[Class A]

We will see. It has been pretty normal for Sigma to not announce a new lens in K-mount.

I agree that based on past experience, it is likely that this lens will become available in K-mount after all.

When Pentax releases the FF body we will see Sigma expand K-mount.

I hope so too.

The 24-105/4 makes more sense on FF, AFAIC, and I'm hopeful that the availability of a Pentax FF will persuade Sigma to offer more of their line up in K-mount.

[Aegon]

I have a Canon 24-105/f4 and love it. Great lens. Rock steady IS, sharp everywhere except at 105mm, extremely fast AF speed, looks great on FF.

If Sigma's is nearly as good then this should be a hot seller for other FF systems.

[Jonathan Mac]

I could see this being sweet on FF but pretty useless on APS-C. Not very wide, big and heavy.

[jrcastillo]

I could see this being sweet on FF but pretty useless on APS-C. Not very wide, big and heavy.

I guess it depends what you take pictures of. a quick filter in my lightroom library says i have taken only a very small handful of pictures below 20mm...
I do have a bunch right at 21mm... but could have been taken at 24mm easily. I would really like the extra reach at 105mm more than the extra 6-8mm in the wide end. (when comapred to something like 17-50 2.8) even loosing an stop

the 18-135WR is there. But it is affected by softness and sharpness problems as the FL range is even bigger than the 24-105.
Of course we need to see how good this lens is once it comes out.

[Jonathan Mac]

I guess it depends what you take pictures of. a quick filter in my lightroom library says i have taken only a very small handful of pictures below 20mm...
I do have a bunch right at 21mm... but could have been taken at 24mm easily. I would really like the extra reach at 105mm more than the extra 6-8mm in the wide end. (when comapred to something like 17-50 2.8) even loosing an stop

the 18-135WR is there. But it is affected by softness and sharpness problems as the FL range is even bigger than the 24-105.
Of course we need to see how good this lens is once it comes out.

I understand there are a lot of old film-era lenses starting at 24 to 35mm that are used a lot, especially on Pentax (I have a Sigma 24/2.8 which is really great). However, how many of them have a massive 82mm filter ring? I just can't see APS-C shooters weighing themselves down with such an enormous lens.

[tram57]

We will see. It has been pretty normal for Sigma to not announce a new lens in K-mount. The Sigma 85mm F/1.4 was offered in K-mount even though it was not listed originally. Sigma told several people that the USB dock would not be released for K-mount, and now they say it will be.

When Pentax releases the FF body we will see Sigma expand K-mount.

we can only hope as this appears to be a great lens for either APS-C or FF!

[PT1]

I recently asked Sigma whether there was a technical reason why the 24-105 F/4 (a full frame lens) couldn't be sold for Pentax? (I currently have the 18-250 Macro on my K-3)

The answer was that there's a shortage due to worldwide demand, but once they are able to fulfill the demand for the current mounts, releasing for Pentax would be contemplated, but not guaranteed.


Usefully, dpreview have reviews for both the 24-105 and the 18-250 Macro on an EOS 7D:
Lens reviews update: test data for the Sigma 24-105mm f/4 DG OS HSM: Digital Photography Review
Sigma 18-250mm f/3.5-6.3 DC Macro OS HSM review: Digital Photography Review

MTF-50 sharpness at 24mm (24-105) and 28mm (18-250):
Approx 1875 (centre) to 1530 (corner) for the 24-105 at f/5.6
Approx 1500 (centre) to 1300 (corner) for the 18-250 Macro at f/8.
Approx 25% centre improvement, 18% corner improvement.

MTF-50 sharpness at 35mm:
Approx 1800 (centre) to 1550 (corner) for the 24-105 at f/5.6
Approx 1500 (centre) to 1300 (corner) for the 18-250 Macro at f/8.
Approx 20% centre improvement, 19% corner improvement.

