leon
22-07-2007, 10:30 PM
Hi All.
I know i do things a bit different than the general main stream, however i thought you may be interested in the way i focus for auto focus lens.
I am only refering to the Canon range of lens here, as that is all i use, but thought you may find this interesting as I'm sure many of you use the Canon Lenses
I use the custom functions in the 5D, and have only the center focusing square operational, which is red, and the focus sound can be heard when the shutter is pressed half way on the TC-80N3 Remote.
If i want to focus on an object which is not visible to me, I first find a reasonably bright star close by, guide the star to the center of the red square , while i press half way on the remote, when in the right spot the lens will focus in auto mode and the sound of focusing will be heard.
At this point i sync the star with the Gemini had controller and there you have it, switch the lens back to manual, and focus is set, this can be done with a lens up to about F/5.6.
I usually refocus at each One degree drop in temp, and i must point out that i also use a Canon Angle Finder attached to the 5D, that certainly makes life easier.
However an interesting thing happened. last night, I went through the procedure mention, and found my star to focus on, and was going to slew to the object to image.
For some strange reason i forgot to slew the scope, and the lens was still on the focusing star, and pressed the remote to take it's 10 images, then found that it was auto focusing itself for each image, because it was still in the red square of the focus screen, and that was at F/4.0
So, if only using reasonably fast lenses, up to F/5.6 and from 28mm to 450mm there is no need for focusing software, because it works every time and is always spot on.
Cheers Leon :thumbsup:
I know i do things a bit different than the general main stream, however i thought you may be interested in the way i focus for auto focus lens.
I am only refering to the Canon range of lens here, as that is all i use, but thought you may find this interesting as I'm sure many of you use the Canon Lenses
I use the custom functions in the 5D, and have only the center focusing square operational, which is red, and the focus sound can be heard when the shutter is pressed half way on the TC-80N3 Remote.
If i want to focus on an object which is not visible to me, I first find a reasonably bright star close by, guide the star to the center of the red square , while i press half way on the remote, when in the right spot the lens will focus in auto mode and the sound of focusing will be heard.
At this point i sync the star with the Gemini had controller and there you have it, switch the lens back to manual, and focus is set, this can be done with a lens up to about F/5.6.
I usually refocus at each One degree drop in temp, and i must point out that i also use a Canon Angle Finder attached to the 5D, that certainly makes life easier.
However an interesting thing happened. last night, I went through the procedure mention, and found my star to focus on, and was going to slew to the object to image.
For some strange reason i forgot to slew the scope, and the lens was still on the focusing star, and pressed the remote to take it's 10 images, then found that it was auto focusing itself for each image, because it was still in the red square of the focus screen, and that was at F/4.0
So, if only using reasonably fast lenses, up to F/5.6 and from 28mm to 450mm there is no need for focusing software, because it works every time and is always spot on.
Cheers Leon :thumbsup: