I've been using Rollei IR 400 film in 35mm and 120 for a year or two now and have had some pleasing results. I generally rate it at 12-25iso with a Hoya R72 filter on and get a very pronounced IR effect. It is however expensive film at £7 a roll for 35mm and £6 for 120. I know that people have successfully used Rollei Retro 400s for IR work and there are plenty of examples on Flickr with good IR effect when shot at 12-25iso. The retro 400s is marketed as having extended red sensitivity but isn't sold as IR film. When you look at the data sheets for the IR400 http://www.maco-photo.de/files/images/TA_Rollei_Infrared400_eng.pdf and Retro 400s http://www.maco-photo.de/files/images/Retro400S_Infrared_aviphot_pan400S_2006_01_09_en.pdf. The shape of the spectral sensitivity graphs is identical and importantly the portion above the 720nm cut of of an IR filter is the same. They are both films made by Agfa and repackaged by Rollei. Is this just a case of clever marketing. Selling exactly the same film at a significant mark up to a niche market? If it is, then on the one hand that sucks, although I guess that's capitalism for you. On the other hand, this film is available from First-Call as their own brand film http://www.firstcall-photographic.co.uk/products/4916/firstcall-400s-135-36-iso-400 for £2.49 a roll in 35mm. Shame it isn't available in 120 from them. So what do people think, is it the same film?