[Parallax]

....

................... Anyhow, real photographers don't use Auto ISO.

[Class A]

I have the Sigma 18-250 OS HSM. ...
The one thing that is not subjective is that, as with other Sigma lenses, it is not identified properly to the camera. The camera thinks it is a 70-200 so when using auto ISO it will let the shutter speed drop to 1/180 before raising ISO instead of holding at 1/250.

Are you sure that is what's happening?

Set your Sigma to 250mm and then check using the camera "Info" display what focal length it thinks you've got. I bet it will show "250" instead of "200". If it does, then all should be good regarding "Auto ISO" and other features.

It might be just the case that your PP software doesn't identify the lens correctly. BTW, one can teach LR to learn the correct identification to some extent. Let me know if that's the problem.

P.S.: All of my Sigma lenses are identified correctly, except for the Sigma 10-20/3.5 which doesn't receive a lens name in LR (but the focal length is always correctly recorded). Not sure whether the lens name issue is a problem of my K100D which doesn't support HSM lenses or a problem of LR.

EDIT: I first addressed Parallax' problem as part of another post but then had additional thoughts about his issue which is why I removed the comment from the other post and elaborated it here. In any event, I stand by my statement "Real photographers don't use Auto ISO".

[Parallax]

Are you sure that is what happening?

Set your Sigma to 250mm and then check using the camera "Info" display what focal length it thinks you've got. I bet it will show "250" instead of "200". If it does, then all should be good regarding "Auto ISO" and other features.

It might be just the case that your PP software doesn't identify the lens correctly. BTW, one can teach LR to learn the correct identification to some extent. Let me know if that's the problem.

P.S.: All of my Sigma lenses are identified correctly, except for the Sigma 10-20/3.5 which doesn't receive a lens name in LR (but the focal length is always correctly recorded). Not sure whether the lens name issue is a problem of my K100D which doesn't support HSM lenses or a problem of LR.

I'll try that.
As far as LR goes; I guess I don't see a particular problem with it not knowing the difference. I generally make my own presets, so is there any particular need, from a processing standpoint, for LR to know? Thanks for the help!

UPDATE: You're right! it says 250 on the info screen.

[deadwolfbones]

That should not depend on the AF drive mechanism of the lens but rather on the AF module of the camera and sometimes the optical properties of the lens.

Yeah, I know. And yet...

The only thing I can think is that the gear mechanism in the screwdrive lenses is less precise than the DC motor, so requires more micro-adjustment, but that's just idle speculation.

I've only used this lens indoors at my desk, so maybe it'll behave more like my screwdrive lenses in time and in more varied situations. We'll see...

[sewebster]

What do you guys think of this lens vs the 16-45? It's what I use for all my hiking photography. I like the constant aperture, but I could probably accept losing the 16 mm for the extra range if the IQ is similar.

[Cannikin]

My 18-135 just arrived this morning, so here are my initial impressions. I haven't had time to do anything extensive, but with some quick and dirty tests, I can say that it is definitely noticably sharper than the Sigma 18-250, and about on par with the 55-300, at least at 135mm (as a curious side note, I found that "100mm" on the 55-300 is about the same FOV as "135mm" on the 18-135... which one to believe? ).

This thing is very compact, and though quite a bit denser than say the kit lens, it is has a good feel, and is very well balanced on my K-5. It's an absolute featherweight compared to the Sigma 18-250. The zoom ring is the smoothest of any lens I've tried, and I seriously doubt zoom creep will ever be a problem (the barrel is just not that heavy, and the WR means the tolerances are tight). The focus ring seems like it'll take some getting used to, though. Not only is its position near the lens mount a bit weird, but the fact that there is no start or end to the ring throws me off a bit. It's also significantly stiffer than other quick-shift lenses I have (almost made me wonder if it was locked in AF, despite it being QS).

Of course the star of the show is definitely the DC motor. I have used Sigma HSM, but man, this is something else. It's smoother than butter; you will barely feel the lens doing anything at all. It's also lightning fast, with very little micro-focus hunting. I also love the sound it makes. It's not totally silent, but it's very quiet (about as quiet as the AF confirm beep at minimum volume) and very distinctive. It sounds quite "electronic", almost like some stereotypical old sci-fi movie laser beam. I've been randomly focusing on stuff just because I love to hear and feel it.

