My offical site is here: http://www.ki.tng.de/~sgude/
Digiscoping
status: preliminary pageI have successfully tested three different setups now, using the Panasonic FZ5, Sanyo xacti E6 and Canon 1Ds, D60.
FZ5
This was just a test to get a closer view of the moon.
Combining the FZ5 afocally with a self-made "telescope".
The eyepiece is of a microscopic type, two versions used a reversed 50mm SLR-lens.
The main lenses (M42) were a MTO 500mm mirror lens and a 500mm Beroflex (Wundertuete).
The effective focal length is around 4200 to 10000mm - starting with the 8x zoom of the FZ5.
The front lens of the FZ5 is quite big. Smaller lenses would be better.
Only the long zooooom helps in this case against vignetting.
For those who are tired of combining teleconverters: 500mm mirror Tele, orthoscopic ocular, F-adapter. A good spotting scope would be better!
It started as a joke...
But a different setup gives some hope:
As fmoore once said: this lens is half way to the moon already
My new toy is a relict of those ancient SLR days. I started to test my 1,8/50mm pentacon lens as reversed lens (covered in the square-cokin sun shade). - Very good results up to now! But looking at the moon, I had to attach my beroflex 8/500mm in front of this lens. 500/50 = 10* Converter. The wide aperture of the reversed lens is essential for this setup. The exact distance of the two lenses has to be tested. Extension tubes and extenders can be used. All this is cheap material, but the tripod has to be extremely good! There is little purple fringing which can be removed easily.
This is my first test: FZ5 8x zoom, f:3.3 t:1/100 full frame
..click to enlarge!
The result can be enhanced by using the green channel only. This has twice the resolution of the other channels and there is no chromatic abberation with a single colour!
A second Test:
10000mm (35mm equiv.), the atmospheric conditions are limiting!
Quite an amazing range for such a small camera!
Xacti E6
The Sanyo Xacti E6 is a small 3x zoom camera with a small fixed front lens.
Bad news: there is no choice of aperture or time!
It can be used in a combination with an astronomic eyepiece (1.25'').
A big front lens of the eyepiece helps to prevent vignetting.
Both of my lenses have an apochromatic correction.
This is my favourite afocal combination:
Sigma 400mm apo tele macro for Canon EF (relatively cheap - not compatible with modern EOS cameras: err99)
Option: Kenko 1.5 tele converter.
Eos rear lenscap glued to a tube or eyepiece adapter.
ED eyepiece 22mm
Selfmade telescope adapter for the Xacti.
Resulting focal length: 2900mm
Can this be used?
Let's start with this round piece of cheese up there:
Next:
Static object , more than 6 m of distance.
Through my kitchen window.
A "not so" static object
Live view: through the window 5m distance.
Seems to be a working combination with a tripod and remote release.
This is quite an attractive setup. Weight and prices of the components are not too high and exposure times can be kept quite short.
As a matter of fact the telescope is concentrating the light and the resulting aperture of the whole system can be two steps better than the basic lens.
In this case the 400mm 1/5.6 lens with 22m eyepiece can give a resulting combination of 2000mm at 1/2.8.
Test with field conditions:
Each year norwegean fieldfares visit the apple trees nearby. It needs one day to get rid of the fruit.
This time we had a heavy snowstorm.
It was quite dark outside due to the overcast condition, but the exposure time is still ok.
...and there was a lot of snow between the camera and the birds at more than 30m distance...
(Xacti E6 60% crop)
Canon EOS
My main concern is the gain of resolution at the far distance.
The following test shows my results for some kinds of digiscoping compared with regular photography using tele-converters.
All pictures were sized to the same detail!
Setup:
1rst row left:
digiscoping 400mm Apo, Eyepiece zoom 8-24mm (@8mm) with a T2-thread, T2-EOS adapter, remote control, mirror pre-release
The worst result so far
1rst row right:
400mm Apo 2*1,5 Kenko tele-converter appr. 1440mm eff.
The winner is: conventional photography! The final resolution was identical with my D60 and 1Ds (not a big surprise).
2nd row left
digiscoping 400mm Apo, 2*1,5 Kenko tele-converter, Eyepiece zoom 8-24mm (@18mm) with a T2-thread, T2-EOS adapter, remote control, mirror pre-release
The tele-converters give a better resolution than using the full zoom range of the eyepiece
2nd row right
digiscoping Panasonic FZ5 12*zoom, 400mm apo, 20mm ED eyepiece
compararable to conventional photography. The FZ5 needs a different setup with bigger eyepieces!
3rd row left
digiscoping 400mm Apo, Eyepiece zoom 8-24mm, Xacti E6 3*zoom, remote control
This is better than conventional photography, not much though
3rd row right
digiscoping 400mm Apo, 2*1,5 Kenko tele-converter, Eyepiece zoom 8-24mm, Xacti E6 3*zoom, remote control
This could be the winner of the test, concerning resolution.
So does digiscoping make sense with my equipment?
- well the gain of resolution is quite restricted at the moment, a "non-zooming" eyepiece could be better
- the Xacti setup is quite cheap and reduces the weight of my equipment
- Xacti captures the pictures with shorter exposure times (factor 1/4) , it can even freeze some movements!
There are a lot of articles about digiscoping in the internet
These are the hints which I read here::
http://www.barrie-tao.com/afocal.html
http://www.ayton.id.au/gary/Science/Astronomy/Ast_Photography.htm
"a barlow lens gives a better eye relief!
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Use an eyepiece with long eye relief.
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Couple the end of the camera lens as close as possible to the eye lens of the telescope eyepiece.
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Set the digital camera at macro mode rather than infinity.
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Use digital camera at full optical zoom.
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Purchase lenses specifically designed for the type of digital camera used.
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If possible, use a camera lens with a focal length longer than the eyepiece focal length."
Thanks for visiting my pages! Have a nice day - Sven
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