with 8 boxes of Kodak Tmax 100 readyloads on the shelf getting further from their expiration date, I decided to pull out the BTZS calculator , 4X5 camera , this time Zeroimage pinhole 4X5. The film was processed in BTZS tube in TmaxRS 1+7 @ 70F . SBR for this scene was 7. I used red filter taped inside. The calculated 10 minute exposure was spot on. Exp date is May 2007 but I see no loss of speed or tonal quality. I am happy ... but time to use up my precious Readyloads ..... sigh !