[Ed Hurst]

Hello all,

Recent discussion of filters has reminded me that I want to get hold of some more filters to use in the filter tray of my 25mm f4 DA lens. The lens was supplied with the CP-L filter and a plain filter (which I presume has to be used whenever the CP-L is not being used so that the focus path works properly - as I believe it requires glass to be there).

I want to get hold of some nice NDs to use in there in place of the CP-L. Does anyone have a recommendations and a good source? Presumably the best ones would be super multi-coated made by someone like B+W or another premium company. I live in Australia (in case that is relevant to where things will be shipped). Also, I believe that some 40.5mm filters would be too thick to fit in the tray, so I'd appreciate it if any recommendations made are for filters known to fit.

Thanks to all in advance!

Ed

[itshimitis]

I picked up Kenko Pro ND4 and ND8 at Yodabashi in Tokyo. They fit perfectly:

The barcode number is 4961607342435

[jwoodland]

I have this filter and it fits just fine - in fact it is a tad thinner than those supplied with the lens - B+W 40.5mm 1.8 ND MRC 106M Filter. I could not stack two of them though, but there is room for a thicker filter to go through the slot, not sure exactly how thick. I found this filter does vignette for some reason vs. the clear filter.

What I have been unable to find anywhere is an extra filter holder - if someone has a source please post. I much prefer to have each filter in its own filter holder, which makes swapping them out a lot faster, plus you don't have to handle the filter at all, and with these tiny suckers it is easy to touch the glass with a grimy fingertip while screwing one off and the other one on.

[itshimitis]

One I will warn you off - Hoya are very good fitters generally, but the Hoya 40.5 don't fit. They are too wide.

[jwoodland]

I looked at the Hoya site and their good NDs were not made in 40.5mm, smallest was 49mm. (Hoya ProND filters that have a Metallic ACCU-ND coating - I was hoping these filters would help with the color-cast issues - the B+W 64x ND had a wried cast that varied across the frame even after color correction via color checker card.)

With the rumor of the 28-45mm zoom perhaps soon (HD Pentax-DA 645 28-45mm F4.5 ED AW SDM SR - Pentax Rumors), I might send my 25mm back and wait on that one, although I've not seen a filter size noted for it.

[mikeSF]

in addition to the CP-L already mentioned, I am using the 40.5mm B+W F-pro 10-stop ND which fits correctly in the slot as well.

here is a link: http://www.bhphotovideo.com/c/product/808846-REG/B_W_65_098008_40_5mm_110_Solid_Neutral.html

I was asking a similar question a year ago too: https://www.pentaxforums.com/forums/22-pentax-camera-field-accessories/225945...nd-filter.html

[jwoodland]

Hey Mike, the B+W F-pro 10-stop ND that I have vignettes and the color cast varies across the frame. Have you been able to correct this?

[grhazelton]

Hey Mike, the B+W F-pro 10-stop ND that I have vignettes and the color cast varies across the frame. Have you been able to correct this?

You might try this Home Quite a range of used, NOS, and new glass.

[jonojono]

Ed, I got the heliopan here. Works like a charm.

Heliopan 40.5mm ND 0.6; 0.9; 3.0 Filter Bundle - Photographic Retailer in London, Ship Worldwide! | Teamwork Digital

[mikeSF]

Hey Mike, the B+W F-pro 10-stop ND that I have vignettes and the color cast varies across the frame. Have you been able to correct this?

I shoot landscapes with the lens stopped down, so I don't have any issues with vignetting of the filter. At wide open aperture f/4, there is some detectable vignetting.
Also, I have not experienced any non-uniform color casting across the frame; that sounds like a specific defect.

[itshimitis]

I am giving the Dörr 10 stop a run. It's very slim so will definitely fit. Got it from Amazon UK. Been persisting down all day with no sky interest so haven't given it a go yet, will report back

[Ed Hurst]

Thank you all so much for your help. I wonder if anyone can weigh up the relative merits of the different filters mentioned? Given the cost of the 645Z and 25mm lens, I am eager to get the best possible optical performance, even if it costs a little more. I used to have a B+W filter for my 6x7 300mm EDIF lens and it was brilliant. Hoyas I have used have been good, but perhaps not quite as excellent as the B+W. However, I have never used a Heliopan, Kenko Pro or Dörr filter, so would be very interested to know which is most highly regarded overall. Presumably coatings are a significant issue. Similarly vignetting and colour issues are a concern if they occur.

I would be getting a few NDs of different densities BTW...

Warmest regards,

Ed

[TheDocAUS]

Lee filters and Singh Ray filters are worth a look. Premium brands, aka premium pricing.

[martini]

Under the assumption that the filter in a FA25 is part of the optical design, the thickness of It (meaning others than the two delivered) could be a factor of decision too.

[itshimitis]

This is with the dörr filter: 57 secs at f/25 - it doesn't seem as dark as the Lee 10 stopper, but seems more in line with the normal 10 stopper according to apps