Pinhole and Harman Direct Positive Paper

[moiz]

Hey guys, I hope I'm posting this in the right place, if not please let me know. <p>

 

Well, here are my two very first images produced with my homemade pinhole camera and Harman positive paper. Now, I know these are

not great so I wanted to post them up and get some advice.<p>

 

 

From my understanding, these have been overexposed. These are the factors I am assuming can have affected this:<p>

 

1) My pinhole size is actually larger than I think it is. (It is approx .5mm which is what I used to calculate my f-stop. Focal length is 120mm

so camera is f240). I might change the estimation to .55mm or .6mm<p>

 

2) The darker portrait oriented image used a digital meter in incedent mode. I set an EI of 3 for the paper and used an online chart to

convert the 1sec f8 it gave me to 15mins 18sec at f240<p>

 

3) The lighter lanscape oriented image was metered using an iPhone app and my iPhone as the light meter. This gave me an exposure of

41 mins!<p>

 

They were both developed in Ilford PQ at 1:15 for 3 mins at 20degC ( I got this from another post on a forum, not sure who but his pics

were great so seemed worth copying)<p>

 

Is this simply a case of getting my pinhole size wrong? What would be the best scientific method to getting a decent image out of my

pinhole camera?<p>

 

Thanks in advance for any help.<p>

 

<IMG src="http://db.tt/F1LwtaPz"><p>

 

<IMG src="http://db.tt/9J9a9Xgy"><p>

[lotuseaters]

<p>It could well be a case of not having the exact pinhole diameter here. How did you determine the size of the pinhole? I've only just started pinhole photography myself recently and scanned the first pinhole I made using a dedicated slide scanner. The measuring tool in Photoshop will show you the exact diameter of the hole. An iPhone is unlikely to have the same field of view as your pinhole camera, therefore the reading might have been off, unless you compensated for this. Your first image doesn't look too badly exposed though. There's a lot of trial and error involved here. But that's part of the fun.</p>

[moiz]

Hi Tom, thanks for the reply.

 

"Part of the fun" is probably why I took out a ruler and magnifying glass and said, "Hmmm, looks like about half a

millimetre" :)

 

I too am under the impression that it is pinhole size that is the culprit. I'll take a couple more tomorrow (it's miserable out

today and I'd have 1hr exposures!) trying it at .55mm and .6mm.

 

I think I was expecting something much more contrasty from the positive paper and this image looked so flat I knew

something needed sorting.