The 40mm 2" to T42mm that you've linked looks good and I would be very surprised if your Canon was more than a couple of mm different to my pentax. However, if you are going to do any serious photography, I'd spend the extra $120 on the flattener instead. You don't need both as the Orion flattener puts the camera in the right spot. The 1.25" adapter looks good too - although it may not be necessary depending on your diagonals.
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