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03-19-2010, 05:49 PM   #16
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QuoteOriginally posted by tibbitts Quote
I'm not an expert, but my 67 and 77mm circular polarizers cost about $10-$15. I tested them by taking pictures and comparing with and without the filter, and using my camera and lenses I can't see the difference at even 1:1 with raw files. However, the only times I've wanted to use a polarizer has been in flat lighting with no backlighting. I can see visibly worse flare if looking into the sun, for example - I've just never wanted to use the filter under those circumstances.

I also have "window glass" UV filters, because for some reason I often use my cameras in rain or snow or salt spray. So there is often some dirt or moisture on the filters that probably degrades the image more then the glass itself. However I try to take them off on the few occasions when I take pictures including a light source.

Paul

Paul, good idea, I think I often use the same practice, which is to remove the filter when I know the condition is safe (without wind blown particles); and when the condition is harsh such as around the beach or high wind, I always leave the "window glass" UV filter on even though I know it may degrade the IQ a bit.

03-19-2010, 07:27 PM   #17
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QuoteOriginally posted by aleonx3 Quote
Hi, Wheatfield, I guess this is a much debated topic already. However, I do have one question. I have recently acquired a nice Chinon multi-coated lens which I find the coating to be quite remarkable as if a polarized filter is already built into the lens. Should I be getting a NDx2 filter instead of a CPL? The ND filter has a different purpose which is to reduce the contrast (often used to slow down the shutter to create silky effect of running water). This is the lens I have:
No, what you have there is probably quite a nice little lens, but coatings on lenses do not act as polarizers.
So, you still need one, if that is what you were thinking.
To be a bit of a pedant, ND filters don't lower contrast (or at least they shouldn't), they just reduce the amount of light coming through the lens.
You might be thinking of a graduated ND filter, which would be clear on one side, and gray on the other, with a gradual increase in density.
03-19-2010, 07:53 PM   #18
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QuoteOriginally posted by Augustus58 Quote
How old is this chart? I recently bought a couple Hoya HMC UV filters and they were made in the Philippines. I did buy them from reputable dealers in Amazon, so they should be okay right? (Why am I so paranoid!) Now it's really hard to get flares in my pictures.
It can't be that old because the HD filters about less than 2 years old. I bought one last year to replace something I regretted buying because of really poor quality.

The Circular Polarizer HD is simply superb. It keeps things real sharp, has very little effect on image quality and is perfectly color-balanced.

My suggestion is to wait to have the budget, there is really no pointing buying something to make crappy pictures.

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03-20-2010, 12:53 AM   #19
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QuoteOriginally posted by tibbitts Quote
I'm not an expert, but my 67 and 77mm circular polarizers cost about $10-$15. I tested them by taking pictures and comparing with and without the filter, and using my camera and lenses I can't see the difference at even 1:1 with raw files. However, the only times I've wanted to use a polarizer has been in flat lighting with no backlighting. I can see visibly worse flare if looking into the sun, for example - I've just never wanted to use the filter under those circumstances.
Paul
I am certainly no expert either but have researched this topic extensively over the last year. First, congratulations on finding ANY kind of 67-77mm filter that cheaply. Never seen one and I won't pass judgement on yours without knowing what they actually are.
Second, if you can't see an OBVIOUS difference when using the CPL then I can confidently say your CPLs are not CPLs or you are not using them correctly.
On a sunny day, focus on a subject about at a right angle (for maximum effect) to the Sun's incident rays. Water is the easiest but foliage with white shine on the leaves and nice billowing white clouds work well plus the sky goes a deeper blue. While looking through the viewfinder just rotate the CPL and watch the subject with glare darken and lighten every 90 degree rotation. If that does not happen with your CPLs then I recommend you remove the glass and use the rims for short extension tubes.

There should be a zillion hits on the interwebs for that kind of test shot but if you would like me to post a few for you I would be happy to.

03-20-2010, 01:18 AM   #20
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I would not risk using a low-quality filter for anything. Why spend good money on good lenses and cameras to then use average glass as the last little element between your camera and a subject? Cheap, low quality filters = bad idea in my opinion.

I'd say use no filter before you use a low-end cheap filter.

I use Hoya Pro1 digital filters. They're reasonably priced, and in tests come out on top or close to it. They seem pretty tough and well made, and are slim. Can't say I've done a before-and-after IQ test but they seem fine.

QuoteOriginally posted by Augustus58 Quote
Btw, does anyone have any tips on how to clean Hoya HMC filters (other than polishing them for an hour)? Now I know I am borderline OCD...
A clean micro-fibre cloth should do the trick in two seconds.
03-20-2010, 12:33 PM   #21
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QuoteOriginally posted by imtheguy Quote
I am certainly no expert either but have researched this topic extensively over the last year. First, congratulations on finding ANY kind of 67-77mm filter that cheaply. Never seen one and I won't pass judgement on yours without knowing what they actually are.
Second, if you can't see an OBVIOUS difference when using the CPL then I can confidently say your CPLs are not CPLs or you are not using them correctly.
On a sunny day, focus on a subject about at a right angle (for maximum effect) to the Sun's incident rays. Water is the easiest but foliage with white shine on the leaves and nice billowing white clouds work well plus the sky goes a deeper blue. While looking through the viewfinder just rotate the CPL and watch the subject with glare darken and lighten every 90 degree rotation. If that does not happen with your CPLs then I recommend you remove the glass and use the rims for short extension tubes.

