[Kunzite]

Steve can you explain what the term "full frame" means? I see that term a lot. Sorry if that's a dumb question.

It's a term invented so that the users of the small format (24x36mm) would feel better about it.

[stevebrot]

Not any longers, they stopped making the OS version in Pentax mount some time ago.

Ummmm...a little tangential to the OP's issues, but the OS version was replaced by the same lens, sans OS, but still labeled "OS" "some time ago" with the EOL for the model being in the more recent past (2016?). Since that time, Sigma has not offered a 70-200/2.8 in other than Nikon, Canon, and Sigma mounts. The exit of Sigma from K-mount in this zoom range corresponded roughly with the release of the Pentax DFA* 70-200/2.8 at a similar price point. It appears analysis indicated insufficient market and/or penetration to justify continuation.

As a result, current offerings for a fast 70-200 AF lens in FF K-mount are limited to the consumer grade Tamron and the upscale DFA* at twice the price. It would be nice to have a third option for this sort of lens, but such is not the case. Sigma and Tamron are the only third-party players for all mounts.


Steve

[stevebrot]

It's a term invented so that the users of the small format (24x36mm) would feel better about it.

It is not well appreciated that for most of the history of the 24x36mm (35mm) format, the cameras were categorized as "miniature". What was special about 35mm was the sweet spot for performance, portability, and utility within the limits of media, technology, and lenses.


Steve

[Mike.P®]

The exit of Sigma from K-mount in this zoom range corresponded roughly with the release of the Pentax DFA* 70-200/2.8 at a similar price point.

Certainly not the case here in the UK where the Pentax Lens cost more than double the Sigma. I would love the DFA* lens but currently cannot justify the price difference over my ""OS" version. Same with my SIgma 24-70mm f2.8.

[JensE]

I'd be really interested in a comparison of the two, the Tamron comparison in the PentaxForums review was very useful to me already. As it is not available new anymore, I patiently sought a reasonably priced used Sigma HSM OS, mainly because of the lower weight. With the occasional 33% off offers by SRS (see market watch), I was still tempted by the DA* for its weather proofing.

My Sigma OS HSM identifies as Lens ID 8 23 and works well on K-1 and K-5.

[Fogel70]

It's a term invented so that the users of the small format (24x36mm) would feel better about it.

It's acutaly a term first used in cinematography for the max size on 35mm film.
As the width of the film used for cinema is 24mm, this full frame is similar in size to APS-C that was invented much later for still photography.

Full frame - Wikipedia

[DeadJohn]

This thread has gone on many tangents.

3rd party support for Pentax: Samyang/Rokinon/Bower and Irix have new lenses. Sigma and Tamron are no longer releasing anything new for Pentax.

Sigma 70-200 firmware: Pentax and Sigma have both acted properly, IMO. The K-1 and KP remain compatible with prior Pentax lenses. It is not Pentax' responsibility to test other brands. Some Sigma lenses had an issue, and Sigma responded with a free remedy.

[stevebrot]

As the width of the film used for cinema is 24mm, this full frame is similar in size to APS-C that was invented much later for still photography.

The Wikipedia article is specific to cinema photography, though the historic reference is pertinent. The term "Full Frame" as related to still photography was not in common use until digital photography resulted in multiple small formats and even then has been a misappropriation. There is nothing particularly "Full" about the 24x36mm (2:3) format other than 24mm being the maximum that will fit between the perforations of 35mm film.

As far as 35mm still photography goes, there have been two major frame formats and several minor deviations:

• 24x36mm (2:3) adapted from cinema film by Oskar Barnack for Leitz in the early 20th century*
• 18x24mm (3:4) "Half Frame" used by various sub-miniature cameras and roughly equivalent with cinema "Full Frame"**
• Specialty formats (e.g. 24x58mm "panorama" such as produced by the Widelux and similar cameras)

APS (Advanced Photo System) film was 24mm wide and supported three formats:

• H - 16.7x30.2mm (9:16)
• C - 16.7x25.1 (2:3)
• P - 9.5x30.2mm (1:3)

The extra space on the film was used for encoded metadata. The digital APS-C format was derived directly from the APS film specification and has no relation to the half-frame film format.


Steve

* I have only been doing photography since the late-1960s, but don't recall ever hearing or reading the term "Full Frame" in reference to the 24x36mm image frame.

** 18x24mm actually predated 24x36mm for still camera use. It was only after the dominance of 24x36mm was established that the smaller format was called "half frame".