From steve.roberts at bbc.co.uk Wed Jul 13 09:09:29 2016 From: steve.roberts at bbc.co.uk (Steve Roberts) Date: Wed, 13 Jul 2016 08:09:29 +0000 Subject: [Tig] Sprit 'Film Type' Setting Message-ID: <4EABF517DC6E484A8D61D210885FE63EB087770E@bgb01xud1008> One of our ops just asked me a really basic question which I'm struggling to answer. In the Spirit setup, you can select eight variations of film type: Print - pos/neg Intermediate - pos/neg Primetime - pos/neg Colour - pos/neg For a projectable print in either colour or monochrome Print - Pos would be used. Is there any circumstance in which you would select Colour - Pos? (the filterwheel would have a blue filter selected at this point to counteract the orange dye mask in neg). What's the difference between a colour neg and an intermediate neg that requires a different filter in the colour wheel? Both are dye-masked, aren't they? Maybe by different amounts? Do some of these combinations simply not make sense for any film stock, so you would never select them in the real world? From kevin.j.wheatley at gmail.com Wed Jul 13 11:35:25 2016 From: kevin.j.wheatley at gmail.com (Kevin Wheatley) Date: Wed, 13 Jul 2016 11:35:25 +0100 Subject: [Tig] Sprit 'Film Type' Setting In-Reply-To: <4EABF517DC6E484A8D61D210885FE63EB087770E@bgb01xud1008> References: <4EABF517DC6E484A8D61D210885FE63EB087770E@bgb01xud1008> Message-ID: On Wed, Jul 13, 2016 at 9:09 AM, Steve Roberts via Tig wrote: > Print - pos/neg > Intermediate - pos/neg > Primetime - pos/neg > Colour - pos/neg > > For a projectable print in either colour or monochrome Print - Pos would be used. Is there any circumstance in which you would select Colour - Pos? (the filterwheel would have a blue filter selected at this point to counteract the orange dye mask in neg). What's the difference between a colour neg and an intermediate neg that requires a different filter in the colour wheel? Both are dye-masked, aren't they? Maybe by different amounts? > > Do some of these combinations simply not make sense for any film stock, so you would never select them in the real world? The filter wheel is used to 'bias' the spectral distribution of the light to better match the sensor sensitivities after passing through the film base. If you look at the colour of a blank frame of the different film types you will see that they are different colours, neg looks more orange than interpos, print is mostly clear (to the eye), etc. So you select the best filter position to get the best signal to the CCD. The negative/positive selection just inverts the interpretation of the signal, most obvious case this is needed for is with intermediate elements used during bulk printing, the first IN made from an original camera neg (-ve image) will be made into a positive image on the IN base, the second IN made from that will be negative image on IN base, the print will then be positive image on a print base. So you can have an intermediate element on intermediate base stock but with either image state. It is possible to have this occur on camera negative too if somebody has a film recorder that can expose onto camera negative, it is unlikely to occur with print or primetime. Kevin