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Wednesday, 12 January 2011

UK Scopes and Binoculars Blog: How to connect a digital SLR (DSLR) camera to telescope for digiscoping?

UK Scopes and Binoculars Blog: How to connect a digital SLR (DSLR) camera to telescope for digiscoping?

Why do I only see a white image when I try to take pictures of the Moon using my Nipon digital eyepiece/camera?

The Nipon digital eyepiece can be used to take pictures of distant objects through a telescope. You can see on the PC screen what you would see through the telescope's eyepiece and take that picture (or video footage) through your computer. However, if you point your telescope to the Moon, you may only see a spot of bright light on your computer screen, rather than the details of the Moon surface. This is because that the brightness of the Moon has exceeded the exposure limit of the camera's hardware chip. You may get a similar result when trying to take pictures of the moon using some other types of digital cameras.

A solution for this: add a Moon Filter to the eyepiece holder of your telescope, before putting the digital eyepiece into the holder. You will get a better image of the moon. This should also help your astronomical observation and digiscoping on stars in the night sky.

User experience with the Nipon digital eyepiece/camera (Model EE300) for digiscoping under Windows Vista system

A customer has recently provided some feedback about his experience in using the Nipon digital eyepiece on his laptop computer which runs the windows vista system. This information should be useful for others who are interesting in digiscoping.

When the digital eyepiece is connected to your PC through a USB slot, the computer should be able to automatically recognise this device and install the software driver. There is no need to install anything from the software CD which comes with the digital device. You should then be able to see a camera icon in "My Computer" programme. This is true when your PC runs Win 2000, Win XP or Win 7. However, in Windows vista, the camera icon becomes invisible. In fact, it has been reported that Win vista does not show other types of digital cameras in the "My Computer" programme. This is one of the problems with win vista.

A solution for this is to install the software programme which comes with the digital eyepiece and to take digital pictures or video recordings from your PC using that software programme. This should achieve the same function as you would otherwise be able to do using a simpler "My computer" programme under win xp or win 7.

How to connect a digital SLR (DSLR) camera to telescope for digiscoping?

Digiscoping is becoming increasingly popular nowadays as people try to combine the function of powerful telescopes with advanced digital photographic technology. We have been frequently asked on how to connect a certain type of digital SLR cameras to a particular telescope model. This technical note is prepared to address some of the common aspects regarding digiscoping using DSLR cameras.

There are basically two methods to connect a DSLR camera to a telescope. The first method is to attach the SLR body without the camera lens directly to the scope using a DSLR camera adaptor. In this way the scope can effectively become a telephoto lens of the camera. Traditionally, this is achieved by using two separate components, a T-adaptor and a T-ring (also known as T2 mount). The T-ring is connected to the DSLR camera in place of the camera lens, and the camera is then connected to the scope’s eyepiece holder through the T-adaptor. There are different types of T-rings for different types of DSLR cameras, but the T-adaptor is designed to fit a range of T-rings. For those who are new to digiscoping, there can be confusions as to what type of T-rings should be purchased to fit a DSLR camera, and what T-adaptor can then fit the T-ring and the telescope.

More recently, a new type of
DSLR camera adaptors
has become available, which combines the T-ring and T-adaptor into one component. Such an adaptor is available for those widely used camera brands such as Canon and Nikon. A major advantage of these new adaptors is that they can fit a wider range of products (eg. the Canon adaptor can fit almost all Canon SLR cameras with up to 135mm lens and almost all types of telescopes with a standard 1.25” eyepiece holder), and you only need one of them for digiscoping.

The second method of connecting a digital camera to scopes is to use a
universal camera adaptor.
These adaptors enable you to attach a digital camera (including both SLR and non-SLR cameras) to a scope’s eyepiece. You do not need to remove the camera’s lens in this case, but the image quality is often not as good as using the first method.

Monday, 3 January 2011

What are advantages and disadvantages of using a Barlow lens?

Some major advantages:

  • Achieve higher magnifications.

  • Provide flexibility of magnification levels with your existing eyepieces. For example, if you have 2 Plössl eyepieces with 16mm and 26mm focal length and use them on a telescope with 800mm focal length, you have a 800/16=50x and 800/26=31x magnification levels respectively. With a 2x Barlow lens, you will get 100x and 62x magnifications as well.

  • Increase eye relief (distance of exit pupil from eye lens). Many eyepieces have an eye relief which is directly related to its focal length. For example, the eye relief of a Plössl is 0.73 x its focal length. Therefore, for these eyepieces, there will be a greater eye relief with a Barlow than without one.

  • Disadvantage: a major disadvantage of adding a Barlow is a slightly decreased brightness in the produced image.

    What is a Barlow Lens?

    A Barlow Lens can multiply the power of the eyepiece by a specified magnification factor. For example a 2x Barlow lens will double the magnification and a 3x Barlow will increase the magnification by 3 times. A Barlow lens is placed between the objective lens and the eyepiece.

    The magnification/amplification factor of a Barlow is a function of its position in relation to the eyepiece and the objective lens. This factor can be increased by increasing its separation from the eyepiece using an extension tube. There are compact shorter tube Barlow lenses and longer tube Barlow lenses, both can achieve the marked magnification results.