| Photography Forum: Darkroom Techniques Forum: |
 |
Q. Film Grain control
Asked by Michael J. Noonan
(K=-17) on 7/13/2002
|
I've been developing my film, (HP5+), in Heico OS at a working solution of 1 part OS 9 parts water, 7 mins at a temp of 68F. I use an agitation method of a clockwise-counter clockwise twist,(fairly rapid, two times), then an inversion, then another clockwise-counter clockwise twist twice. I do this continously for the first 30 secs, then once every 30 secs.
I developed all my film at 68F. I tried two rolls at 70F and the grain was noticably larger. My Nikon N80 has been a vary reliable machine for reading DX coding so I know the speed was was right. Other then shooting at different ISO speeds what are the factors that affect grain size during the processing stage.
Thanks,
Mike N.
|
|
|
|
|
|
|
Christopher Thompson
(K=145) - Comment Date 7/14/2002
|
Agitation frequency and vigor will affect grain size. I'm not sure but there grain size may also be affected by development time with respect to your film's EI - in your case you developed using a temperature of 70 degrees where you'd previously used 68 degrees. If you didn't adjust your development time I think you may have effectively overdeveloped and that might have had an effect grain size. I hope someone else answers who know for certain, but that's my 2 pennies worth.
|
|
|
|
Nigel Smith
(K=3834) - Comment Date 7/15/2002
|
that agitation method sounds almost spiritual! due you chant to the Gods of Grain at the same time :)
when anyone asks about development in continous rotating drums (like Jobo's) the people that do it (not me) always say that they get the same negative as small tank inversion development as long as they reduce the time to suit. So, according to them, agitation shouldn't increase grain and I can't imagine anyone doing that for too long if they got more grain from it. However, I've also read not to agitate too much for a number of reasons including issues about grain. Never tested this so can't add my own findings.
Your increased temp is going to have an effect because the developer will be more active. Film developers usually come with a hard to read temperture adjustment graph (it's on this site too in one of Nanettes articles on film development) which would let you work out a revised time to suit the higher temp. My other thought is that the two rolls your souped at higher temp were shot in different lighting and were not exposed accurately.
For the record, I usually agitate by 2 or 3 inversions per minute (for Rodinal 1:100 I do 2 inversions per minute for the 1st 10mins and then 2 inversion/2 mins for the final 10minutes)
|
|
|
|
Dallas Simpson
(K=269) - Comment Date 8/18/2002
|
There are a number of factors involved here. temperature and time of development have been discussed - longer times, higher temperatures give coarser grain and higher effective film speed with the penalty of higher contrast in the negative. Also the converse is true - shorter times, lower temp finer grain, slower film speed lower contrast.
Other factors affecting grain size involve developer composition. The type of developing agent will effect the grain and the incorporation of mild silver halogen (silver salt) solvents like high concentrations of sodium sulphite will also effect grain size. D76, D23, D25 type developers, for instance use high concentrations of sulphite to keep the grain size low.
Some developing agents like p-phenelenediamine are weak silver halide solvents themselves and have low activity so give fine grain with considerable loss of film speed.
However, it is important to understand that the relationship between grain size and visual definition, often called acutance, is not simple. Ultra fine grain may not mean high visual definition or "acutance".
There are certain boundary effects which are achieved using highly active (medium to coarse grain!)low concentration developers with limited agitation. Such "acutance" development enhances the boundary at the edges between light and dark on the negative and so gives visually sharper detail, but not the finest grain.
Dallas Simpson
|
|
|
|
Michael J. Noonan
(K=-17) - Comment Date 8/18/2002
|
Thanks guys for the input. All the info you have given me has been extreemly helpfull. When I first started developing my own film the negs were thin. I then started playing with the time/temp and got the density where I liked it. I am now running my temps slightly on the cool side rather then the hot and am in the process of trying different agitation methods.
And Nigel, when I first started I was chanting to the gods just hoping things would work !!!!!
-mn
|
|
|
|
|
