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08-21-2015, 08:51 PM   #1
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Sigma C 18-200mm is optically stellar for a superzoom, but is it worth losing WR?

The reviews I'm seeing for the new Sigma C 18-200mm lens are very impressive for a $400 superzoom (cf. Lenstip). It's very sharp in the center across the zoom range and only slightly soft in the corners, and aberrations are controlled remarkably well. It's optically superior to the Pentax DA 18-135mm in pretty much every way, which has really bad corners towards the long end of the zoom range.

But is it worth losing the weather sealing?

—DragonLord

08-21-2015, 08:57 PM - 1 Like   #2
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How often do you shoot in a drizzle or worse, and would not a $5-dollar camera condom work for those times?
08-21-2015, 09:37 PM   #3
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QuoteOriginally posted by DragonLord Quote
It's optically superior to the Pentax DA 18-135mm in pretty much every way...
Where did you find this information? I haven't seen any comparison between those 2 lenses.
08-22-2015, 04:23 AM   #4
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QuoteOriginally posted by DragonLord Quote
The reviews I'm seeing for the new Sigma C 18-200mm lens are very impressive for a $400 superzoom (cf. Lenstip). It's very sharp in the center across the zoom range and only slightly soft in the corners, and aberrations are controlled remarkably well. It's optically superior to the Pentax DA 18-135mm in pretty much every way, which has really bad corners towards the long end of the zoom range.

But is it worth losing the weather sealing?

—DragonLord
To me it look similar to the 18-300 C. You exchange less reach for a bit lighter/smaller/cheaer lense

08-22-2015, 06:25 AM   #5
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QuoteOriginally posted by luftfluss Quote
Where did you find this information? I haven't seen any comparison between those 2 lenses.
Well, ePhotozine had found poor corner sharpness and high chromatic aberration on the DA 18-135mm (review) especially at longer focal lengths, and sadly, this is consistent with my experience, to the point where it is seldom on my K-3 II (whose 24MP sensor is very picky about glass). The Sigma C 18-200mm (review) just seems to be much more consistent corner-to-corner with no glaring weaknesses. I know they're tested on different systems, but the difference in optical performance is substantial.

Sigma needs to make more weather-sealed lenses. I know this is a common complaint, but it's just one I can't avoid making here.

I have a feeling I'd still choose the DA 16-85mm over this because it goes down to 16mm, is weather-sealed, and is optically excellent, but the Sigma sure looks like a very tempting alternative...

QuoteOriginally posted by Nicolas06 Quote
To me it look similar to the 18-300 C. You exchange less reach for a bit lighter/smaller/cheaer lense
The Sigma C 18-300mm is actually considerably worse than the 18-200. Lenstip's review shows poor edge sharpness at longer focal lengths irrespective of aperture typical of superzooms of this kind. The 18-200 is much more balanced. Again, different systems, but the optical performance difference is nontrivial.

---------- Post added 08-22-15 at 10:01 AM ----------

The point is that Sigma's lenses often perform surprisingly well but seem to lack the features we're accustomed to on the Pentax K system. I'd love to have some of these new Sigma Global Vision lenses, but weather sealing just seems to be too essential of a feature for us Pentax users.

I'm not here to bash any particular lens manufacturer, but I really think Sigma would gain more adoption if they had more sealed lenses.

—DragonLord

Last edited by bwDraco; 08-22-2015 at 07:02 AM.
08-22-2015, 08:23 AM   #6
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QuoteOriginally posted by DragonLord Quote
I'm not here to bash any particular lens manufacturer, but I really think Sigma would gain more adoption if they had more sealed lenses.
How many other camera bodies besides Pentax is WR? Sigma and other companies respond to the largest buyer's group; so Pentax is a rather small buyer's group, making it very costly to have WR lenses; and if the body is not WR, not that important to have a lens that is.

I only have one WR lens. If I want to shoot in dampness, rain, etc., I simply use an OpTech rain cover. But it's very rare that I would be shooting in these conditions, so WR lenses are not a high priority for me.

