Telescope Ccd Electronic Eyepiece Camera St4 Autoguider Reviews

An autoguider is a digital camera with a CCD or CMOS detector at the focus of the guidescope or, in the case of an off-axis guider, at the focus of the imaging instrument after some of its low-cal has been diverted by a small prism.

The autoguider captures regular snapshots of the heaven and a computer compares them to notice star drift caused by the apparent move of stars across the night heaven, issuing corrections to the mount via a cable attached to the autoguide port to keep the mount on track.

Why utilize an autoguider?

Today'due south digital cameras possess awesome potential, empowering more people than ever to become astrophotographers.

But, while it's easy to produce passable wide-field constellation portraits using zero more than a DSLR, a fixed tripod and exposures of upwards to half a minute, capturing a detailed image of a typical deep-sky object is a bit more involved.

As a minimum, you'll need to utilize much longer exposures and a lens with a focal length of at least 200mm.

Ideally, the photographic camera needs to be fastened to an equatorial mount that has been precisely polar aligned and then that information technology accurately tracks the stars every bit they move against the nighttime sky – otherwise y'all'll meet abaft in your images.

If y'all need help picking out a mountain, read our guide to the best telescope mounts bachelor.

Vega and the surrounding stars through a telescope. Unguided, the scene looks blurry and indistinct. Compare this to the 1 taken with a guided setup at the top of the article. Credit: Ade Ashford.

Even so, even the most expensive and precisely polar-aligned mount will exhibit unavoidable paradigm trailing with long focal length lenses or long exposures.

For example, my 25-year-old Vixen GP mount is capable of unattended exposures with a 400mm lens – only only for exposures up to three minutes.

This limitation is due to the cumulative effects of infinitesimal imperfections in the drive organization's gears (termed 'periodic fault'), flexure in the photographic camera and mount, and atmospheric refraction.

To maintain pivot-point stars, we must resort to guiding the mount throughout the exposure.

Traditionally, astrophotographers would do this by advisedly monitoring a star on the reticle of an illuminated eyepiece in a guidescope – a minor scope mounted in parallel with the imaging instrument – making tiny drive corrections with a paw controller as and when required for the duration of the exposure.

Fortunately, today's computerised equatorial mounts free us from such drudgery by possessing an autoguide port (sometimes called a CCD port) conforming to the de facto standard set by the Santa Barbara Instruments Group's ST-iv autoguider virtually 25 years ago.

With an off-centrality guider, in that location'southward no need to attach a dissever guidescope to your setup.

What'due south in an autoguider?

An autoguiding system consists of the following parts:

• equatorial mount

• guidescope or off-axis guider

• autoguider (camera)

• computer

• guide software

• a link to the mountain

The camera, computer and software are oft integrated into ane unit in standalone autoguiders such as the popular Celestron NexGuide or Sky-Watcher SynGuider.

Off-axis guiding has the advantage of eliminating a divide guidescope, thereby avoiding the potential for flexure and reducing load on the mount.

A popular culling to a guidescope is a modified 50mm finder, particularly if your imaging scope has a focal length less than 1m.

If your upkeep doesn't stretch to an all-in-one solution, you could use a cheap modified USB webcam every bit a guide camera.

Software such as PHD Guiding can automate the guiding procedure for you, while interface adaptors such every bit GPUSB tin handle the connection between your computer's USB port and the mount.

Do behave in mind that both options require ability, so a rechargeable 12V ability pack capable of running all your equipment is essential.

Also, characterization your cables well, since you will be assembling and operating your equipment in the nighttime.

For extra aid, head online – forums such as Stargazers Lounge and Cloudy Nights are frequented by experienced imagers willing to assist to you lot create a working organization that permits exposures of several minutes even with minor specification mounts – paving the style to capturing your perfect deep-sky image.

Can y'all autoguide an altaz mount?

While it is technically possible to autoguide some altaz mounts, yous can still just synthesise long exposures, equally you'll need to use image editing software to combine a number of shorter exposures and remove the rotation between them.

Using a computerised equatorial Go-To mount with a built-in autoguiding port is much preferred.

Likewise as the autoguiding benefits, it volition brand locating target objects simpler, peculiarly since many deep-sky subjects will be as well faint to exist seen visually.

Should I use a standalone autoguider?

Standalone autoguiders such as Celestron's NexGuide or Sky-Watcher'southward SynGuider (pictured to a higher place) combine a guide imager, computer and guide software into single hardware packet, offering an attractive culling to taking a laptop outside with you.

• Read our total SynGuider review

On the other manus, standalone systems typically possess small configuration screens and may require considerable tweaking to play nicely with your mount, though often crave little intervention thereafter.

A self-congenital system employing a webcam, a GPUSB interface adaptor and a laptop running guiding software is potentially much easier to use – and cheaper, if y'all already own a laptop and a webcam.

Ade Ashford is an astronomer and science journalist. This article originally appeared in the November 2014 outcome of BBC Heaven at Night Magazine .

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Source: https://www.skyatnightmagazine.com/advice/what-is-an-autoguider/

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