Re: Images shot on X-ray film
Quote:
Originally Posted by
towolf
F-number is ratio of pupil diameter to focal length. So 35mm camera f9 is the same as 8x10 f9.
8x10 lens has much larger diameter to reach f9.
Aside: The conventional f-number scale is stupid. It should be in stops, increment 1 to halve exposure. But we are stuck with square root of two based scale.
Thanks for your quick answer. Finally I will be convinced that you are right and my confusion comes from my limited familiarity with photography, but presently it seems to me that even with the same camera and lens and pupil diameter if you take a picture of a light source, the blackening of the film will be different according to the distance between the camera and the light source.
In fact the backening will be proportional to the intensity of light, and from my intuitive reasoning it will be proportional to the pupil area, and inversely to the square of the distance lens-source multiplied by the square of the enlargement, that is the ratio between the dimension of the source and that of the image on the film.
As an example, let me take a lens of 10 cm focal length, and at a F to reach a pupil of 3 cm (any value will however work for this example).
Let me place the source at 20 cm from the lens, I will see an image of the same size at 20 cm from the other side of the lens.
Now place the source at 10 cm from the lens, that is at its focus, and it will give an image at infinite ditance from the lens, with infinite size.
Infinitys are not fair, and we can consider a position near the focus, say at 11 cm from the lens, which will give a very large image.
If we make the calculations, we can easily see that a small nearing to the focus point will result in a very large image dimension, while the fraction of light entering the lens will be almost unchanged.
Obviously may be that my reasoning is wrong, and I will be happy to correct my thought.
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Re: Images shot on X-ray film
Here is one of my early attempts with Fugi HRT green and Rodinal. I just scanned into photoshop sized it and did a quick levels on the whole image. My DIY camera has the potential now I have to learn how to use it
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Re: Images shot on X-ray film
The Wray lens does not quite cover 8x10 but it is not bad.
Attachment 129371
Re: Images shot on X-ray film
8x10 Kodak CSG, 1:100 Rodinal (i think or a little bit more condensed), 5.30m rotary.
https://farm8.staticflickr.com/7296/...ae7114d5_o.jpgHiding smile by Sergei Rodionov, on Flickr
Re: Images shot on X-ray film
Love that portrait!
Quote:
Originally Posted by
SergeiR
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Re: Images shot on X-ray film
Fuji HRT Green in Rodinal 1:200 10 minutes. The Wray 8 1/4" lens does not cover 8x10, but I kinda of like the effect.
Attachment 129451
Re: Images shot on X-ray film
Quote:
Originally Posted by
SergeiR
Wonderfu portrait!
When you say Rodinal 1:200 do you mean that the basic Rodinal formula:
http://www.digitaltruth.com/data/rodinal.php
is diluted 1:200?
Re: Images shot on X-ray film
Thank you. Yes, when i say 1:100 it is basic R09 diluted as 1:100.. I honestly gave up on doing exact measurements , so i just do it by eye, pulling R09 into syringe - 2ml or so, markings are long gone ;)) and then dropping it into 270mm Jobo container
Re: Images shot on X-ray film
Figured I should post this here too.
Wista 8x10, 210mm f/9 Graphic-Kowa, 2-stop GND, Fuji HR-T x-ray film rated at 50, developed in Acufine:
http://www.oceanstarproductions.com/...810-1232ss.jpg
Re: Images shot on X-ray film
