Quick question...

Do i need a ´slim´ polarisation filter for my 17-55?

only if you wish to avoid vignetting IMO

NEVER need 'slim' with any lens of that quite modest AOV (74 degrees) on an APS-C body. Even with wider 84 degree AOV (15mm on APS-C, 24mm on FF) they never need it. 17mm on FF (with 104 degree AOV) may need it, depending upon whose 17mm lens and the setback of the front element, but typically only for the polarizer which is inherently thicker. For example, the B+W F-Pro MRC polarizer will not vignette on the Canon 17-40L at 17mm on a full frame, so a 'slim' is not needed.

Cool thanks! Any recommendations?

Same as for any other filter - B+W MRC, Heliopan SH-PMC or Hoya S-HMC or HD.

I saw a B+W kaesemann, but that isnt a 'MRC', and i saw a MRC that isnt a kaesemann... Which would you pick? (both not-slim)

I have non-Kaesemann MRCs. If, however, you were looking at B+W's Circular Polarizers, the only kind you should consider for a DSLR, the Kaesemann's are all MRC (Linear Kaesemann's are not available in MRC).

Here see this;

http://www.kamera-express.nl/Products.as​px?c1=3408

The KSM is cheaper than the 'MRC'. You're sure all KSM's are MRC?

muusers wrote in post #10612006
The KSM is cheaper than the 'MRC'. You're sure all KSM's are MRC?

http://www.schneiderkr​euznach.com/neuheiten/​kaesemann_mrc_e.htm

"B+W was successful in combining Kaesemann circular pol filters with MRC coating technology".
They used to NOT be MRC, the announcement was made at Photokina 2002.

muusers wrote in post #10612006
Here see this;

http://www.kamera-express.nl/Products.as​px?c1=3408

The KSM is cheaper than the 'MRC'. You're sure all KSM's are MRC?

According to B+W's product guide, yes. If you get a Kaesemann CP, it's MRC. If you get a Kaesemann LP, it's not MRC.

Jon wrote in post #10612088
According to B+W's product guide, yes.

Only up to 95mm diameter IIRC. My 105mm KSM CPL is not MRC.

Although that's pretty inconsequential to most people.

rvdw98 wrote in post #10612515
Only up to 95mm diameter IIRC. My 105mm KSM CPL is not MRC.

Although that's pretty inconsequential to most people.

In 2006 Schneider said,

"All these beneficial properties of the MRC coating, which is now celebrating its '10th anniversary'
were the reason why SCHNEIDER-KREUZNACH also provided its B+W clear glass protective
filter 007 Clear with the MRC coating as the perfect mechanical front lens protection some years
ago. It is available in all commercial thread sizes from ¡9 mm to 86 mm and can thus be used with tiny
digital cameras or large field scopes."

Then they later stated efforts in progress to add MRC up to 95mm. I have not found a reason why no MRC for larger sized filters. It might be simply a process limitation of getting larger sizes into the plasma-assist vapor deposition equipment used for MRC