Film Speed and Development Test (Excel spreadsheet supplied)

[Lee L]

Don't know why I didn't think of this earlier. The open source spreadsheet gnumeric. http://projects.gnome.org/gnumeric/ Perhaps I mistakenly recalled that it was linux only. There is a Windows XP or later version, but not a Mac version.

Gnumeric loads and displays Ralph's posted .xls spreadsheet correctly, including the summary page and graphs. It's also not as poor as excel in areas like linear regression, random number generation, etc. Anyone who doubts the merits and responsiveness of volunteer developers of open source vs. big-money backed programs like excel and MS office should read this evaluation of excel vs. gnumeric:

http://www.csdassn.org/software_reports/gnumeric.pdf

The abstract for which is:

Title: Fixing Statistical Errors in Spreadsheet Software: The Cases of Gnumeric and Excel
Content: The open source spreadsheet package "Gnumeric" was such a good clone of Microsoft Excel that it even had errors in its statistical functions similar to those in Excel's statistical functions. When apprised of the errors in v1.0.4, the developers of Gnumeric indicated that they would try to fix the errors. Indeed, Gnumeric v1.1.2, has largely fixed its flaws, while Microsoft has not fixed its errors through many successive versions. Persons who desire to use a spreadsheet package to perform statistical analyses are advised to use Gnumeric rather than Excel.
Contact Information: B. D. McCullough, Department of Decision Science, LeBow College of Business, Drexel University, Philadelphia, PA 19104

[RalphLambrecht]

I suggest folks wait until Thursday when I will be posting a much improved version, dealing with 21 or 31-step tablets and no need for multiple linear regression either. And this time, it will have proper instructions.

Thanks to Lee, everyone outside of Excel will be able to use it too.

If the entire world would work like APUG, mankind would be a huge step ahead.

[djhopscotch]

I use the Darkroom Automation Enlarging Meter for this purpose. It works very well as a baseboard densitometer, reading in stops with repeatability of about 0.02 stops in my experience. That's 0.006 optical density units. Overkill for a film curve, and less expensive than a decent used densitometer. I use a spreadsheet and type in the stops and let the spreadsheet convert to optical density (simply multiply by 0.3), calculate and subtract fb+f from a 'clear' area of the film, and draw the film curve.

Lee

Curious about the set up to use the enlarging meter, would save me the purchase of a densitometer. Thanks.

[Lee L]

Curious about the set up to use the enlarging meter, would save me the purchase of a densitometer. Thanks.

Support files, specs, and instructions for the meter are at http://www.darkroomautomation.com/ Be sure to look at the support pages for lots of good information.

Don't want to hijack this thread, so look for a response in a thread that's more on topic:
http://www.apug.org/forums/forum44/8...-exposure.html

Lee

[RalphLambrecht]

I'm glad to report that a much improved version of the spreadsheet is now available. It is flexible enough to deal with 21 and 31-step tablets and has an improved interface, allowing for some user intervention at every stage to provide more robust results. Detailed instructions are not quite done yet but should be available by Sunday.

You'll find it again at:

http://www.waybeyondmonochrome.com/WBM2/Library.html

and at:

http://www.darkroomagic.com/DarkroomMagic/Darkroom.html

As far as I can tell, it should be compatible with OpenOffice without recoding, but I have no way to check that. Therefore, I hope you will report back with any issues you may have.

PS: It would help me to improve this spreadsheet if people could supply 21 and 31-step sample data to info@darkroomagic.com.

Thanks in advance.

[Ian Grant]

Seems to be compatible with Libre/OpenOffice, can't see any issues. Will have a better look when you've posted the instructions.

Ian

[bascom49]

I bought the book, Beyond Monochrome 2ed, and can certainly say that my photography has improved substantially in all phases.
Now I'm ready for film testing. The one thing that I have not quite figured out is how to expose my film using the step wedge.
It would seem that it would have to be back lit, and as the text points out the light source should be the same temp. as the light that I typically
shoot in. No problem there. I shoot medium format, 6x7, so I'm thinking that a 4x5 size should be large enough, but perhaps an 8x10 would be better. So now the question. Is this as simple as taping the step wedge to a window, metering the middle steps for zone V and firing away ?
Would a light table be better with the proper temperature light source ? Do I need to be concerned about light around the edges of the step tablet
or do I need to mask out all light from around the edges of the step tablet ?

Any advice would be appreciated. The process is quite an investment in time. I'd hate to spend a day shooting and developing film and find out at the end that my technique in exposing the step tablet was flawed.

Charles

[Mainecoonmaniac]

Thanks Ralph for your generosity with your information.

[RalphLambrecht]

Thanks Ralph for your generosity with your information.

You are welcome!

[RalphLambrecht]

Is this as simple as taping the step wedge to a window, metering the middle steps for zone V and firing away ?

yes, a north-pointing window and stable light conditions would be best

Would a light table be better with the proper temperature light source ?

that's possible, so is an electronic flash and a neutral diffuser

Do I need to be concerned about light around the edges of the step tablet or do I need to mask out all light from around the edges of the step tablet ?

yes, masking is a good idea, because it will cut down on flare