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04-07-2011, 12:52 PM   #1
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is this lens for real ?? SMC K 18/3,5

i just want to ask about this lens ..because recently .. i find this on ebay , and i take a look that this lens has a 4 built in filter ???
can someone please explain this ? i never heard before about this lens ... is the quality good , and how you change the filter if has 4 built in in your lens body ??

thx b4

regard

04-07-2011, 12:57 PM   #2
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Check the lens database for more details on the lens:

Pentax Reviews - Pentax Lens Reviews & Pentax Lens Database

The filters are internal because external filters would likely cause vignetting. There's a ring at the end of the lens that let's you change filters, but in the digital age, they're still borderline useless.

The lens is probably no better than a consumer zoom would be these days at 18mm- this has been my experience with the k15mm.
04-07-2011, 02:01 PM   #3
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QuoteOriginally posted by Adam Quote
The lens is probably no better than a consumer zoom would be these days at 18mm- this has been my experience with the k15mm.
Allow me to disagree.
In a (fairly well controlled) comparison of K15/3.5 and Sigma 10-20 set at 15mm, I found
- that center performance was similar in terms of sharpness, with visible differences mainly due to white balance control;
- that K15 outperformed Sigma 10-20 in terms of off-center sharpness and distortion control.

A similar comparison between K18/3.5, Tamron 17-50 at 18mm and Pentax 18-55 at 18mm revealed K18/3.5 as a clear winner (except for the presence of chromatic aberration, which - as often with lenses from the manual era - is stronger in K18/3.5).

In addition, let me quote from my comments on K20/4.0 in the lens review section: "I have compared the K20/4.0 on digital with the DA21 and the Tamron 17-50. My conclusion is that K20 outperforms the other two, in terms of detail rendered and in terms of liveliness of colors. It is not as superbly sharp as K28/3.5 or K35/3.5, but it's better than the widely acclaimed DA21 or a very good zoom like the Tamron."

I imagine there will be other voices to make themselves heard, but my experience concerning K-series lenses in comparison to modern zooms (and even some primes) is consistently in favor of the K's.
04-07-2011, 02:38 PM   #4
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QuoteOriginally posted by ewig Quote
i just want to ask about this lens ..because recently .. i find this on ebay , and i take a look that this lens has a 4 built in filter ???
can someone please explain this ? i never heard before about this lens ... is the quality good , and how you change the filter if has 4 built in in your lens body ??

thx b4

regard
As well as the K18/3.5, the following K series lenses had built-in filters, which are selected via a filter ring.

K15/3.5
K17/4 Fisheye
K28/3.5 Shift
K1000/11 Reflex (ND & filter)
K2000/13.5 Reflex (ND & filter)

The quality of all K series lenses is superb.

Phil.

04-07-2011, 02:49 PM   #5
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The DA 15mm (it is a prime after all) and the DA 12-24 sit the K lens down as far as I've observed- the zoom might not be sharper, but the exposure and CA are both much better.

There's some unexplained issue with the A 15mm also, as it overexposes by 1.5 stops on digital (consistently) whereas this isn't the case on A-series film bodies.,
04-07-2011, 04:14 PM   #6
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That lens only makes sense on film I'm going to guess.
04-07-2011, 05:46 PM   #7
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QuoteOriginally posted by paperbag846 Quote
That lens only makes sense on film I'm going to guess.
Agreed, all those K series ultra wides I listed above are better suited for film.
On film the 15/3.5 is still the king of ultra wides, an amazing 111 degree angle of view with no distortion!

Phil.
04-07-2011, 10:17 PM   #8
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i think the quality of SMC its not going to be ask here, i mean even its A or K or M series...... all bring the superb IQ, i just wonder how 4 built -in filter can be in the same lens..

event though some of thread in forum argued about the significant CA that occurred in digital Body.. UW manual prime lens still the best value in my opinion... thats why sometimes i just hope the price K 15/3,5 not even ekspensive then sigma 10-20 ... but now its kinda rare ...huh

i try to look for other variant , like 18 or something else, but its not cheap either

04-07-2011, 10:19 PM   #9
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QuoteOriginally posted by gofour3 Quote
Agreed, all those K series ultra wides I listed above are better suited for film.
On film the 15/3.5 is still the king of ultra wides, an amazing 111 degree angle of view with no distortion!

Phil.
Though there is some stiff competition from M-mount rangefinder lenses at the same or shorter focal lengths.


Steve
04-07-2011, 10:22 PM   #10
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Imo don't waste your money on this legacy lens. It's just no longer wide enough on digital, it costs too much money, you can only use it in manual mode, you can't mount filters in front, it is a challenge to focus manually at this focal length even with a focusing screen with manual focusing aids, there are modern lenses that perform a lot better or a lot cheaper.
04-08-2011, 05:10 AM   #11
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QuoteOriginally posted by creampuff Quote
Imo don't waste your money on this legacy lens. It's just no longer wide enough on digital, it costs too much money, you can only use it in manual mode, you can't mount filters in front, it is a challenge to focus manually at this focal length even with a focusing screen with manual focusing aids, there are modern lenses that perform a lot better or a lot cheaper.
yup...im agree with you.. just looking the value because recently ..friend of mine just got sigma 18/3,5 with cheap price ..
04-08-2011, 06:23 AM   #12
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While I don't disagree that the K ultra wides, 15, and 18 mm rectalinear and 16 and 17mm fisheye are excellent lenses, they are quite expensive for what you get in terms of an ASP-C sensor.

While not as good on linearity, I opted for the samyang 14mm F2.8.

It does have barrel distortion which is easliy corrected, and has excellent sharpness, control of CA even at the corners, as well as excellet resistance to flare. For the price, it may be the best bang for the buck.

Unless you are a collector, I am not sure why you woould go after some of the legacy lenses. (although I find myself keeping an eye open for them , but only cheap)
04-08-2011, 06:49 AM   #13
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If it was cheap as Lowell says then grab it otherwise for digital there are many better lenses as pointed out by all the above posts,
Also if you shoot film regularly on a k mount body then it may be well worth a look (the built in filters then become damn useful for a b/w shooter like many of the film community are)
it was a pretty expensive lens back in the day and a pretty esoteric piece even then, that's why you see so few and they go for so much
04-09-2011, 06:58 AM   #14
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QuoteOriginally posted by Lowell Goudge Quote
Unless you are a collector, I am not sure why you woould go after some of the legacy lenses.
Well, have a look at some pictures: corner performance on K7 of DA21 to the left, K20 to the right; the subject is a dimly lit railway hall.



Now convince me that (convenience of lighter weight and AF apart) a legacy wide-angle like K20 is not a good choice on digital ...
04-09-2011, 10:04 AM   #15
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QuoteOriginally posted by creampuff Quote
Imo don't waste your money on this legacy lens. It's just no longer wide enough on digital, it costs too much money, you can only use it in manual mode, you can't mount filters in front, it is a challenge to focus manually at this focal length even with a focusing screen with manual focusing aids, there are modern lenses that perform a lot better or a lot cheaper.
You can mount filters in the front of the K18/3.5, as it has a 58mm filter thread. It also has a 58mm diameter clip-on plastic lens hood.

It’s vignetting that will be an issue with front mounted filters. You can also use rear mount gelatin filters, so you have three choices.

Phil.
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