Some testing results

Light, film, exposure..
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Alastair Moore
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Some testing results

Postby Alastair Moore » 08 Mar 2013, 09:29

So managed to shoot another batch of tests yesterday lunchtime with a wider brightness range. I metered at 8 seconds for the shadows, 1/30th (it might have been 1/15 though - need to check my notes which are at home) for the highlights in the window and exposed all sheets at ISO50.

I put the shadows in zone 3 and exposed for 1 second at f/16. The film I was using was Fomapan 100 and developed in a fresh batch of D76 at 1:1. I'm using continuous agitation with the BTZS tubes. The tempering bath was at 24c and I let the chemicals in their caps and the tubes with the film in them temper for about 10 minutes so they should have been well up to temperature.

These were all scanned essentially the same way in Epson Scan. I corrected the output settings to go from 0 to 255 and the input settings to stop shadow and highlight clipping, as explained by Ken Lee:

Image

My screen is calibrated with a Spyder 3 Elite although it tends to run a little dark.

So here are the results:

Developed for 3 minutes 30 seconds

Image

Developed for 6 minutes 30 seconds

Image

Developed for 12 minutes 30 seconds

Image

Developed for 9 minutes 30 seconds (scanned emulsion side up)

Image


Incidentally, the 9 minute scan above was scanned emulsion side up, the following was the same negative scanned emulsion side down:

Image

I think there's probably a bit to get out of this. I'm wondering if shooting Foma 100 at ISO 50 is possibly not right for me. I may start shooting it at ISO 80 or even box speed. To me, with all the above taken into consideration, 3:30 looks pretty much on the money but seems incredibly short considering I'm using 1:1 dilution. But it is exactly how I saw it, so that is good. But of course, I'm scanning in and it could easily be that the image looks crazy bright to the rest of you. When I look at the negative, it doesn't look particularly thin or thick, it looks pretty good.

What I also find strange is that the window seems brighter in the 3:30 scan than the rest where I'd have thought it would have been the other way round. I will double check I scanned in the right order when I get home. It certainly makes me wonder about scanning and its consistency.

My agitation of the tubes was pretty consistent I believe so a little surprised by the results. Anyway, if anyone has any comments, I'd definitely appreciate it!

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RoganJosh
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Re: Some testing results

Postby RoganJosh » 08 Mar 2013, 11:06

Did you use exactly the same histogram setting for each output image? that could explain why 3:30 has brighter whites, or it could be one of the other many variables involved with hybrid digi-chemical film testing...

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Alastair Moore
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Re: Some testing results

Postby Alastair Moore » 08 Mar 2013, 11:11

RoganJosh wrote:Did you use exactly the same histogram setting for each output image? that could explain why 3:30 has brighter whites, or it could be one of the other many variables involved with hybrid digi-chemical film testing...


The histograms were different (obviously) but I used the same method of making sure the shadows and highlights weren't clipped and that the middle tone/gamma adjustment was set to 1.0. So pretty much exactly the same. I might rescan them this evening if I get time and have another look, perhaps do a screen capture of the histograms as well.

Lachlan717
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Re: Some testing results

Postby Lachlan717 » 08 Mar 2013, 15:41

To me, it seems like these are in the wrong order…

Can you check that you put them in the correct order?

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Alastair Moore
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Re: Some testing results

Postby Alastair Moore » 08 Mar 2013, 15:58

Lachlan717 wrote:To me, it seems like these are in the wrong order…

Can you check that you put them in the correct order?


It seems like that to me too. I shall have to have a look when I get home. I find it rather strange too but anyway. Will confirm when I get home!

Lachlan717
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Re: Some testing results

Postby Lachlan717 » 08 Mar 2013, 16:25

In relation to the use if the scanner, this is where you need a Densitometer to get accurate data. I think that I've read that you can use a scanner, but I just went with the Densitometer.

Simply put, you're reading the varying light transmission through the same areas of differently processed negs. You compare this to your Base+Fog transmission and use the Dev time that gives you the density closest to the theoretically correct density of N, N-1, N+2 et al.

smbooth
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Re: Some testing results

Postby smbooth » 10 Mar 2013, 16:52

If your developing for scanning you (in my opinion) can forget about N-1 / N+1 the scanner and software will take care of that. Actually I think you will find that a thinner neg scans better too. Perhaps that's why you think Foma at 100 is better than Foma at 50.

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Alastair Moore
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Re: Some testing results

Postby Alastair Moore » 10 Mar 2013, 18:11

smbooth wrote:If your developing for scanning you (in my opinion) can forget about N-1 / N+1 the scanner and software will take care of that. Actually I think you will find that a thinner neg scans better too. Perhaps that's why you think Foma at 100 is better than Foma at 50.


The 3:30 neg is definitely thin compared with the others and did scan in better than the others, so you might be on to something there. Developed a few other negs at 6:30 before I left for Tassie and they looked really good. So I think I'm pretty close to my ideal EI and developing time. I feel like I'm getting close now anyway!


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