[rcheshire (Rowland)]

Just modified a spare sensor assembly for the 1000D. Images showing a method of removing the ircut filter in one piece with no need to remove the plastic frame and break the seal.

Do this after fitting and sealing the cold finger to the sensor.

Eventually, I will fit clear glass in place of the coated lowpass filter - experimental at the moment.

The low pass filter is removed along with the rubber seal which is adhered to the bottom of the glass. Double sided gel tape 21 x 19mm is stuck to the face of ircut filter with a piece of PCB on top. The glue is cut in the corner recesses and the ircut is levered away - no mess, no contamination.

Before lifting the ircut out of its seating and exposing the sensor face, paint a very thin layer of silicon sealer (neutral cure - selleys roof and gutter) in the low pass filter seal channel, then lift the ircut out taking the backing seal with it - else, just leave it in place, if it doesn't come out.

No time for photos of this bit of the operation - replace the lowpass or clear glass straight away. If replacing the ircut with an astro filter change as quickly as you can, sealing the corners afterward. Then replace the lowpass. I'm using a clipin astro filter so no replacement of the ircut.

Quickly replace the lowpass filter with its seal and leave to cure. Not sure if it helps but I put the whole assembly in a clip lock bag with a dessicant and leave overnight.

The result; -10C and no condensation in the sealed cavity.

Next step is sealing the camera and filling with Argon. Meantime an SMD resistor network is heating the lowpass filter glass ~20ohm 5v. All works very well. Ramping the heater output along with cooling level.