A Look In The Mirror Slap – Contax vs Hasselblad H
Forever I have read about the impact of mirror slap on the resulting image. That at slower shutter speeds, mirror slap can make some cameras unusable, the images soft. The Contax 645 AF has traditionally been thought of as the minimal mirror slap king for medium format 645 bodies. And indeed, when you shoot with a Contax the sound and feel of the mirror does live up to that description of “buttery smooth”. In contrast, the Hasselblad H camera system has been thought of as the huge mirror, hard slap 645 camera body. And for sure, the Hasselblad H Series (H1/H2/H3D/H4D/H5D, etc) has a viewfinder significantly larger and brighter than the Contax. The mirror makes a loud Puh-Chat! sound, you can feel the camera shake from the force of it.
I was curious, and honestly, I’ve been wanting to do this test for years. Is the difference as great as we’ve been led to believe? Aside from the tactile feel and sound, much of the evidence of the impact on the image is anecdotal. So we tested it.
In this test, we took captures with the Hasselblad H2 Camera with a Phase One P65+ digital back in Hasselblad H mount and a Contax 645AF Camera with a Phase One P65+ in Contax mount. The lenses in each case were: Contax 80mm/2 and Hasselblad 80mm/2.8 HC. There were 2 test sessions, with one capture session at f/11 and 1/125th of a second (the maximum flash sync speed of the Contax) and a second capture session at f/11 and 2 seconds.
The resolution from each lens was very close at 1/125th. But more interestingly, when shot at 2 seconds, there is only the slightest difference in sharpness, compared to the captures at 1/125th. All captures were with mirror down, so the full force of each respective mirror would come into play.
This could lead to some interesting conclusions. First, the difference in mirror slap effect on the Hasselblad H camera vs say, a Contax or other camera, seems to be negligible.The results were very interesting. First off, depending on your persepective, the Contax 80mm holds up very well to 60 megapixels and also compared to the Hasselblad 80mm HC lens, but also, the same could be said in reverse for the Hasselblad 80mm HC!
This would seem to fly in the face of accepted anecdotal evidence. The relatively minimal difference between the shots at 1/125th and 2 seconds makes one wonder whether it is the heavy mirror of a camera responsible for the majority of the softness at 1/90th -1/30th of a second or some other factor? If a photographer is hand holding at those shutter speeds, then the evidence raises the question whether it is the mirror or the movement of the photographer or the subject that might create a soft image. Even on a tripod, it brings into question the technique of taking the capture. Is a remote release being used or is the shutter release of the camera being manually pressed? Is the tripod and head really locked down tight? I’ve seen tripod/heads in use that were shaky without the user fully realizing just how shaky things were.
In any event – shooting at slow shutter speeds hand held is a challenge and the results will vary from photographer to photographer. Those who ace it – our hats are off to you! And shooting on a tripod at slow shutter speeds is not a guarantee of sharp images. There still should be absolutely no play (or as little as possible) from the top of the head to the foot of the tripod for best results.
For those concerned about mirror slap – we believe the results of this test are good news for those who might wish to consider a Hasselblad but are concerned about mirror slap compared to other cameras.