same for a FF and equivalent APS-C lens. And the diameter of the lenses is the biggest factor in weight.

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It doesn’t scale like that, as @AlanF stated. For example, my RF 100-400mm f/8 has a front element of ~50 mm in diameter. 400 mm / 8 = 50 mm. So far so good.

If that relationship scaled across all focal lengths, my RF 10-20mm f/4 would have a front element of ~5 mm in diameter. In fact, its front element is ~60 mm in diameter, larger than that of the 100-400/8.

Lens design matters. The takeaway is that the entrance pupil is at the front element for long telephoto designs, so that becomes the limiting factor in lens diameter. At shorter focal lengths, other factors are limiting.

However, since f does scale down for APS-C, that equivalent lens will be shorter, which should yield some saving in the length dimension and weight too.

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For equivalent framing. Focal length is an intrinsic property of a lens, independent of the sensor behind it.

nadroj said:

I did quite a bit of research on this when I bought the Sigma 17-40mm f/1.8 and while it's difficult to find solid answers, what I found seemed to indicate:

• "Not available with the attached lens" for distortion correction is actually because it's force to be ON, similar to many Canon recent lenses. It's a very confusing message because it seems like it's off, but from what I read (and have experienced), it's actually on.
• "Cannot correct - no data" for Digital Lens Optimizer is actually OFF because Canon does not provide the physics mapping provided for these more advanced corrections (which include diffraction, low-pass filter blur, and more specific optical aberrations).
• Peripheral illumination and Chromatic Aberration corrections are ON for the Sigma lenses (not sure which menu this option this is covered under, but it seems to work).

My experience with the Sigma 17-40mm f/1.8 has reflected those findings, the JPEGs seem to be very well-corrected. Why Canon has made the menu so confusing, I'm not sure. I can't speak to Contemporary Sigma lenses that may need more advanced corrections and could benefit from the DLO mapping, but the 17-40 is beautifully corrected with the available correction profiles.

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Thanks for the clarification - this helps a lot. I've noticed that the lens corrections appeared to be working despite what I thought the menu was saying. I know that the Sigma Contemporary lenses lean heavily on digital corrections, and the embedded jpegs don't show noticible distortion. It makes sense that the distortion correction is forced on, because it's an integral part of the design of these lenses.

How I would have liked a replacement to the 15-85 for my R7 but sorry Canon - too late. I got tired of waiting and just three days ago picked up a Sigma 17-40 f1.8.

Yeah I know it's only 40mm at the long end but I've got it and I won't be stuffing around selling it and purchasing another lens.

But never say never I guess

AlanF said:

The crucial point in these discussions is as follows. Above a certain focal length, 50-100mm or so, the natural image diameter of a simple lens is larger, or as the focal length increases, many times larger than the diameter of the circle required to cover a full frame sensor. So, a lens for sensors smaller than full frame will also cover full frame, and the lens cannot be made smaller just to have a smaller diameter for crop, M4/3 etc. Conversely, for shorter focal length lenses, the natural image circle of a simple lens becomes smaller than required to cover the full frame and so clever optics with complex elements is required to expand effectively the image circle. The smaller the sensor, the easier it is to make a lens to cover its image circle. The comparison is not a "Not a strict apple to apples..." but is a quite different situation.

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But no commercial lens is a simple lens. In a complex lens, the size of the rear and intermediate elements can scale with sensor size, as these elements determine the image circle, not the front elements that set the entrance pupil.

15-70 f/4 would be a great video lens for me - especially when it is equipped with motorized zoom (PZ). Could "replace" the cinema lens with 18-80 range for simple applications.
I always wanted a 15-60 f/4 with high correction - if this lens has it, might be a replacement for my RF-S 24-105.

neuroanatomist said:

Indeed, there is a size/weight advantage when designing lenses for a smaller sensor for focal lengths in the ultrawide, wide, normal and short/mid telephoto ranges. But at longer focal lengths, there is no advantage to designing lenses for a smaller sensor.

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Right, if D = f/N, (D=entrance pupil, f=focal length, N=f number) and f and N both are scaled by the same crop factor for an equivalent focal length and aperture, then D is the same for a FF and equivalent APS-C lens. And the diameter of the lenses is the biggest factor in weight. However, since f does scale down for APS-C, that equivalent lens will be shorter, which should yield some saving in the length dimension and weight too.

neuroanatomist said:

The main advantages of crop over FF are that the former can yield a system that is smaller, lighter and cheaper. Those are definitely tangible and significant benefits. Higher pixel density can be another one, for some use cases. But FF systems generally offer better image quality in many settings, and more control over DoF when wanted (try finding an APS-C lens to match the framing and DoF of an 85mm f/1.2 lens on FF).

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I agree. I have a FF Nikon (Z7), which is what I use when I want top image quality. Especially when I can use a tripod and use the base ISO of 80, the IQ is top notch. I don't have any f/1.2 lenses though - I'm not really into super short DOF. The R7 makes a great birding camera, due to high pixels density, as you mention, and a great lightweight travel camera with limited financial exposure should some low life steal it.