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Showing results for tags 'autofocus'.
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Hi. Just starting to use autofocus with the Celestron motor focus and SGP. Can anyone give me some starting points for step size, backlash etc. I’m getting there but wasting a lot of imaging time just trying to get this to work accurately. I’m currently trying a step size of 75 and a backlash of 50. Any tips most appreciated.
Hello Guys, I'm about to start work on upgrading my focuser. I did buy a SkyWatcher electric focuser, but because of the slop in it it never worked with a heavy DSLR on the tube, which is exactly when you want it. So I'm embarking on a project to: Do the PTFE thing on my focuser tube; Connect my Arduino (which already does GOTO and DSLR remote control timer) to the SkyWatcher focuser; Write a bit of python to do the autofocus search and this what I'm asking here: What focus algorithm have people played with? I'm thinking of starting with the scan of contrast along vertical lines, like this: img=imread(“test.jpg”); contrast=0; (x, y) = img.size() for j in range (0, x): contrast=contrast + img[j]-img[j+1] print contrast Sorry, about the syntax! So I'll create a v-diagram and move focus in and out until contrast is at a minimum. There are other algorithms out there, but this seems to be the simplest to implement. What do people think? Regards Steve.
Cloud, cloud and more cloud – but looking on the positive side, this presents an opportunity for a ‘project’. Now, I’ve already done the observatory ‘spring clean’ – I even have the photos to prove it – so I thought I’d tackle a project that has been on the back burner for years; auto-focusing my camera lens(s) for wide-field imaging. Despite two attempts at putting the TS Telefokus 105 microfocuser on my Christmas list so that I could accurately focus my Canon 200L telephoto lens on the stars, there were no takers so the project stalled. However, having bought a second motor for my existing autofocus controller to install on a new telescope got me thinking that maybe this would actually be a better way of controlling focus and might even allow autofocus during a long imaging session to compensate for temperature changes. So, I put a third motor on my birthday list and my two sons clubbed together to buy it for me moving the project forwards! Yesterday, I completed it with the addition of a finder-guider that I had in my ‘goodies’ box that is normally used for guiding short focal length review telescopes. Now, in fairness, it is untested on the night sky (cloud, remember, hence the project!) but what I can tell you is that the focuser moves in invisible increments or quickly as required, is ultra smooth and shows no sign of slipping! Unfortunately, much as I’d love to, I can’t install my mono camera as, with its built in filter wheel and OAG, there is insufficient back-focus. This means that the system will be used with my OSC SXVF-M25C coupled to the Canon 200 L lens using a custom adaptor I had made when Adam was a lad. What could possibly go wrong? Front View The two pictures above show the 72mm lens has been stooped down to 52mm using a step-down ring. This reduces the aperture from f2.8 to f3.8 to improve star shapes at the periphery of the FOV but without adding the diffraction spikes that would be a feature of stopping the lens down using the iris. Belt Drive Finder-Guider Connection
Hi SGL Wizards, I'm using an ED-80 with HitecAstro DC Focus, and am controlling it via SGP Pro. I've got autofocus working well (hooray!) but notice that each night the Focus Control's Current Position number gets larger and larger. For example, a month or so ago it was around 9000 for focussed stars with a H-a filter. Tonight it's 12884. Is this normal? I'd expect the number to be absolute, i.e. always around the same number but with some slight variations given temperature and the like. Thanks in advance, - Lee
I am looking to upgrade from my SW Equinox 80 which has been a great little scope for AP combined with an Atik 460 mono with Atik filter wheel. EQ6 mount. With our weather and not unlimited time for imaging I am hoping to get better results with a faster scope, but can't afford thousands for a fast refractor such as Takahashi. I have been looking at the SW MN 190 and the ofputtingly named ES comet hunter. Firstly is the advice that this would be an upgrade in terms of brighter images or should I be looking elsewhere? I looked at the SW quattro but read horror stories about collimation. Secondly I have an autofocus setup with the ED80 using a Moonlite focusser and Lakeside motor which works well with SGP. I have advice from FLO that they can supply equipment to adapt the SW MN 190 in this way but does anyone know if autofocus can be retrofitted to the comet hunter? I would like to focus from the warm room of my obsy or even indoors if I can get TeamViewer to link Any advice welcome, thanks
OK, I give up! I am just doing the final set-up of my homebrew autofocus - based on the excellent design from Robert Brown in New Zealand. Everything is going swimmingly except that I don't know if there is a convention for the direction of travel of the focuser and the number of the pulse count. To be a bit clearer, if my autofocus numeric range is 0 to 10000, should I set the program to give 0 at the maximum extension of the focuser or at the other end of it's travel, closest to the objective. And, does it matter? I have yet to try and use it with a control program, such as Focusmax so I don't know if such programs expect a certain convention for this. Regards, Hugh PS - If you ever catch Sucofotua, I can assure you there is no known cure!