After my recent purchase of the Canon EOS 400D 10 million pixel digital SLR, I was interested to see what results a DLSR could produce compared to a compact digital camera and what technique would produce the best digiscoped images.
Due to the different technology of an SLR camera compared to that of a digital compact camera, a different approach is required when digiscoping.
There are two different digiscoping options available using a DSLR. Firstly you can attach the SLR body direct to your spotting scope using a T2 mount and digital camera adapter so the scope then effectively becomes a telephoto lens. Or you can attach the SLR complete with a lens to the scope via a stepping ring and digital camera adapter as you would if connecting a digital compact.
The first major effect that I noticed when I first tried digiscoping with a DSLR was the fact that you don't have the benefit of a live preview LCD screen. You have to use the viewfinder of the SLR to find the subject and to get focus with your spotting scope. For me, this method is not as convenient as using an LCD screen of a digital compact to compose the shot as I often found my self having to stretch or lower myself depending on the angle of the scope.
One benefit of using the viewfinder was that I found it extremely easy and clear to focus my scope through the viewfinder, I instantly new when my scope was in focus, (something I have struggled with in the past when using a compact camera LCD screen, especially in bright conditions). Back then, I could only afford a compact camera because my savings were not enough to pay for an expensive camera. Thus, I was overwhelmed with the superb focus feature of my SLR.
I also noted that when attaching an SLR body direct to the scope, the closest focusing distance increased compared to using a digital compact camera. Trees in my garden that I could focus on using a compact camera became to close to focus on.
Method 1 - DLSR body connected direct to scope.
I began by attaching my Canon EOS 400D direct to the Olivon T90ED via the Olivon digital camera adapter and a T2 mount. This, in effect transforms the scope in to a powerful telephoto lens with an approximate aperture value of F14. Good light is essential using this method in order to achieve faster shutter speeds.
With the camera set to aperture priority, it defaults to an aperture of 0.0. Shutter speeds are then dictated by the available light, plus the ISO and exposure compensation controlled by the user. I had to push the ISO up to as far as 800 in order to achieve shutter speeds above 1/250. Thankfully the noise is minimal even at ISO 800 on the Canon EOS 400D.
Once the camera was connected, I simply looked through the viewfinder and focused the scope and fired the shutter using an electronic shutter release cable.
Advantages of method 1
Connecting the SLR body direct to the scope reduces the amount of glass between you and the subject.
The zoom on the scope can still be used to increase/decrease magnification easily.
Almost no vignetting at all on the captured image.
Easy set-up and simple operation.
Disadvantages of this method 1
The aperture is in effect around the F14 mark, meaning that good light conditions are required to achieve high shutter speeds.
Minimum focus distance becomes greater between yourself and the subject.
The outer edges of the image seem to blur.
Method 2 - DLSR body and lens connected to scope.
I then tried adding an EF28-80 Canon zoom lens to my EOS 400D and connected this to the scope via a 58mm stepping ring and digital camera adapter.
With the lens set at it's widest, I noticed some vignetting, but this was easily removed by increasing the zoom of the lens. It surprised me that I was still able to do this even when connected to the scope, but I had no problems.
I then had to set my lens to MF. With the lens set to AF, focus could not be achieved.
I had complete control over aperture, and set it to the largest size (smallest F number). I then looked through the viewfinder and focussed the scope on the subject.
With an aperture around F4, I was able to achieve fast shutter speeds more easily than method 1.
Advantages of method 2
Wider apertures can be set using a standard lens which achieves faster shutter speeds.
Closer focusing distances can be achieved.
The scope can still be zoomed if required.
Disadvantages of this method 2
With a lens and camera body attached, the whole set-up can become bulky and more prone to camera shake.
Vignetting is apparent at wider angle lens positions.
Adding a lens means more glass between you and the subject matter, therefore reducing quality.
Method 1 and 2 Comparison shots
After trying both of the above methods and comparing the results, personally, I don't think there is much difference in the final image captured.
However, I did find using a lens attached to the SLR body and then attaching them both to the scope, for me was an easier and better way to get the shot. Faster shutter speeds were more easily achieved which is essential when digiscoping.
Using a DSLR offered me a great deal of control. Plus the latest digital camera technology found in the Canon EOS 400D was fantastic. 10 million pixels allows for better image cropping, low noise even at ISO 800 and control over exposure meant I could achieve shutter speeds around 1/1000 and still get good detailed images. Also the Canon can shoot at 3 frames per second with virtually no start-up lag which was a real bonus.
Personally, I prefer using my compact camera for digiscoping, I feel that it's just a better all round tool for the job. Having the benefit of a live preview on an LCD screen, for me makes finding the subject so much easier plus the smaller, more compact size is easier to carry.