Andrea B. Posted May 26, 2023 Share Posted May 26, 2023 In our list of recommended gear, LINKIE, I have of course listed the following stacks. ZWB1 + QB39 ZWB2 + QB39 ZWB3 + TSN575 But I don't know anything about the typical thicknesses of ZWB glass sold on Ebay. Also, does anyone have any recommendations for thicknesses of the IR-blockers? I will try to investigate on my own, but would also welcome any input from folks actually using ZWB stacks of any kind. Thank you in advance. Link to comment
Stefano Posted May 26, 2023 Share Posted May 26, 2023 The most common thickness is probably 2 mm. Link to comment
photoni Posted May 26, 2023 Share Posted May 26, 2023 these are the filters i got from Tangsinuo, and the thickness i measured. If I remember correctly @ulf measured them more precisely QB39 = 1,6 mm - (similar to BG39 is too thin to block IR. with 2 together it works as TSN) TSN575 = 2,25 QB29 = 2,1 ZWB3 = 2,15 (now oxidized - not usable) ZWB2 = 2,15 ZWB1 = 2,2 in many of my posts you can see the results Link to comment
colinbm Posted May 27, 2023 Share Posted May 27, 2023 @photoni As mentioned on UVP before, Phosphoric Acid will clean the ZWB filters. Link to comment
photoni Posted May 27, 2023 Share Posted May 27, 2023 2 hours ago, colinbm said: @photoni As mentioned on UVP before, Phosphoric Acid will clean the ZWB filters. Thanks, I didn't read that. with what dilution? does 10% nitric acid work? Link to comment
Akira Posted May 27, 2023 Share Posted May 27, 2023 A 28mm ZWB2 I bought recently from amazon is 2mm thick. Link to comment
ulf Posted May 27, 2023 Share Posted May 27, 2023 8 hours ago, photoni said: these are the filters i got from Tangsinuo, and the thickness i measured. If I remember correctly @ulf measured them more precisely My thickness-results are at the very last post of this thread, not only for Chinese filters, but also American made: https://www.ultravioletphotography.com/content/index.php?/topic/5518-new-tangsinuo-filters-which-to-get/page/2/#elControls_61509_menu The thicknesses can have a rather wide spread and if not clearly stated, that is a problem as the thickness is just as important as the filter glass material used. I think that is partly due to ignorance of the buyers not asking for that information causing a distinct demand. The exact thickness might not be that important, one tenth of a mm more or less for normal photography will be OK. Some of the bad reputation for Chinese filter glass, beside batch spread and possibly bad mechanical manufacturing might be that comparisons were made without any attention to the thickness. Link to comment
otoien Posted May 27, 2023 Share Posted May 27, 2023 The recently purchased QB39 from Tangsinuo in 20mm diameter size is 2mm thick (or perhaps 2.05mm), . The 20mm diameter ZWB1 I purchase long time ago from ebay seller mei-2014 is also 2mm thick. The IR leakage of the combination seems minimal, beyond any practical effect (see this thread: https://www.ultravioletphotography.com/content/index.php?/topic/5818-opportunistic-reflected-uv-with-planetary-astrocam/#comment-62320). Link to comment
Wayne Harridge Posted June 8, 2023 Share Posted June 8, 2023 On 5/27/2023 at 2:53 PM, photoni said: Thanks, I didn't read that. with what dilution? does 10% nitric acid work? I have an oxidised filter too, just wondering if you can use Coca-Cola to remove the oxidation as I understand it contains phosphoric acid and it does seem to clean up things like tarnished coins. Link to comment
Andy Perrin Posted June 8, 2023 Share Posted June 8, 2023 Cadmium used to recommend hydrogen peroxide soaks for oxidation. Link to comment
Andrea B. Posted July 11, 2023 Author Share Posted July 11, 2023 holy heavens!! Please do NOT use nitric acid or phosphoric acid to clean your filters. You could as easily corrode the glass as clean it depending on how strong the acid is !! Not to mention what it might do to your skin if you splash it. Acids might also react with the filter mount. If the oxidation is not too advanced, oxidized blue-green filter glass can be soaked overnight in hydrogen peroxide to remove it. Or you can polish the filter with very fine-grained cerium oxide glass polish if the filter is not coated. Glass polish is a little messier. Link to comment
colinbm Posted July 12, 2023 Share Posted July 12, 2023 5 hours ago, Andrea B. said: holy heavens!! Please do NOT use nitric acid or phosphoric acid to clean your filters. You could as easily corrode the glass as clean it depending on how strong the acid is !! Not to mention what it might do to your skin if you splash it. Acids might also react with the filter mount. If the oxidation is not too advanced, oxidized blue-green filter glass can be soaked overnight in hydrogen peroxide to remove it. Or you can polish the filter with very fine-grained cerium oxide glass polish if the filter is not coated. Glass polish is a little messier. Andrea, Phosphoric Acid is used to cleanup the glass filters OK. It is not a strong acid & with care to not get it on your shin. People consume it everyday, in the correct application ! Works well for me & should be finished cleaned with Hydrogen Peroxide. Link to comment
Andrea B. Posted July 17, 2023 Author Share Posted July 17, 2023 Col, thanks for the update. I was remembering my days in my college chem lab seeing bottles of thick, strong phosphoric acid. I took 4 chem courses as an undergrad (basic, analytic, organic), but decided not to pursue it further. Link to comment
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