Yea I know but sometimes they give out slowly and you don't know / realize over a 2 hour period. Also in snow/cold they are hard to turn tight. Just personal preference....Quote:
Originally Posted by bobwysiwyg
~Stone
Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk
Reciprocity failure comes up all the time in daylight when shooting with pinholes. The problem is that doubling the exposure time no longer results in doubling the effective exposure, so additional time is needed. Compounding that over a number of attempted doublings can lead to large increases. The program Pinhole Designer can output a small table in Excel format that can include compensation for reciprocity with a number of popular films. The results are quite sobering. The table is indexed by the shutter speed measured for f/22. That value is multiplied by a factor related to the pinhole aperture relative to f/22, a factor that can be well over 100, and then compensated for reciprocity. With a typical pinhole, a reading of 1/4 second can call for a four minute exposure! And a few stops beyond that, it starts calling for hours.
It can turn out that some films like Acros 100 with lesser reciprocity failure can effectively be faster than 400TX at long exposures.
Almost all films hit problems at 1 seconds...ACROS a little later. In low light/long exposures there is so little light hitting the shadow areas of the film, that there is not enough energy to cause the same rate of change in the silver salts as there are in the mid-tones and high lights. In a normal exposure, there is hundreds the times of light hitting a highlight area than a shadow area...and the shadows and highlights react to the light in a normal proportional manner. In a low light situation, the silver salts of the shadows lag in their reaction to the low light, while the midtones and highlights have enough exposure that they still are exposing in the normal manner. Thus one needs to give more exposure for the shadows, and reduce development to hold back the highlights.Quote:
Originally Posted by StoneNYC
All very informative, this. Thanks guys. I had a basic understanding of RF before this but now much better.
My longest exposure was 25 seconds, if I recall, using Fuji Velvia (attached) to photograph a St Ives cobbled street. So I'm not used to thinking beyond that.
Attachment 62017
As for home development....an interesting point. I actually have an enlarger (Ilford 400HS multigrade head) with a fantastic Apo Rodenstock lens. I have some dev tanks, red lights, etc etc and have, in the past, produced some prints with it and I really enjoyed it....the only problem is somewhere to do it now, since our kids came along and occupied the room I used to do it in! In addition, I don't have a room that I can sufficiently darken (I have tried in one room but it was always a major hassle to get it dark enough) and, in the past, despite practising, I screwed up quite a few rolls of film with photos I had hoped were going to be good. Based on my failures, I thought "Oh well....I'll just send to the lab - it's easier and at least I won't screw up my films" and then any "keepers" from the proof sets I'll send off back to the lab to be hand printed.
I know the next suggestion will be to buy one of those little tents to do the film tank loading etc, but I still need somewhere to do the printing. And then there's the frequency...developer goes off once opened of course, after a few months (if kept in an airtight thing). I don't do enough photography, really, to use up the liquids I buy in time before they go off. 8 months ago I poured 5 litres of developer away that had gone brown and manky 6 months beyond it's use by.
ted_smith...Quote:
Originally Posted by ted_smith
Start a new thread. I can give you encouraging news! And I am sure there are many other voices who can join in to tell how to run a makeshift darkroom.
You can load film onto reels and put in tanks in a "changing bag", you don't "need" a full-on tent.
All the bedrooms in my home are occupied. So my current darkroom is in the garage. Don't know if you have one. Dusty as it is, it works. I've had darkrooms in the closet under the stairs. The back bathroom of dad's apartment. The basement of an ancient house. Once built a stunning darkroom with a huge ventilation fan in the corner of a bedroom with one bed set along outside the tray wall and the other bed set along the Byzantine light trap.
The one-gallon batches of Dektol decant nicely into four "quart" plastic bottles. In my experience, the sealed bottles last far, far past the manufacturer's recommendation. A quart is good enough for a "session".
You only need to work at night in most cases, when you can't darken the room enough. The proper safelight is a dull amber (not red). You might start out with small packs of paper (10-sheets) in case you fear your darkroom isn't dark enough... you won't ruin a fortune.
What bill said... Plus RF is usually use for Range Finder which is a type of camera so I would type out reciprocity failure as to not confuse folks.
Good luck!
~Stone
Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk
And for clarity, I find it really important to understand one thing about reciprocity failure.
Although we often speak about the effect in terms of exposure times, the sort of low light corrections we are talking about here are not caused by the long exposures - they are caused by the extremely low light levels.
If you wish to try and emulate Michael Kenna's night shots, also note how he often anchors his composition with say a bridge, the sea or a cooling tower and how he also makes use of artificial light combined with starlight. On a starlit night it often looks very black, but with several hours of exposure, things we can’t see begin to register.
I don't doubt your correctness but can't get my head around your statement... Don't know how you can have one without the other (unless for instance you are saying there isn't a significant difference between an intentional 10 stops overexposed 2 minutes exposure compared to a 10 stops overexposed but 1/10th second shot)...Quote:
Originally Posted by MattKing
Six of one thing, half-dozen of another, and three pairs of something else!
It is not the level of light -- it is how much light we allow to hit the film. Thus reciprocity also fails on very short exposures.
