I have the 3 mp Contax version which I find is a decent little camera and there are quite a few very good photos taken with the SL400 in the Gallery.
My only issues with this camera design is the poor battery life and 3 mp sensor - a 4 mp sensor would have bene so much better. The battery issue is addressed using a battery pack. Even as it is though, it can still out perform the Nikon CP4500 in some circumstances.
Using the shutter release bracket/cable and digiscoping adapter you should be able to remove camera shake entirely - provided the tripod is rock steady. I regularly go down to 1/8 or 1/15 sec shutter speeds if the subject is static.
Marek's settings advice looks pretty good - the only point I'd take issue with is the aperture. The standard advice for digiscoping was always to use maximum aperture as depth of field counts for nothing. This isn't actually true and as in most photography around f5,6 or higher usually gets better results out of the lens. Using a smaller aperture also gives noticably more depth of field. Nowadays I go for the highest aperture setting I can so as to maintain at least 1/60 - on a sunny day I can sometimes get 1/500 at f11 or higher. Sometimes though if it's dull then I'll still drop to the widest aperture and even down to 1/8 second exposure if the bird is static.
The other point to make is that although it's a scope and photos can be taken from a long way off, if you can get a bit closer then do so and the results will be markedly better. Not that this advice would help as far as the Hobby is concerned. Congratulations on getting a decent shot of such a wary bird :t:
This last shot is nicely exposed but still just a little bit soft. The limiting factor could very well be the scope optics however first I'd try using a little less camera zoom. Even with the Contax using it a 3x zoom can lead to soft photos - anywhere between 2x-3x is better and the scope eyepeice set as you have been at 20x. It's better to have less zoom and a smaller image than a full frame image that is soft. Most instances you have to crop and resize anyway - a smaller more detailed capture may just need cropping - which I always find more preferable.
It's most likely in these circumstances though that the softness is down to atmospheric pollution - in this case heat haze and really there isn't a thing you can do about that. You can't always see the heat haze clearly in the scope but all cameras seem prone to picking it up.
To test the scope combination simply take a few photos of a static subject from the scopes minimum focus distance and then maybe around 30 yards - a fence post or panel is quite useful to use as there's plenty of detail. I don't think there'll be any problems with the scope as the Opticrons are pretty good actually.
Another useful tip is that if you do have a slightly soft image then resizing it downwards to 640x480 allows for a little more sharpening and on viewing a slightly more apparently sharp image.
Also running it through a fitler program such as the freebie
www.neatimage.com as I did here most often can improve results.