Optical limits review of rf 24-105/4-7.1

Started 2 months ago | Discussions thread
jwilliams Veteran Member • Posts: 6,176
Really there's no problem with software correction IF ...

MatsP wrote:

Tristimulus wrote:

MatsP wrote:


They don't like it very much. Seems like they are very negative to all kinds of software corrections.

This lens is designed to be supported by digital correction.

Testing how such a lens performs without digital correction is just plain stupid.

Lens design is a tradeoff between abberations (reduce one and the others will grow).

When computers can take care of distortion and residual transverse chromatic aberration (which computers are good at) then the lens designers are left with more degrees of freedom to design better lenses at a given cost.

Digital correction became part of lens design decisions pretty long ago.

Yes, exactly. If you read their review of the Olympus 12-40/4 Pro, a lens I have owned, you'll find that this lens uncorrected at 12 mm has a distortion very similar to that of the RF 24-105/4-7.1 at 24 mm. But in this case they say that it doesn't matter, it's the corrected result that counts. They praise that lens. Correctly, it's very good. I just wonder why they have changed their opinion in this matter.

Really there's no problem with software correction IF it works well. Correcting distortion always makes a lens less sharp. If you start out with a really sharp lens before the correction you stand a good chance of decent results after correction. If the lens is already somewhat weak and the amount correction needed large you get results similar to what the RF 24-105 4-7.1 returns at 24mm. I have the lens and really the results at 24mm leave a lot to be desired and I'm being kind.

I'm not sure what Oly Pro lens you're referring to as there is no 12-40 4 lens. There is a 12-40 2.8 and a 12-45 4. I have both. The 12-40 is an example of lens that has a great deal of native distortion at 12mm (24mm equiv.) but is sharp enough that even after distortion correction results the results are very good. In fact it is the best m43 lens I've found at 12mm. I also have the 12-45 4 and it isn't as good at 12mm as the 12-40 2.8 but still much better than the RF 24-105 4-7.1 at 24mm.

Now the RF 24-105 4L IS I have is very good at 24mm and is overall the best standard zoom I've ever had.

OpticalLimits might have been a bit harsh in their wording but basically they are correct. The uncorrected results at 24mm don't even cover the whole frame (much like many compact cameras) and when corrected leave very soft edges. They seem to be upset that Canon left 24mm in the zoom range. I see their point but for people that never print or only do small prints having 24mm for the 'look' will be beneficial.

My biggest disappointment with the lens is that Canon kind of blew their chance to show how you can make compact but very usable FF lenses with smaller apertures. I'd rather have had a lens with a smaller zoom range on both ends, better results and even less size/weight. Hopefully they take a look at the Sony 28-60 (or Nikon 24-50) for how to do a very compact FF zoom lens.

Which is new for Canon, although mft as well as (I believe) Fuji have used this many years, hidden in the RAW files.

Canons had distortion correction in JPGs for EF lenses for some time. Now the mirrorless lenses from Canon (and everybody else) have pushed the amount of native distortion that is acceptable. Sometimes it works out Ok, other times we get something like the RF 24-105 4-7.1. For some the results of a lens like the RF 24-105 4-7.1are OK. For others not so much.

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