A New Constant f/4 Aperture RF-S Zoom Coming

[DocInfoSci]

You are 100% wrong. A speed booster reduces the size of the image circle, as stated by @Bob Howland . If it increased the size, it would spread the light over a larger area and be a speed reducer. A speed booster works by reducing the focal length of a lens.

Building on this response from AlanF, it might be handy if you ready the Metabones white paper on speed boosters. It's quite informative:

The Speed Booster – a New Type of Optical Attachement

You might even notice Metabones states:

[...] since the Speed Booster essentially compresses the image formed by the objective lens into a smaller size it helps to undo the cropping effect.

i.e., in effect the lens is wider relative to the physical actuality from the perspective of the sensor.

 

[DocInfoSci]

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

I think from a standard consumer perspective I'd agree, but if we take the R7 it's pro turf in appropriate contexts. I think in that case bright glass design makes lots of sense, in which case a sealed edition of the 17-55 (or now 15-70) at 2.8 or better would be great just for the normality of the effective perspective range provided that would be much better than simply attaching a copy of the 24-70 or 14-35.

 

[DocInfoSci]

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.

100%

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.

Interesting. I hadn't looked into crop market at all -- once I went full frame I never looked back. As much as I liked the reach of my crop cameras I was never ever satisfied with the noise or the hassle of cleaning it up before sharing anything remotely serious on a family or friends outing at the end of the day around the hotel room or camp site. So, while I miss my reach — I've simply compensated by getting or borrowing or renting longer lenses.

But, that stated, I acknowledge that the crop format let my family buy into the digital game when we were poor graduate students. For interchangeable cameras I wonder if it's the same game? Or is it really just smart phones and then straight to FF. A quick search shows the RP still available for only $1,099 CAD from Henry's. My kiddo was lucky enough to skip the line by inheriting my name brand retired gear.

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.

Memories.

The lesson I remembered from shooting film was glass >> body.

100%. Although another lesson I learned mid-way.

 

[xmarijan]

It would have been better if Canon had chosen a constant f3.5 aperture lens, from a commercial perspective it sounds more appealing than f4, even though the difference is only 1/3 of a stop

 

[swingman]

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

I bought it as well. I took it to Japan with R7. I only took this combo and a very good combo. I am going back next month with the same combo. You will enjoy using this fast zoom morning to night. No swapping

 

[swingman]

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.

Only new comers might be tempted if sold as kit with R7Ii. This is not going to affect Sigma and Tamron sales as they are aimed at a different market segment. Cannon once again slow zooms for APSC cameras. Why?

 

[AlanF]

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.

It is the exit pupil that determines the image circle. The important points that were in in my reply are: that the image circles from the longer telephotos are so large that an APS-C or smaller sensor lenses cannot be made significantly smaller than those for full frame - indeed the lens often has to be baffled to stop the light outside the sensor from bouncing onto the sensor; for wide angle lenses the smaller the sensor the easier it is to make complex lenses to enlarge the circle to cover the sensor - it is cheaper and easier to make a light wide angle lens for crop, however, this is offset to various degrees by needing a wider angle lens to give the same field of view.

On the other hand, at the trade-off of increased noise and increased problems with diffraction, a crop camera with a shorter length telephoto lens can give you the same reach as full frame. As I very frequently crop my FF images to less than APS-C size, the noise problems are the same for both and I am very happy to use APS-C cameras, and have an R7 along with my R5ii.

 

[EOS 4 Life]

Nikon is getting lighter and smaller telephotos reducing image circle and correcting vignetting on processing. Just go further and you have more.

Can you provide an example?
Canon does that on the wide end, but not for telephoto.
If you are referring to Nikon lenses with built-in teleconverters, then those lose a stop of light when the teleconverter is activated.

 

[Maximilian]

An RF-S 15-70mm F4 IS STM sounds interesting. Esp. together with an R7m2.
Would I buy it?
Likely not. I have the 18-50/2.8 from SIGMA.
I would sacrifice the high light output and the extremely compact design in exchange for a longer focal length at both ends, IS, and an OEM lens.
It would really depend on the final spec. esp. the size.