What speed to develop at?

auntiemaryscanary

auntiemaryscanary

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I used my Mamiya C3 the other day. I metered and shot the Kentmere at ISO 100. BUT it was Kentmere 400 in the camera. To compound matters (or not?) there was a Y2 filter on the camera which I didn't compensate for.

I can't get my head round by how much I've underexposed this film in stops or what ISO to develop the film at to try and recover some images. Could someone explain this to me and give some suggestions please?

(I'll be buying one of those cold shoe things to remind me of the film in the camera. As for forgetting I was using a filter, well it's up to me to notice the yellow taking lens :) ).

Edit: or have I over exposed it?!
 
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If it's 400 film exposed at 100, it will be over exposed rather than under. Taking a Y2 as 1 stop, it reduces the iso to 200, so only 1 stop over exposed. This isn't much at all, and many suggest overexposing and reducing the dev time by 20%, but I'm sure others will be along to give better advice! It's not a lost cause by any stretch!
 
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I agree with Peter's assessment. I haven't used this film, so the usual caveats apply, but I'd just treat it as normally exposed. FYI I set my meter to 80ASA (it's marked in ASA, not ISO) for the 125 ISO FP4 I use.

A counsel of perfection would probably advise looking at the characteristic curve to see if the extra exposure was likely to push important detail too high up the shoulder, but the same counsel would probably add that the filter factor depends on the colour temperature of the light at the time of exposure...

I'd personally do nowt.
 
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I agree with the above. It's only one stop over exposed which is easily dealt with. Altering the development is just confusing things.
 
As a thought that just occurred to me, based on David's post above, the net effect of your metering plus the filter means that effectively you exposed the film as if it were 200 ISO. Back in the early 1960's, that would actually have been the box speed, because the rating system was changed and box speeds doubled overnight while the box contents remained unchanged. Put another way, films were consistently exposed one stop over for years...
 
If it is an old lightmeter, it could well be giving readings that could mean 1 or 2 stops under exposed, which would further eliminate the error.
 
Sangoma said:
If it is an old lightmeter, it could well be giving readings that could mean 1 or 2 stops under exposed, which would further eliminate the error.
Click to expand...
It is an old light meter however I'd recently had issues with one of them. Following advice from the forum I tested 3 of them - it's in a thread somewhere. It was one of the "good" ones I used. The "bad" one is permanently relegated to the naughty shelf with the broken cameras ;)
 
Let us know how it turns out. I have a Mamiya C220, and was thinking of trying some Kentmere instead of my usual HP5.
I overexposed the HP5 quite a bit when I tried to do the exposure compensations marked on the focusing scale, but managed to get usable images once I'd scanned it in, so I think you should be alright with yours.
 
Tonight I dev'd the film. I went with the Massive Dev Chart times for the Kentmere 400 exposed at 320. That took 45 secs off the box speed for stock ID-11. Negs looked good whilst still wet. I'll scan and post a sample another day.

Thanks to all for the previous advice and reassurance.

Edit: wet negs looking promising
IMG_20230510_203306025_HDR.jpg
 
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