Electronic Filter Wheel Worth It?

[Astroblagger]

Hello, What's your thoughts on electronic filter wheels, i see the benefits for having it change round the filters remotely etc but my badder filters still need refocused anyway with my manual filter wheel.  i would assume people set it up to rotate round after a certain amount of subs at the start of their imaging session and then leave everything to run. but if you need to refocus every time anyway it kind of defeats the purpose or am i wrong?? 

[pipnina]

I believe the main benefit is for people using auto-focusing systems. So the filter can switch over, and the auto-focuser refocuses, and imaging can continue : D

 

[Astroblagger]

didnt know there was a program that can do auto focus between filters? what software is this?

 

[bottletopburly]

Apt can be set with offsets for each filter  you can also run a script to refocus after filter change and some filters as I see it are par focal , most imaging software will be able to do the same .

[scotty38]

It's even better than that with offsets so once the relative focus positions for each filter are known (done manually or even automatically) then each time a filter is changed the focuser just moves the amount required by the offset. A focus run is typically done at the start of imaging and at points determined by the user based on temp, HFR or whatever but the offsets remain......

Edit - didn't spot the comment re offsets above, apologies 🙂

Edited February 28, 2022 by scotty38

[teoria_del_big_bang]

If using a mono CCD then an electronic filter wheel is a Godsend, but if your filters are not parfocal and you need to focus on every filter change then you really need to have an electronic focusser as well to get the full benefits.

The focusser is basically a stepper motor with some electronics to drive the motor that is controlled by the sequencing software that you choose to use (there are several flavours of software, mot free or pretty cheap).When you have this combination of FW, focusser and sequence software you can choose to re-focus on filter change, or as @scotty38 says you can learn what the offsets are and then instead of actually re-focussing it can save time and just move the focusser by the offset.
Also it is a good idea to re-focus every so often as big temperature changes can noticeably affect the focus. 

Software (Windows based) that can do this include:

• APT - I have not used for a while but when I did I really liked this software, there is a free version that does everything you need but I liked it so well I got the paid version which is only about £15.
  APT
•  NINA - again free but great software and donations to the developers can be made. This is very popular with imagers, there is a lot of things this software can do and is a bit more complicated to use than APT (but soon get used to it) . This is my choice of sequencer at the moment.
  NINA
• Sequence Generator Pro - Not free but I think also great software. I never used but used to be very popular when it was a one off reasonable price but a lot of people got very upset when they started charging around £140 one off then about £50 per year ongoing cost.
  Sequence Generator Pro
• Maxim DL Again not free but I think just a one off cost. I never used but this is very popular with the more advanced imagers who seem to love it.
  Maxim DL
• Voyager - Also not free and this is the software I was going to try until I tried NINA. Its about £120 one off payment then about £20 a year which isn't bad as remember with these ongoing payments you get support including some remote support with this.
  Voyager

I am sure there are others, these are just the ones I am aware of.

As well as the above one very good and popular bits of software is EKOS, or more often Kstars (which is EKOS and a Stellarium called Kstars). This is a free and a great piece of software and real easy to use but only available for Linux based software. Many use it on a Raspberry Pi  version 3 or 4 (RPi), which can be fixed to the mount and run remotely via WiFi from a warm room and so makes a very cheap method of controlling your scope with loads of features.
One very popular way of achieving this it to load a RPi3 or RPi4 with Stellermate (around £40) or Astroberry (Free) which is a package that can load all the required files including PHD2 and star bases for Platesolving.
I used this software for quite a while and loved it, only moved because I did not get on with Linux (my problem!)

Stellarmate
Astroberry

 

Steve