Last edited by csa; 08-22-2015 at 08:42 AM.
08-22-2015, 08:47 AM   #7
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I have lenses such as the Sigma 150-500 and 18-300, both for Pentax mount. I can see the use of a cover may be effective for some, but I prefer to just carry a plastic bag to cover my camera and lens if the precipitation becomes steady enough to possibly get my equipment wet. The longer zoom you may want to have, and the IQ and silent autofocus of the Sigma lenses may come in handy, depending on what you want for versatility and need.

08-22-2015, 08:48 AM - 1 Like   #8
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QuoteOriginally posted by SpecialK Quote
How often do you shoot in a drizzle or worse, and would not a $5-dollar camera condom work for those times?
Even without weather resistance, a little bit of moisture won't do any harm. If you take it out in a driving rainstorm, that's a bit different, but WR is pretty new. Cameras weren't all destroyed by a hit from a spinkler or some drizzle all those years.

---------- Post added 08-22-15 at 09:49 AM ----------

QuoteOriginally posted by csa Quote
How many other camera bodies besides Pentax is WR? Sigma and other companies respond to the largest buyer's group; so Pentax is a rather small buyer's group, making it very costly to have WR lenses; and if the body is not WR, not that important to have a lens that is.
Canon has started to do WR on their high end stuff. The difference seems to be that no one really cares in the Canon crowd, whereas here it gets talked up like the greatest feature since autometering.
08-22-2015, 09:29 AM   #9
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QuoteOriginally posted by DragonLord Quote
Well, ePhotozine had found poor corner sharpness and high chromatic aberration on the DA 18-135mm (review) especially at longer focal lengths, and sadly, this is consistent with my experience, to the point where it is seldom on my K-3 II (whose 24MP sensor is very picky about glass). The Sigma C 18-200mm (review) just seems to be much more consistent corner-to-corner with no glaring weaknesses. I know they're tested on different systems, but the difference in optical performance is substantial.

Sigma needs to make more weather-sealed lenses. I know this is a common complaint, but it's just one I can't avoid making here.

I have a feeling I'd still choose the DA 16-85mm over this because it goes down to 16mm, is weather-sealed, and is optically excellent, but the Sigma sure looks like a very tempting alternative...
I'm sure you are correct about CA and corner sharpness. But "It's optically superior to the Pentax DA 18-135mm in pretty much every way" is a strong statement. How does center sharpness, contrast, and microcontrast compare between the 2 lenses? I'm not saying this to be a Pentax shill, just that there's a difference between hyperbole and opinion based of verifiable information.

I agree with you that Sigma really ought to WR the 18-300. IMO, it doesn't make much sense not to.
08-22-2015, 12:30 PM   #10
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QuoteOriginally posted by DragonLord Quote
The Sigma C 18-300mm is actually considerably worse than the 18-200. Lenstip's review shows poor edge sharpness at longer focal lengths irrespective of aperture typical of superzooms of this kind. The 18-200 is much more balanced. Again, different systems, but the optical performance difference is nontrivial.
18-300 border sharpness:
Sigma C 18-300 mm f/3.5-6.3 DC MACRO OS HSM review - Image resolution - Lenstip.com


18-200 border sharpness:
Sigma C 18-200 mm f/3.5-6.3 DC Macro OS HSM review - Image resolution - Lenstip.com


Comparing the 2 graphs:
the 18-300 is a bit worse at 18mm and 100mm, bit better as 50mm. There is more difference at 200 in favor of the 18-200, but it stop at 200. There no doubt that is you need to shoot past 200mm the 18-300 is better.

It is so funny that for 5lp/mm, sometime in favor of the more criticized lense one is said to have poor corner sharpness and not the other.

And if you look at the center the 18-300 is equal or better depending of the focal length.

If you want something that has sharp corners at all focals, the 16-85 seems to fit the bill and is WR
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