Hi SC
If you are autoguiding with a webcam or dedicated guiding camera then the short tube should be long enough. manual guiding is a different story though. You're guidescope should be at least the same focal length as your imaging scope. Preferably 1.5 times at least.
For example: If your imaging scope is 2000mm FL and you are imaging with a 35mm camera. That will give a magnification of around 40 times. If you are using a DSLR then the mag is around 65 times. But if you are using a DSI then the magnification is around 200 times (I don't know the chip size off hand so approximating with a toUcam).
Now if you are using a short tube at say 500mm then using a 12mm reticle (you are using a reticle?) will give you a magnification of just over 40 times. You may get away with that for the 35 mm camera if you are good but it's likely you will get blurry stars. Your eyes just can't pick up those small movements early enough to prevent some sort of movement occuring across the film. If you keep the images standard size you probably wouldn't notice them, but blow them up and that would be a different story.
Now let's put a 2X barlow in the system. That's about 85 times mag. You should, theoretically be able to guide a DSLR now (the 35mm should be apiece of cake as you now have more than twice the magnification. Really it's focal length that is important here, but were cheating a bit by using magnification). But you still can't effectively manually guide for long exposures with the DSI. So what to do? Add another barlow, a 2.5X barlow. That brings us up to a focal length of 2500mm and our magnification up to 208X which should be just long enough. Just!
Now as I said talking about magnification isn't technically true. What we are trying to do is improve our ability to identify movement over arcsecond distances. To do that you need to increase focal length and resolution (aperture), but talking about magnification helps to get the point across.
So now what do you do. Well you could go out and buy two barlows, which would be expensive, plus you would be pushing the resolution limit of your little scope anyway so your accuracy is going to be reduce. You could buy a longer FL scope with a wider aperture along with a couple of barlows. Again possibly expensive. Or you could experiment with your DSI and your short tube with one barlow and see how long you can go before you start to see star trails. See if you can find someone with a 9mm reticle and borrow it for a while and see if that improves.
The other thing to check, from a purely mechanical point of view, is how bad is your backlash in dec and RA and how responsive are your drives.
Or just so you can start getting trail free images (job satisfaction factor) you could image through your Short tube, comvert to grey scale (to negate most of the chromtic aberation. Grey scale looks pretty good when done well, with good contrast and sharp images) and guide through your 8" Saxon. It would be a hell of a lot easier, plus you would get practice without the stress levels.
Sorry about the story but I felt it was important you got a good picture of what could be happening. And it is only that, one possibility. But it's one you can work with immediately and see if your results improve. It costs you nothing and it will eliminate one possible source of trailing: too short a guidescope.
Now if you find errors in here, so be it. I'm like a good reporter, just because I write it doesn't mean I have to read it
Good luck
BTW what do you mean by a "flash Mount" If your guidescope isn't held firmly then you could go mad trying to guide because of movement of the guidescope. See if you can come up with some sort of ring system to hold your scope. Lack of flexure in your imaging train is crucial to achieve good guiding.
![[1ponders]'s Avatar](../vbiis/customavatars/avatar45_9.gif){kind=avatar}
.cheers
