Combi Plan ... better than expected!

[Wheelie52]

First of all .. it doesn't leak. I expected it to by all the reports I had read but it doesn't leak a drop. I also discovered that by fitting a much larger funnel to the inlet it gives the developer a little head pressure and it fills faster ... under fifteen seconds in fact. You can also get it to dump much more quickly by having a piece of tube a foot or so long at the ready to slip over the inlet nozzle when you pull the bottom bung off ... blow in the tube to pressurise the tank slightly and it empties a lot faster.

However I am very new to this 4x5 developing thing and I seem to be getting slightly patchy developing of my negs. Particularly noticable when there is a large expanse of clear blue sky ... it seems to be rather uneven! This was when using TRI-X developed in Rodinal at 50+1 for 14 minutes.

Any suggestions ... am I agitating incorrectly or do you think there may be some other reason? I agitate initially for one minute then a couple of inversions each minute from there on!

[Gene McCluney]

I would use inversion agitation every 30 sec. That should clear up your "patchy" skys.
5 sec. every 30 sec.

[Toyon]

I would allow the developer to fill/empty without assistance until you determine it is not responsible for the patchiness. After thousands of negs run through a combi, I find that agitation is best when it is a gentle end to end (turn on the narrow side) wrist movement with a few seconds in the upside down position to let the fluid subside.

I also suggest you never photo flo/lfn in the tank as over time it seems to alter the flow of water and leave effects on film edges. Kodak discovered that detergent bonds to plastics and forms an unremovable coating.

Of course there is always the guy who pipes in "I've done such-and-such for 20 years and never had that problem [i.e. you must be an idiot]", but ignore him.

The tank may leak a little bit as the seal wears down, but I've never found it to be significant.

[redrockcoulee]

Toyon

Thanks for the tip on photo flo. Did not know that and have been using it in my tanks. An easy remedy to find an alternative.

Loading Technical Pan has been a big challenge in the Combi tanks due to its extreme thinness.

I have two, one of which does not leak and the other seems to occassionally. There are great for the price, especially if one currently does not have a darkroom. Will try out the tube idea.

[Patrik Roseen]

I use a combi plan with diluted developer so that I get development times of 14-18 minutes in 20C (depending on developer/film) with agitation the first 30-45secs and then 5-10 secs every minute.

There are three things to watch out for:

Do not dilute the developer too much, it need to last for the amounts of sheets in the tank.

Make sure there is enough developer to cover the sheets. I usually pour 1200ml into my tank.

Make sure the sheets are evenly distributed/separated on the lower part of the sheet holder...otherwise they might get too close and stick to each other.

Good luck!

[Jon Shiu]

Hi, try giving a water pre-soak of 4-5 minutes.

Jon

[Wheelie52]

Thanks for the tips. I dont use photoflo in the tank or any tank for that matter as I read about it's effects a while ago and hadn't realised that it could cause these problems.

The quantity of developer recommended is strange ... the leaflet that it came with recommends 1050 ml but when you look on the underside of the lid it says 1200 ml ... so who's right? I actually filled the tank to about a cm above the level of the film sheets and measured what came out and it was 1050 so that's what I use.

The pre soak might help, I hadn't thought of trying that. In spite of the criticisms leveled at these tanks occasionally I thought it was good value (new from Freestyle) and I'm very happy with how easy it is to use. I'm pretty new to large format and film in general and the prospect of tray developing which had been suggested to me ... wasn't appealing!

[Toyon]

I didn't mean to imply that the problem is with photo-flo. No flowing agent (essentially soap) should be used in the tank at any time. Simply dip the negatives into a second container holding photo flo or LFN.

[Bjorn Nilsson]

What is says in my Combi-Plan lid is "10 x 15cm = 1250ccm" and "4 x 5 in. = 36 ozs.". The latter (36 ozs) should be around 1050ml. Please note that it's two different tables and that the film sizes doesn't correspond.
It needs more developer for the 15cm high films/plates as that is close to 6 inches.

//Björn

[Bob Salomon]

What is says in my Combi-Plan lid is "10 x 15cm = 1250ccm" and "4 x 5 in. = 36 ozs.". The latter (36 ozs) should be around 1050ml. Please note that it's two different tables and that the film sizes doesn't correspond.
It needs more developer for the 15cm high films/plates as that is close to 6 inches.

//Björn

That is on all of the tops for the Combi-Plan T tanks. There was a thread about this earlier this year a well.