To summarise, got the GSO .5 FR working OK on the EOS 1000d, but with a little bit of vignetting.
Using a Meade DSI III OSC, perfect.
Follows are some posts I made on MAS during troubleshooting, I'll paste them here in case someone may find it useful........
It had never occurred to me that you could remove the T-threaded insert from the bayonet-mount EOS adaptor ring. There are three little grubscrews that when loosened, allow the round T-threaded section to come out, leaving a larger hole, into which the GSO .5 FR fits quite nicely, and can be locked in place with the grubscrews, leaving about 1cm protruding to use as a very short 2" barrel.
Be aware that some EOS to Tthread adaptors don't seem to have the removable T thread portion, I have one of each type, all bought on Ebay from HKG. The key to identifying the correct one is the three grubscrew holes around the periphery of the knurled front section of the EOS adaptor. The other (unsuitable) one doesn't need or have these grubscrews. I now use it for my 1.25" nose adaptor.
In doing all this, one stands a good chance of marking the exterior of the FR body with the grubscrews, but hey, small price if it works. I plan on trying it tonight with both the C8 SCT and ED100 crayfords. I'll pass along any results.
If it does work, I plan on buying a 2" barrel adaptor, 1" long, from Scopestuffs or such, to screw into the filter thread on the front of the FR, so you can get a bigger "2 nose" after the FR, for a more solid insertion into the focuser.
Following day:
Just a quick update to advise that the GSO .5FR worked with my EOS 1000d, but with some minor vignetting in the corners. I tried it on both the C8 and the ED100 f9 refractor, pretty much the same amount of vignetting, which I guess says it either is still a bit too far from the camera sensor, or that the sensor is just too big for it
Anyway, it now reaches focus and appears to give about .5 FR. I just used a local tree as a subject, as clouds here.
I then tried it with my Meade DSI III OSC, using a 1.25 to 2" adaptor on the front of the standard 1.25 nose, which has a T thread to the DSI sensor opening. I screwed the FR on the front of the 2" adaptor. It worked perfectly, with no vignetting.
As this will probably be my main mode of operation with it, and using the 1000d more in piggyback widefield with camera lenses, I may try and get a direct T to 2" adaptor so that I don't need the 1.25 nose in the Meade. More for cosmetics and reliability than performance I guess.
Cheers,
, I too cannot get focus.
