DSLR and mount only for astrophotography

[Tommohawk]

, so do you think the 200p on an EQ5 will be OK, I've heard people saying that an HEQ5 is needed as the 200p is too heavy?

I think this would be really pushing your luck especially if you mean a 200p skyliner converted - 1200mm isn't it?

I may be wrong but I think those folk advocating the EQ5 meant for DSLR only or maybe with guide scope, but not with your existing scope. My HEQ5 with both weight at full extension will just balance an F5 200p with guidescope and camera.

That said, I like the idea of a 200p 1200mm and was going to go that way myself - with an HEQ5 -  except that an F5 came up at a good price.

[Knight of Clear Skies]

Even an unmodified camera will still pick up the brightest red nebulosity

(Cygnus 80mm lens 300 seconds @ ISO1600 F4, Fujifilm DSLR unmodified)

Very nice. I'm struggling to get much red from my unmodded Canon 1100D. Is that just a single sub, and did you do much processing on it?

[bendiddley]

Sorry if this is a dumb question but can someone explain guiding? I don't properly understand what it's for. Why does the camera need to be guided? I understand it is for longer exposures but that's all.

[ollypenrice]

It is impossible to make a mount that can track the sky with the precision needed for astrophotography unless you give it some feedback on how it is doing. Mostly this feedback comes from a parallel telescope and camera which take short exposures in succession. The position of a chosen star is noted by the 'guiding software' and corrections are sent to the mount. This is autoguiding. In the past it was done by nutters peering through a parallel telescope and correcting the mount by manual input. I was once one of those nutters. Very fancy mounts costing something approaching £10K can guide on themselves using encoders but most people on here autoguide on stars.

Olly

[Scott]

The "readers digest" version of guiding goes like this. You get a second camera and using software it "locks onto" a star so if there are any slight errors with the tracking or polar alignment etc, it tells the mount to correct for these errors. of course it's a lot more in depth than that but that's about it in a nutshell.

There are a variety of cameras, guiding methods (enough to make your head spin). Get yourself a good book on dso imaging (making every photon count is brilliant) and read,re-read and read it again. It could save you a fortune

[Tommohawk]

Sorry if this is a dumb question but can someone explain guiding? I don't properly understand what it's for. Why does the camera need to be guided? I understand it is for longer exposures but that's all.

Ok well first thing as I'm sure you know is that your target will be moving - or we are (or both) - so if you take a long exposure it will suffer movement blur. The length of exposure you can get before this becomses apparent you can estimate from earlier comments. Of course you might like star trails in which case this effect might be desirable.

If you want sharp long exposure images you will need to follow the target across the sky. Two bits to this. If you have an equatorial mount and its motorised it will follow your target - and you can get some decent images like this - see my earlier comment. BUT even the best of the mounts discussed arent perfect - there will be backlash in the gears and periodic error ie the drive will periodically run fast then slow.

To prevent this you mount a second scope and camera, typically a CCD camera, and the live camera signal is fed into a software program like PHD2, which then sends tiny correcting signals to the ST4 port on the mount drive to correct for these small errors. This unfortunately adds to the cost and complexity of the system but is the only way to get good long exposures. I was convinced I could tune my HEQ5 mount to work without this, but failed completely even with belt drive conversion.

Hope that makes sense!

[Tommohawk]

Hmmm... looks like I got the slow typist award!

[bendiddley]

Got it!! Thanks that helps loads, starting to build a better understanding of it all now. I think I might also buy the book making every photon count and spend some time getting finding out more. Thanks again guys.

[wuthton]

 what they don't tell you is the shear frustration  you will go through throwing away many subs because a frog burped and the resulting wind upset the balance of your scope.

Could I beg to differ on this?

I was a long time user of a Eq5 Pro and it guides perfectly well with 5kg on board (plenty for a small refractor, guide scope and camera). Yes, my NEQ6 is superior but it is heavy and expensive. Clearly the OP is on a budget and a used Eq5 pro can be picked up for £300 less than a Heq5, this is a lot of money to me and many others.

[Scott]

Could I beg to differ on this?

I was a long time user of a Eq5 Pro and it guides perfectly well with 5kg on board (plenty for a small refractor, guide scope and camera). Yes, my NEQ6 is superior but it is heavy and expensive. Clearly the OP is on a budget and a used Eq5 pro can be picked up for £300 less than a Heq5, this is a lot of money to me and many others.

Ah, if only you also quoted the first and last lines of my quote .

The first relating to everyone have differing opinions, the last to being on a budget. The OP clearly stated "mount plus Camera only"