1. Why is ROBO-FOCUS better than careful hand focusing?2. Will ROBO-FOCUS fit on my focusser and scope?
3. Can I remove ROBO-FOCUS or use it on multiple scopes?
4. Can I write my own control program for ROBO-FOCUS?
5. Is ROBO-FOCUS useful for visual observing?
6. Is ROBO-FOCUS compatible with Digital Dome Works?
7. Is focusser spelled with one or two “s”?
8. Can I set up the ROBO-FOCUS to do totally automatic focusing?
9. Can I focus my CCD camera on the planets and the moon using ROBO-FOCUS?
10. Is ROBO-FOCUS good for photographic focusing?
11. How does ROBO-FOCUS handle focus changes due to mirror flop and other telescope problems?
12. How much does ROBO-FOCUS weigh?
13. Does ROBO-FOCUS require its own computer serial port?
14. How does the Serial "pass-through" work?
15. Does Robo-Focus include temperature compensation?
1. Why is ROBO-FOCUS better than careful hand focusing?
Accurate focussing requires that the eyepiece or imaging device be set to a precision of a few thousandths of an inch. It is almost impossible to do this by hand because of the inability to make such small manual changes, the inability to make the same change in reverse, due to the inherent backlash in most optical systems. To accomplish this only a digital focusser will do.
ROBO-FOCUS will fit nearly all scopes. In some popular scopes (e.g., LX200) it is feasible for us to provide custom brackets and hardware. In other cases, such as the many variations of the Rack and Pinion focusser, the physical geometries are so varied that this is impossible. If the focusser has a 1/4-inch shaft, our standard coupling will fit. We can provide for other shaft sizes on special order (no charge). Once the motor is connected to the focusser shaft, the other step is to install brackets to support the motor. To allow the user to fit almost any application, we provide a pair of simple brackets that can easily be bent to fit.
Yes. ROBO-FOCUS brackets and mounts are held on the scope using high grade double-back tape that can be removed if needed at a later time. Of course, some users will choose to use screws, or even make their own custom brackets. If you want to use ROBO-FOCUS on more than one scope, we recommend installing a separate stepper motor on each scope and transferring the control unit as needed.
Yes. You can base it on the control program we supply (it is open source). Or you can write your own program to take advantage of the various ROBO-FOCUS commands that are a part of our documentation. The control program is also ASCOM compatible for those writing their own control routines.
Yes. Although many scopes focus easily and accurately when you have the instant feedback of the visual image, others (such as S-Cs) are difficult to focus accurately due to their high backlash. ROBO-FOCUS will compensate for the backlash. In many cases, you will find that the hands-off focussing (not having to touch the scope) reduces vibration and makes focussing quicker.
Yes. It complements the remote operating capability of DDW. ROBO-FOCUS and its control program can also be used in parallel with all scope control programs. If you are short of RS232 COM ports, in most cases you can even run ROBO-FOCUS on the same COM port as the telescope. If you use the optional Remote Power Module plus the two channels of remote power control you have with the DDW, you will have a total of six independently controlled outlets.
We have had many debates about this. Sometimes we use one, sometimes the two “s” version. Even Microsoft Word spellcheck can’t make up its mind. How do you vote?
Software for automating the Robo-Focus has become available from two sources in the last few months:We did extensive testing of these two programs with both actual and artificial stars, then wrote up the results in a paper which you can download and print (pdf file, 41K).
- @Focus (a part of CCDSoft image processing software from Software Bisque)
- HFR Focus (uses MaximDL software from Diffraction Limited for image processing; beta version available as of this writing)
The bottom line is that either program will deliver good focus under good conditions, though HFR is superior under poor focus and image conditions or frequent setup changes. On the other hand, @Focus is simpler in the initial setup. The choice between them for most people, will turn on which CCD software the user already has or prefers (CCDSoft of Maxim DL).
The quickest way to focus is to image using a medium bright star. Most CCD software supports a convenient focus mode providing peak brightness and/or image size measurements. A quick succession of images will converge quickly on perfect focus. Using ROBO-FOCUS, you can focus directly on the moon or planets; however, it is usually faster to use a nearby star.
Yes, particularly because of the ability to make accurate small focus movements and to return to the best focus found.
The best way is to refocus regularly if you think the focus may be changing (ROBO-FOCUS makes that a quick process). Mirror flop appears to be less severe with ROBO-FOCUS because the mirror is always moved in the same direction.
The ROBO-FOCUS stepping motor and typical bracket weigh about 15 oz.
If you will run the ROBO-FOCUS from a PC, yes, you will need a serial port. If your PC has an available serial port, you're all set. If you are lacking an open port, we offer a "pass-through" feature on the ROBO-FOCUS control box which allows you to connect from your PC port to the box to your telescope. This setup will require an adapter between the control box and your telescope. You should contact us about the kind of adapter needed for your scope.
The physical set-up is that you connect a cable (provided) from your PC to the ROBO-FOCUS and another cable (provided when you get the proper adapter from us) between the RF and scope. Both the scope software and the RF Control program will be running in your PC. Each program will have a menu item for opening/closing the com port, so you switch between programs by controlling which one is open on the port.The ROBO-FOCUS pass-through jack is the same one you would use for the RF hand control, if you have one. The scope adapter that you can get from us will allow you to connect both the scope and the RF hand control for simultaneous scope and focus control when you are in the observatory.
The latest version of Robo-Focus, RF3, includes temperature compensation. Some scopes change focus as the temperature changes. Thus, you will benefit from a technique for measuring temperature and automatically making the appropriate focus changes.We've put a temperature sensor into the RF control box. The RF control program includes a module for creating a dataset to record how your scope's focus responds to temperature changes. You can then set Robo-Focus to adjust the focus automatically.
We also can provide a separate external temperature sensor.
We evaluated the quality of focusing an LX200 using Robo-Focus (with HFR Focus) on the scope's focus knob and on a separate JMI NGF-S Crayford style focuser. The results showed that Robo-Focus on the focus knob performed as well as on the NGF-S.We put the results in paper that also discusses backlash measurements on the LX200. Click here to download and print this paper (pdf file, 32K).
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