Density Filter
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 Sunpak 67mm Graduated Neutral Density Filter 06GND CF7332GD6 $15.50 Time Remaining: 21d 16h 54m Buy It Now for only: $15.50 |
 67mm Gradual Color Set Graduated Neutral Density ND Grey+blue+Orange for 67 lens $20.99 Time Remaining: 30m |
 58mm 4Pc UV NEUTRAL DENSITY FD POLARIZER FILTER KIT FOR CAMERA CANON FREE POUCH $16.99 (1 Bid) Time Remaining: 46m |
 NEUTRAL DENSITY ND2 ND4 ND8 FILTER +HOOD F KODAK ZD710 $19.99 Time Remaining: 29d 2h 14m Buy It Now for only: $19.99 |
 Hoya Pro 1 Digital 82mm ND 16 Neutral Density AUTHORIZED HOYA USA DEALER $79.95 Time Remaining: 1h 1m |
 Sunpak 52mm Graduated Neutral Density Filter 06GND CF7328GD6 $11.03 Time Remaining: 27d 3h 10m Buy It Now for only: $11.03 |
 Hoya Pro 1 Digital 77mm ND 8 Neutral Density AUTHORIZED HOYA USA DEALER $63.50 Time Remaining: 1h 4m |
 Hoya Pro 1 Digital 77mm ND 16 Neutral Density AUTHORIZED HOYA USA DEALER $63.50 Time Remaining: 1h 8m |
 Fader ND ND2 ND400 77 mm 77mm Neutral Density $39.95 Time Remaining: 9d 20h 30m Buy It Now for only: $39.95 |
 Hoya Pro 1 Digital 77mm ND 32 Neutral Density AUTHORIZED HOYA USA DEALER $63.50 Time Remaining: 1h 8m |
 72mm GRAD ND FILTER GRADUATED NEUTRAL DENSITY NEW $17.95 Time Remaining: 23d 19h 1m Buy It Now for only: $17.95 |
 Hoya Pro 1 Digital 77mm ND 4 Neutral Density AUTHORIZED HOYA USA DEALER $63.50 (1 Bid) Time Remaining: 1h 8m |
 Hoya Pro 1 Digital 77mm ND 64 Neutral Density AUTHORIZED HOYA USA DEALER $63.50 Time Remaining: 1h 8m |
 Tiffen 37mm Neutral Density 09 ND 8 Filter $15.95 Time Remaining: 21d 21h 25m Buy It Now for only: $15.95 |
 VIVITAR 37MM ND8 NEUTRAL DENSITY FILTER FOR 37 MM LENS $5.00 Time Remaining: 1h 12m Buy It Now for only: $9.95 |
 Opteka 82mm HD Variable Neutral Density Fader ND Filter $34.95 Time Remaining: 17d 20h 51m Buy It Now for only: $34.95 |
 Hoya Pro 1 Digital 72mm ND 32 Neutral Density AUTHORIZED HOYA USA DEALER $52.50 Time Remaining: 1h 15m |
 Hoya Pro 1 Digital 72mm ND 64 Neutral Density AUTHORIZED HOYA USA DEALER $52.50 Time Remaining: 1h 15m |
 72 72mm Neutral Density ND2 ND4 ND8 ND 2 4 8 Lens Filter Set Kit $21.99 Time Remaining: 12d 7h 43m Buy It Now for only: $21.99 |
 Hoya Pro 1 Digital 72mm ND 4 Neutral Density AUTHORIZED HOYA USA DEALER $52.50 Time Remaining: 1h 15m |
 Marumi 49mm 49 mm Neutral Density ND8X ND8 ND Filter $16.80 Time Remaining: 26d 9h 44m Buy It Now for only: $16.80 |
 Hoya Pro 1 Digital 72mm ND 8 Neutral Density AUTHORIZED HOYA USA DEALER $52.50 Time Remaining: 1h 16m |
 Hoya Pro 1 Digital 72mm ND 16 Neutral Density AUTHORIZED HOYA USA DEALER $52.50 Time Remaining: 1h 17m |
 Hoya 77mm PRO1 NDx16 ND 16 Neutral Density Filter 77 mm Made In Japan Genuine $63.90 Time Remaining: 24d 2h 29m Buy It Now for only: $63.90 |
 Hoya Pro 1 Digital 67mm ND 4 Neutral Density AUTHORIZED HOYA USA DEALER $49.50 Time Remaining: 1h 23m |
 B+W Neutral Density ND 1000x 110 30 10stop Filter 77mm Made In Germany $113.50 Time Remaining: 26d 2h 7m Buy It Now for only: $113.50 |
 Hoya Pro 1 Digital 67mm ND 64 Neutral Density AUTHORIZED HOYA USA DEALER $49.50 Time Remaining: 1h 23m |
 Hoya Pro 1 Digital 67mm ND 8 Neutral Density AUTHORIZED HOYA USA DEALER $49.50 Time Remaining: 1h 23m |
 Hoya 77mm ND16 12 Pro1 DMC Neutral Density Filter $64.00 Time Remaining: 24d 16h 49m Buy It Now for only: $64.00 |
 Hoya Pro 1 Digital 67mm ND 16 Neutral Density AUTHORIZED HOYA USA DEALER $49.50 Time Remaining: 1h 28m |
 58mm ND2 ND4 ND8 ND10 Neutral Density Filter Grey ND Set kits with 58 mm lens $24.99 Time Remaining: 16d 1h 9m Buy It Now for only: $24.99 |
