Software for Focussing

[narrowbandpaul]

Hi Guys/Girls.

Iam looking for preferrably free software that will tell me quickly the FWHM or Half Flux diameter of my focus shots.

Just now I judge by eye/max brightness using the SX camera control software, but would like to replace this sloppy technique with something more robust.

Ideally it would take an image of the test star, and spit out the FWHM, like ImagesPlus does with DSLR's.

Does anyone know of such software

Thanks for your help

Paul

[bazza]

FocusMax does this I think?

Incidentally, I use FocusMax and once set up, it is absolutely superb for every time, 'in focus' images.

Barry.

[narrowbandpaul]

great barry.

I will give this a look.

Cheers

Paul

used imagesplus last night to focus....took star image in SXV software, opened in IP, checked FWHM manually.

clouds rolled in, so never got to test how good the focus was. It was laboriuos a bit, but if its reliable then Im fine with it.

[Hicks]

If you haven't tried this already, DIY or buy a Bahtinov mask. I found it much easier and a lot quicker to achieve focus using the mask than FWHM. My focuser is partly to blame for that, it's remote operated but relative only, but I'll be using the mask from now on

[Paxo]

I use FocusMax Paul, it requires certain camera control software to work though, MaximDL/CCD or CCDSoft, check out the focusmax website for more details on which other software it requires to run. Not sure whether it works for manual focussing, I thought it needs an electronic ASCOM controlled focusser.

It's interesting, I've just purchased one of trhe new SXVR -H36 cameras, and that uses the same brightness routine for focussing as you are talking about, or use Maxim/FocusMax for a very accurate focus.

You might be better off looking at something like a Bahtinov or Hartman Mask initially, many here swear by them.

Steve

Steve

[SteveL]

I use a Bahtinov mask for my C11/190MN/FLT98/WO66 and that works great... but for the really tricky focusing of the QHY8 + Nikon Lenses, I use the fine focus option in Nebulosity, which never fails to get perfect focus in a very tricky imaging setup.

[narrowbandpaul]

thanks steve, and steveL

I have checked out focusmax, and saw that it needed MaximDl or CCDsoft to work through. Damn!

its a shame that imagesplus doesnt allow camera control with CCD's just DSLR's.

i will look at nebulosity....

i thought that the new SXV cameras, the SXVF came with FWHM as well as max brightness info on the focus screen. The SXVF-H16 used at the uni obsy certainly has this feature.

i may ask terry if an update is available.

thanks again.

paul

do any of you guys use a motorised focusser? I would be interested in finding out which ones work best/are most general (ie interchangeable to use)

[Paxo]

Paul,

Take a look at the Lakeside focusser on the Ian King Imaging homepage, seems to get a good write up and is a good price compared to others.

Steve..

[RobH]

Hello Paul,

I used to use robofocus with a moonlight focuser with focusmax and maxim DL with my 14 inch SCT.

Once I got a Bahtinov mask, I did some tests, and found that focussing using the mask was as accurate as using focusmax, but a lot faster.

I checked this by referring to the FWHM values.

My advice, if you're using a scope, and not using camera lenses, would be to invest in a motorised focuser but use a Bahtinov mask to do the focus.

If you're using lenses, as Steve says, you're probably best to use the FWHM method.

Cheers

Rob

[Paxo]

Paul,

Which scope would the motorised focusser be for? If it's for your OO, as Rob said, a moonlite focusser would probably be the best option.

Starlite Express issued SX_Hmf_USB ver 3.8a software with the new camera, just talks about brightness levels in the manual still. Haven't had the chance to use yet though.

Steve..

[steve51450]

Paul

you could get a bahtinov mask and then try this as i am going to give this a try over the next few weeks

http://stargazerslounge.com/heads-up/81288-bahtinov-grabber-now-autofocus.html

as for motorised focuser's...............try lunatico in spain as there system is cheaper than all the others, its usb, temperature controlled and it will run to focuser's at the same time or run a filter wheel and focuser

[Hicks]

Paul

you could get a bahtinov mask and then try this as i am going to give this a try over the next few weeks

http://stargazerslounge.com/heads-up/81288-bahtinov-grabber-now-autofocus.html

That sounds interesting. I'll have to give it a try next time I have everything set up.

[SteveL]

I used the auto grabber with my WO66/Maxim/Mask last week... works exactly as advertised!

[narrowbandpaul]

thanks guys....

it wouldnt be for my OO, although I dare say I should get one one I get a good mount and a mono ccd.

it would mainly be used with refractors with various focusser sizes, from 2-4", and with a OO astrograph.

so the motorised focusser would have to be interchangable with various scopes for it to be really useful.

i will look at the bahtinov mask, no matter how good, its still got to be slightly subjective...there must be at least a small amount of guess work as to when you are perfectly focused?

nebulosity looks good actually, its only £50. Does this have focus FWHM info as well as camera control. I see it supports SXV's

thanks all for your help. Appreciated

paul

[SteveL]

The fine focus option on Nebulosity is sweet. Take a full size frame, click on a star, and Neb then zooms in on that one sub-area and goes into constant exposure loop. It shows 1/2FD, FWHM, and also brightness, along with a graph over time of all three.

[narrowbandpaul]

well that sounds perfect....may have found the answer to the problem.

thanks steveL