Development times 35mm and 120

[Matt5791]

Can anyone help me here - I see different suggested development time for 35mm and 120 film sometimes - such as here:

http://www.digitaltruth.com/devchart.html

for delta 400 and Aculux2

What is the reasonong behind this - especially as the time difference seems quite significant?

Thanks
Matt

 

[argus]

The reasoning behind this might be very easy to explain:

the tables are built on user input and it is not assured that the dev.times for 35 and 120 in the same combo and dillution have been submitted by the same person.

On the other hand, it is quite possible that you need to adjust dev.time between formats but I don't do it.

G

 

[eddym]

Don't know what their reasoning is, but Fred Picker used to teach developing 35mm film for a shorter time, for printing on grade 3 paper instead of grade 2. I usually do this myself, with good results.

 

[jim appleyard]

There is speculation that times for 35mm are shorter because of the sprocket holes helping agitation. I don't know whether this is true or not, but I often shorten my time for 35mm by 1-1.5 min from my 120 times. I have found that this depends on which dev I'm using.

 

[Marco Gilardetti]

It's probably not a report bias, as Ilford itself in its papers gives different development times for ID11 at some dilutions. Developer exhaustion compensation, perhaps? Differences are so minimal, however, that I have always disregarded them.

 

[r-brian]

I always guessed it was the different film base used for 35mm vs 120.

 

[pentaxuser]

Can anyone help me here - I see different suggested development time for 35mm and 120 film sometimes - such as here:

http://www.digitaltruth.com/devchart.html

for delta 400 and Aculux2

What is the reasonong behind this - especially as the time difference seems quite significant?

Thanks
Matt

Matt. Les McLean makes this very point in his book. In the case of ID11 and D400 the difference is 1 and a half minutes(8mins for 35mm and 9.5 mins for 120). His experience is that 35mm is generally higher in contrast than MF of the same type. However he cannot give a reason or reasons for this. As he says in practical terms it is of little interest to him.

You may have the book. If not, it's worth obtaining. The more you read it the more you find.

Pentaxuser

 

[Tom A]

I'm glad to read this thread!
Last weekend I develope my first 120 B&W-slides using the times I had found worked for efke 25 in 35mm-format. The 120-slides came out quit dark/underexposed. Some of the differences can be explained by differences between the ligthmeters I have used, this may explain the rest of the differences.
Thanks!

Tom