ChrisJ

Pentax have just unveiled a mirrorless version of their K5 called the K-01. The video on a K5 was pretty much an afterthought, it will be interesting to see what they have done with this new mirrorless version. [url=http://www.pentaxforums.com/news/pentax-k-01-officially-announced.html]http://www.pentaxforums.com/news/pentax-k-01-officially-announced.html[/url] Chris

The Panasonic 20mm f1.7 is a surprisingly good lens too. But expensive for what it is. [url=http://***URL removed***/lensreviews/panasonic_20_1p7_o20/]http://***URL removed***/lensreviews/panasonic_20_1p7_o20/[/url] I have a Jupiter 8 50mm f2, not my first go to lens, but it does have smooth focus and a variable aperture without stops, it's main disadvantage is it won't focus close. I have had a lot of success with Pentax 110 lenses. as most people know they have no aperture adjustment, but I have got around that by using slide in apertures in the adapter I made. These lenses are tiny, but have great image quality even wide open and they are cheap - very cheap. The range includes everything from 18mm to 70mm and has a good 20 - 40mm constant aperture zoom, all are f2.8. The flat field (maintaining focus from corner to corner) is exceptional on these lenses and contrast is very good. Stop them down and the Bokeh is, shall we say, different. Here is my photostream for these lenses. [url=http://www.flickr.com/photos/chris-judge/sets/72157624912287716/]http://www.flickr.com/photos/chris-judge/sets/72157624912287716/[/url] Some of my test images show some vignetting in the top corners, this was caused by my adapter not being parallel to the sensor plane, I've since cured it. They are perfectly usable wide open using a variable ND filter in your matte box for exposure. Chris

The 5D does get more photons, but over a larger area. The number of photons per square mm is exactly the same on both cameras. Noise is added to the image signal from the sensor, 60% of noise is caused by heat within the sensor, the more heat the more noise, it's electrical noise. Larger sensors need more energy to heat them up than smaller sensors do, therefore larger sensors have less noise. Used to be true, but not necessarily so these days, if you reduce the current the sensor requires it will run cooler and you'll get less noise. There are more efficient sensors than those made by Canon which are relatively old technology, the sensor in the GH2 is one of these more recent ones. Most of the other 40% of noise comes from the A/D converter, or more especially the high impedance connection from the sensor to the A/D converters, by simply integrating the A/D converters within the sensor the noise from this source is virtually eliminated. The GH2 sensor has this feature too. This noise threshold is ever present in all digital sensors, lower on modern sensors than older ones, the only 100% way to get zero noise is to use more light, then the exposure is well above the noise which is why movie companies spend loads on lighting the scene, if you want it to look dark, record with bright lighting and then turn the exposure down in post processing, result, dark moody image without noise. Chris