GOTO ?

[BrightestBlue]

Hi all and apologies in advance. I understand that GOTO will take you to your desired target. Does it however then track that target. If so would a GOTO set up be suitable for astro photography?

[sunshine185]

Yes,goto will track too. I believe an EQ mount is required for advanced photography.

[malc-c]

Martin,

Can you define what you mean by astro photography. If you want to take images of the moon and planets then you can use web cams and then mount type is less critical, and an alt/azimuth goto mount would be fine But if you want to use a digital slr camera and take images of the deep sky objects then the mount is more critical, and you are looking at an HEQ5 as being the minimum for serious imaging work.

[BlueAstra]

Note an equatorial mount is the best for Astro photography. Try eyepiece projection first into a camera for stars moon and clusters, and maybe try a webcam for the moon and planets. Do plenty of research here first before committing to expensive kit, and buy the 'Every photon counts' book (from FLO?) for good background .

[pete_l]

Yes,goto will track too. I believe an EQ mount is required for advanced photography.

An EQ mount is definitely the most popular choice, but it's not the only one.

What happens is that objects: stars, planets, the Moon (and Sun) all follow a curved path across the sky. The path is part of a circle centred, more or less, on Polaris. If you take several photos of an object during the course of a night using a camera that is parallel to the ground (for example: on a tripod, or attached to a telescope that's just sitting on a tripod) then when you look at the various images, the object will appear to rotate as the night goes on.

If you combined all those photos, or took a long exposure shot, then that rotation would blur the detail and the image would be low quality.

The simplest way to deal with this image rotation is to have your camera (or telescope) on a motorised mount that follows the same curved path, at the same speed as the stars. You can do that in two ways: either with an EQ (Equatorial) mount that has been aligned to point to Polaris, and rotates around the pole, or with an Alt-Az mount that is tipped over (but held firmly) so that its axis of rotation is also pointing at Polaris. if people buy a normal Alt-Az mount, they need to purchase a wedge in order to get the mount at the right angle to follow the curve - you can't do it just by shortening the tripod's legs (see above, about being held firmly. Telescopes are fragile and heavy, it *will* tip over if you try this).

EQ mounts are simpler in construction and cheaper to buy than an Alt-Az plus wedge. But they do have one big disadvantage. Typically, because of their construction they can only track in either the east OR the western half of the sky. If the thing your photographing (or even just observing) moves from the eastern half to the western half your EQ mount can't follow it across the meridian into the other hemisphere. Having said that, Alt-Az mounts aren't perfect. They tend to have a base unit that stops the telescope from pointing low to the south, and the same base unit can get in the way of pointing an attached camera to locations close to the pole - but they can track across the meridian without having to do a "flip".

[BrightestBlue]

Thank you for your concise replys This is what i had in mind.

I have heard that this is a good telescope with which to start astro photography. By Astro photography I mean planetary, clusters and maybe nebulea if possible.

Am I barking up the wrong tree?

I already own a Celestron Atromaster 130 eq, and find it difficult to use. I don't want to get too frustrated and let my enthusiasm wain.

Any comments or advice would be greatly appreciated.

[malc-c]

Martin, read Pete_l's post above.

An alt / Azimuth mount is not ideal for long exposure photography for nebula and other deep sky objects. Also the large focal ratio of f11 is more suited for planetary work.

An f5 reflector such as the 150P / 200p on a suitable driven EQ mount is a good basic all rounder, and on the right mount will give you decent long exposures when coupled with a digital SLR, or planetary images with a web cam - but this may be out of your budget as a 150P on an goto EQ3 mount is £500, and in practice isn't the ideal mount for imaging with.

[BrightestBlue]

The thing is, that after my experiences with the 130 eq, I really am not sure if I want to lay a great deal of money out an something I may still find difficult to use, or is a motor driven mount much easier to use? I have read an article about the 130 eq that did say that the 130 eq wasn't user friendly and even a more experienced person found it difficult to use.

[malc-c]

Martin,

The decision as to buying something basic now to get you by, or something that will do the basics and then later cater for your needs as you grow into it is something only you can make.

When I used to go fishing there was a term on the forums - "tackle tart". It referred to someone who had to have the latest gizmo, the top of the range rod etc etc. And to a degree there is a similarity in this hobby, where it's easy to get sucked in and spend a fortune buying top of the range gear. Taking the fishing analogy one step further, the chap with a £100 rod will still catch fish the same as the guy next to him with a £1000 rod... but the £1000 rod will handle and perform a lot better under similar conditions, and conversley a lot of people sell the £100 rod and upgrade to a £1000 rod once the limitations of the £100 rod had been discovered.

[pete_l]

Thank you for your concise replys This is what i had in mind.

[ Skywatcher Skymax 127 SynScan AZ GOTO ]

I have heard that this is a good telescope with which to start astro photography. By Astro photography I mean planetary, clusters and maybe nebulea if possible.

The problem with this scope (and all the others like it, such as Celestron's Nexstar range) is that they are only supported on a single arm of the Alt-Az mount. So all the weight of the scope and the accessories is borne on a single bearing, the same one that provides the up/down movement.

What that means is that the scope is unbalanced and can make tracking a problem. People did try to use the Nexstar 8's for photography (admittedly a bigger 'scope) but I don't believe the results were satisfactory.

Although GE mounted telescopes are also only supported on one side like the SkyMax 127, the difference is that they are balanced on the motor-drive by a counterweight. That means that the actual weight that the motor has to move is smaller - though the moment of inertia is the same or greater.

Generally the secret to getting a good combination of telescope & mount for photography is to follow the herd. It might sound boring: to only use equipment that others have demonstrated is good enough, and unadventurous. However the manufacturers do seem to be rather "optimistic" in their claims - especially where suitability for photography is concerned.

[BrightestBlue]

Ok, I think I shall find out where my nearest Astronomy Society is and talk to them also. I really appreciate all of the help I have received, you have probably saved me quite a bit of money.

Many thanks to you all.