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10-13-2010, 10:28 PM   #1
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Pentax DA WR 50-200mm: why the 49mm filter thread?

I am a new DSLR guy and have recently acquired a pentax K-7 and the kit WR DA lenses (18-55, 50-200). Because I will be doing fly fishing photography in environments filled with saltwater and sand and rain I want the protection of a UV/clear filter as well as the effects of a polarizer filter.

The 18-55 WR has 52mm filter threads, and I have had no problem finding many options for this camera (I am going with the Hoya HDs as they had a good price on 2filter.com and though I can't afford a better lens like a DA* yet I want the best IQ possible).

But the the supposedly matching kit lens has 49mm filter threads....which I understand is a change as the not WR predecessor 50-200 was apparently 52mm. I am having serious trouble finding decent but affordable filters for this camera. If these two lenses were still both 52mm I could just have two filters, but now I need 4 because I don't want to deal with adapter rings and then lens caps and hoods that no longer fit. On top of having to buy twice as many filters, 49mm seems to not be a standard size at all. Sure, there are some offerings out there, but I have found so many places where the filters start at 52mm and go up from there. I did find what Adorama calls "Hoya 49mm Multi Coated Starter Filter Kit" for $65, which strikes me as expensive enough for decent MC filters but not breaking the bank, but they are out of stock and not be found anywhere else.

So, any ideas as to why this lens got changed to 49mm? Any recommendations on good multi-coated filters that won't break the bank for this lens? Sorry for the rant!

-LE

10-13-2010, 10:41 PM   #2
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Get a 49-52mm step-up ring.

Treat yourself to a collapsible rubber hood. With the CPL screwed into the hood ring, you can fold it back for access to the filter.

H2
10-13-2010, 11:11 PM   #3
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I highly recommend Marumi Super DHG UV filters. Excellent coating and water repellent plus a slim profile. OEC and Ace Photo sells them on Amazon and Ebay for around $25.

Some pictures, just for fun.


Here you can see the coating.

Last edited by Skullsroad; 10-13-2010 at 11:39 PM.
10-14-2010, 01:32 AM   #4
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QuoteOriginally posted by Loren E Quote
So, any ideas as to why this lens got changed to 49mm? Any recommendations on good multi-coated filters that won't break the bank for this lens? Sorry for the rant!

-LE
Agree that having to buy bunch of filters of different sizes can be annoying. But why the change to 49mm, I'm guessing because most of the Pentax lenses, especially the small primes use 49mm filter. So while it's bad for you it's not necessary bad for others who happen to have a lot of Pentax primes.

Smaller filter means smaller lens and small is a theme of Pentax. Pentax has been revising their lenses formula to achieve smaller lens (and with smaller filter as the consequence) ever since the introduction of the Pentax-M series.The 50mm 1.4 for example, the original version (M42) has 55mm filter size but now it has been since changed to 49mm, same as the D-FA 100mm macro, it uses 49mm filter while the previous version F & A used larger diameters.

On a side note, AFAIK 52mm filter size was introduced by Nikon (at one time Nikon was promoting one universal filter size), other manufactures usually prefer to use 55mm then skip to 49mm. There are exceptions of course, but I don't think there's many Pentax lenses with 52mm filter size. While I never actually found such claim I think 49mm is the preferred (universal) filter size by Pentax.

I actually decided to buy D-FA 100mm instead of F 100mm which has better reviews, because it is smaller and it uses 49mm filter. Because I already have invested on good 49mm filters (CPL, ND4, ND8 & IR) for my other Pentax primes.

But of course the world is not ideal So I do have some lenses with 52mm and 55mm filter size. I solved the problem by getting step down rings (52to49 & 55to49). All these lenses are normal to short tele so I don't get vignettes even when using the slightly smaller filters. As a bonus, the step down ring also acts as a short hood similar to DA 40 and DA 21 hoods.

I also have some big lenses requiring big filters, up to 77mm, but for these I just don't bother to use filter or just buy a protector / UV filter and that's all.

So to end this post, I think you are making a good investment by buying 49mm filters because well, if you buy more lenses in the future, especially the Pentax primes, you'll likely find them very useful


Last edited by sajah; 10-14-2010 at 01:59 AM.
10-14-2010, 04:38 AM   #5
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As sajah says, an awful lot of Pentax primes use a 49 mm filter size. I think the DA 15, 40, 35, and 70 all do, as well as the DFA 100 mm. So, if you get one or a couple of these lenses down the road, those filters will serve a couple of lenses again.

The expensive filters are the bigger ones, like the 67 mm filters that the DA *16-50 takes.
10-14-2010, 04:52 AM   #6
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The 49 mm filter thread is amazingly common. Nothing special here.

When using lenses, you will find that the number of thread diameters varies greatly. In the last year I have used 49, 52, 58 67 and 72 mm threads. I curently own all these diameters except for 67 mm. No biggy.

As others have recommended, use a 49 to 52 step-up ring and you'll be all set. Be glad Pentax manage to keep their lens diameter down. Try to purchase quality 72 mm filters and you'll understand...
10-14-2010, 07:51 AM   #7
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Fish-cam

Hey, so you got your gear, eh? Congrats! Hope you love the K-7 as much as I do.

