- Posts: 2
- Joined: Thu Aug 14, 2014 9:25 pm
I do not know how to remove the IR cut filter from your BM 4k but I once tried to remove the filter from a defunct Sony PD 150 sensor. There seemed to be no easy way and I virtually chipped it out and never tried again. I was surprised at its thickness and seem to remember it consisted of two bits of glass cemented together. Had I been successful in removing the filter I would have had to find another piece of glass of the same properties to compensate for the removal of the filter. Without a substitute the lens-flange to sensor distance would have been incorrect.
I have done some IR work using cheap surveillance cameras. The advantage of the cheap cameras is that they have no IR cut filters whereas more expensive surveillance cameras may have filters that retract automatically with falling light intensity. I tried one of these and found that when the filter was automatically retracted the camera would decide that it was not so dark after all and put the filter back again. It would then remove the filter again and the cycle would continue. The most expensive surveillance cameras permit either manual or auto filter removal.
I now have two cameras that I hope to use for more IR work, one is a surveillance camera - the IOC ‘Orion’ CHDC-34BSDC and the other is a ‘C’ mount converted GoPro 3+ black that has a removable and replaceable IR cut filter.
Finally there is at least one business that modifies various cameras for IR use.