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10-07-2010, 01:34 AM   #1
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Should I get a CPL for my DA 15mm?

Hi,
i just ordered a DA15mm from BH photo which is gonna arrive sometime next week. Should I get a CPL with it or would it cause vignetting? I'm thinking of getting the Marumi DHG 49mm, does it interfere with the lens hood?

What's a general rule when using the lens? I heard you should use between f8-14, but what shutter speed for sunny or cloudy conditions?

Thanks.

10-07-2010, 04:30 AM   #2
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Somebody asked this last week about B+W filters. ......oh, it was you.!


The normal B+W filters fit under the DA15 hood but remember the slim version does not as it has a wider outer ring
There's another thread about this issue and one post mentions the Marumi DHG Super does fit OK under the hood.
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/79232-b-w-slim...tml#post802331
If you buy it I would still ask whether the outer ring has a wider "knurling" on the outer edge for gripping it.

I couldnt see any addtional light fall-off using the B+W standard (pretty thick) width filter even at f4 but if you use it for outdoors landscape in sunny whether you probably would be around f8-f11 anyway so no vignetting.

The centre resolution is great even at f4 and to the edges at f8 which is appropriate for outdoor landscape condtions where you need sharpness across the frame.

Shutter speed?
Well in bright sunny condtions f16 1/125 @ iso100 is the general sunny 16 rule an this is the same as f11 1/250 or f8 1/500. But remember you lose 1&1/2 to 2 stops of light with a polariser fitted on top of that so it might be back to f8 1/125
(Anyway I just use Av mode mostly at present)

Cloudy sky is 2 or 3 EV stops below this so at f8 it would be 1/125 or 1/60 at iso100. A polariser is of less benefit in cloudy skies unless you are reducing reflection from water etc.

If you want to, and like reading here is Luminous Landscape page on Polarisers
Polarizers

Remember you get a 49mm polariser for your DA15, it will also fit your DA35, FA43, FA50, DA70, FA77 and DFA100WR when you buy those too!
10-07-2010, 04:41 AM   #3
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I would not recommend you get a polarizer for such a wide lens. The reason is taht the effect of the polarizer will not be uniform at such a wide focal length. Shooting the sky, for instance, you will get something looking like a gradient of colours in the blue of the sky.

The effect will be less visible shooting water or foliage, but for the sky it's pretty dramatic, and often unexpected.

I have a CPL that I use with my Sigma 17-70, and I avoid using it at 17 mm. You've been warned

Using a polarizer at around 21 mm yields results that are nearer to what you'd expect, but even then it's not without flaws.
10-07-2010, 05:05 AM   #4
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QuoteOriginally posted by bdery Quote
I would not recommend you get a polarizer for such a wide lens. The reason is taht the effect of the polarizer will not be uniform at such a wide focal length. Shooting the sky, for instance, you will get something looking like a gradient of colours in the blue of the sky.

The effect will be less visible shooting water or foliage, but for the sky it's pretty dramatic, and often unexpected.

I have a CPL that I use with my Sigma 17-70, and I avoid using it at 17 mm. You've been warned

Using a polarizer at around 21 mm yields results that are nearer to what you'd expect, but even then it's not without flaws.
+1. Looks like there's a dark cloud or something in the center of your image.

10-07-2010, 06:41 AM   #5
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IMO there is no reason why you can't use a polariser with the DA15 Limited... But only if you keep your angle relative to the sun in mind. What I mean is that there is an angle from the sun (I think it's 90 degrees) where the polariser has the greatest effect. From memory this is where you will have the most problems with a graduated sky.

I have used a slim C-PL filter before on the DA15 and managed to avoid the harsh gradient effect.
10-07-2010, 06:55 AM   #6
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QuoteOriginally posted by catastrophe Quote
Hi,
i just ordered a DA15mm from BH photo which is gonna arrive sometime next week. Should I get a CPL with it or would it cause vignetting? I'm thinking of getting the Marumi DHG 49mm, does it interfere with the lens hood?

