Sunday 14 April 2013

Digiscoping with a TAL-120 telescope (part 1)

A small panasonic compact camera attached to a digiscoping bracket,
which is mounted on a TAL-120 telescope
.

"Digiscoping" is usually taken to mean
taking a photograph with a digital camera through the eyepiece of an optical instrument - it can be through a microscope, a "spotting scope" or a telescope.
It is the easiest way of recording an image, and can be used with just about any type of optical intrument that you put your eye to.
In its simplest form, you just set up the telescope (or whatever) so you can see the thing you want and focus it properly, and get it nice and in the middle. then just hold a camera up to the eyepiece, and take a picture.
This is an example of such a shot:
Digiscoping example.

I know it is not an "astronomy" picture, but it is one I have handy, and clearly shows that the picture is taken through an optical device other than just the camera - it is actually taken using a cheap mobile phone camera pointed through an old Pentax 50mm SLR lens, which is being used as a magnifying glass to give a bigger image! The picture also shows a possible problem with digiscoping - the picture shows "vignetting" - that is to say that you can see the edge of the lens in the picture. Whether this is intrinsically good or bad is a matter of taste, but most folks expect a picture to not show signs of the device it was taken through.

The easiest cure is to zoom in a bit, and then something like this can be achieved (the picture is pretty much as taken, and isn't cropped at all - that's why it isn't in the middle! - and no "stacking" or other fancy techniques were involved.):
Our 10-year old daughter's digiscoping shot of the Moon,
taken with a low-cost Canon A3000 compact camera,
handheld, through the 25mm eyepiece on a TAL-120 telescope,
on a slightly cloudy night :-(

The poor viewing meant we couldn't get a better shot that night - not many stars were visible, and the moon kept disappearing behind bands of cloud. But you can see the principle.
Of course, there are "pros" and "cons" to hand-held digiscoping.
The main two "pros" are:
  • nothing fancy to buy - just the optical device (in our case a telescope), and a compact camera (in our case a Canon A3000 "low-end" model - certainly such cameras (or better) are available in the $100 dollar (60 pounds, 72 Euros) range, NEW!!! You could, of course, also use the camera on a mobile 'phone, but in general, they tend to have VERY small sensors, so a compact camera often gets better results.
  • it works with just about any optical device - we have used a similar technique to take pictures with a low-end microscope, a telescope, an SLR camera lens, a magnifying glass, spectacles - just about anything with lenses or curved mirrors - your imagination is the limit!
The main two "cons" are:

  • shaky hands mean blurry pictures - the more the magnification, the steadier the camera has to be held and/or the faster the shutter speed needs to be to "catch" the image without blurring caused my camera movement
  • it can be tricky getting everything aligned enough so that the image is nice and in the middle, It is easy to be a bit off line and lose part of the image because part of the optical instument is in the way:
at 1/30th of a second exposure,
and almost filling the frame of a compact camera,
shaky hands are always a risk.
not lining the camera and the telescope up
properly can cause this sort of effect




Both pictures were taken by our daughter.

2 comments:

  1. I like the way you wrote this article it is awesome pictures.

    iPhone Scope Mount

    ReplyDelete
    Replies
    1. Your IPhone Scope Mount is yet another example of digiscoping. Same techniques apply. A user can take pics through their telescope eyepiece with an Iphone, or some other brand :-)

      Delete