Worldwide Pinhole Photography Day 2018

Well I've got some shots but have not devved than yet. The first 3 shots were all set up, tripod and cable release, and I timed them as a bracket. It was only when I got to the second location that I realised I hadn't changed the shutter speed from 1/125 to B! I did manage to go back again later in the afternoon, so I hope I've got something.

I remembered from last year that the pinhole doesn't cover the full frame when screwed in directly, so I added 38mm of extension tubes, making it about a 80mm focal length, so f/320 or so. I'm hoping this will work out OK. Maybe I should have tried a few shots on a shorter extension, which would give me a slightly better aperture...

My entry should appear here once it's been approved: http://pinholeday.org/gallery/2018/index.php?id=822

The photo...



I had what looks like some trouble with the masks I made to reduce the format to 6x6, with the result that a lot of shots were duffers. I haven't worked out what the mechanism was yet, but the duff area on each photo was consistently mask-sized and on the left. This photo was only slightly affected, and some trickery in Photoshop pretty-much sorted it out.

(EDIT: Link corrected.)

I dev’d mine yesterday and there’s definitely something there, hopefully I’ll get the chance to scan tonight.

ChrisR said:

Well I've got some shots but have not devved than yet. The first 3 shots were all set up, tripod and cable release, and I timed them as a bracket. It was only when I got to the second location that I realised I hadn't changed the shutter speed from 1/125 to B! I did manage to go back again later in the afternoon, so I hope I've got something.

Click to expand...

The first set of pinhole frames were completely blank when processed; I wasn't sure if this should surprise me.

The cheat sheet I have with the pinhole suggests metering at f/16, then going from that metered shutter speed to the exposure time at various pinhole apertures via a table. Mine was a 0.25mm pinhole and a 80mm focal length, giving an aperture of f/320. The table gives 2 seconds at f/256 and 4 seconds at f/360. With an allowance for reciprocity failure, I was generally going for an exposure of about 4 seconds. So, by my calculations, 1/125 at f/320 would be 9 stops under-exposed! Highlights should be maybe 3 stops better than the scene average, which still would make them 6 stops under-exposed, I guess Tri-X doesn't like 6 stops of under-exposure and normal development!

Here are 3 shots that did work reasonably well, although the result seems a LOT softer than Nomad's...

a) Abbey Fields lake, re-shot:

1805BPMXBW32 by Chris R, on Flickr

b) Kenilworth Castle

1805BPMXBW21 by Chris R, on Flickr

c) Some dead tree roots...

1805BPMXBW27 by Chris R, on Flickr

All taken with a Holga pinhole and 32mm of extension tube on a Pentax MX, using Tri-X film, home processed in Ilfosol 3 for 6 minutes in a Rondinax 35.

I can only assume the softness has something to do with the size of the pinhole in conjunction with the distance. Optimal distance for a 0.25mm pinhole is 35mm, while the optimal pinhole for 80mm is about 0.38mm, using the calculator here...

http://www.mrpinhole.com/calcpinh.php

In other words, it's presumably affected by diffraction if the pinhole diameter is smaller than optimal for a given distance.

Well maybe next time I'll try it straight onto the body again (42mm?), but ISTR that last time I tried that I got vignetting, not just darkness but blackness!