Topic: Paper Negs

[Ed Wenn]

Team, I've decided to have a crack at using Silverprint's Solar Paper in my 5x4 camera and wondered what sort of ISO I could expect it to have. Please don't get all sciencey on me because I am not going to spend hours on calculations and angles of dangle. I just want a vague idea of the type of ISO to expect....or the recommendation not to proceed. Here are the only two 'ballpark' figures I can give you from my experience using the paper to print with:

• In direct sunlight you can make a solargraph in a couple of minutes.
• In diffuse, weak winter light you can make a decent print from a digi neg in about 3 hours.

[jojonas~]

somewhere around iso 6 in sunshine. that's what I calculate on atleast. some papers seem slower and different light can give seemingly other isos.

I'm sure someone else here has more experience though

[LT]

I'm not entirely convinced it will work given it has no real colour differentiation in its reaction to light. I'm interested to see though.

Given that it is MUCH less sensitive than darkroom papers, I think Jonas's recommendation is overambitious.  I'd try the same rimes as you use for printing, seeing as the light source is the same.

[jojonas~]

oh, sorry ed!  was way too tired be be writing that and didn't properly read your post. 

[Ed Wenn]

Jonas: No worries at all.

Leon: Interesting point and one which could be on the money. I've so far tried two exposures of between 10 and 45 mins in fairly bright sunlight and neither produced anything on the paper.....however, thinking about it, I would expect the paper to have been completely blue due to over exposure instead of completely white if the paper was just reacting to all light in the same way, because it was definitely being exposed. Hmmm. Onwards and upwards. I may have time for another go today.

[LT]

I completely forgot about aperture! I think you;ve got to give at least double the time the paper would need to produce a sun print to make up for the reduction of light through the lens.  I'd try 2 hours at max aperture and see what you get from there ..... ?

[Francois]

I don't want to be a party pooper but I don't think it's going to work at all.
I think the paper might be a bit like a cyanotype which needs UV rays to make an image. Now, the amount of these that get in through a lens are so minimal that I think you'd need a week long exposure to get just a hint of an image!

If I had to put a guesstimate on the sensitivity, I'd be tempted to say something like 0.01 ISO... too slow for a camera.

[Ed Wenn]

Good news. It does work. Exposure times are painfully slow, but I'm just scanning a two hour exposure (wide open at f4.5). It's super faint, but there's definitely something there.

[LT]

Good news. It does work. Exposure times are painfully slow, but I'm just scanning a two hour exposure (wide open at f4.5). It's super faint, but there's definitely something there.

excellent!

[Ed Wenn]

OK, here we go. A 'quickie'  test shot to see if Solar paper can be used as a paper neg. This is a 2 hour exposure in fairly bright (UK) sunlight at f4.5. The wrinkles are from the paper and - I guess - could be eradicated by ironing or mounting the neg on card. They look rubbish at the moment, but this is just a proof of concept so I would expect to have to iron out the odd wrinkle....see what I did there?
 


Solar Paper Neg Test by Ed Wenn, on Flickr

It's actually a promising start - although I'm not sure how usable this combo will be. "Now, if you could just hold that pose for another 2 hours and twenty minutes."

BTW, the shot is of a kids' water play table thing in the garden. Hard to work it out. I should have taken something more recognisable as a first shot.

[Miles]

Cool, I've got some I'll have to try out too.

It's blue though right, and you used the pooter to desat etc ?

[Ed Wenn]

It's blue though right, and you used the pooter to desat etc ?

Yep, the solar paper is blue. I've had some success making decent prints on it using digi negs (from 'proper' source images, natch) and thought I'd give it a go as a 'capture device'. It's just another fork on the journey to nowhere, but it definitely appeals to me in that I can pretend I'm an old school photo practioner (i.e. big camera with bellows) without needing a darkroom 

http://www.silverprint.co.uk/ProductByGroup.asp?PrGrp=44

[Nigel]

That looks interesting, and not bad results for a first attempt. For one stupid moment I thought 'Oh, I could try some of that in a pinhole' forgetting, at f180, I'd probably have to leave it for a week! 

[Francois]

I'm really surprised you even got something on the paper!
I guess you'd need a few stops more exposure to get a working image... but somehow, I kind of like the grubby grainy look the scans have.

Maybe you could pretend you're Niepce and go for an 8 hour shot out the window

That would be only 2 stops more exposure!


Edit:
I just went and used the Black Cat Decoder (http://www.blackcatphotoproducts.com/bcat_decoder.html) as a starting point. Then I used a spreadsheet to calculate the approx ISO... I know I started with a 1/3 stop difference so the sensitivity is off by quite a bit but I did get an ISO of about 0.0000144839286514597 !
That's like 100,000 EI lower than the lowest my exposure meter will go!

[Ed Wenn]

Thanks, Francois. I'll be sure to bear that in mind when I do my next set of exposure calculatio....heck, who am I kidding?!! 

Well, given the summer we're having I would need to move somewhere which does a better job of being sunny than the UK if I decide I want to use this process seriously.

Update: This afternoon I tried a 3+ hour exposure in full daylight, but with very little bright sunlight and got zippo, nada, nichts, rien. It looks like bright sunlight is the key. Tomorrow, I'll point it out of the upstairs window and leave it there all day....I should get a result of sorts.

[Francois]

During a sunny day, objects probably reflect just enough UV to get an image...
I've discovered that UV rays are somewhat different than regular light.
My mom got me this year a small UV meter. While her intent was to prevent me from burning under the sun, so far I've found it just a fun toy going around the yard taking measurements for fun!

I've found that a passing cloud can affect the amount of radiation by as much as 1 unit out of a maximum 10, and sometimes more if it's really dense. It is also very directional. And in the shade (under a tree), it falls to a definite zero...

Very strange behavior when compared to regular light.