There should be a zillion hits on the interwebs for that kind of test shot but if you would like me to post a few for you I would be happy to.
You misunderstood. I meant difference specifically in resolution and contrast. Because I've had so many difficulties with my 10-20mm sigma, I've developed a standard picture I use for testing edge resolution, using the stop sign on my street (at a distance, of course.) What I'm saying is that with my $10-15 filters (ebay) on and off, using the same lenses (I've tried the sigma, plus my 16-45 and 50-200), I just can't see the difference in sharpness or contrast, given the light coming from behind (me.) Shooting into the sun is a whole different story. I also use the polarizer occasionally, sometimes adjusted for minimal polarizing, as a 1-plus-ish stop ND filter. The color is slightly different with my polarizer (more than I'd like), and the polarizer has the expected effect.

I also use my '80s era (they were sure cheaper then!) Cokin split gray 1x and 2x filters. They are visibly not gray - more sort of greenish. And for $8 (then - more like $30 now?) they're obviously not even glass, and definitely not coated. But sometimes there is just no affordable alternative - it's that or blow out skies.

To do the two split filters plus polarizers for all my lenses plus haze filters in high quality (for weather/salt/sand) would cost as much as the 10-20mm sigma. Given that like most people I have a finite amount to spend, I think I'm better off with the sigma and the $10-15 filters, than not having the sigma and having super quality filters.

Incidentally, using the window-glass haze filter, I honestly can't see any difference when there are no light sources in the image. I'm not saying there is no difference, I'm just saying I can't see it with raw at 100%.

Paul
03-20-2010, 01:18 PM   #22
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QuoteOriginally posted by tibbitts Quote
You misunderstood.
Paul
Yes, I did.
03-20-2010, 07:23 PM   #23
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Cost aside, which is the better brand to go with for a CLP? Hoya HD or B+W?

03-20-2010, 10:36 PM   #24
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QuoteOriginally posted by Perrumpo Quote
Cost aside, which is the better brand to go with for a CLP? Hoya HD or B+W?
They both have multiple grades and either brand's mid-grade product with coatings on all surfaces should be difficult to tell from the other. The "better" one is probably personal preference. Its not something I could fight over. Some are arguably easier to clean, some have better knurling on the rim, some are thinner to help prevent vignetting on ultra-wide lenses. Pick the one you feel good about and start shooting.
03-21-2010, 03:37 PM   #25
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actual comparison

Here is the 50-200mm Pentax lens, k100d, raw converted to jpg, crop from 100%, 200mm, f8, with and without one of the most notorious "window glass" filters (tiffen haze1). Although the light was behind me, there is somewhat of a backlight effect here with the bright sky. However, as I said earlier, I would try to avoid using the filter with an actual point light source or reflection in the image.

Paul
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Last edited by tibbitts; 03-21-2010 at 03:47 PM.
03-21-2010, 05:21 PM   #26
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It's kind of hard to tell because the second shot is out of focus and has a touch of camera shake going on.

With regard to Hoya versus B&H. I haven't used B&H but the top ranges sound excellent. They're also a lot more expensive then similar Hoya ones from what I've seen. Whether there's a real difference I'm not sure, but in a UV filter test (on the net somewhere) the Hoya Pro1 digital came out on top.

The Kenko Pro1 range is meant to be a different branding of the same Hoya filter, sometimes a tad cheaper.

I often use UV filters, not so much because I think that they offer much more protection that a lens hood in normal environments, but because I shoot lots around a city, sometimes passing spraypainters etc, and I can also wipe rain off a UV filter quickly without worrying about causing any damage to my lens surface. Using UV/protector filters tends to be controversial as they add no IQ benefit to DSLRs, but only the possibility of reducing IQ. So it all depends on whether you think it's worth it for any possible protection to your lens surface (which is already quite tough).

Polarisers aren't controversial - their effects would either mean a lot of long/destructive photoshop work or be impossible to replicate after the shot has been taken. In my experience, a good polariser can only enhance shots, but you have the light loss which means I wouldn't leave one on a lens all the time for my own stuff.
03-21-2010, 08:42 PM   #27
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QuoteQuote:
It's kind of hard to tell because the second shot is out of focus and has a touch of camera shake going on.
I'm not sure, but I think it's more a matter of the light changing and the exposure being a little different due to the clouds behind the scene moving a bit. But that's my point - if you can't tell the difference in your own pictures, don't worry about which filter you use. With a little tweaking these two pictures could certainly be made identical by my standards. The test everyone refers to on the net was for the worst possible cases, where it would obviously be best to remove any filter. My test used the filter they rated the worst. Not that it matters, but the first picture is with the filter, the second without.

What I'd be interested to see is if somebody will post pictures showing that there really is a difference, using plain old front lighting, but maybe a high-mp body, DA 77, or something. That won't make me run out and get a fancy filter, since I can't reproduce what they did, but at least I'll know I'd have to budget for filters if I could ever afford all that other expensive hardware.

Paul
03-22-2010, 10:37 PM   #28
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Here's a comparison of 2 filters. They're UV filters, not polarizing filters, but the comparison here is between coatings so it's still relevant. On the left is a high end Hoya HD UV filter. On the right is a super cheap Targus "multi coated" filter that I bought at WalMart (UV + CPL costs all of $16 USD). Both filters are angled so they reflect the exact same light bulb, a 40 watt CFL in my home office. Both filters are sitting on a white towel.

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Now remember, the coating on a filter i supposed to help PREVENT reflections. The idea is to allow more light through the glass by reflecting less of it. So the brighter the reflection, the crappier the coating. I think the picture speaks for itself. It's worth noting that the effect is even more dramatic when I'm holding the filters away from a surface. Having the towel right behind the filters is creating sort of a "mirror" effect. But I have yet to figure out how to precisely aim both filters to simultaneously reflect the light while taking a picture of them.

Keep in mind, even the crappy Targus filter is marketed as "multi coated". An uncoated one would be worse. All that reflected light is light that doesn't get into the camera when you need it.
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