Imaging DSO's

[lukebl]

Guiding is basically about fine-tuning the tracking to precisely follow the object. The motor on the mount will roughly guide the telescope, but for imaging you need to counteract errors in the motor drive by using a guide camera which, with the appropriate software and hardware, sends pulses to the mount to make minor adjustments in Right Ascension and Declination to keep it exactly on track. Without guiding and with perfect polar alignment you might get a minute or two exposures without star trailing (I could never manage more than about 30 seconds), but with guiding you can get 10, 15, 20 minutes or more.

[marcosa666]

Ahhh I see! Ooo well with my budget I might have to try unguided first to see how I get on before jumping straight in the deep end!

[marcosa666]

Also I was originally looking to buy an LX90 or something along those lines. Would there be a massive difference in quality between that and the skywatcher 200p EQ5? Because I don't want to comprimise too much on observing to test the waters with imaging.

[Whippy]

Ahhh I see! Ooo well with my budget I might have to try unguided first to see how I get on before jumping straight in the deep end!

By all means do, I originally started out with a camera attached to an eyepiece (the afocal method) and had a lots of fun. Just be aware that you'd save money in the long term by buying a decent mount (HEQ5, EQ6) with autoguiding capabilities built in, buying a cheaper mount now will cost you more in the long run.

why pay for a guiding setup running into a couple of thousand pounds when he might not have the knowledge of guiding just for reasonably clear images.

I don't know where you go shopping (maybe astronomy shed should be called astronomy palace? ) but you can easily buy an excellent guiding setup for less than £500. I used a QHY5 and an ADM sibe by side bar and it never let me down. Even cheaper would be the finder/guider route .

Tony..

[marcosa666]

I agree Tony I think I will get a mount ready for the leap to guiding! Definitely seems like the sensible way to go about it!

Marcus

[Whippy]

Definately Marcus, once you've got over those initial hiccups that always come with starting on a new learning curve, you'll make huge strides and you want your kit to take you there .

Tony..

[rocketandroll]

Just to quickly add....

If you're looking to dabble in imaging, especially starting off unguided... I'm afraid I have another spanner to throw in your works in terms of making a decision about a scope :-)

I'd definitely recomend you get a good EQ mount, HEQ5 or EQ6 ideally. The EQ5 is, I think motorised? You're better off putting more money into the mount now rather than regretting it later (as others have said).

You really do however need to consider the 'speed' of the scope, that is, it's focal ratio. This is normally expressed as it's 'f number'. A catadioptric scope like the LX90 (apart from often coming on an Alt-Az mount, which is no good for imaging DSO's, though ok for the moon or planets) will be about f10 at best. The 200P is about f5 or so.

Each full f stop lower is twice as fast, so actually, the 200p will gather the same data in something like 1/8th the time the LX90 would. (Sorry if that's way off, but it's something like that sort of ratio).

What this means in real terms for you is... you should be able to get 40 - 50 second exposures unguided on the 200P without the stars starting to trail at all. On the LX90 you'd be lucky to get 20 - 30 seconds, and you'd need more like 6minutes to gather the same data as the 200P would have got in 40-50 seconds.

In other words... get a fast scope on an EQ mount if you want to dabble in DSO imaging at all. The 200P is a good compromise if you want to observe too, as has been said before.

Hope that helps a little :-)

Ben

[marcosa666]

Thanks thats a lot of help!

Marcus

[ollypenrice]

The mount must always track the stars by being polar aligned and motorized. When we say guided (really autoguided) we are talking about adding a parallel scope or Off Axis Guider which has its own little camera. It takes a pic every few seconds and any movement in a chosen star is detected and the mount given an electrronic command to put it back in the right place. When it works (!!!) you can get an average tracking error below a tenth of a pixel.

Olly

[IvanT]

I've a 200p on a goto upgraded EQ5 and am very happy with it, but as others have mentioned, the 200p + finder/guider + dslr + due shield etc puts it pretty much at the limit of the mount, with the benefit of hindsight I'd have gone EQ6. One other thing, if you do go for the 200p be prepared to learn how to collimate it.

Sent from my iPhone using Tapatalk

[BertUK]

I've a 200p on a goto upgraded EQ5 and am very happy with it, but as others have mentioned, the 200p + finder/guider + dslr + due shield etc puts it pretty much at the limit of the mount, with the benefit of hindsight I'd have gone EQ6. One other thing, if you do go for the 200p be prepared to learn how to collimate it.

Sent from my iPhone using Tapatalk

i can collimate my 200p in less than 2 minutes using the baader laser collimator

[brantuk]

Here's a typical guiding setup made up of mostly second hand gear. Along with an image taken with it.

It includes: imaging scope and camera, guide scope and camera, goto mount, side by side mount bar, dew controller, connectors and cables to convert/feed image and control signals via usb, and a laptop (not pictured) with mostly free software to run it all. It cost around £1000-£1500 to build. Brand new it would be well over £2000 (plus the laptop of course). Not the best but it works well. Hope that gives you a good idea

[BertUK]

I don't know where you go shopping (maybe astronomy shed should be called astronomy palace? ) but you can easily buy an excellent guiding setup for less than £500. I used a QHY5 and an ADM sibe by side bar and it never let me down. Even cheaper would be the finder/guider route .

Tony..

a full guiding setup for £500......get me 5 next time you go to wherever they sell them

[BertUK]

maybe brantuk has paid too much for his then

[Whippy]

a full guiding setup for £500......get me 5 next time you go to wherever they sell them

QHY5 - £180

ADM side by side bar - £180

ST80 - £95

As I'm a nice guy, I won't charge you commission if you want my to buy the 5 for you . The ST80 would be about £50 secondhand and the QHY is about the £130 mark. As I said, the finderguider route does away with the side by side bar and the ST80 so it's even cheaper.

Tony..