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06-18-2009, 09:48 PM   #1
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Filters?

Aloha....so I finally bought my first SLR....the K200 with the Pentax 18-250 lens. Why I did this (ofcourse this forum was a great help) and my initial reviews of the K200 will be posted in the review section in the next few days.
In addition to the camera body and the lens, I bought the basic necessities like the Sanyo eneloop chargeables (thanks to the numerous posts related to the topic on this forum) and the tamrac camera bag.
Now, the next item in line is a filter which protects my lens as well as provides me with little/no deterioration in picture quality. This is where I am stumped. I do a lot of bird and wildlife photography (only at the local parks and zoos though) and landscapes too (including some low light ones).Like the lens I want the filter to be always on rather than fiddle with it at all times

Questions

1) Would a polarizer meet my requirements or will the UV filter be suitable. Why I am inclined towards the polarizer is it gives me a lot more privileges for a little extra money
2) If I go in for the polarizer would the speed of high speed shots be effected asI understand they reduce the incoming light by around 1 stop.
3) With the Pentax 18-250 lens is it justified to go in for the more expensive PRO filers?
4)Some shopkeepers say I need the filters with thin rims (about 3-4mm) to avoid vignetting at the wide angle. But is the 18mm wide enough to warrant this?

Would appreciate your valuable responses so that I can make an informed decision

06-18-2009, 10:15 PM   #2
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1. A polarizer isn't something you want to use by default. You adjust the polarizer to have more or less effect; light loss is often more than 1 stop at typical settings.

2. 1 stop is close to the minimum possible reduction with a polarizer. You may lose much more light than that.

3. It's generally never bad to buy a better quality filter, but you'll find no universal agreement as to what is adequate or the best value for your money. I have mostly uncoated filters, along with a couple of single-coated Hoyas. I recently added a lesser-brand multi-coated filter that looks like the front element of my old 35/3.5 SMC Takumar (in other words, it doesn't appear to my non-expert eyes to be multi-coated at all.) I would suggest that if you get a multi-coated filter, you might want one that at least claims to offer tough multi-coating. I regularly rub my uncoated filters with whatever is handy. The glass is harder than many things you might wipe it with. Not true of most coatings.

4. I don't have your lens, but I can tell you that there is no rule for what constitutes "thin." I have otherwise identical filters of the same brand, bought a few years apart, that aren't designated "thin." But some are much, much thinner than others. I doubt you need a thin filter, but it's easy enough to experiment to find out. Thin isn't always good, even for a wide-angle lens. One of those new, "non-thin" (but actually thin) filters hits the front element of one of my wide zooms when fully threaded in. An older "non-thin" version doesn't.

Most people would probably say that a polarizer is the most important filter, besides possibly the Haze/UV. Not everyone agrees that the protection afforded by the Haze/UV is worthwhile.

Paul
06-18-2009, 11:24 PM   #3
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If you buy Hoya, and I do, these charts are the only way to figure out which version is which. You can go by case color more than naming and should find them invaluble if trying to figure what you are getting for the extra cost. Also, huge discounts on the very expensive large ones are available if you dont mind a 10-day wait from Hong Kong like from maxsaver.net.

Ok, had to attach the UV table but link to a thread with the CPL table as I cant upload it a second time according to the attachment button. Its at the bottom of the For Sale message. Enjoy


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CPL table ===> http://https://www.pentaxforums.com/forums/sold-items/59322-sale-sold-hoya-67mm-pro1-cir-pl-filter-new.html

Last edited by imtheguy; 06-18-2009 at 11:30 PM.
06-18-2009, 11:47 PM   #4
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A UV filter on digital is worse than useless, unless you're shooting in a situation with rocks flying in the direction of the lens, or for some reason don't use a lens cap when storing your camera. A non-multi-coated UV filter will only add flare and reduce contrast. Optical glass is hard and so are high quality modern coatings--it sounds like you can easily damage the coating on a Zenitar 16 fisheye, though. Buy a lens pen and a multi-coated polarizing filter.


Last edited by asdf; 06-19-2009 at 05:26 AM.
06-19-2009, 02:31 AM   #5
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Filter ring vignetting depends on the lens as well.
The 12-24 was designed with filter additions in mind - optical glass fitting well within the 77mm diameter lens barrel size, so can take the 5mm filter rings without vignetting.
The 16-50 has very little space between the glass and the edge of the lens barrel, which MAY vignette with thicker filter (I wouldn't know, as I have a thin filter on mine).

Should you get one - that really is up to you..
Will your 18-250 vignette with a thicker filter? Probably not, but be sure that your vignetted shots are not from using the lens at large apertures at the wide end.