 Hoya Pro 1 Digital 67mm ND 32 Neutral Density AUTHORIZED HOYA USA DEALER $49.50 Time Remaining: 1h 28m |
 Hoya Pro 1 Digital 62mm ND 64 Neutral Density AUTHORIZED HOYA USA DEALER $49.50 Time Remaining: 1h 31m |
 VIVITAR FILTERS 72MM UV+CPL+ ND8 Neutral Density FUNDAMENTAL VIV FKND 72 $19.99 Time Remaining: 29d 7h 37m Buy It Now for only: $19.99 |
 Hoya Pro 1 Digital 62mm ND 64 Neutral Density AUTHORIZED HOYA USA DEALER $49.50 Time Remaining: 1h 31m |
 67mm ND Fader Neutral Density Adjustable Variable Filter ND2 ND4 ND8 to ND400 $19.57 Time Remaining: 5d 1h 52m Buy It Now for only: $19.57 |
 Hoya Pro 1 Digital 62mm ND 8 Neutral Density AUTHORIZED HOYA USA DEALER $49.50 Time Remaining: 1h 31m |
 Hoya Pro 1 Digital 62mm ND 32 Neutral Density AUTHORIZED HOYA USA DEALER $49.50 Time Remaining: 1h 35m |
 Slim 58mm Fader Neutral Density ND Filter ND2 to ND400 $20.00 Time Remaining: 5d 15h 7m Buy It Now for only: $20.00 |
 Hoya Pro 1 Digital 62mm ND 16 Neutral Density AUTHORIZED HOYA USA DEALER $49.50 Time Remaining: 1h 35m |
 58mm 58 mm Neutral Density ND 2+ ND 4+ND 8 Filter New $16.22 Time Remaining: 11d 1h 43m Buy It Now for only: $16.22 |
 Hoya Pro 1 Digital 58mm ND 64 Neutral Density AUTHORIZED HOYA USA DEALER $36.50 Time Remaining: 1h 38m |
 Hoya Pro 1 Digital 58mm ND 8 Neutral Density AUTHORIZED HOYA USA DEALER $36.50 Time Remaining: 1h 38m |
 67mm Neutral Density ND Filter Kits SetND2+ND4+ND8 $15.90 Time Remaining: 15d 3h 16m Buy It Now for only: $15.90 |
 Hoya Pro 1 Digital 58mm ND 16 Neutral Density AUTHORIZED HOYA USA DEALER $36.50 Time Remaining: 1h 41m |
 52mm Fader Variable ND Filter Neutral Density ND2 ND4 ND8 ND16 ND32 to ND400 $19.99 Time Remaining: 21d 23h 13m Buy It Now for only: $19.99 |
 Hoya Pro 1 Digital 58mm ND 32 Neutral Density AUTHORIZED HOYA USA DEALER $36.50 Time Remaining: 1h 41m |
 Hoya Pro 1 Digital 58mm ND 4 Neutral Density AUTHORIZED HOYA USA DEALER $36.50 Time Remaining: 1h 42m |
 B+W 502 Graduated Neutral Density ND Gray Filter 49mm $38.90 Time Remaining: 12d 2h 3m Buy It Now for only: $38.90 |
 Hoya Pro 1 Digital 55mm ND 8 Neutral Density AUTHORIZED HOYA USA DEALER $33.50 Time Remaining: 1h 44m |
 Slim 67mm Fader ND Filter Neutral Density ND2 to ND400 $19.99 Time Remaining: 13d 9h 48m Buy It Now for only: $19.99 |
 Hoya Pro 1 Digital 55mm ND 16 Neutral Density AUTHORIZED HOYA USA DEALER $33.50 Time Remaining: 1h 48m |
 Hoya Pro 1 Digital 55mm ND 4 Neutral Density AUTHORIZED HOYA USA DEALER $33.50 Time Remaining: 1h 48m |
 Slim 77mm Fader Neutral Density ND Filter ND2 to ND400 $20.99 Time Remaining: 5d 8h 10m Buy It Now for only: $20.99 |
 Hoya Pro 1 Digital 52mm ND 64 Neutral Density AUTHORIZED HOYA USA DEALER $33.50 Time Remaining: 1h 50m |
 Brand New Hoya 77mm 77 mm HD High Density Digital UV Haze Filter XHD 77UV $69.99 Time Remaining: 3d 17h 4m Buy It Now for only: $69.99 |
 Hoya Pro 1 Digital 52mm ND 8 Neutral Density AUTHORIZED HOYA USA DEALER $33.50 Time Remaining: 1h 50m |
 Hoya Pro 1 Digital 52mm ND 16 Neutral Density AUTHORIZED HOYA USA DEALER $33.50 Time Remaining: 1h 54m |
 67 67MM Neutral Density ND Filter KIT ND2 ND4 ND8 $15.99 Time Remaining: 4d 8h 11m Buy It Now for only: $15.99 |
 Hoya Pro 1 Digital 52mm ND 32 Neutral Density AUTHORIZED HOYA USA DEALER $33.50 Time Remaining: 1h 54m |
 67mm Neutral Density ND 400 filter for Camera lens US $28.00 Time Remaining: 27d 4h 37m Buy It Now for only: $28.00 |
 HOYA HMC ND400 58mm Neutral Density ND 400 Filter 58 mm $49.99 Time Remaining: 1h 56m Buy It Now for only: $54.99 |
 POLAROID 82MM NEUTRAL DENSITY VARIABLE FADER ND FILTER ND6 ND9 ND16 ND32 ND400 $49.00 (1 Bid) Time Remaining: 1h 58m |
