Film for long exposures

[phildaintith]

Well for one of my final college projects im going to focus on long exposures both night and day (with a 10 stop nd). I've heard that some film goes vary grainy during long exposures, is this true?

I'm hoping that someone could recomend me some nice 100ish ASA/iso (whatever its called) thats not particularly expensive.

Cheers

 

[s162216]

Film doesn't neccessarily go grainy, it depends on the reciprocal failure of the film so you need a longer exposure for a shorter one if you understand what I mean. Because of underexposure from this, with negative film when printed, the paper will be overexposed to compensate but this increases grain.

For example, with Efke IR820C, for a 4 second exposure you actually will need a 8 second exposure.

You've not said whether its black and white or colour or negative or slide film that you want, but I would use Fuji Velvia 100 slide film (not 100F) as you can expose this up to a minute without any other filters and up to 8 minutes with a 2.5M magenta correction filter and slightly more exposure.

Datasheet: http://fujifilm.co.uk/shop/consumer/digital/professional-film/professional-colour-reversal/fujicolor-professional-reversal-film-velvia-100-rvp

For black and white, you could use Kodak Plus-X 125 as this is the only 100/125 film that I know of with reciprocal failure corrections published. The datasheet is linked below, on the second page "Exposure and Development Adjustments for Long and short exposures"

http://wwwuk.kodak.com/global/en/professional/support/techPubs/f4018/f4018.pdf

 

[EdMoss]

I've never noticed a big problem with grain, unless it was grainy to start with.
Are you looking for b/w or colour?

Which ever you choose go for one with the best reciprocity as film gets slower the longer you expose it for. A metered 30 second exposure could result in a real exposure of 5 minutes. Reciprocity tables are usually included with the film, or with Ektar, Kodak helpfully recommends you make you own tests.
Fuji Acros is the best b/w for long exposures, not tried it myself but the increase in exposure is very small compared to other films.

 

[Gandhi]

Acros is definitely the best film for reciprocity characteristics although I have never been happy with the tonal range at longer exposures. That's probably just my technique though more than anything. I have much more success with Adox chs25 for some reason.

You may also want to consider a reduced development, either by dilution, time or agitation as long exposures will inherently build contrast into the shot. This is due to the shadow areas hitting reciprocity failure before the highlights, so less effective exposure here while the highlights continue to expose correctly for longer.

 

[joxby]

Film doesn't go grainy during a long exposure, its one of the advantages it has over digital.
Fuji Velvia 100F slide (not 100 or 50) lends itself nice to long exposures, also 64T I've heard is useful for night scapes.