Determining Personal Seed Point for Winplotter

Silverpixels5 · Mar 14, 2006

I need to calibrate my personal speed point, but don't have any TMX or Delta 100. The only films I have on hand are FP4+ and TXP. Is it possible to use one of those in combination with the developer and times included in the Winplotter sample database, to calibrate for a 2.4 speed point? Like TXP in ID11? Thanks!

JHannon · Mar 14, 2006

I just did the calibration with the recommended Delta 100 in D76 1+1 at 70F. It is worth the trouble to get your test light source calibrated properly. Phil recommends this combination because it has been tested and shown to produce a honest 100 speed. From there you close down 1 stop for ISO 200 films etc.

You might want to post this question on the BTZS site http://BTZS.org. There may be other combinations that will work.

oops, I see you did post it there already. Phil is good about responding to questions there..Good luck

--John

Silverpixels5 · Mar 14, 2006

Yea I posted on BTZS site first, but I know APUG probably gets more traffic so I posted here too. I had hoped I wouldn't have to buy any new film, but its looking like that won't be the case. Thanks though!

sanking · Mar 14, 2006

I read Phil's response on www.btzs.org. From what he said I believe you would be ok in using FP4+ and developing it in D76 1:1 at 70F, assuming you rate the EFS down to 100. Just make sure that your D76 is fresh, or is one of the buffered versions that will not gain energy with age.

Sandy

Silverpixels5 said:
I need to calibrate my personal speed point, but don't have any TMX or Delta 100. The only films I have on hand are FP4+ and TXP. Is it possible to use one of those in combination with the developer and times included in the Winplotter sample database, to calibrate for a 2.4 speed point? Like TXP in ID11? Thanks!

Silverpixels5 · Mar 14, 2006

sanking said:
I read Phil's response on www.btzs.org. From what he said I believe you would be ok in using FP4+ and developing it in D76 1:1 at 70F, assuming you rate the EFS down to 100. Just make sure that your D76 is fresh, or is one of the buffered versions that will not gain energy with age.

Sandy

Will do. Thanks!

DeanC · Mar 14, 2006

FWIW, I just had the same issue and resovled it by using my FP4+ in DD-X @ 1+6.

L Gebhardt · Mar 14, 2006

Where is the method for our speed point determination documented? I looked for it when I got the program but couldn't find it. My method has so far been to use the program to plot the curves, find the normal dev time, the shoot another sheet or two to find the speed at the normal dev time. This works well enough for me, but next time I think I will try to do it right.

DeanC · Mar 14, 2006

It's in an article and in several forum posts on btzs.org.

JHannon · Mar 15, 2006

L Gebhardt said:
Where is the method for our speed point determination documented? I looked for it when I got the program but couldn't find it.

Here is the link http://www.btzs.org/Articles/PSP.htm

mikepry · Mar 15, 2006

When I used Xtol 1:1 with my FP4 it gave me the true film speed. I didn't use this to calibrate(I used the Delta) my PSP but rather was a pleasant surprise after testing.

Silverpixels5 · Mar 15, 2006

OK now I have a bit of a problem. I tested the 3 sheets of Fp4+ and entered in the data, but I'm not getting the triangle showing the speed point. Am I doing something wrong?

Jorge · Mar 15, 2006

Silverpixels5 said:
OK now I have a bit of a problem. I tested the 3 sheets of Fp4+ and entered in the data, but I'm not getting the triangle showing the speed point. Am I doing something wrong?

You need more curves, at least 4 and preferably 5. For an accurate placement of the triangle you are required to have at least 3 curves entering the triangle at the bottom and leaving it with the same spacing at the right hand side. If this placement is not possible then the triangle does not show. You should not worry about this as the program is still able to calculate the PSP.

Silverpixels5 · Mar 15, 2006

Jorge said:
You need more curves, at least 4 and preferably 5. For an accurate placement of the triangle you are required to have at least 3 curves entering the triangle at the bottom and leaving it with the same spacing at the right hand side. If this placement is not possible then the triangle does not show. You should not worry about this as the program is still able to calculate the PSP.

Thanks! Looks like its back to the darkroom.

JHannon · Mar 16, 2006

Just to add something about the plotter program...If you leave the default curve names "curve1" etc..you won't get the efs/sbr charts.. you need to label each curve 4 min, 8 min etc. . I found this out the hard way. It is a great program and so far it is working very well for me.

Silverpixels5 · Mar 16, 2006

Well I added another curve, but still can't get the triangle showing the PSP for the family. Although, just from looking at the data and comparing it to the FP4+ in D76 1:1 that Phil includes with the program, its seems that I'm overexposing by one stop. Is this correct? For instance, for a G-bar of about 0.56 my Emin is at 2.59, while Phil's is at 2.22. So should I just cut the exposure by a stop and repeat the testing, or is there something else at fault? Thanks for any help.

JHannon · Mar 16, 2006

I remember reading about this same problem in the BTZS forums and I can't seem to find it again...So when you click on the analyze box you get just the family of curves with no reference points? My first test PSP reading was 2.9 and I still had the triangle displayed.

Maybe Phil will have an answer for you today. Sorry I am not very helpful here.

bobbysandstrom · Mar 16, 2006

I'm not at the software but believe there's a checkbox in the preferences(options) menu that needs to be checked.

Silverpixels5 · Mar 16, 2006

bobbysandstrom said:
I'm not at the software but believe there's a checkbox in the preferences(options) menu that needs to be checked.

If you mean the PSP checkbox, then yes its checked. I'm attaching a snapshot of my family curves for review.

JHannon · Mar 16, 2006

bobbysandstrom said:
I'm not at the software but believe there's a checkbox in the preferences(options) menu that needs to be checked.

Yes, good idea Bobby...under File ---> Options there is a checkbox to turn on/off the PSP.

JHannon · Mar 16, 2006

Boy I need to type faster...

Plil recommends the test using 4, 8 and 16 minutes.

Silverpixels5 · Mar 16, 2006

JHannon said:
Boy I need to type faster...

Plil recommends the test using 4, 8 and 16 minutes.

yea i'll be running a longer one this evening. I need to make up some new d-76 though. I'm so used to using one-shot developers that I dumped mine out at the end of the development cycle.....twice.

Silverpixels5 · Mar 16, 2006

Based on the data that I've gathered so far, should I decrease exposure one stop and then repeat the tests at 4, 8, and 16, or should I just do the 16 minute one at the current exposure and go from there?

Determining Personal Seed Point for Winplotter

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