Of course, it comes with a price over and above the dollars to purchase: We will expect fish-heads now, you know.
10-14-2010, 07:57 AM   #8
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I'm surprised the OP is having so many problems finding reasonably priced 49mm lenses, as, since others have kind of implied, it's a VERY common filter size, moreso than 52mm in my opinion.

10-14-2010, 08:46 AM   #9
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not to point fingers here but the reason for different filter sizes is as follows:

on telephoto lenses, and telephoto zooms, the filter diameter is determined by the lingest focal length and the aperture at that focal length.

therefore, for a 200mm lens, F4 should be 50mm in diameter for the objective.

For wide angle lenses and zooms, the diameter of the filter is generally selected based upon the detail of the lens design, and the need tohave the filter ring far enough away from the field of view to avoid vignetting. therefore the filter diameter is not dictated by the maximum aperture of the lens as it is with telephoto lenses


for the da 50-200F4 lens, the implications are that the lens is eigher a little bit slower than F4, or a little bit shorter than 200mm. In fact, I read a test report in popular photography and the sample they tested this month was I think 191or 193mm focal length at F3.9

I believe you will find that these are both within the tolorances accepted by the industry, with respect to marking.
10-14-2010, 09:39 AM   #10
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Why is my 55-200mm DA zoom a 52mm filter thread ? That's quite odd that they changed it isn't it?
10-14-2010, 12:33 PM   #11
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QuoteOriginally posted by Lowell Goudge Quote
not to point fingers here but the reason for different filter sizes is as follows:

on telephoto lenses, and telephoto zooms, the filter diameter is determined by the lingest focal length and the aperture at that focal length.

therefore, for a 200mm lens, F4 should be 50mm in diameter for the objective.

For wide angle lenses and zooms, the diameter of the filter is generally selected based upon the detail of the lens design, and the need tohave the filter ring far enough away from the field of view to avoid vignetting. therefore the filter diameter is not dictated by the maximum aperture of the lens as it is with telephoto lenses


for the da 50-200F4 lens, the implications are that the lens is eigher a little bit slower than F4, or a little bit shorter than 200mm. In fact, I read a test report in popular photography and the sample they tested this month was I think 191or 193mm focal length at F3.9

I believe you will find that these are both within the tolorances accepted by the industry, with respect to marking.
Lowell: Nice explanation. FWIW, the lens is actually a stop slower at f/5.6 at 200 mm.

Last edited by MSM; 10-14-2010 at 12:33 PM. Reason: typo
10-14-2010, 03:13 PM   #12
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QuoteOriginally posted by kp0c Quote
Why is my 55-200mm DA zoom a 52mm filter thread ? That's quite odd that they changed it isn't it?
Because 300mm /f 5.8= 51.72mm.
You do mean 55-300 f 4-5.8?.
10-14-2010, 10:08 PM   #13
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I found that many filter lines started at 52mm and went up. Found it odd like KpOc that they changed the sizing as it used to be 52mm on that lens.

Anyways I think it is probably easiest to just get 4 filters total, rather than buying an adapter ring, another lens cap, and another hood. Not sure if the 49mm filter will help me anytime super soon, as the only lens pentax has out currently that might become mine in a year or two is the 62mm 18-135 WR (shooting around surf spray a lot and in the rain means I am only open to WR lenses).

It sounds like everyone has had good experiences with MaxSaver even though I am hesitant as I'm scared of getting a fake. Is nobody worried about getting fakes from this company?

If not then I might go for Hoya HD 52mm UV and CPL pair, and then to Amazon for the 49mm Marumi Super DHG (thanks for that tip S.R.) pair. The Marumis sound just as good (a little better according to the lenstip review) as the HDs, but they don't advertise extra strong glass like the HDs, which could come in handy for me as I will travel so much with my camera.

I read in a few places that the Kenko Zeta series is the same as the Hoya HD just branded differently, but also found contradicting information, and the write-up on this series on the kenko site didn't really sound like the HD at all (no mention of the extra strong glass).

Wayne: should have the two WR kit lenses and the body in the next week or two! Very excited.

Thanks again everyone for all the advice -LE
10-14-2010, 11:13 PM   #14
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maxsaver.net inquiry:

Comments or Questions: Also who is your Hoya filter supplier? Do you have any proof of authenticity of these filters? Thanks

Dear Loren Elliott:
This is a trade secret, please be understanding! Don't worry all of the filters are genuine on our websiter.

Best regards!
Sarah


....not sure whether this should be something to be really concerned about or not.....?
10-15-2010, 12:56 AM   #15
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OK just ordered 4 of the Marumi supers on amazon from a place in Texas (OEC camera accessories..seemed legit?) for a total of $136...seems like a pretty good deal! Hopefully having a set for each lens will end up being nicer than buying a step-up ring, plus and lens cap and hood. I decided that it seems like all I'm losing by not going with the Hoya HDs is the strengthened glass, which I would love, but they are a lot more expensive! Maybe HDs once I'm not a broke college student spending too much money on photo equipment

Fingers crossed on these Marumi SUPERs! -LE
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