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I'm want to get into AP iamging DSOs but have focusing issues - nothing new there I guess.

My basic question is this:

Is it possible to use a DSLR and USB link to display live images on a Windows PC (or Android Tablet) with sufficient resolution to use a Bahtinov grating for focusing?

If so, which DSLR have people used in this way? And which software?

I have been trying without success to use my Sony A300 DSLR  but the built-in LCD display is far too low resolution to see the fringes from a Bahtinov grating. The grating works great with an eyepiece so nothing wrong with the grating. And the Sony video out is of similar low resolution to the LCD display. And unless I'm missing a trick (please tell me if I am!) there is no way to get live images over the USB link.

As a very poor second best, is there any single software (for Cannon, Sony, whatever) that will allow triggering of images (Bulb mode) and upload the image almost immediately. I guess I could live with that just so long as I end up with a properly focused system.

My scope is a 6" f10 CS. And yes, I know f10 is too slow and I need a field expander but it's where I'm at at the moment. And unless I can crack the focusing all other issues are secondary.

Many Thanks for reading this far!

Geo

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Hi and welcome

first of all yes all the things you want to do are very possible and almost easy to do.

if looking for a new camera, look for a secondhand canon 450D, 1000D or 1100D, all these have live view and will allow pictures to be displayed on a PC screen, which as you say is the way to go for focusing with a mask.

As for software, well in my opinion try APT which is designed for using DSLR cameras exactly as you describe, it is full of functions and tools entirely for this purpose, and had great focusing tools which almost fully automate focusing....you will find it here:

http://www.ideiki.com/astro/Default.aspx

Your scope is pretty slow at f10, but it is doable, but a focal reducer will help a lot, as I say as you would be using a DSLR which has a nice big sensor, then even at f10 you will get some superb images... :)

 

 

Edited by SkyBound
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I used to use a Sony a290 but had to bite the bullet and bought a second-hand canon with live view. 

Like you say there is no live view and,my a290 didn't even record video either. There wasn't any intervalometer connection either but I'm not sure if that's the same for the a300. 

See this link for a way of tethering the camera to a computer...

http://alphasight.blogspot.co.uk/2008/09/tethered-shooting-with-your-alpha-dslr.html?m=1

But I'm not sure if this method of tethering will give you what you need, I never tried it. 

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A low-end camera body is fine for starting out in Astro photography.  As SkyBound says a canon 1000d (old and not available new) 1100D (ditto) or 1300D are good starter cameras.  Used is fine as long as they work !! :)  Check http://www.camerapricebuster.co.uk/ for new prices.

Canon supply "Utilities" with their cameras that allow you to use a computer to control the camera and see the Live view screen.  It works well.  APT (as above) has far more additional functionality if you think you need it - or you can simply download the free version to try it out first.

You can use a Bahtinov mask with live view (zoom in to see the pattern) or "Bahtinav Grabber" which shows the pattern and tells you when focus is achieved.  https://web.archive.org/web/20160220123031/http://www.njnoordhoek.com/?cat=10    It is also included with Astro photography tool.

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Rather than changing camera, isn't it possible to digitally zoom in on the live view with the Sony?

If not, take a picture and zoom in in the preview, I used to do that with a 10D taking a series of 5-10 second shots (it doesn't have any live view) and it only took a minute or two to get focus spot on.

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9 hours ago, SkyBound said:

It is Bahtinov grabber not grating .... :) 

Actually, the mask is technically a grating. The "Bahtinov Grabber" is a piece of software written to evaluate how close to focus your system is, based on the diffraction spike pattern produced by the Bahtinov mask. Jus' sayin' :)

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11 hours ago, geoscope said:

I'm want to get into AP iamging DSOs but have focusing issues - nothing new there I guess.

My basic question is this:

Is it possible to use a DSLR and USB link to display live images on a Windows PC (or Android Tablet) with sufficient resolution to use a Bahtinov grating for focusing?

If so, which DSLR have people used in this way? And which software?

I have been trying without success to use my Sony A300 DSLR  but the built-in LCD display is far too low resolution to see the fringes from a Bahtinov grating. The grating works great with an eyepiece so nothing wrong with the grating. And the Sony video out is of similar low resolution to the LCD display. And unless I'm missing a trick (please tell me if I am!) there is no way to get live images over the USB link.

As a very poor second best, is there any single software (for Cannon, Sony, whatever) that will allow triggering of images (Bulb mode) and upload the image almost immediately. I guess I could live with that just so long as I end up with a properly focused system.

My scope is a 6" f10 CS. And yes, I know f10 is too slow and I need a field expander but it's where I'm at at the moment. And unless I can crack the focusing all other issues are secondary.

Many Thanks for reading this far!

Geo

I've used the windows software supplied with canon cameras D600/D700/D70 to focus with a Bahtinov mask.

BackyardEOS (windows) 

SofortBild (free for OSX) works with Nikon D90. There is also BackyardNikon (windows) which should also work

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2 hours ago, Pompey Monkey said:

Actually, the mask is technically a grating. The "Bahtinov Grabber" is a piece of software written to evaluate how close to focus your system is, based on the diffraction spike pattern produced by the Bahtinov mask. Jus' sayin' :)

Oops, my mistake sorry.... :) meant to put Mask.....

Edited by SkyBound
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Thanks everyone for the useful feedback. Lots to pursue now and I'm feeling a bit more optimistic. I think I'll be heading for a Canon 1100 or 1200.  The APT s/w looks good value, also Backyard EOS. Lots to go at now, inputs much appreciated.

Geo

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