Bes of luck...
06-19-2009, 05:46 AM   #6
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The 18-250 vignettes at 18mm and wide aperture even without a filter, so I'd say a high quality thin filter like the Hoya or B&W premium lines would be the way to go.... if you want to use a filter. I've decided I don't need lens protection and the digital sensor doesn't need UV protection, so I no longer use clear or UV filters. As several others have mentioned, you can't leave a polarizer on at all times because it's slow and awkward to use and loses too much light.
06-19-2009, 05:59 PM   #7
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I think a polarizing filter is mainly used in a couple of situations -- if you want to make your sky bluer and if you want to reduce reflections (off of water, glass, etc). As to whether or not you use UV filters, this is a hotly debated topic. I am paranoid about my lenses and would rather lose a filter than a lens, so I keep a UV filter on, but understand that it will increase your risk of having lens flare and may slow down your auto focus, particularly in dark situations.
06-19-2009, 06:27 PM   #8
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Rondec - I can only agree with what you said but I have never heard of the"slow down the auto focus" item before. Is this due to cheap filters that only transmit 90% of the light or something systemic to having any filter? Can you point me to any discussion threads? Reason I ask is I have high-quality filters on all my lens and will rethink that for my low-light situations if it applies to me. Thanks.

Also about the CPL filters, I shoot 98% wildlife and use CPL at times to reduce glare off green foilage if that is my backdrop. Same effect as with water.

And just to demo what Rondec said, I have 2 pics I uploaded when I tested my CPL. Positioned 90 degrees to the sun, straight from camera to downsize utility (no pp) to see the difference. It also filters the blue color cast from the tree leaves...they look warmer right? This was not a scientific test, no worry of which camera settings, WB, etc. Just shoot with and without at whatever setting and metering I happened to have.

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06-19-2009, 07:14 PM   #9
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my personal experience especially with wide lenses

I keep UV filters on all my lenses but the only one that worked for me where the B+W multi coated filters
cheap filters does not work
Hoya HMC gets really good reviews as well , so yes if you choose to have a filter ( and I recommend to have a filter to keep your glass) get a good filter

Last edited by redpigeons; 06-20-2009 at 07:33 AM.
06-19-2009, 09:21 PM   #10
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I only use a CPL filter under certain circumstances. My 'rule of thumb' is that if a filter's price doesn't make you gasp in horror at how much it is, it's a waste of money. I only buy B+W filters now. The CPL I use now, cost more than I paid for my first lens. UV filters were necessary in the days of film, not any more. Use your lens hood to protect your lens and put the lens cap on when you're not using the lens.
06-19-2009, 09:30 PM   #11
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Ok, you folks have asked for it. Here is the only scientific study I know of for UV and Haze filters, cheap to expensive. As I recall, they clearly show the damage that can be done by using poorly designed filters in high-glare environments and also measure all the light transmission broken down by wavelenght (UV vs visable vs IR). Most expensive not necessarily an improvement for your pictures either.

UV filters test - Introduction - Lenstip.com

Last edited by imtheguy; 06-19-2009 at 09:36 PM.
06-20-2009, 02:52 AM   #12
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Thanks

Thanks a lot guys....you have been a great help. The link from imtheguy was really helpful.
Though the UV filters are dont do much good technically speaking, but being a new SLR user I am concerned about my expensive lens and might as well spend some money for its protection. You guys rock!
Check out the reasons why I bought the K200 i posted in the Welcome section
06-20-2009, 04:10 AM   #13
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I can only tell you that I use a Hoya UV filter on my FA 50 lens and saw significantly less hunting in a (quite) low light situation, after I took it off. There was a thread a while back where someone took their filters off and their wife asked them what they had done to speed up their camera, but I couldn't find it. Truthfully, I have tried the rest of my lenses with and without and haven't noticed any difference.
06-20-2009, 07:41 AM   #14
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QuoteOriginally posted by Mr. The Guy Quote
I only use a CPL filter under certain circumstances. My 'rule of thumb' is that if a filter's price doesn't make you gasp in horror at how much it is, it's a waste of money. I only buy B+W filters now. The CPL I use now, cost more than I paid for my first lens. UV filters were necessary in the days of film, not any more. Use your lens hood to protect your lens and put the lens cap on when you're not using the lens.
true true yet it would be interesting in 5 years of constant shooting to compare a glass the had a UV on and one with out

I rather don't take the chance with my expensive lenses... I shoot AF all the time never felt a difference .
I saw more flaring from a cheap filter that I used but never had any flaring with B+W filter
06-20-2009, 09:02 AM   #15
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QuoteOriginally posted by imtheguy Quote
Rondec - I can only agree with what you said but I have never heard of the"slow down the auto focus" item before. Is this due to cheap filters that only transmit 90% of the light or something systemic to having any filter?
I'd imagine it would be a combination of slightly less light transmitted and slightly less contrast.
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