mdemeyer Offline Upload & Sell: Off
|
bjornthun wrote:
On a full spectrum modified camera you can use a Schott BG38 filter on the lens to get back to a normal colour response from the camera.
Does the thin filter mod on the sensor alter the colour response enough for AWB not to work?
How is the infrared response of a thin filter modded camera? Is there any IR contamination? A B+W 486 filter on the lens should solve any IR contamination issue, just like on the Leica M8.
Guys,
This is discussed at length earlier in the thread, including some suggested adjustments to the color balance settings using the in-camera settings. My experience, based on the original mod with the BG38 glass, is that there is a slight shift in white balance, but I have not had any problems correcting it in post. (I process from RAW so adjust WB in post anyway.) I originally planned to develop a custom profile for the camera, but have not found it to be necessary so have not made the effort. The AWB settings can be tweaked with the in-camera adjustments enough to get very close and, let's face it, AWB is rarely perfect anyway.
Remember that the glass was changed a few months back to one with better long-term humidity resistance, which is what is used today. I don't remember if Kolari Vision has made a public statement of what glass is used in the current modifications, so I'll not state it here since they have invested a lot in this project and I see no reason to give that information to potential competitors.
Regarding IR leakage, the replacement glasses were chosen to have similar IR rejection characteristics as the standard Sony filter, even with the thinner filter taken into account. I don't remember hearing anyone complain about IR leakage issues, and I have not seen any. I think the original BG38 filter passed a little more UV than the stock filter, but I use UV filters so have never seen any issue and, again, have not heard anyone else comment negatively on it.
I think one area for improvement, which was an issue with the stock A7 filter too, is A/R coating to reduce reflections in the filter under extreme conditions. I have seen that when shooting low-light architectural shots that included bright light sources (for example, in the wine storage caves at Del Dotto winery recently). I've discussed this with Ilija and he has identified a source to have the filters coated, but needs a high enough volume commitment to make that economically practical. Unfortunately, at the moment this remains a fairly specialized and low-volume activity.
Michael
|