Does a cheap polorizer degrade image? examples

[juno_first]

I recently bought a filter kit from the rain forest as I also needed a UV filter to protect the lens.
For some strange reason the kit also has a purple filter for tube lights, well it comes in handy as a 2 stop neutral density filter as the Auto-WB compensates ok.

£16.30
Zeikos ZE-FLK67 67mm Professional MULTI-COATED Glass Filter Kit UV Polarizer Flourescent

Maybe the VR lens cant hack long exposures or something else, but shots with the polarizer set to cut out reflections seam a bit fuzzy.
I dont know if im going paranoid here and without doing a load of tests, does anyone with experience here know if a cheap polarizer is even worth putting on your lens, or even a cheap UV filter

Thanks

Polarizer set to accept reflections (not removed):

Polarizer set with no reflections:

Rest of the album here if you're interested, all with polarizer except 50mm.
Flickr 14pics

 

[juno_first]

The colours are certainly more saturated with the polarizer & im wondering if the same could be achieved by shooting in the vivid shooting mode, or would that look a bit fake?
I knew the D90 gave softer/less punchy images before I bought it, which is no big deal & maybe better.

Oh, a bit off topic but Im trying get to grips with Lightroom & dont know how much sharpness to add or if theres a pre-set amount that should be added with a particular camera?
ta

 

[juno_first]

Hey nice sharp results there.
It boggles me how a Jessops CP filter costs £50 but my 3 filters inc CP cost £16.30.
I was going get a battery pack next, but im tempted get a descent CP filter now, although I'll run some tests with/without the CP filter first to make sure.
I bet the girl shot was interesting to use with the CP filter, what with the water/foreground wood reflections & sky.

 

[juno_first]

Ok, I just did a simple still life of some detail.
Both shots the same except with non CP filter the exposure has been corrected.
Now obvious that with JUST the cheap CP filter theres a drop in sharpness.
Hopefully when I get a Jessops CP filter there wont be such a drop in sharpness?

NO CP FILTER

WITH CP FILTER

 

[juno_first]

Nice & sharp there SteveM. The 4/3 sensor is quite good.
Well I used to work in a photolab years ago & that pic is what we used to call '1 button cyan'.
I've been learning how to use Lightroom tonight & I hope you dont mind me giving your pic a little more punch:

 

[juno_first]

When I used to print photos in a 1hr lab back in the late 90s the Fuji printer I worked with corrected cyan, magenta, yellow. If your original shot printed like that we would reduce cyan by 1 or 2 buttons which is the same as adding red, or in modern language changing the tint to more warm.
I also added more contrast and adjusted blacks etc.

 

[juno_first]

Yes, like i say, it made no difference. There are no markings at all on the filter (fully on ect), should there be to indicate what effect the filter would have?

If moving the CP filter made no noticeable difference then theres probably not many reflections to remove, although it should still give a more saturated image.
Why not test a landscape with/without.

 

[juno_first]

Ok, I just spent ages getting these 2 shots as close as possible to compare a cheap CP filter against without.

18-105 @ 105
Selected from a 1ev bracketed shots & adjusted the brighntess of the white label on the non cp filter shot to match the cp filter shot which is nicely clipping around 255.

Original image (no CP) at best aperture f5.6.

no CP

with CP

Should I spend £50 on a Jessops CP filter is the question?

 

[juno_first]

my example of a jessops UV filter was to show an example of a cheap one by the way :s

Not as cheap as £16.30 for this:

 

[juno_first]

I say this because those 100% crops do not look very sharp too me so there could be a number of factors here hiding any effects.

Interesting you mention the sharpness, as Ive not really been enthralled with the sharpness of shots with the D90 so far, maybe its the 18-105 or DX sensor, I dunno. Maybe I should try use the 50mm prime as much as possible.


Wow thanks for the info. A lot to figure out.
My 50mm 1.8 has a different thread mount & I didnt want get a CP filter for a 50mm on a APS-C sensor as the filter would primarily be used for landscape scenes.
I suppose Im limited by cash atm, so Im thinking a battery pack would be more useful for now and then a descent 28 or 35mm lens.

As I cant really tell a difference between the 2 shots I may as well keep the cheap CP filter until I maybe go full-frame one day & get some good filters too.
Being as you say the Jessops is cheap too & I cant guess at this point if it will improve IQ significantly.

 

[juno_first]

Phew, Ive done this before but this time Ive been as accurate as possible: old 50mm vs 18-105@50mm @f5.6.
The darn cheapo tripod kept moving between changing lenses/zooming, but I did the best I can & its yielded interesting results.
Corrected the RAW in Lightroom with lens corrections/CA & added sharpness until just before halos appear around contrasty lines, as the D90 shoots a bit soft by default.

Even with the C.Aberrations fix, the 18-105 still shows more flaws which I presume is normal.

A bit off topic, but comparing 50mm vs 18-105@50mm (considering the CP filter fits the 18-105)

full 50mm

Comparison