# Print Magnification / Conversion Formula!



## romie (Oct 20, 2003)

Enlargement  Question 
  Having the exposure time and the  lens opening of a enlargment and wanting to changing the height size of a print  say from a 8x10 print @ f16 @ 00:15 exposure time to a 11x14  what is the  formula to make the change from one size print to another?


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## oriecat (Oct 20, 2003)

Well I don't know what the formula is, but according to a spreadsheet that Will gave me, I think it would be 26.75 seconds, provided I did everything right, which is no guarantee.


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## romie (Oct 20, 2003)

Thanks Oriecat!
  Somewhere I read or was told that times 10 (X10) is the formula for calculating the time needed in making a print larger timewise with the same f-stop of the original print.
I will do some test to see. :roll:
romie- Boston, MA.[/u]


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## motcon (Oct 21, 2003)

romie said:
			
		

> I will do some test to see. :roll:
> romie- Boston, MA.[/u]



Orie has it correct.

why bother asking if you are going to do tests anyway? 

a 10x rule? u realize that takes you to nearly 3 minutes of exposure from 15 seconds? common sense should tell you to not even waste a sheet of paper on it.


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## ksmattfish (Oct 22, 2003)

Will is right.  Don't worry about crazy math.  You need to be doing a whole new test print for the 11x14 anyway.  When you increase enlargement, you decrease contrast, so you're basically starting over.  Don't skimp on the test prints.


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## Jeff15 (May 12, 2018)

It amazes me how many people still use film..


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## 480sparky (May 12, 2018)

snowbear said:


> Come on, folks - the thread is from 2003.
> 
> View attachment 157694



That's usually what happens when an app developer comes to the forum, ignores the rules about advertising, and tries to peddle his $9.99 app.


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