DSLR focusing

kingkong · Post by **kingkong** » Sat Sep 30, 2006 1:09 pm

or you can make something like this to start with:
http://www.dd1us.de/Downloads/focusing% ... %201_0.pdf

aquillae · Post by **aquillae** » Sat Sep 30, 2006 3:33 pm

I'm also new on dSLR focusing, usually I just eyeball the object (bright stars / moon / distance street light (for wide angle lens) working back and forth from inside focus to outside focus couple times until i'm satisfied.

I wonder how DSLRfocus works, i know it's going to be displayed "live" on the screen, but does it take 1 shutter mechanism (open-close) to snap the image? if it does, I'm pretty concerned that it would "used up" my camera's shutter life, especially since I'm also using the cam for daytime photography.

or does the dSLR stream the image (like webcam) with the shutter opened (mirror lock)?

Post by **weixing** » Sat Sep 30, 2006 4:02 pm

Hi,

I wonder how DSLRfocus works, i know it's going to be displayed "live" on the screen, but does it take 1 shutter mechanism (open-close) to snap the image? if it does, I'm pretty concerned that it would "used up" my camera's shutter life, especially since I'm also using the cam for daytime photography.

or does the dSLR stream the image (like webcam) with the shutter opened (mirror lock)?

It'll not stream the image... most DSLR can't do that... may be Canon D20a can. It's actually using the same method as taking a image, focus and take another image and compare the focusing... just that it'll display the image side by side at the same magnification level and at the same area of the image for you, so that you can compare on the laptop screen more easily and got some function that inform you of your focusing result. Also, if I remember correctly, it got an option take the image continously (as fast as your DSLR allow) or one at a time.

Also, I think it got some other function to help you determine the best focus. You can take a look at their website for more information.

Have a nice day.

aquillae · Post by **aquillae** » Sat Sep 30, 2006 4:46 pm

hmm, the more we tinker with the focuser = more pics used to focus = less shutter life

.

"Also, I think it got some other function to help you determine the best focus. You can take a look at their website for more information. "

is it the FWHM ? from my past experience, using the FWHM amplitude to focus on a star is really convenience.

btw guys, any recommendation for Canon EOS eyepiece magnifier?

clear skies!

kingkong · Post by **kingkong** » Sat Sep 30, 2006 5:06 pm

aquillae wrote: any recommendation for Canon EOS eyepiece magnifier?

afaik, there's none

Post by **weixing** » Sat Sep 30, 2006 5:06 pm

Hi,

hmm, the more we tinker with the focuser = more pics used to focus = less shutter life

Don't worry about shutter count... I think a DSLR use for astrophotography usually have a lots less shutter count compare to a DSLR use by amateur photographer even you focus a lots... due to the fact that we don't shoot in continous mode and we don't shoot a lots... our DSLR just "open" longer... ha ha ha

btw guys, any recommendation for Canon EOS eyepiece magnifier?

Get the Canon Angle Finder C lor... it gives you a right-angle view (save your neck at the sametime) with switchable 1.25x and 2.5x magnification. I currently use my friend Minolta Right-Angle finder which work quite well and help a bit in focusing... I think I'll soon get one for myself.

Have a nice day.

aquillae · Post by **aquillae** » Sat Sep 30, 2006 5:21 pm

cool, thanks a lot guys, gonna go check local camera shops later.