Why is one side of my Pentax K1000 photo darker at 1/1000s?
Asked 1/28/2024
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Some scans from my Pentax K1000 on Kodak UltraMax show a gradual dark-to-light gradient across the frame. It was most noticeable in shots taken at 1/1000s from behind a car window, and it appears in other photos from the same situation too. What could cause one side of the image to be darker, and how can I avoid it in the future?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
2y ago
2 Answers
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The possible reason
In a focal plane shutter at high speeds, the two curtains go across the focal plane close to one another, producing a traveling slit. The width of the slit determines at exposure time.
Since the K1000 shutter has horizontal travel, it could be that the two curtains aren't exactly moving at the same speed, causing a widening or narrowing of the slit as the two curtains go across the focal plane at high speeds. This makes the picture lighter on the side where the slit is wider.
If the picture look a bit under-exposed (the brighter side being correct) that would be a 1st curtain slower than the 2nd (narrowing slit), and if it looks a bit over exposed (darker side correct) that would be the 2nd curtain that is slow (widening slit).
And this would become more visible as you use higher speeds.
How to avoid this
If the above is correct, then either:
- Have the camera serviced
- Replace the camera (several millions K1000s have been made, so it isn't a rare camera, how much would be a replacement on eBay)?
- Avoid fast exposures (which is quite easy on a film camera, given the low sensitivity of film)(or get a ND filter...)
Originally by user75947. Source · Licensed CC BY-SA 4.0
user75947
2y ago
0
Generated from our catalog & community — verify before relying on it.
The most likely cause is uneven exposure from the K1000’s focal-plane shutter at its highest speeds. At 1/1000s, the shutter exposes the film with a narrow moving slit. If the two shutter curtains aren’t traveling perfectly evenly, one side of the frame can get a little more exposure than the other, creating a gradient. This tends to show up more at faster shutter speeds.
A second possibility is the car window itself. Some tinted or polarized window films can darken part of a scene unevenly, especially skies, producing an effect somewhat like a polarizer.
To avoid it:
- Test the camera at slower shutter speeds and see if the problem disappears.
- Compare shots made through the window vs. with the window open.
- If the gradient appears consistently at high speeds, the shutter may need service.
- If it only happens through the car glass, avoid shooting through that window when possible.
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