MTF-50 sharpness at 80mm:
Approx 1700 (centre) to 1375 (corner) for the 24-105 at f/5.6
Approx 1500 (centre) to 1130 (corner) for the 18-250 Macro at f/8.
Approx 13% centre improvement, 22% corner improvement.

MTF-50 sharpness at 105mm: (interpolated approx between 80 and 135 results for the 18-250)
Approx 1600 (centre) to 1375 (corner) for the 24-105 at f/5.6
Approx 1440 (centre) to 1070 (corner) for the 18-250 Macro at f/8.
Approx 11% centre improvement, 29% corner improvement.


The EOS 7D is 18 Megapixel, rather than approx 24 Megapixel for the K-3, but hopefully the sharpness improvement scales between the two cameras?

If so, I'd say it's worth the upgrade to buy the 24-105 for my K-3, if or when they make it. (Ok, it heavy, equivalent to approx 36 to 158mm on the 1.5x crop factor K-3, and needs 82mm filters, but it's impressive!)

And it might perform even better on a full frame camera? (The 22.3 Megapixel full-frame 5D mk3 alternative is selectable in the review, with an MTF-50 up to 2500)

[Winder]

I recently asked Sigma whether there was a technical reason why the 24-105 F/4 (a full frame lens) couldn't be sold for Pentax? (I currently have the 18-250 Macro on my K-3)

The answer was that there's a shortage due to worldwide demand, but once they are able to fulfill the demand for the current mounts, releasing for Pentax would be contemplated, but not guaranteed.

Since they have stopped producing the 70-200mm F/2.8 in K-mount because of low demand/sales I doubt we will see this lens in K-mount. I sales of the new Pentax FF stay strong for a couple of years, then we might see Sigma produce this lens in K-mount, but Sigma is a small company and its all they can do to keep up with demand for Canon and Nikon mounts.

[rawr]

Lenstip have a good technical review for the 24-105 lens.

I have used it on a Nikon D610. It's a great lens, if a bit large and heavy. It would be wonderful on a Pentax K-3 or Pentax FF.

Sigma have been producing it in batches - initially for Canon, then Nikon. Then the Nikon batch sold out, and now it's back-ordered everywhere for every mount. The Pentax version is probably going to take a while to appear.

Hence opening up an opportunity for Pentax to release a FF lens of their own in this class. And I think there is indeed such a lens on their roadmap.

[Winder]

Hence opening up an opportunity for Pentax to release a FF lens of their own in this class. And I think there is indeed such a lens on their roadmap.

I think we will see a 24-120mm or a 24-104mm F/4 released as a kit lens for the new FF. Ricoh really can't afford to release any "average" glass with the initial launch, so I think we are going to see a really good lens.

[PT1]

It would be interesting to see comparison tests, like fine-detail test charts, https://fstoppers.com/studio/fs-review-sigma-hits-success-again-24-105mm-f4-os-hsm-lens-8219 and

You Tube

You Tube

If the 24-105 range or similar provides a standard (very usable) zoom range with very good results, maybe this shows why demand has outstripped supply! (can always crop instead of having a higher zoom, but how much of an issue the loss of the wide angle is? - might just need to carry a wide lens as well?)

I'm certainly happy to change from 18-250 to 24-105 for better pictures.

p.s. New on dpreview is Making 'Art': We go inside Sigma's lens factory: Digital Photography Review

[rawr]

Ricoh really can't afford to release any "average" glass with the initial launch, so I think we are going to see a really good lens.

Hope so. The Nikon 24-120 and Canon 24-105L are very decent kit lenses, so Pentax has some easy reference points for whatever they design.

maybe this shows why demand has outstripped supply! ... but how much of an issue the loss of the wide angle is?)

Demand exceeds supply because Sigma is on a roll at the moment, but they are a small shop, hence have a limited capacity to meet global demand.

On FF, 24mm is a handy wide. On crop it's less wide, of course, but still useful. Better than 35 at the wide-end, like my long-time favorite the SMC A 35-105 f3.5.

But 900g means it's a tank.