How to determine best exposure and ISO

[kornkobgrunt]

I have a film camera and I want to take prime focus shots of deepsky objects. How would I determine the best camera settings prior to taking a shot? I don't like to waste film and don't get to see what results my shots wielded until later after paying to develop them. Am I going to have to guess and check?

[wornish]

I am certainly no expert but I am guessing that the answers on here will basically be Yes - its guesswork, which can be helped with a little prior calculation.

[Davey-T]

Have you thought of using colour slide film and developing it yourself ?

Assuming the processing kit is still available, it's what I used to do before digital.

Dave

[celestron8g8]

I use to use film alot before digital . It’s hard getting use to settings . I used a Olympic OM-1 but mainly a Pentax K1000 both SLRs’ . For quick shots like meteor showers and landscape at sunset i used Fuji Superior X , 800 SPD . For planets i used Kodak 200 or 400 SPD. I also used Kodak for Nebulae's . Fuji was dominant in green color . Kodak more red dominant . However the film is different now . They quit Kodak film but Fuji still makes some but not as good as back when film was popular . Kodak quit making developing fluids so youll be lucky to find any now . The best slide film i used was Kodak 200 Slide Film . 

Now for settings use bulb setting for Nebs and Galaxies and Star Clusters . If your piggybacking with a lens and camera depending what film determines the f/stop and timing . For high speed film for meteor showers in dark skies you can go several minutes but you’ll have star trailing which is fine if that’s what your shooting for .  If your PB you can go longer if tracking is good with no trailing . But as i said nebs and etc.... , use low SPD like 200 or 400 and up to an hour exposure if very dark skies and tracking . For planets i used 800 SPD with 1-10 secs exposure . My lens was my C8 at prime focus . Scope was f10 so exposures needdd that longer timing . The moon being very big and bright i used shorter exposures , sometimes slow as 1/800th or 1/1000th . With a lens like a 400mm your at the mercy of whatever the f/l is for given lens . 

All in all it’s trial and error , depending lens used, f/l , film speed and your object of interest . Hope this helps some . Post your picts when you get some . Clear skies !! 

[kornkobgrunt]

Thank you! I work at an observatory and I plan on using the camera on a 24" scope so I'm those exposures will be much shorter. I'm aware focusing may be a bother but I can work around that.

[Rodd]

A friend of mine uses film.  He was exited when he discovered a tool that is perfectly suited for determining exposure times for film.....dice.  Let em roll!?

Rodd