The ALPA Log

FPS Shuttertest


A comaprison between Copal and the FPS focal plane shutter regarding shutter vibration.

July 7, 2014
FPS Shuttertest

We got an overwhelmingly positive response on our first test and the shutter memory game. Some customers asked if we could show results from several more exposure settings. So we did this quick test in the neighborhood yesterday evening with more shutter time variants.The target was performed along the street with the tower of the University of Zurich in the center (distance roughly 1,400 meters or 4,600 feet for a maximum effect of the Copal/focal plan shutter in the target - click on the above images for illustration). Again we used the same Apo-Digitar 5.6/150 mm lens (set for infinity) for Copal and FPS exposure on the ALPA 12 FPS, same Phase One IQ180 and Gitzo 3541L tripod (no additional weights) with ALPA/Linhof Micro 3D head straight from the walkway.Light was fading away, the histogram was already left sided and keeping aperture constant (f11) was anyway quite a bit tricky. So we had to alter the ISO. Once again it became obvious: the IQ180 is shining at base ISO 35 up to maybe ISO 100. The performance beyond is definitively degraded in comparison. So please take this set (1/60 sec) with a grain of salt as also the variance of the effective shutter time of the Copal was kicking in. Remember: Accuracy of Copal shutters is defined with +/- 1/3 EV for aperture AND shutter time.For this quick test we developed the RAW files in C1 7.2.2 with standard parameters including sharpening. Again we took three images with the Copal and three with the focal plane shutter for a more representative range of results. You will find technical details and the index for the six images in total indicated on every image at the right.Another very helpful input from real world users of the ALPA 12 FPS came regarding "long lens support". When using extreme tele lenses and mounting them just on a built-in lens tripod socket it is crucial to stabilize the camera body too. This applies for every camera with built-in shutter as the kinetic energy needs to get disseminated. In our test this is nicely absorbed by the body and the tripod head/tripod. Some interesting gear can be found at Really Right Stuff or Sunwayfoto and others too.Test OverviewBest viewed in Photoshop at 100%. The images show the identical details of six images. The key which detail was taken with which shutter is listed in the right part of the image.ALPA Shutter Test No 2 - Exposure Time 1/4 secALPA Shutter Test No 2 - Exposure Time 1/8 secALPA Shutter Test No 2 - Exposure Time 1/15 secALPA Shutter Test No 2 - Exposure Time 1/30 secALPA Shutter Test No 2 - Exposure Time 1/60 sec