Developing time 35mm vs. 120

Film Photography & Darkroom discussion

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coralie73
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Joined: Fri Jul 13, 2007 5:01 am

Developing time 35mm vs. 120

Postby coralie73 » Sat Oct 10, 2009 9:04 am

I'm new to medium format photography, and need to process my first couple of rolls. I've checked the development chart, and don't understand why the developing times for 120 are sometimes different from the 35mm counterpart. I want to process Tmax 100 in Ilfotech HC. The time for 120 film is only 5.5 mins, while for 35mm it's is 7.5 mins. Can anyone confirm if this is correct? A different emulsion perhaps? Or a typo? With HP5+ there is no time difference when using the same chemistry... Thanks guys! :wink:


Keith Tapscott.
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Re: Developing time 35mm vs. 120

Postby Keith Tapscott. » Mon Oct 12, 2009 9:43 am

Ilfotec-HC is similar to Kodak HC-110. Download the technical data for T-Max films from Kodak`s website and use the same dilutions and times given for HC-110 as a starting point.

Digitaltruth
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Re: Developing time 35mm vs. 120

Postby Digitaltruth » Mon Oct 12, 2009 4:17 pm

Some manufactures publish different times for different formats. In some cases the emulsions are not identical or the film base may be different, but in general you can use the 35mm times as a starting point for most films regardless of whether there is separate data for 120 rolls.
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Ornello
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Joined: Thu Jan 19, 2006 9:49 am

Re: Developing time 35mm vs. 120

Postby Ornello » Fri Oct 16, 2009 11:38 am

coralie73 wrote:I'm new to medium format photography, and need to process my first couple of rolls. I've checked the development chart, and don't understand why the developing times for 120 are sometimes different from the 35mm counterpart. I want to process Tmax 100 in Ilfotech HC. The time for 120 film is only 5.5 mins, while for 35mm it's is 7.5 mins. Can anyone confirm if this is correct? A different emulsion perhaps? Or a typo? With HP5+ there is no time difference when using the same chemistry... Thanks guys! :wink:
For optimum results with 35mm film, 35mm requires less development and lower contrast than 120 film can tolerate. It's that simple.


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