Adox chs-50 underexposure

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Neil Barnes
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Adox chs-50 underexposure

Post by Neil Barnes » Thu May 05, 2011 10:33 am Etc/GMT-1+01:00

Well, this is annoying...

I've just shot a dozen or so 4x5 CHS-50, mostly for testing... half developed in Germany last week in ADH49 at 1:40 (10 minutes) and half last night with ID-11 at 1:3 (17 minutes) - all have come out so underexposed I can't get a decent scan off them. For comparison, the FP4+ I developed a couple of weeks ago in the same ID-11 came out fine - which suggests that the camera and my light meter are ok.

But the FP4 is at least one stop denser, maybe two...

I've attached two images: on the left, the Adox and on the right the Ilford, using the laptop screen as an impromptu lightbox. The first image is a pixel-value invert of the second.

The scanner software shows - after its inversion - no pixels brighter than half-scale.

Thoughts? Longer exposure (though Adox advises against this) or longer development?

Thanks,

Neil
Attachments
inverted.JPG
inverted.JPG (63.71 KiB) Viewed 4478 times
negatives.JPG
negatives.JPG (63.73 KiB) Viewed 4478 times

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Re: Adox chs-50 underexposure

Post by Joanna Carter » Thu May 05, 2011 11:40 am Etc/GMT-1+01:00

To me, the Adox looks low contrast, rather than just under-exposed; there doesn't appear to be any blocked shadows.
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Neil Barnes
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Re: Adox chs-50 underexposure

Post by Neil Barnes » Thu May 05, 2011 1:11 pm Etc/GMT-1+01:00

I wondered about that - but there's very little if any detail in the shadow under the car, though there's detail in the visible tyre. The sun was in the classic 'over my shoulder' position; I'd have expected something in there.

But this is supposed to be a high-silver emulsion... I'd expect much higher contrast than this. Unfortunately I don't have the facilities to print it - though I suspect even #5 might be a bit low for this.

Neil

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Re: Adox chs-50 underexposure

Post by richard littlewood » Thu May 05, 2011 5:00 pm Etc/GMT-1+01:00

Despite the exposure issues I'd say theres under development there.

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Re: Adox chs-50 underexposure

Post by Ed Moss » Thu May 05, 2011 5:21 pm Etc/GMT-1+01:00

Agree, the Adox is lacking a bit of development.

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Re: Adox chs-50 underexposure

Post by Robert J Fallis » Thu May 05, 2011 9:23 pm Etc/GMT-1+01:00

Just a thought.. did you invert the negs in the scanner? or in image software,? I find I can get better results if I do it in the software ..GIMP in my case...

bob

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Re: Adox chs-50 underexposure

Post by Neil Barnes » Thu May 05, 2011 10:25 pm Etc/GMT-1+01:00

Tried it both ways, Bob - Xsane both standalone and as a front end to the Gimp. With all the autocorrects off on the scan, the range is under half the full scale; if I let Xsane do the inversion it comes out massively black crushed. The images I attached were just from the electric camera and inverted in Gimp.

Even Digital Truth's enormous database doesn't include data for this combination... I'll try cooking some for maybe 25 minutes instead of 17, and maybe meter it a bit lower too. Just a shame my tank eats so much developer every time!

Neil

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Re: Adox chs-50 underexposure

Post by Neil Barnes » Fri May 20, 2011 4:12 pm Etc/GMT-1+01:00

I tried some more shots today; nothing very exciting, just my back garden in sunlight and shadow.

Four combinations: exposed at 50 ASA and 25 ASA - the meter showing an EV of 12.5 on the average, 14 in the sky and 11 on the shadow - and developed for 17 and 28 minutes in ID-11 at 20C with 10 seconds agitation every minute, 1+3 dilution. 28 minutes because I was aiming for 25, plus 10% because I used the same developer for each batch - so two batches of developing, two sheets each. Two minute prewash to shift the anti-halation dye, two minutes wash in plain water after development, and two minutes fix (to avoid any possibility of the hypo eating the silver) in Hypam.

And *still* this stuff comes out as very insensitive in the shadows. Without a doubt, the best image was the one at 25 ASA and the long development - but it's still crushed in the shadows. There's detail in the negatives, but not a huge amount. I'm beginning to think this stuff is a return to the days of 'expose for the shadows and let the highlights look after themselves'!

With apologies for the size of this image - I'm not quite sure what the forum software and your browsers will do to it - it's a 16 bit png. Saved from the scanner with no corrections, peak white at about 65-70 percent, then corrected for maximum range without changing the gamma in Gimp. I can see I'm going to have to get my hands on a chip chart.

Neil
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