StevePM

23 hours ago, Stuf1978 said:

Seems odd, I did the self mod as you're describing and I haven't had any focusing issues. Must admit though I've given up using the 70-300L for astro as it shows significant coma especially at 300mm which is a poor show for such a pricey lens. 

It’s all ok - have dived back into the guts of the camera and removed the 0.2mm shims from under the sensor to move it forward in compensation for the loss of glass. 
Fiddly as hell but had the desired effect...

On 23/07/2019 at 08:39, Stuf1978 said:

Hmmm may just send it off to cheap astrophotography services and get it modded with the shim then I know I'll have no issues. 

I’ve just done the self mod and opted to leave the LP1 in place with no replacement for the LP2. The mod appears to have worked functionally but I have issues with focus. 
I also have the 70-300mm L and tried to focus this last night. It appears to move through the point of best focus (so I don’t think I have an infinity issue) but the best focus is still pretty fuzzy compared to my unmodded body. 
I’ve ordered a CLS CCD clip in filter to see whether that sorts / improves it. Other than that I guess getting the shims checked or adjusted will be my option. I could go with the Baader replacement glass but I don’t want to throw more money at it if that’s still going to leave me out of focus...

Any thoughts?