Lee Big Stopper - (Lots of ND filter)

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Originally Posted by dperez

I have been using it with color negative films. I've recently used the filter with Ektar 100 8x10 at Shell Beach, CA. I will post my results as soon as I process the negs.

-DP

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You just addressed my next group of questions. I don't have any reciprocity charts for color negative films. I'm using Kodak Portra NC & VC 160. Does anyone have some "starting points" for long exposures? I hate to run a batch of C41 with perfectly good film just to get to a starting point that someone may already be able to share. I'm also wondering how far you can go with long exposure before color casting gets to be too much of a problem for filter corrections during printing.

My corrections for Delta 100 are based on 1.15567 X i^1.4379. That's a good starting point. It's produced a very workable negative every time.

I look forward to seeing your examples dperez.

Jehu,

I used the Reciporicty Timer App on my iPhone for the shots using the Lee Big Stopper. Ektar was the only color negative film in the app, and it just so happened that I had that film. I am going to try a few shots with Portra 400, and I'll share the results as well.

-DP

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Originally Posted by channelhugger

Just a thought but are you sure it's 10 stops. My Lee big stopper is a touch over 11 stops. I've not been very successful metering through the filter but I've used a digital camera to allow me to check the actual strength of the filter and apply that to all my subsequent medium and large format shots.

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My example in post #4 seems to indicate a little less than 10. I'm just getting started though. The sky is looking real good for more experimenting this week. Hopefully, I'll find time to get out some more this week.

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Originally Posted by dperez

Jehu,

I used the Reciporicty Timer App on my iPhone for the shots using the Lee Big Stopper. Ektar was the only color negative film in the app, and it just so happened that I had that film. I am going to try a few shots with Portra 400, and I'll share the results as well.

-DP

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Thanks DP. I'm looking forward to that.

My bad on the "Reciporicty Timer App " it should have been "Reciprocity Timer App"...

I'm curious, does this app have reciprocity tables for any color slide films like Velvia 50, Velvia 100, etc? Thanks. Jim

Color films have much less reciprocity failure than do b/w films. I want to say that something like Ektar 100 or Portra 160 only requires 1 stop reciprocity comp between 1 second and 30 seconds, and then 2 stops beyond that. It's been a while since I looked up the tables for it but my experience of shooting 5x7 color neg at night recently (Portra 160) would bear that out.

The app doesn't present tables. It has a list of mostly B&W films. The user selects the film, filters, bellows, etc. and the initial meter reading, then the app will give the adjusted exposure time taking into consideration all the variables the user provided. For more information about the app see this thread:http://www.largeformatphotography.in...city-Timer-1-0

Looks like the current supported films for this app include:

Velvia 50
Velvia 100F
Provia 100F
Ektar
Efke
Fomopan 100
Fomopan 200
Illford HP5
Illford Delta 100
Illford Pan-F+
Illford FP4+
Illford SXF 200
Illford XP2
Kodak T-Max 400
Kodak T-Max 100
Kodak Tri-X 400
Kodak PLUS-X
Kodak Tech Pan
Kodak T400 CN
Kodak TMZ
Generic Formula

-DP

Given that there is detail in the sky, you ought to be able to burn.

I do LOTS and LOTS of really long exposures and have my own little chart which I use for TMY,TriX and Hp5, using the same factor for all three. I would have exposed this for 77 seconds...E Clarke