Electronic focusers

Hi Dave,

I use three electronic focussers.

These were each bought depending on the level of application.

The JMI NGT-S is quite good with its hand push button controller. However, I discovered it has some sluggishness when putting on a camera and filter system. I also discovered it was slightly off axis from the principle axis. I think this was due to ratching out to far with such a weight. It also depends on the orientation of the OTA and weight of the camera. However, if you are using light accessories it's fine.

Optec TCF - S has the added automatic facility of conpensating for temperature drop during a nights observing. Actually I use it both manually and automatically. It can take alot more weight than the JMI NGT -S. I like the DRO lit up in red, easily seen at a distance. Ratcheting I/O shows a very slight rotation in the image. ie. slight movement of target within the FOV. Not really important unless you are at high magnification doing webcam work on planets. The focusser is a solid piece of engineering. It also has the added feature of PC link up. to available software like Maxim DL for remote access.

Van Slyke. The focuser is absolutely amazing, the Rolls Royce of focusers. Of course the price is huge.

Again, it depends how serious you are in doing observational work. In my case I am serious. In fact Van Slyke didn't have what I was after so I had to send him a specific design that had a much wider entrance hole for the steep cone of light that would be passing through. This cost me alot more.
In what I have read in your previous mail you may not need this type of focuser for the type of telescope you are thinking of purchasing and camera/ filter system. BTW you can do remote access by adapting the focuser with ROBISCOPE. You then can use Maxim DL. I use a Mititoya DRO for focussing read out. There is no backlash in the system.

Out of the three I would go for the Optec TCF-S

I hope this helps

Eamonn

Michael - nice review of the Borg! Might take a look at getting one for my new ETX-70 :shock: Seriously though, for the kinds of prices on the board you posted, looks like it'll be nice addition to the armoury!

Eamonn - thanks for the feedback. Like anything else in this hobby, one pathway soon splits up into three or four! I've simply been researching focusers that out there without currently looking at matching it up to a particular scope/camera/filter wheel outfit. This is where the level of complexity starts getting a bot hairy and even the websites have a paucity of information. But if I at least narrow the field down, the final choice(s) will start to become clearer.

Van Slyke - the images on their site are truly objects of immense desire! I'd even just put it on the mantlepiece and gaze at it all night!

Once again folks - thanks for your invaluable and much appreciated feedback. The journey continues....

Dave

Hi Dave,
I'd have to agree with all above, an electronic focuser is a godsend.
I have one for the SCT, its a dedicated meade focuser and it really helps with webcaming as it prevents image wobble.
Since mine actually moves the primary mirror, I get about 20-25 arcseconds on image shift, which isn't alot, but it could have been worse.
I might go to a helical microfocuser in the near future, I'll have to make sure it has a scale on it for repeatable focusing.

Programs like astrosnap help you focus the webcam, this program is used for capturing images images and does the focusing as a side fuction.

DSLR focus is used with the digital SLR camers such as the 300D.

So there are many programs out there to help you along.

Have fun.