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Bahtinov - It's sooooo purdy :)

samtheeagle

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Tim

Tim

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That is pretty ;)

And there's not much more satisfying than seeing a perfectly bahtinov-focused star, is there?

You're right Shibby :)

Funnily enough, your pic there, that doesn't look quite in focus, if it was mine, I wouldn't be happy with that. Its very very close, but not perfect. :)

There is a program somebody has written which tells you when it is perfect, I dony use it personally, but some here do.

The bahtinov mask has made the single biggest difference to my imaging than any other factor, I never realised how fine the adjustments needed to be before Psychobilly very kindly sent me a couple of masks.

Cheers

TJ

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samtheeagle

samtheeagle

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Yeah, I did think on closer inspection that it wasn't quite 100%, but it was merely for tracking test purposes so I wasn't really worried.

Interesting to know that you think that's not sufficiently good, I probably would have used that if I was imaging, not really knowing just how precise to be... Obviously the closer to perfect the better, but do you think that tiny bit off would cause serious deterioration to the captured image(s)?

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Tim

Tim

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Actually Sam, I meant Shibbys piccy ;) Its hard to tell on yours, the colours and squiggles make it difficult to tell, doesnt look far off though, the central bar looks slightly weighted towards the upper side, and the central region isnt balanced in shape.

As to how much difference it makes, when you are chasing faint stuff, it really does seem to make a difference to the overall contrast and sharpness of the image. Given that the stars etc are always going to be bloated a bit by the atmosphere, it makes sense to get them as small as possible to begin with. As mentioned, before getting the masks, I had no idea how fine adjustments were required to nail the focus, and I find the masks much easier and intuitive to use than the FWHM tool for focussing. When I use the mask alone, compared to using the FWHM tool visually, I always get a lower FWHM reading after using the mask. Might be my eyesight of course :)

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samtheeagle

samtheeagle

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Heh heh ;) Cool. I guess that it makes sense to get as near to perfect as possible, as everything else will compound on top of it during a session. Still it is pretty hard to tell how close, or otherwise, I am using the titchy screen on the 350D. I really should use a laptop for inspection purposes, but that's an extra complication that eats in to my precious imaging time. I need an observatory so I don't have to set up and break back down all the kit every time I want to get out under the stars...

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samtheeagle

samtheeagle

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Yeah, it does have a good amount of zoom on the camera, but still, the contortions required to see the wee screen clearly sometimes :)

I know that it's totally counter productive, but given my usually short amount of time available for imaging I'm always in a hurry to start getting subs. Pointless getting lots of subs if they're not well focused I know, but when time's slipping away from you... I shall endeavour to nail the focus even more precisely than ever before! The extra minute or two taken will be well worth it.

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Shibby

Shibby

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That's a nice app! Though to be honest, minor tweaks to focus isn't my main worry at the moment - the tracking is so bad with my Alt-Az, I need to 'focus' on resolving that first, probably by looking for a new mount. Everything looks slightly out of focus anyway with poor tracking.

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