Canon 1000d Full Spectrum Mod

[frogdr1ver]

Hi,

Been ages since ive posted on here. The bugs caught again (if the clouds ever clear), so today ive done a full spectrum mod (both filters removed) on a 1000d. I want to use it for daytime IR as well as astro. As expected the AF is now a bit out using the viewfinder but seems to be ok using live view. I have an IR fllter arriving in the next couple of days.

Ive read and read threads all over the net and cant quite work out if i can just shim the sensor to the thickness of the LPF2 to re-align the AF or do i need some glass to be in, be it the astronomik clear glass filter or if i get a clip filter such as a CLS-CCD or the UV-IR will that sort out the AF?

It would be nice to use the viewfinder again but im chuffed the mod has worked as expected

Any suggestions ??

[Merlin66]

I have a similar modded 1000D and use the Astronomik clear clip in filter to allow me to focus with standard lenses. This only works with EF lenses.

[pete_l]

Ive read and read threads all over the net and cant quite work out if i can just shim the sensor to the thickness of the LPF2 to re-align the AF or do i need some glass to be in, be it the astronomik clear glass filter or if i get a clip filter such as a CLS-CCD or the UV-IR will that sort out the AF?

I recall the amount you need to shim the sensor depends on the difference in refractive index of the filter, compared to air (R.I = 1) as well as the thickness of the filter.

So for a filter with an R.I of 1.3, the shim would need to be 0.3 * the thickness of the filter that was removed.

[frogdr1ver]

I have a similar modded 1000D and use the Astronomik clear clip in filter to allow me to focus with standard lenses. This only works with EF lenses.

Thanks for the reply and that gives you accurate AF through the viewfinder?

I recall the amount you need to shim the sensor depends on the difference in refractive index of the filter, compared to air (R.I = 1) as well as the thickness of the filter.

So for a filter with an R.I of 1.3, the shim would need to be 0.3 * the thickness of the filter that was removed.

Thanks for the reply, so according to my calcs (based on Gary Honis website) of (1.517-1)/1.517 x 1.4mm = 0.478mm of shims. And that would be fine with no extra glass in the optical train?

[frogdr1ver]

Ive been mulling this over, any idea if i need to shim the sensor to the RI of air (which is 1) or the RI of the filters that were removed? Im assuming that its the RI of air which works out at zero shims plus any that are in to keep the sensor square to the lenses?