What's a general rule when using the lens? I heard you should use between f8-14, but what shutter speed for sunny or cloudy conditions?

Thanks.
Answering without editorial. The Marumi Super DHG low profile CPL fits fine, does not interfere with the hood (though you must retract the hood to adjust the CPL) and does not seem to cause any vignetting wide open.

Hope this helps.

woof!
10-07-2010, 07:07 AM   #7
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QuoteOriginally posted by woof Quote
Answering without editorial. The Marumi Super DHG low profile CPL fits fine, does not interfere with the hood (though you must retract the hood to adjust the CPL) and does not seem to cause any vignetting wide open.

Hope this helps.

woof!
So will this one work well?
Marumi DHG SUPER Circular Polarizing CPL Filter 49mm - eBay Polarizing, Filters, Lenses Filters, Cameras Photo. (end time 11-Oct-10 22:04:01 AEDST)

There's also this one which is much more expensive but looks the same...
marumi 49mm 49 DHG Super CPL Circular Polarizing Filter - eBay Polarizing, Filters, Lenses Filters, Cameras Photo. (end time 17-Oct-10 21:50:12 AEDST)


btw, I'll be using a DA15 and 40 limited setup, will the CPL will more beneficial on the 40mm but not the 15mm? I'm not too sure about the negative effect on the skies...I heard the DA15 is capable of producing very nice shots even without CPL.
10-07-2010, 06:45 PM   #8
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QuoteOriginally posted by goddo31 Quote
What I mean is that there is an angle from the sun (I think it's 90 degrees) where the polariser has the greatest effect. From memory this is where you will have the most problems with a graduated sky.
My point exactly. When facing the Sun, the polarizer has little effect, but when you do want it to have an effect, it's all over the place.

That's my experience, and trust me, the physics back me up

10-07-2010, 09:47 PM   #9
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QuoteQuote:
Hi,

What's a general rule when using the lens? I heard you should use between f8-14, but what shutter speed for sunny or cloudy conditions?

Thanks.
It's photography - there are no rules.
10-08-2010, 03:21 AM   #10
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Will a graduated ND be more useful for the DA15mm then?
10-08-2010, 04:43 AM   #11
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QuoteOriginally posted by catastrophe Quote
Will a graduated ND be more useful for the DA15mm then?
It depends what you're trying to achieve. These two filters are quite different.
10-08-2010, 07:24 AM   #12
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49 mm is a very common size for Pentax lenses and a CPL and graduated ND in that size would not go to waste if you are serious about photography and use Pentax cameras.
10-08-2010, 08:11 AM   #13
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I bought a B&W CP for my 15mm Limited. Big mistake, although I can use the CP on other lenses, so it wasn't a total waste of money.
I tried to make it work, but on every shot in which I tested it on a tripod (same scene and lighting), the shot without the CP was far better than with it.
In the first place, the 15 preforms as if it had a built in polorizer. Best skies I've seen from any lens on digital, with colors and contrast that reminds me of Kodachrome. In the second place, the 15 is so sharp at around f-11 that even the slightest degregation from an extra piece of glass is noticable. When I used the CP on an overcast day over water, it messed the colors up.
I have, however, used a High-Tech GND with good results and almost no degregation of IQ at 100 percent. By the way, I bought the High-Tech GND after giving up on a Lee GND that had been backordered for a couple of months. The High-Tech is half the price of a Lee and, I believe, every bit as good.
10-08-2010, 08:47 AM   #14
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QuoteOriginally posted by Ron Kruger Quote
I have, however, used a High-Tech GND with good results and almost no degregation of IQ at 100 percent. By the way, I bought the High-Tech GND after giving up on a Lee GND that had been backordered for a couple of months. The High-Tech is half the price of a Lee and, I believe, every bit as good.
Interesting. There seem to be so many conflicting opinions about regarding Hitech.
10-08-2010, 08:53 AM   #15
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More on why you shouldn't use polarizers with wide-angle lenses:

How to Use Filters
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