Bahtinov Mask Focus...

[Ian McCallum]

Just looking for some input, please.  Does this image look like it's correctly focused using a Bahtinov mask for imaging?  Please bare in mind that this is from an achromatic refractor, with only a single speed manual R&P focuser.

[knobby]

Slightly unusual looking bahtinov pattern but looks bang on in focus 👍🏻

[Ian McCallum]

10 hours ago, knobby said:

Slightly unusual looking bahtinov pattern but looks bang on in focus 👍🏻

Here at the two Bahtinov masks that I use, both bought from eBay. The small green one is a 3D printed one for the guide scope and the larger adjustable one is for either my Sky-Watcher Startravel 120 achromat or Evostar 120 achromat. 

I'm pretty that I had 'nailed' the focusing. Many thanks for confirming that. 👍

[knobby]

Mine looks straighter, but yours is still doing the job well.

 

[Xilman]

13 hours ago, Ian McCallum said:

Just looking for some input, please.  Does this image look like it's correctly focused using a Bahtinov mask for imaging?  Please bare in mind that this is from an achromatic refractor, with only a single speed manual R&P focuser.

If you can feed your images directly from the camera into a computer I heartily recommend getting hold of Bahtinov Grabber.  Available from https://www.dropbox.com/s/tp9cvni3okk1azd/Bahtinov_grabber64.exe?dl=0 and https://www.dropbox.com/s/k3tb6n32k8v78bo/Bahtinov_grabber.exe?dl=0

Works regardless of focuser type (I use it manually and with a relative motor focuser) and gets a much more precise focus than doing the same job by eye.

to me your image looks very slightly out of focus, but likely not enough to be important.

[Ian McCallum]

3 hours ago, Xilman said:

If you can feed your images directly from the camera into a computer I heartily recommend getting hold of Bahtinov Grabber.  Available from https://www.dropbox.com/s/tp9cvni3okk1azd/Bahtinov_grabber64.exe?dl=0 and https://www.dropbox.com/s/k3tb6n32k8v78bo/Bahtinov_grabber.exe?dl=0

Works regardless of focuser type (I use it manually and with a relative motor focuser) and gets a much more precise focus than doing the same job by eye.

to me your image looks very slightly out of focus, but likely not enough to be important.

I use the connection between my Raspberry Pi and laptop, so I've got a live FITS viewer on KStars and Okos, that allows me to see what's going on with the focus.  I still have to go out and manually focus the telescope, then come back in to see what difference it's made...

[Xilman]

1 hour ago, Ian McCallum said:

I use the connection between my Raspberry Pi and laptop, so I've got a live FITS viewer on KStars and Okos, that allows me to see what's going on with the focus.  I still have to go out and manually focus the telescope, then come back in to see what difference it's made...

Are you able to take the laptop outside temporarily just while you focus?

I have to do much the same with the manually focused scope. Forever trotting up and down the stairs between the control room and the dome.  I really must fit an electric focus; they are relatively simple and inexpensive.

 

[Ian McCallum]

39 minutes ago, Xilman said:

Are you able to take the laptop outside temporarily just while you focus?

I have to do much the same with the manually focused scope. Forever trotting up and down the stairs between the control room and the dome.  I really must fit an electric focus; they are relatively simple and inexpensive.

 

Yes, I can.  I'd like an electric focuser, but there are none that I know of that would fit my telescopes.

[bosun21]

56 minutes ago, Xilman said:

I really must fit an electric focus; they are relatively simple and inexpensive.

Depends what one regards as inexpensive. An electric focuser controllable from a laptop is over £200

[bosun21]

17 minutes ago, Ian McCallum said:

Yes, I can.  I'd like an electric focuser, but there are none that I know of that would fit my telescopes.

Which scopes do you have? Is it both the 120 Evostars?

[PeterC65]

Your focus looks spot on.

SharpCap has a Bahtinov focus aid built in that highlights and monitors quantitively the state of focus with a mask.

I focus only once or twice at the start of a session, taking the laptop outside while I do so (and trying not to drop it - again).

The downside to an electronic focuser is that it is a permanent addition to your scope and so prevents you form focusing manually should you wish to use it for a visual session with minimal electronics.

 

[Xilman]

1 hour ago, bosun21 said:

Depends what one regards as inexpensive. An electric focuser controllable from a laptop is over £200

I was looking at the Lakeside gear for my scopes, which is admittedly over £200. So I did a rummage around.  RVO may have something appropriate for you. The page I last looked at is https://www.rothervalleyoptics.co.uk/motorized-focusing-units/page/2/?.70001220703125&scroll=2180.466552734375 and has units somewhat cheaper.

