Imaging with Film

[Stub Mandrel]

I want to try something exciting and different for the widefield challenge, so I've ordered a couple of rolls of 120 file, Previa 100 ISO.

Can anyone offer me advice on exposure times, otehr than 'as long as possible'?

I'll be using a Yashica Mat, so it's 80mm focal length, apertures f22 to f3.5.

[michael.h.f.wilkinson]

I took a decent image of comet Hyakutake on 100 ISO film (Fujichrome Sensia 100) at 12 minutes exposure time at F/2. At F/3.5 that works out as 36 minutes . Much depends on LP levels, of course.

BTW, this is a scan of a print of a slide, hence the poor quality

[coatesg]

Used to enjoy film photography (but always used Kodak, as it had a better balance than Fuji in my experience - Fuji positives always had a blue/green cast to me!). 

Reciprocity failure means film has a non-linear response to light - anything in the 10-20min range is a good starter for widefield, but you'll want to be in as dark a place as you can be, as it's much harder to "subtract" away gradients or LP!

[Stub Mandrel]

Thanks both.

The Yashica Mat is supposed to be sharpest at f8 to f16, but I've read reviews claiming they are better than contemporary Rolleiflex, so I have high hopes!

At 80mm I could get away with long unguided subs, say 14minutes, and periodic error will be too small to worry about. I may try guiding though, I think I will experiment with 30-60 minutes at f8. I can get the film push processed to gain a stop or two.

These days you can get the slide scanned when it is processed, so although I doubt I will be able to stack the images, I will be able to post-process them. If I want I can get it scanned at 80Mb a frame!

[Starlight 1]

All I can add is take notes of every setting you use, I done a lot of infra-red slide film back in the 80s and have a dark room  as there is no setting on how long to do anything and shops would not look at it .

[coatesg]

Don't think there's any reason as to why you couldn't scan positives and stack - doing it on computer is much easier than a darkroom only process! 

(see: View of the Universe by David Malin - I'm sure he did darkroom based stacking, RGB combination, enhancement, unsharp masks(!) for his work from the scope on La Palma/the AAT :-O)

I'd try something like f5.6 on a 3.5 lens just to get the most light on the emulsion (without too many seagulls) - unless you're in a really dark location, light pollution will be your limiting factor and at 30min I'd expect it to be well fogged. As you say, post processing the scanned result might help you here. Push processing will definitely help!

[Stub Mandrel]

Two rolls of Previa 100 120 film have arrived. I've managed to remember how to load one and I've found my remote release and Yashica adaptor and my other remote release with a locking screw. The latter is never used, bought at least thirty years ago and in as-new condition. Deep gadget joy

[Starlight 1]

hope you have fun,  my old 35mm have a computer  back panel  and that was fun setting it up for a night  out.

[laser_jock99]

Hyakutake- great memories of that comet!

My efforts on Ektachrome 400 colour slide film and a home made tracking mount....

[MartinFransson]

Don't get me all nostalgic over here! I've still got some of this in the fridge...