Film Speed and Development Test (Excel spreadsheet supplied)

eggen

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OK, I think I stay at .ODS file. Thank You for an advice!

Regards
Esko
 
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RalphLambrecht

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Michael

Thanks for your support. I prefer the 31-step version, because it gives more data points, and hence, smoother curves. However, some 35mm workers have trouble reading the thin bars with their densitometers and prefer the wider 21 steps. On the other hand, they could use their enlargers and their enlarging meter if it provides a density function.
 

Lee L

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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
 
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RalphLambrecht

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Lee

I have changed the spreadsheet to flexibly work with 21 and 31-step tablets. I will only make it available if their is a strong interest, because I cannot expect you to constantly follow with open-office modifications. I'm sure you have better things to do.
 

chromemax

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I'm impatient for the new version, using 21 step tablet and OpenOffice.
Thank you very much Ralph and Lee for yours efforts.
Regards
Diego Ranieri
 

Lee L

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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:
 
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RalphLambrecht

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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

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

Lee L

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

Lee
 
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RalphLambrecht

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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:

Dead Link Removed

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.
 

bascom49

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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
 
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Thanks Ralph for your generosity with your information.
 
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RalphLambrecht

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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
 
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RalphLambrecht

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By the way:

The latest update of the spreadsheet, including very detailed instructions are now available.

You'll find it here:

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

and here:

Dead Link Removed

The spreadsheet is now fully compatible with 21 and 31-step Stouffers. The instructions could use another English edit, but that would have delayed posting by another week. I hope it helps and you will report back with any issues you may have, so, I can improve it for future use.
 

bascom49

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I can't wait to get started. Thanks for the book and the reply.

Charles
 

PeterB

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Thank you for providing these instructions and Excel Worksheet Ralph.

page 3/8 of the pdf says "Film has a different sensitivity to different wavelengths of light. Therefore, select a light source with a color temperature representative of your typical subject matter and setup."

How do I measure the colour temperature of my light box upon which I will place the Stouffer step wedge ? Can I do this with a digital camera ? I'd like to ensure it is close to daylight.

regards
Peter
 

PeterB

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Lol ! I guess I had incorrectly assumed that wouldn't give me diffuse light but if all the background terrain is out of focus then of course it will be diffuse. Then I also thought it wouldn't necessarily be at the right colour temperature because unless it was pointing straight up it would pass light reflecting from the surrounding terrain. OK so perhaps if I find a window with a view of a landscape plus blue sky with some puffy clouds thrown in for good measure it should be perfect.
 
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