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Old 30-11-2009, 07:47 PM
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telecasterguru (Frank)
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Bahtinov masks and DSLR

I have tried to use a bahtinov mask to focus my 1000D but it has been pretty unsuccessful.

Are there any tricks that I should be made aware of? Haven't tried liveview. Would this work?

Thanks

Frank
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Old 30-11-2009, 08:22 PM
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zipdrive (Dave)
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It works well on my 8" reflector with 350D.
I take 1 or 2 sec exposures at ISO800 on a bright'ish star using Canon's remote capture utility for a quick download and review(got no liveview).
Can we have some more detail on your setup?

Dave
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Old 30-11-2009, 08:23 PM
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Frank I too had trouble with my 5D through the Tak, I was easier to eye focus, with better results, I sold mine in two days.

Leon
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Old 30-11-2009, 08:31 PM
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citivolus (Ric)
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Use the furthest zoom you can in live view to see the spikes. Also, the longer the focal length of your main optics, the larger the spikes in my experience. The shorter the focal length, the longer the exposure will need to be to show them.
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Old 30-11-2009, 08:33 PM
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[1ponders] (Paul)
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I use one on mine and its fantastic. You do need a bright star and a fairly long exposure > 20+ @ ISO800 for me using medium fine jpeg downloaded to the monitor. Very simple once you get used to it. I even use it very successfully with prime lenses down to 85mm. Bright star is the main thing and good exposure next.
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Old 01-12-2009, 06:22 AM
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telecasterguru (Frank)
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Thanks for the info everyone. Will try these tips. I have only ever used eye focus.

I have a 350D as well as a 1000D. I tried to get my 350D to work in nebulosity but the camera wasn't able to be read. Don't know why.

If the 1000D is in focus, and I put the 350D on the scope, will it be in focus as well. Is the distance to the sensor the same?

Frank
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Old 01-12-2009, 06:27 AM
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[1ponders] (Paul)
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Very unlikely Frank when your talking fractions of a millimeter for critical focus
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Old 01-12-2009, 06:30 AM
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Try Focus Assist and see if it recognises the 350D. Its mean for 400D and up I believe but it's a free download so wouldn't hurt to try. You may need to magnifier (the inbuilt one in in start>all prog>accessories>accessibility. Or download a free one)


Focus Assist
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Old 01-12-2009, 09:00 AM
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Omaroo (Chris Malikoff)
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I posted this a while back Frank:

http://www.iceinspace.com.au/forum/s...light=bahtinov

Works a treat, but you have to expose for a necessary length of time for it to work well as Paul has also mentioned. I achieve a FAR better focus than via any other method using this mask.
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Old 01-12-2009, 09:02 AM
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Paul,

I run Vista so focus assist is out. Thanks anyway.

Frank
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Old 01-12-2009, 11:01 AM
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Not sure what software you have. I'm using Nebulosity now, but I was successfully using Canon's EOS Utility and it's remote shooting feature. Live view is very handy too. You're only after focus, not image quality. Crank the ISO right up to max value (not sure what the 1000D is, ISO3200?) to speed up your focusing and get nice bright stars. Just make sure you drop it back down for imaging

Don't think the 350D will play nicely with Nebulosity without one of those Shoestring adapters - Nebulosity plays nicer with Digic III or newer cameras. The 1000D should be fine, though.
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Old 08-12-2009, 10:29 AM
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Use live view Frank. Get the Canon EOS facility up and running and then zoom in on the star. Then just focus. The mask will work with that.
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Old 08-12-2009, 03:24 PM
pjphilli (Peter)
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Hi Paul - I have a Canon 400D. What is the EOS facility and how do I use it to zoom? Cheers Peter
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Old 08-12-2009, 04:29 PM
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Unfortunately your 400D does not have live view and so this feature is not in the EOS utility (facility). It is only available for cameras with live view.
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Old 08-12-2009, 05:54 PM
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I have used the masks, however recently I've focused manually in a minute or so, then borrowing a friends mask to confirm focus I found that my manual focusing was right on the money...


When using Canon prime lenses, I've got to say that auto focus has never failed me yet... my 200/2.8L and 135 F/2L both autofocus on bright stars with surprising accuracy...
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