Category Archives: Vintage

How to measure the speed of my antique shutter

My Boots branded 100 year old Thornton Pickard camera has a new addition – a mechanical shutter. This allows me to shoot at speeds under 1 second. With these faster speeds I can use 200 ISO sheet film instead of the much slower photo paper.

To measure the speed of this shutter, I fixed it in front of my digital fuji XT20. I set the Fuji on a 5 second exposure on f8 (as wide as the old camera goes). This gave me time after pressing the Fuji shutter to then trigger the old shutter.

I then viewed the histogram of the image taken – which was of course, at the speed of the old shutter.

I then moved the old shutter out of the way and took a few images on the Fuji adjusting the shutter speed until I found a speed that gave me a similar histogram to that obtained with the old shutter. This turned out to be a useful 1/30s.

The speed of the old shutter can be changed – but it is a bit of a fiddle.

 

Sheet film experiments

I now have some 7″x5″ sheet film for the antique Thornton Pickard (Boots) bellows camera. Unfortunately the film/plate holders are slightly less than 7″x5″ so in complete darkness, using masking tape stuck to the bed of the guillotine as guides, I trimmed down the film to fit. What you see here is my third day’s experiments – Day one produced under-exposed images, day two over-exposed and today – just right (mostly).  Setting up the still life by the kitchen window, I took light readings off each piece of fruit and the black paper backgroud – yielding recommended exposure times ranging from 4 to 30s at F32. As the 30s was for the black background I went for a 20s exposure and was very happy with the result. I used the same settings for my portrait shot.

Contact prints were made, experimenting with exposure here too. I am exposing using a flashgun held 45cm above the paper. The flashgun has a controllable intensity. – level 4 seems optimum – but doesn’t give quite the contrast I hoped for – I have ordered some filters on ebay to make the flashgun light more magenta as I have read this increases contrast – we’ll find out when they arrive.

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Optimum exposure for the film and print
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Under-exposed print (flash setting 3)
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Over-exposed print (flash setting 5)

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One problem was the film/plate holders are old and fragile and some wood splintered off – the pieces that make them light-tight. So I had to make (using some mahogany veneer) replacement pieces.

The other problem I have encountered with these film holders is that the metal plates that sit in the middle separating the two pieces of film have springy pieces in the middle and these scratch the film and they don’t fit too well either. I am replacing these with stiff black paper and we’ll see how they perform.

My Day two efforts were outside – around Glastonbury – Godney. The light was too bright and I had to deal with exposure times of only half a second with this ISO 200 film even on F64. It wasn’t possible to accurately judge taking off and replacing the lens cap in these circumstances – though I did try. I have sourced on Ebay a shutter mechanism that will fit on the front of the lens allowing me to make theses shorter exposure times. Something to play with over Christmas 🙂

Going back in photo-tech with a pinhole camera

Having the chemicals and photo paper to hand, I thought I’d try a coffee-tin pinhole camera. I drilled a 2mm hole into the tin and sanded the inside of the tin to remove the burr. I had read a perfect hole is needed for the best images. I lined the inside of the tin with black paper and cut some photo paper to fit inside.

On-line at Exposure Times for Pinhole Photography – rahji.comwww.rahji.com/wordpress/2007/05/12/pinhole-exposure-times/

I found that my camera has an f stop of 35. Using my iPhone’s Lux app to measure the exposure on the basis that the photo paper is ISO6 I got an exposure time of 10 seconds. My results have encouraged me to explore this further.

Still life indoors – a metering challenge

The iphone Lux app reading indicated F2.8 Iso 6 for 15s. In fact 2.25 mins was needed.

This needs investigation.

Interesting that since the paper negative is not sensitive to red light that the oranges in the RH image showed up as so dark. Still some work to do on focussing – though with such  wide aperture the depth of field is going to be very shallow.