lewis_riches

Not putting an eyepiece in the train for guiding. My mistake, should have said "helical eyepiece FOCUSER". I have updated the comment. Sounds good. I'll be using a Raspberry Pi for the guiding calcs, operating the mount over GPIO and controlled by an Android phone via Bluetooth but the idea of having a video feed from the guidecam sounds like something I'd like to add. So, this bit is the easy part! Lewis

Thanks for the responses, guys. I had considered selling the finder and going for an all-in-one kit. Some are very reasonably-priced. Unfortunately, there are various issues in attaching most of the cheaper kits to the top side dovetail bar of the OTA which, for the sake of brevity, I won't bother going into. I decided to buy some throw-away used eyepieces and just unscrewing the barrels. This actually turns out to be rather cost-effective if a little wasteful. As for the finder attachments, I still can't find any details on the thread gauge of the tube, so am taking the vendor's words on trust that the attachments fit the onto the finder tube. I gave ModernAstronomy a go (which was very helpful - thanks for the pointer, there) and found these: http://www.modernastronomy.com/shop/accessories/adapters/sky-watcher-clones-to-t-thread-adapter-for-straight-through-finders/ http://www.modernastronomy.com/shop/accessories/focusers/t-thread-to-1-25-helical-fine-focuser/ The helical eyepiece focuser is needed to bring the sensor to focus. There are non-rotating alternatives for roughly the same price but not with a female T-thread on the scope side, adding the need for more adapters and thus extra cost. I'll post updates once it's fully assembled. Thanks again Lewis

So, here's what I'm trying to achieve and what I mean by the eyepiece barrel I'm looking for. This one came straight off an old T-adapter (pictured). Thanks!

After doing a little scanning of the internets, I have seen that this is a rather popular method of obtaining a guide scope. I'm at the very beginning of this and have notice that much of the crucial detail is left out of all of the tutorials I have seen with all the obvious stuff left in. The way I want to do this: The kit must function as both a finder and a guide scope (after the necessary dis/reassembly, of course) Use a webcam as the sensor placed into the guide scope via a 1.25" eyepiece barrel (that will be glued onto the webcam casing) Use an eyepiece adapter in place the finder's crosshair eyepiece (this obviously needs to be detachable if the first requirement is to be met) Preferably have some kind of sensor focusing so the primary focus can be left in the same position for both purposes. So, in order to achieve this, I need to know (but can't seem to find anywhere else): The focal length of the finderscope's primary lens (this might determine whether or not it would be worth getting a helical eyepiece focuser to add to the train) The thread type at the end of the tube or if there are any attachments I can buy that would allow a 1.25" eyepiece to replace the original crosshair eyepiece Where on earth I can buy some 1.25" eyepiece barrels. Seriously, I've looked everywhere! How else could I attach the cam sensor to the guide/finder scope? If anyone else has tried/is trying this your advice would help immensely! (Tried adding photos but the site says that my 220Kb and 223Kb files are too big! - ???) Thanks Lewis