An electronic focuser is in a similar price range to a half-way decent eyepiece or filter set.  Not cheap but hardly anything is in this hobby.

 

Edited January 26, 2023 by Xilman
Add last sentence.

[CraigT82]

11 minutes ago, PeterC65 said:

The downside to an electronic focuser is that it is a permanent addition to your scope and so prevents you form focusing manually should you wish to use it for a visual session with minimal electronics.

The skywatcher auto focuser is a great bit of kit for the price and I use them for visual observing on my big scope (moonlite focuser) it totally eliminates any focussing wobble at all you just stand/sit there looking through the EP with the handset (9v batt) in your hand controlling the focus. You can fit it with a thumb screw instead of a grub screw so that you can quickly decouple the motor shaft from the focuser shaft and have proper manual control if you wish.

Whilst not technically computer controllable you can replace the supplied handset cable with a much longer one for more ‘remote’ control, or even get the 4tronix wireless remote controller for it.

I’ve e had the lakeside kit and it was great, worked faultlessly although the brackets for both focusers I used it on weren’t straightforward to fit to the focusers (Moonlite CR2 and Baader Diamond Steeltrack).

Motorised focusing (not necessarily computer controlled) is totally worth the money for an imaging rig in my opinion, and makes a shaky mount with big or long scopes much more of a pleasure to use for visual. 

[Ian McCallum]

3 hours ago, bosun21 said:

Which scopes do you have? Is it both the 120 Evostars?

It's the Evostar 120 achromat and the Startravel 120 achromat.

[iapa]

I use the ASI focuser on my Esprit 80, they provide several brackets options.

Also have used the sky watcher unit on the equinox 80 and both 200pds and 250pds, adequate with few issues

There is a number of videos on utoob for installing to a variety of focusers.

At the end of the day, your choice which motor, but I would say essential for observing or imaging

 

Edited January 26, 2023 by iapa

[bosun21]

13 hours ago, Xilman said:

I was looking at the Lakeside gear for my scopes, which is admittedly over £200. So I did a rummage around.  RVO may have something appropriate for you. The page I last looked at is https://www.rothervalleyoptics.co.uk/motorized-focusing-units/page/2/?.70001220703125&scroll=2180.466552734375 and has units somewhat cheaper.

An electronic focuser is in a similar price range to a half-way decent eyepiece or filter set.  Not cheap but hardly anything is in this hobby.

 

It’s not me that’s looking for one! It’s the OP.

[Ian McCallum]

From what I've read, the focus wheels on my refractors can't be removed, therefore can't be fitted with the likes of the drive shaft type EAF.

[AstroMuni]

18 hours ago, Ian McCallum said:

I use the connection between my Raspberry Pi and laptop, so I've got a live FITS viewer on KStars and Okos, that allows me to see what's going on with the focus.  I still have to go out and manually focus the telescope, then come back in to see what difference it's made...

I use Team Viewer on a phone to connect to my laptop. This way I can view the screen of the laptop while I am changing focus at the scope. BTW, have you tried the Bahtinov mask focus assistant in Ekos, that should help.

[Ian McCallum]

36 minutes ago, AstroMuni said:

I use Team Viewer on a phone to connect to my laptop. This way I can view the screen of the laptop while I am changing focus at the scope. BTW, have you tried the Bahtinov mask focus assistant in Ekos, that should help.

I've got VNC Viewer on my smartphone, so I should try that out more...

[TiffsAndAstro]

On 26/01/2023 at 11:33, Xilman said:

If you can feed your images directly from the camera into a computer I heartily recommend getting hold of Bahtinov Grabber.  Available from https://www.dropbox.com/s/tp9cvni3okk1azd/Bahtinov_grabber64.exe?dl=0 and https://www.dropbox.com/s/k3tb6n32k8v78bo/Bahtinov_grabber.exe?dl=0

Works regardless of focuser type (I use it manually and with a relative motor focuser) and gets a much more precise focus than doing the same job by eye.

to me your image looks very slightly out of focus, but likely not enough to be important.

Ty for this been trying to find it to download and struggled:)

[Xilman]

On 12/04/2024 at 13:54, TiffsAndAstro said:

Ty for this been trying to find it to download and struggled:)

I had problems too. If anyone else here would like assistance, please ask. Either by posting or by messaging me directly.

In particular, there is an excellent chance I still have the distribution kits stored on my systems.

[TiffsAndAstro]

50 minutes ago, Xilman said:

I had problems too. If anyone else here would like assistance, please ask. Either by posting or by messaging me directly.

In particular, there is an excellent chance I still have the distribution kits stored on my systems.

Turns out Nina image pane has a very similar feature.

Make sure you're zoomed out click bahtinov icon move box over you target make box a bit bigger if you need to

It's pretty handy