Large-ish Format w/ Digital Back and Stitching

**bieber** · 20-May-2018, 18:06

I'm pretty sure that's what the back's doing when its noise reduction kicks in after a long-ish exposure. The problem is even with that, medium format sensors heat up quickly, generate a lot of noise when they heat up (at least from this generation, some of the new ones are amazing), and worse yet the differences between the four separate sensors that make up the "sensor," which are normally controlled for by a correction factor, seem to start to grow beyond the level you can neatly correct for.

Attached to a MF camera, I can shoot dark scenes like this and get beautiful clean images, as long as I'm using nice short exposures with strobes and keeping the ISO low. The problem is that when you use it with the contacts disconnected, you have to manually signal the back to wake up the sensor before making the actual exposure, so (a) the sensor has to be awake for much longer than it normally would, generating heat, and (b) since the whole thing is manual and controlled by human reflexes, it's not repeatable enough to even attempt a flat field image. All that being said, with a little bit of redundancy in the stitching everything seems to be turning out pretty okay

**Nodda Duma** · 21-May-2018, 06:11

Sounds very familiar. Astrophotography exposures can run minutes-long, and a major concern is, as you can relate, sensor temp. One technique to address this is to enclose the entire camera in a cooling box with a TEC ( an extreme solution but very effective), and the other is to generate a database of dark frames catalogued not only by exposure time but also sensor temperature. I’ve found this makes a significant difference. Not only do dedicated astrophotography imagers report sensor temp, but even my Canon 40D provides that info. So you might be able to get at that data likely through a software interface.

Hope this helps! Sometimes cross-pollination of ideas from other hobbies can be useful.