Changing Paper Size

[mryoda]

Hey!
Currently i am printing on Ilford Multigrade 5x7 and i want to make a bigger
print using Ilford Multigrade 8x10
Will i need in increase exposure times for the bigger paper or will it stay the same ?
Is there anything else to know ?
Thanks!

 

[Paul Howell]

In most cases es, increasing magification requires addtional time. But in some cases one brand of paper may be faster so changing from 5X7 to 8X10 may take more or less exposure. My quess you will need to increase your times.

 

[Nicholas Lindan]

Big long thread here:

(there was a url link here which no longer exists)

Time multiplier = ((New Magnification + 1) / (Old Magnification + 1)) ^ 2

For 35mm going from 5x7 to 8x10, as close to full frame as you can get and with 0.25" margins:

Old magnification = 4.76
New magnification = 7.94
Time multiplier = 2.4

 

[tkamiya]

It takes about double the exposure. You can either double the exposure time or open up the lens one stop.

You may need to fine tune it a little. When size of images change, the way they look, perception wise, change. I often end up needing more contrast and little more exposure than what calculation tells me. I go between 8x10 and 11x14 all the time.

 

[mryoda]

This sounds interesting, another step on the learning curve.
I am looking forward to this
Thanks to you all, i will get reading that thread...

 

[Kevin Kehler]

Save yourself the headache - make new test strips and a new print. Not only can you discover a better print but trying to do the math often leaves to a disappointing print. You're more likely to throw away more paper from disappointing prints than the cost of a series of test strips.

 

[mryoda]

In truth, i would have always done a test print, but
I wanted to get in the ball park and would have never guessed that
1 size up in paper was more than 2x the exposure time or at least 1 f/stop
It was exactly the fear of wasting paper that led me to the question,
10x8 is twice the price of 5x7

 

[Nicholas Lindan]

10x8 is twice the price of 5x7

See, that's why it needs twice the exposure...

 

[mryoda]

lol i wonder if it works out like that, all the way
up the paper scale

 

[tkamiya]

Here's an easy way to figure it out.

Take the standard size.... 5x7, 8x10, 11x14, and 16x20
When you go up a size, it's about twice as much surface area. It's not exact because the aspect ratio is little different and thus your cropping won't be the same. In addition, as I said earlier, your eyes will interpret contrast and density differently.

Nevertheless, giving twice as much exposure as you go up a size either by doubling your time or opening the aperture one stop will get you in the ballpark.

Obviously, if you go up two sizes, then you have to double the double so you'll be quadrupling the time, or opening two stops. (oh, yeah.... and you pay 4 times as much)

 

[mryoda]

Thanks for that
As soon as my paper arrives i am going to give it a go,
I may scream for help later lol or get a decent print,
The Mrs wants this bigger


Marble!

 

[MattKing]

Thanks for that
As soon as my paper arrives i am going to give it a go,
I may scream for help later lol or get a decent print,
The Mrs wants this bigger


Marble!

I shouldn't, but I cannot resist.

I trust that your dog's name isn't "The Mrs."?

 

[mryoda]

Lol there is a resemblance but no!