For more accurate
webcam focusing using an Olympus Varimagnifier/webcam setup CLICK HERE.
I have been doing astro and infrared
imaging with a modified Canon Digital Rebel. My preferred method
of focusing has been using an Olympus varimagnifier that fits
on the viewfinder of the Canon DSLRs. I have tried the focus assist
software programs DSLR Focus and Images Plus for focusing that
assure perfect focus. But, I found the USB transfer speed of the
Canon Digital Rebel to be much slower than that of the 10D, which
I also use. It takes a lot of time to achieve focus using the
slow USB transfer rate of the Rebel. I missed the live-view focus
capabilities of the Olympus C2000 series digital cameras that
I had been imaging with before the Canon DSLRs.
I have also done a lot of imaging
over the years with webcams. I have a few Philips Vesta Webcams
including an SC Modified Vesta Pro for long exposures.
What I have put together is an
easy to make adapter mount for attaching a Philips webcam to the
viewfinder of the Canon Digital Rebel. The viewfinder of the Canon
10D is the same as the Rebel and I guess other Canon DSLRs. The
webcam can display the view through the viewfinder in real time
using any webcam software. Focus is achieved by looking at the
webcam display on a computer monitor and adjusting focus using
this live video display. The webcam can be easily placed on and
removed from the camera's viewfinder as needed.
Here is the Philips Vesta Pro
webcam attached to the Canon Digital Rebel:
For the adapter mount I used a
plastic pill bottle. A slot was cut in the lid of the bottle with
a razor knife. The slot was cut to the size needed by using the
viewfinder eyepiece cover on the camera strap as a guide. The
top of the plastic bottle was cut off at an angle as shown below
and a hole was cut using a razor knife for a 1/4 - 20 knob used
to attach the webcam using the tripod socket:
The nylon washer fills a gap between
the bottle and camera tripod socket.
a solid connection I epoxied the cap to the bottle. This adapter
mount allows the lens of the webcam to be rotated for best focus
of the viewfinder image. This crude adapter fit surprisingly well
on the camera and snapped securely into place. As a first test,
I used the camera with a telephoto lens on a backyard bird feeder.
I used GUIDEDOG as shown below
in focus mode. Note the webcam image is upside down, since I mounted
the webcam so that the camera's LCD display is fully visible.
Focus was fast and easy; I used a sun glint on the bird feeder
Live Video Focusing:
This is the image taken:
I removed the webcam and checked
focus with the Olympus varimagnifier and it looked good.
From the above test, daytime focusing
works well with the setup. I will try next with imaging through
an h-alpha PST scope. Solar focusing has been tough; there are
no star images for software like DSLRFocus to lock onto. For infrared
and deep sky imaging, if a brighter viewfinder display is needed,
I plan to use the SC modified Vesta Pro webcam that can do long
exposures. Even if one or two second exposures are required while
focusing, the immediate feedback of live video focusing, should
make focusing easy and quick.....I hope........testing will tell.