Very long exposures -- daytime

[Hektor]

Rob, if you scan paper negs on a flat bed by reflected light, just like any other paper original, it doesn't matter what's on the back.

 

[Hektor]

BTW, you used to be able to buy paper "film" in spools,for reflection printing,

i think it was sold by a firm called "Granville"

 

[rbiemer]

Rob, if you scan paper negs on a flat bed by reflected light, just like any other paper original, it doesn't matter what's on the back.

DOH :bang: I was thinking of contact printing. Of course you're right.
Note to self: Read all the post before replying...
Rob

 

[Pherdinand]

stacking ND filters (opr any filters) will seriously degrade image quality + immensely increase ghosting probability. Maybe that does not matter for a lubitel, though; your goals might not have anything to do with image sharpness or clarity.

 

[Hektor]

Lubitels are capable of making very good photographs.

 

[lubitel]

Thank you all, these are some great tips. I do want the pictures to be relatively sharp. I will try the pinhole method first, if that dont work, I will buy a ND filter ( I saw some for about 35 euros on the web).

thanks again.

 

[Sonnar Brian]

Try two Polarizers stacked and turned to almost cancel each other out. That should act like many stacked ND's.

 

[Pherdinand]

Try two Polarizers stacked and turned to almost cancel each other out. That should act like many stacked ND's.

Actually that might be the best idea so far. Although with colour film you might get a colour cast - the polarizers act non-uniform on the visible spectrum of light, as far as i know.

I apologize, i did not mean that with Lubitels you can't produce great results. And in fact I don't think at all that sharpness or other technical requirements are a must in all kind of photography.

 

[Hektor]

It's alright if your awash with polarizers, like some of us old-timers, but if you've gotta buy 'em, pinholes are real cheap.

 

[Sonnar Brian]

I'm awash in Polarizers. From 29.5mm to two that will cover the lens and rangefinder of my Speed Graphic.

 

[Hektor]

Do you happen to know how much ND two crossed polarisers produce ?

I have never measured it myself, and it would be useful to know.......

 

[breakaway]

Sorry i have a question here. Suppose i metered the scene and it's f/4 at 1/250 and i put on a ND4, what then should my settings be? Does the 4 mean slower by 4 stops?

 

[jlw]

Sorry i have a question here. Suppose i metered the scene and it's f/4 at 1/250 and i put on a ND4, what then should my settings be? Does the 4 mean slower by 4 stops?

Although you may have run across a new-wave ND filter marked in f/stop equivalents, traditionally ND filters are marked in "logarithmic density units," because these units also are used in film sensitometry and such.

I'm groping in foggy memory here, so someone correct me if I'm wrong -- but I believe that a one-f/stop change corresponds to 0.3 log density units. So a filter with a density of 4.0 requires an exposure increase of (4/0.3), or 13-1/3 f/stops (yikes!)

Now you see why these filters are so useful for making long exposures in daylight!

By the way, it should be easy to tell whether your filter is marked in f/stops or density units. A filter with an ND of four f/stops will merely be dark gray, while a 4.0-density-unit filter will be darn near opaque.

[Obligatory RF-related content: The ability to use this type of filter easily is a big advantage of RF cameras. Can you imagine trying to focus an SLR through a 4.0 ND filter?!?]

 

[Pherdinand]

I think the ND filters *made for photography* are marked in f-stops, that is, ND4 means 4 stops. The 10-base logarithmic units for non-photographic ND filters are marked as OD, optical density.
By the way - it's easy to do the math. 1 F-stop means 2 times less light going through, 2 f- stops means 4, etc, while OD1 means 10 times less light, OD2 means 100 etc.
A ND4 filter should mean 2^4 that is 16 times less light, while an OD4 filter means 10.000 times less light, or, as jlw says, 13 1/3 stops.

 

[sf]

long exposures

long exposures

I recommend that you use the bulb setting for shutter movement, and calculate for reciprocity failure (if you have not already). I think it has a bulb setting, but i may be wrong.

 

[principe azul]

Do you happen to know how much ND two crossed polarisers produce ?

I have never measured it myself, and it would be useful to know.......

Hektor, I don't know either, but this thread suggests between 2 and 8 stops, depending on positions.

There's some information on different strengths of ND filters here. I'm still looking for an ND400 - actually to take photos at night, like Matthew Pillsbury.

 

[Sonnar Brian]

At least on my Nikon filters, an ND2x is 1/2 the exposure, 1 F-Stop; ND4x is 1/4th the exposure or 2 F-Stops, ND8x is 1/8th the exposure or 3 F-Stops.

Note the "x". Tiffen filters use density. A 0.3 is 1 stop, 0.6 is two stops, 0.9 is 3 stops.

http://www.2filter.com/tiffen/tiffenfilterinfo.html

Two Polarizers turned 90 degrees to each other "should" cancel all light. Depends on the filters leakage, but they are very dim.

http://www.2filter.com/tiffen/TiifenNDfilters.html

 

[naturephoto1]

For 5 to 30 minute exposures with color film there will not only be a reciprocity correction for time but there will undoubtedly need to be color correction unless you wish the color shift that the film will record. If you can find information on the film (s) you will be using for color shift for such long exposure, great. Otherwise you will need to conduct some experiments.

Rich

http://www.nelridge.com
richard@nelridge.com

 

[WDG]

The Hoya NDx400 is a 9-stop neutral density filter. This might get you into the ballpark with slow film.

http://www.thkphoto.com/products/hoya/oef-07.html

 

[Stu W]

I had that idea once. I saw in a photo mag some dreamy ocean shots where the long exposure made the waves look sort of like a fog. Very mysterious looking. Anyway, I used my LX Pentax, which meters off the film, and a stack of nd filters. The view through the viewfinder was almost black, yet the exposure times were not that long. Several seconds. Developed, the film was properly exposed but the grain was horrific, and the waves still looked like waves. I have no idea how this guy achieved the effect. All that he said was "a long exposure".