Problem With TMax in RB67 ProS Film Back

[RolleiCO]

Has anyone had any issues with TMax 120 B&W film advancing strangely in your RB67 ProS film back? The number of times I need to “cock” the back until the frame counter reads “1” is far more than with the Ilford HP5+ I have been using. I am getting only 8 frames per roll and the frame spacing is also inconsistent. Any help would be appreciated.

Thanks,
Jim

 

[MattKing]

Everything is working fine for me, both with older T-Max 400 and the newest, post backing paper revision, versions.
Inconsistent spacing tells me that the back needs servicing.
HP5+ and T-Max 400 may be slightly different, leading to different results from an out of specification back.
Those backs do need regular maintenance if they get regular use.

 

[Lachlan Young]

Improper loading is almost always the cause of the problems you describe - usually from failing to position the start mark correctly & not keeping the paper under tension as you wind up to the mark. It may be that the Ilford film you used was spooled some time before the Kodak rolls and therefore was more tightly 'set' into a roll & therefore did not loosen itself if loaded without being kept under appropriate tension.

 

[RolleiCO]

Improper loading is almost always the cause of the problems you describe - usually from failing to position the start mark correctly & not keeping the paper under tension as you wind up to the mark. It may be that the Ilford film you used was spooled some time before the Kodak rolls and therefore was more tightly 'set' into a roll & therefore did not loosen itself if loaded without being kept under appropriate tension.

 

[RolleiCO]

Thank you for your responses. I will be more attentive to maintaining tension when loading the next roll of TMax. I am very careful to be sure that the arrow on the leader lines up with the mark on the film cassette.

If there is a mechanical problem with my film back, I would think that I would experience issues with any film used. That is not the case. I have never had problems with Ilford FP4, HP5 or with Arista EDU Ultra - all used very recently (though I really dislike the Arista and have too many rolls taking up freezer space) - sorry, I digress.

 

[paul ron]

sounds like the roller that connects to the counter may be slipping.

but... how consistent are your errors between the brands of film? eg: does the illford require the same number of winds every time?

try running backing paper without film and mark the frames in the front mask as you wind up. any difference between brands?

inconsistent frame spacing says something is slipping.


time for a service call.

 

[WilmarcoImaging]

I have not had the mentioned experiences. Agree with the comments about film loading and correct starting. Also the back could be in need of CLA. Or buy another back.

 

[shutterfinger]

The RB67 film holders use a clutch system for film advancing. Loose film and film thickness will cause spacing problems.
Kodak 400TX old spec sheet listed it as .0045 inch (4.5 mil) thick, measures .005 on my digital caliper, its backing paper measures .003 inch thick.
Kodak TMY 400 spec sheet says .0045 inch (4.5 mil) thick, measures .005 inch thick, backing paper .003 inch thick.
Arista EDU 400 measures .0035 inch thick, backing paper measures .0035 inch thick.
Ilford Delta 400 measures .0045 inch (4.5 mil) thick, its backing paper measures .004 inch thick.
Fuji color film is .0035 (3.5 mil) thick according to its spec sheet.
I have yet to expose any Across or HP5+ but HP5+ should be the same base as Delta.
A .001 inch thick difference in film base will cause spacing problems in mechanical (geared/locking cam) advance film holders and will likely cause problems in a clutch l advance system.