 Fotga 6pcs Full Neutral Density + Graudal ND 2 4 8 Filter Kit for Cokin P series $27.38 Time Remaining: 26d 8h 32m Buy It Now for only: $27.38 |
 HOYA HMC ND400 58mm Neutral Density ND 400 Filter 58 mm $49.99 Time Remaining: 1h 58m Buy It Now for only: $54.99 |
 B+W Neutral Density ND 301000x 110 Glass Filter 58mm $50.50 Time Remaining: 8d 4h 14m Buy It Now for only: $50.50 |
 POLAROID 77MM NEUTRAL DENSITY VARIABLE FADER ND FILTER ND2 ND8 ND16 to ND400 $49.00 (2 Bids) Time Remaining: 3h 7m |
 NEUTRAL DENSITY FILTER DISK FORCONTOURHD GPS 1080P HD $9.99 Time Remaining: 3h 44m |
 Slim 52 mm Fader Neutral Density ND Filter ND2 to ND400 F6P $15.94 Time Remaining: 24d 8h 56m Buy It Now for only: $15.94 |
 MARUMI 67mm DHG LIGHT CONTROL 8 Neutral Density 09 $33.50 Time Remaining: 3h 49m |
 Hoya HMC 77mm ND 400 Neutral Density MC AUTHORIZED HOYA USA DEALER $145.35 Time Remaining: 6d 17h 56m Buy It Now for only: $145.35 |
 MARUMI 72mm DHG LIGHT CONTROL 8 Neutral Density 09 $37.50 Time Remaining: 3h 49m |
 MARUMI 77mm DHG LIGHT CONTROL 8 Neutral Density 09 $41.50 Time Remaining: 3h 49m |
 Hoya 52mm NDX8 HMC Filter 52 mm Neutral Density ND8 09 $25.35 Time Remaining: 25d 16h 42m Buy It Now for only: $25.35 |
 MARUMI 49mm DHG LIGHT CONTROL 8 Neutral Density 09 $19.95 Time Remaining: 3h 53m |
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Filter Aid
Kieselguhr
Is the term used for fossils of diatoms (single cell algae containing silicon dioxide, SiO2) of which there are more than 15,000 types in the sea. They must have existed for millions of year in isolated seas or regions of the sea in such quantities that their fossils in the course of time covered the bottom of the sea in a very thick layer. Depend on their processing there are three groups of guhrs;
1. Dried kieselguhrs The material is dried at about 300 oC & then milled. So called fine guhrs are produced in this way. Ignited & calcine guhrs. The raw material is heated in large rotating ovens at 600 to 800 oC & then screened. This produces depending on the combustion temperature & sieving, fine & medium guhrs
2. Guhrs ignited with a flux additive These are produced by recombustion at 1000 oC of the already ignited guhrs with the addition of CaCO3 or other flux additive & the diatom skeletons are thereby cemented together into larger structures which are require for precoating. The white guhrs are formed in this way.
3. Finer the guhr The finer the guhr the better it clarifies but at the same time the lower the filtration speed. An important feature for the economic use of kieselguhr is the wet density. By this meant the volume which the guhr occupies under pressure. Kieselguhrs with a wet density less than 300 g/l are most suitable for filtration. With higher wet densities must expect to use more guhr & to obtain a higher pressure increase. Kieselguhr usage can vary between 80 to 200 g/hl. Kieselguhr is not only very expensive, it also result in costs for disposal of the kieselguhr slurry
Perlite
Is a material of volcanic origin & consists principally of aluminium silicate, Raw perlite is heated to 800 oC. The water contained in it expands & leads to swelling & bursting. The glassy structures produced are milled. This give rise to a very light, loose powder which weighs 20 to 40% less than kieselguhr. At low pH values perlite release chalk & iron.
About the Author
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Neutral Density Filter
August 13th, 2010 in
Lenses & Filters | tags: assumed density filter, density filter, filter, filters, graduated density filter, graduated neutral density filter, nd, photography, tutorial, variable density filter