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Trying to find a Star in Live View


johnb
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Hi

Cannon 450 attached to my Skywatcher 250 I had Altair lined up but just could not get anything in Live View, took camera off scope and shined my torch into the camera and live view was a whiteout (so its working) but back in the scope nothing, Im guessing now im at home in the warm i probably just need to move the scope a little ?

John B

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I struggled the first few times to get a star showing in live view. I did manage it a few times but only with some of the really bright stars, if you set the camera to bulb, iso to 1600 or higher if you have it that will give you the best chance, you only need to find one once for each session, the other way is to use the moon, once you have focused on the moon because of the distance involved it will work for other targets. The first few times you do it, try and use an EP to get the star in the center before popping the camera on there, will make it much easier.

Edited by simon84
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Hi

Cannon 450 attached to my Skywatcher 250 I had Altair lined up but just could not get anything in Live View, took camera off scope and shined my torch into the camera and live view was a whiteout (so its working) but back in the scope nothing, Im guessing now im at home in the warm i probably just need to move the scope a little ?

John B

You can double check and look through the viewfinder as well to see if you can see the star there.

Other than that, my theory is that you were out of focus enough that the star was too diffuse to be visible.

I don't know if the 450D does "exposure simulation" for its live view... you can try cranking the ISO up to max to see if anything appears then. I have to do that with my 1000D... ISO1600 for focussing and then back down again for exposing.

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The 450d does exposure simulation... set to BULB, ISO1600... the brighter stars will show up nicely. If you couldn't see it, the scope wasn't quite focused. The FOV is approx equivalent to a 20mm ep so it's not likely to be targeting.

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The two problems I have had are star is too faint (seems to work with stars of about m2 or brighter) and star is out of focus (requires a 'good' turn of the focusser [outwards] to get anything like focus). If both of those are ok ... maybe it is not properly centred?

HTH

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I generally use the viewfinder to sight up the star, assuming it is bright enough. This allows me to focus approximately via the viewfinder, such that the star will be sharp enough to be visible on the Live View screen. I then do 10x zoom to get focus as accurate as I can.

If your star is not bright enough, none of this may work. If so, I'd suggest focusing on a bright star first of all, then slewing back to your intended target. If you still can't see it in Live View, then maybe it's just too dim for that. Only taking a sample exposure will confirm if you have the target framed correctly.

There are also some software packages that can help with that. I use Nebulosity, which can control my 450D and do a kind of looping exposure while I fine-slew the scope to arrange the framing of the shot. If you do use this method, be sure to check the ISO setting on the camera afterwards and also reset the capture quality to RAW as Neb shifts it to JPG.

David

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I agree with the previous opinions. Set the camera to ISO 1600 and exposure over 2" - this will give the maximum LiveView sensitivity. Use land target to mark the position of the focuser when you reach focus. Then use this mark as raw focus during the night. Usually I use the second alignment start to focus. A Bahtinov mask makes the things much more simple :)

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Iso high and bulc and i use the x5 rather than x10 , seems to show stars better than non magnified. Other optionis do quick exposure and look at the photo on playback adn it will give u a good idea where to place the magnifying box on the magnified live view screen. I also use an angle viewer that attaches to the camersneyepiece as it has an optical magnification of 1.6 on it

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