Camera Labs

Took apart the 450D today. Some might remember in the past I had it converted to work in full spectrum by removing the infra-red filter and replacing it with clear glass, which also retains normal phase AF performance. There were two annoyances with this. One is a single large enough spec of dust which is visible in use, and the other is I suspect the sensor isn't parallel with the mount which is causing my focus field to shift in critical situations.

In doing so, I removed the clear glass filter totally so there is nowhere for dust to get trapped. I noticed there were three coarsely cut thin metal spacers added, presumably to get the AF working accurately, but in themselves may be responsible for the non-parallel enough sensor so they've been removed. Have since re-assembled the camera and all works.

My remaining concern was the focus now both the original filter and the replacement glass have been removed. The nearest lens I had to hand was the 35mm f/2 so I did a quick infinity test on that. Couldn't reach it! Repeating the test with the 135mm f/2 that could reach infinity. Thinking I can re-add glass, I put the CLS filter in the body and that then allowed the 35/2 to focus to infinity.

I really need to get the CLS-CCD filter now to get rid of that IR stuff, and see if they also do a similar IR filter which is it's second use. Viewfinder is now uncalibrated so can't be used, I'm thinking of blocking it off.

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.

Looking like this it has a Terminator feel about it now.

regards,
HTG

Hi PoPo

I would be interested to hear more about your full spectrum 450D.
I have a 450D that was converted to 720nm IR and am considering altering again to full spectrum. Do you have any photos from the resulting conversion?
Where did you purchase the clear glass, I have heard that microscope slides are a similar thickness and easy to obtain.

Thanks.

_________________
5DMKII, 7D, 50D, (EF17-40-L-USM) (EF24-105-f4L-IS-USM) ( EF100-f2.8L-IS-USM) ( SIGMA 15mm f/2.8 EX DG Diagonal Fisheye ) (SIGMA 50mm f/1.4 EX DG HSM)
Holiday Home Rentals

The full spectrum 450D was chosen originally as I wanted one camera to do three things:
1: IR (with IR pass filter)
2: astrophotography (with suitable filters as needed)
3: visible light photography (with IR block filter) - for this part, I wanted the phase AF system to remain functional.

I got the conversion done elsewhere. In order to satisfy #3 in particular, this meant a clear glass "filter" was needed to maintain the focus distances. That was supplied by the modifier, who used Astronomik MC clear glass which you can buy that from their web shop. I noticed the modifier also added spacers, presumably to fine adjust the sensor position to maintain focus.

My problem was, there was one speck of dust that was just big enough to be annoying trapped under the new filter. Further to that, in application #2, I found I had an effect where the lens axis was not adequately perpendicular to the sensor plane. So basically at the waste of having the modification done in the first place, I removed the filter totally. You can't trap dust under something that isn't there. I haven't yet verified if the filter and spacer removal has helped with the alignment at all yet. This does means #3 is no longer possible but I think I have more than enough bodies now as backup. Focus distances are now off, but that is in large part offset by the body clip filters I use.

With hindsight, I would just remove the filter myself, and not go for a filter replacement unless you wanted the camera dedicated just for one of the uses above.

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.