Most sensitive paper currently available?

[pentaxuser]

Thanks Andy for your explanation as to what you are doing and it all makes sense as it did from the start. Yes it makes sense to establish the relationship between paper speed and its equivalent in film speed for the very purpose of exposure in camera and everything was fine in terms of what I understood the paper equivalent of film speed was i.e somewhere between say 3-6.

Then a figure of ISO 24 was mentioned and this threw me completely so I was looking find out if the 24 is right but not strictly relevant to camera exposure of a paper negative or just wrong.

Not sure where the source is for ISO 24 but it would look to be wrong and although the new MGV is a stop faster than MGIV this would not appear to change its film equivalent ISO speed of 3-6

So all is cleared up I think but I am still curious about the source of ISO 24.

pentaxuser

 

[Raghu Kuvempunagar]

I am still curious about the source of ISO 24.

(Edited)

I remember PE saying that film speed of paper is 25 and showing an example paper negative.

FWIW my EI for in camera reversal prints using Fomaspeed RC paper is around 1. Would definitely love to get a paper that would give me speed of 20 in reversal processing.

 

[pentaxuser]

Thanks for the link Raghu. The jury still appears to be out as they say on the speed but yes it looks as if 25 might be OK although this was I think on Arista paper. PE mentioned 25 but he may not have presented any pictures.

It would look as if there may well be faster papers that Ilford's ISO 3-6 and there is a case for graded paper at grade 2 according to JoeVanCleave

I presume that the ISO equivalent of film ISO of 25 acts like film in that it obeys the Sunny 16 rule? What this opens up in say a 4x5 camera is the opportunity for handheld paper negative shots at maybe f16 but certainly at f8, doesn't it?

pentaxuser

 

[Raghu Kuvempunagar]

PE mentioned 25 but he may not have presented any pictures.

He did.

 

[Raghu Kuvempunagar]

What this opens up in say a 4x5 camera is the opportunity for handheld paper negative shots at maybe f16 but certainly at f8, doesn't it?

Not just 4x5 camera but also any of the medium format cameras. Somebody on FB showed how to roll paper like film and use it in a medium format camera. You could do what he did or simply stick appropriate sized paper strip to pressure plate and shoot just one frame. Can be a great tool for one picture every day type of fun projects.

 

[MattKing]

I'm guessing, but I expect that the difference in "speeds" observed by Andy M for Kodak and Fuji RA-4 papers may be due to different reciprocity characteristics.
Andy M is using materials with very long, very dim exposures. Any speed measurements made for these (and other) printing materials are likely to be greatly affected by these non-standard uses.
A relatively similar example - if you get into the ranges where reciprocity failure becomes important, T-Max 100 quite quickly becomes "faster" than Tri-X 400.

 

[Donald Qualls]

if you get into the ranges where reciprocity failure becomes important, T-Max 100 quite quickly becomes "faster" than Tri-X 400.

And back in the day, Tech Pan (ASA 25) was the fastest film there was for astrophotography, even without hypering, because of its exceptional reciprocity characteristics.

 

[Raghu Kuvempunagar]

It's said that paper is optimised for exposure in the range of a few seconds to a couple of minutes. Too short an exposure or too long an exposure is likely to create problems.

Interestingly, in an old thread on paper reciprocity, PE says paper gains speed when the exposure is short (less than 1 second). I now wonder if this is how he got EI of 25 for Ilford paper while most others have arrived at 3-6. Could it be that 1/25 - 1/50 is the sweet spot where the paper gives EI of 25?

I shot mine in a speed graphic outdoors and metered with a Seconic spot meter. The exposure times were in the range of 1/25th and 1/50th of a second. Could it be that we are seeing a speed / reciprocity failure problem. I'll warrant that you are using very very long exposures, a situation for which the paper is not designed, any more than it is for my rather short exposures.

IDK, but the speed I have been using is ISO 25 and my reference in the same camera is /was Polaroid at ISO 100 along with Portra VC at 100. The pictures included a MacBeth color checker as reference.

Oh, I also cut small sheets and placed them in an old empty Polaroid pack and exposed them in my RZ67 with the autoprism set at ISO 25. Same results. The one sitting next to me right now was exposed at f8 1/50". Scans of the negative and print are attached.

PE

 

[Donald Qualls]

PE says paper gains speed when the exposure is short (less than 1 second). I now wonder if this is how he got EI of 25 for Ilford paper while most others have arrived at 3-6

This seems entirely likely; most folks using paper negatives are using them in pinhole cameras. Joe van Cleave is an exception, in that he uses them with a lens at times (especially in his "Afghan box camera" street portrait setup), but even then, he's stopping down his lenses in order to use lens cap exposure (the lens in that camera may not have a working shutter). When I get my darkroom a little more situated (i.e. find my safelight) I may have to cut some fresh Arista multigrade paper and try it in my Speed Graphic at various EI settings with "instant" exposure times. Can't say I'd object to the cost savings using paper vs. sheet film, never mind the ease of handling being able to load the holders under safelight.

 

[removed account4]

It's said that paper is optimised for exposure in the range of a few seconds to a couple of minutes. Too short an exposure or too long an exposure is likely to create problems.

Interestingly, in an old thread on paper reciprocity, PE says paper gains speed when the exposure is short (less than 1 second). I now wonder if this is how he got EI of 25 for Ilford paper while most others have arrived at 3-6. Could it be that 1/25 - 1/50 is the sweet spot where the paper gives EI of 25?

Thank you for digging up the thread and posts that Ron discussed this. I too ( as read in the thread ) was a skeptic( I always shot at ISO 6 ) but he showed the Macbeth color chart and his negative and I never forgot it.