Haven't gotten a chance to really test the weather sealing, but there was some minor drizzle today. Some droplets got on the barrel, but when I retracted the barrel and zoomed back out, the droplets were instantly wiped away, so I assume the sealing is doing its job. Hopefully some more serious weather comes along. After all, WR is the primary reason I got this lens in the first place. November is supposed to be the wettest month for the PNW, and it's a La Niña year to boot (supposed to be wetter than normal), but we've hardly gotten any serious precipitation this month (besides that nasty snowstorm last week).

I see this thing replacing the 18-250 as my general-purpose travel lens, in addition to being the all-weather lens I originally got it for.

[audiobomber]

My 18-135 just arrived this morning, so here are my initial impressions. I haven't had time to do anything extensive, but with some quick and dirty tests, I can say that it is definitely noticably sharper than the Sigma 18-250, and about on par with the 55-300, at least at 135mm (as a curious side note, I found that "100mm" on the 55-300 is about the same FOV as "135mm" on the 18-135... which one to believe? ).

It sounds like the 18-135 is an internal focus lens. Trust the 55-300. The 18-135 will probably show a 135mm fov at infinity focus. The Pentax 18-250 does the same thing. At 10 meters (thirty feet) and 250mm it looks like the 55-300 at 200mm, at 3m (10 ft) it has a fov like the 55-300 at 160mm.

[Loren E]

Speaking of the 55-300, this lens has been talked about a lot as a hopeful future WR lens as we all know....if this DC motor is reliable and reviews stay this good, maybe we will see it in some other DA lenses to accompany the 18-135 like the 55-300?

[audiobomber]

Speaking of the 55-300, this lens has been talked about a lot as a hopeful future WR lens as we all know....if this DC motor is reliable and reviews stay this good, maybe we will see it in some other DA lenses to accompany the 18-135 like the 55-300?

I'd jump on that one. Since we're wishing, I'll take the rounded blades too.

[yipchunyu]

I'd jump on that one. Since we're wishing, I'll take the rounded blades too.

What exactly is the dc motor? It's not sonic motor? It's not a ring sonic motor? It's only available in Pentax brand?

[Cannikin]

Just another small thing I've noticed in my testing: the lens hood will cause shadowing with the pop-up flash at 18mm. This is caused by the hood only, not the lens itself; removing the hood eliminates the shadow.

Tested on both the K-5 and K-x.

[ManuH]

Just another small thing I've noticed in my testing: the lens hood will cause shadowing with the pop-up flash at 18mm. This is caused by the hood only, not the lens itself; removing the hood eliminates the shadow.

Tested on both the K-5 and K-x.

Ah yes, I wanted to hear about that because I like to use fill flash outdoor. With the hood up to which FL and distance can you use the internal flash? The K-5 flash should be slightly better (more powerful, a bit higher).

[Cannikin]

Ah yes, I wanted to hear about that because I like to use fill flash outdoor. With the hood up to which FL and distance can you use the internal flash? The K-5 flash should be slightly better (more powerful, a bit higher).

The shadow from the hood will generally not be visible on the ground starting at about 28~30mm on the K-5 (it's barely visible at 24mm). It takes about 40mm to get rid of it on the K-x.

Of course, you will have to go a little longer if you're very close to the target (shoot a wall at minimum focus distance and it will appear even up to 135mm), but the above focal lengths should be good for anything 3 ft away or further.

Also, as I said before, without the hood the shadow generally does not appear at all. However, if you're at minimum focus distance then the lens' own shadow will show up just a little at 18mm, but this is a ridiculously close distance (less than 1 ft in front of the lens), so I really don't see this ever being encountered in real life. Who would use a pop-up flash at that distance?

[ManuH]

Thanks for this information, reputation points added.

I wanted a compact WR zoom for the time I go with my kids to the park, etc. I was hesitating between the 18-55 and the 18-135. The 18-55 is very compact and of good quality but the 18-135 is of course more useful. I glad to see it's compact enough to not hamper the use of internal flash.

[cgeiser]

I also am interested in this lens for hiking. Anyone use it for this and have comments? Any lenses you like better for hiking?
Thanks