Topic: Faster films with larger negs

[choppert]

Now here's a stoopid one for you

Am I right in thinking that if I like an enlargement from a 35mm film by taking the photo on a larger neg I can use a faster film and get the same graininess on the same enlargement?

I'm happy with 35mm enlargements at 16"*11" so using that same logic I could take the same photo on 6*9 film (which has a surface area 6 times that of 35mm film) with a speed of 6400 (six stops faster than 100)

That doesn't make much sense to me!  6400 film would be a bit grainy whatever the enlargement??

I'm confused

[Nigel]

I think your theory is correct, you can use a faster film on a larger negative and get the same results for a given print size. What you can't do is say that six times the area equals six stops. You'd have to do some tests but maybe six times the area equals two stops or three stops.

I think! 

[Francois]

This one's a bit hard...

35mm film makes a 24 x 36 mm negative which is 864 sq. mm with a ratio of 1.5 to 1

6x9 negatives are 60 x 90 mm which is 5400 sq. mm with a ratio of 1.5 to 1 (wow... I'm surprised since 6x9 looks a lot more "panoramic").

So, 6x9 is 6.25 times the surface of 35mm...
So grain should be that many times smaller for the same sensitivity.
Where the difference lies is in the film contrast. Since I don't know of any 6400 ISO film, I can only try and figure out something based on the comparison of T-Max 100 (tmx) and T-Max P3200 (tmz).

Tmx resolves 63 lines/mm (low contrast target)
Tmz resolves 40 lines/mm (low contrast target)

Using a larger negative of higher sensitivity would give the apparent resolution of around 100 lines/mm... (sqrt(6.25) x 40 lines/mm ... hope my math is good enough)

So the reasoning is good.

[Ed Wenn]

...please can I have my brain back now!?

Chops, don't ask stuff like this again...it only brings out the intelligence in people.
 

[LT]

Francois lost me at the bit where he said "this one's ... "

Logic says you would be able to enlarge to a larger size before the grain kicks in, but at what size it starts to lose it's advantage depends on so much else - type of enlargement (digital, analogue), then type of scanner resolution/ light source (condensor/ cold light/ diffusion). how the film is developed - if you're looking at 6,400 you'll have to push develop one of the superfast films - say ilford delta 3200 which is in fact a 1600 iso emulsion, so that would be pushed 2 stops, raising contrast and grain somewhat.......

so much in assessing outcomes in photography is subjective anyway.  Lens resolution or film resolving power is only really relevant in scientific applications - if you're all about making nice pictures, then you'll have to decide for yourself what you like or dont Like, dont let some cold regimented scientific test rule your choices, man.  try it out and see.

[Pete_R]

Am I right in thinking that if I like an enlargement from a 35mm film by taking the photo on a larger neg I can use a faster film and get the same graininess on the same enlargement?

I think the simple answer Chops is no. Mainly because as soon as you change to a different film/camera, you change the conditions so you can't extrapolate from what happens on 35mm to what will happen with 6x9. That doesn't mean you couldn't achieve what you want, it just means you can't assume it.

I suppose what you could say is that, if you use the same film in both formats, then the smaller degree of enlargement required with the 6x9 will give you proportionally smaller grain for the same print size.

Somehow, this simple answer has become complicated. Heck, like Leon said, just go try it.

[Francois]

...please can I have my brain back now!?

Francois lost me at the bit where he said "this one's ... "

Sorry for the headache guys
I guess the explanation was a bit mind numbing 

I was trying to find a comparison for grain size (which would have been simply fantastic) but had to settle for resolution tests as a comparison method... not the most obvious stuff to play with.

To make things simple:
big negative = less enlargement
less enlargement = smaller looking grain
smaller looking grain = possibility to substitute grainier film
grainier film = still smaller looking grain than a small negative enlarged a lot more.

That's why using 400 ISO film in a medium format camera isn't too bad compared to 35mm...

Hope that simplifies things.

[Heather]

http://www.stargazy.org/wedding21-04-07/roll02/05.jpg kind of big, scan of 8x10 print from a holga neg, delta3200 pushed to 6400 in microphen. It looks quite nice to my fuzzy eyes.