what is off axis guiding

[chemtom24]

can someone please explain to me what off axis guiding is, and what will need to set it up? got a 200p on an eq5 and will be modding the handset soon for an st4 port. will also be buying a usb guider which will connect the laptop to the st4 port and allow me to run a prog to guide the mount.

ive only just about got my head around all of the above using a guidescope, then someone suggests off axis guiding

anyone??

[daz]

Instead of using a 2nd scope with the guide camera, an off-axis guider uses a prism in the light path to divert a small amount of light to the guide camera.

The prism can be adjusted to allow a guide star to be selected from the field.

The guide camera is then working at the same focal length as the imaging camera, and can help to reduce flexure in the system, and of course, reduces overall weight on the mount.

Hope this helps

[chemtom24]

thanks

so in essence its the same - still need usb guider, st4 port, guide camera etc - only instead if a heavy guidescope gathering its own light you use the off axis one which nicks a bit of light from your imaging scope? how much are they to buy, can someone you reccommend a good one that will work with the 200p, eq5 and 400d ?

[Catanonia]

thanks

so in essence its the same - still need usb guider, st4 port, guide camera etc - only instead if a heavy guidescope gathering its own light you use the off axis one which nicks a bit of light from your imaging scope? how much are they to buy, can someone you reccommend a good one that will work with the 200p, eq5 and 400d ?

Correct mate.

As an example, i used to have a MN190 reflector with heavy CCD camera and filter wheel mounted side by side with an ED80 and guide camera all on a EQ6 pro.

To balance it all I have 4 counterweights.

By using a OAG on the MN190 I lost the ED80, dual bar and 2 weights, about 15kg and balance is so much better.

Now instead of 8 mins best guiding time, I can easily get 20 minutes and probably as much as I want.

Here is a link for you. The TS OAG is very good

Accessories @ Modern Astronomy

[chemtom24]

thanks catanonia - will i need an illuminated ep too? just trying to work out overall cost. and is th eonly difference between the ts one and the brightsar one the low profile? cos for a hundred quid less id b tempted to at least try it!

[SlipperySquid]

To be honest mate you are pushing the limits of the eq5 with a 200p for astro-photography and if a gnat farts within 10 meters of the mount it's going to show on subs!

I know because I used to have the same platform. You may get some decent guided subs in the best conditions but to be honest even with my 200p mounted on a HEQ5 the wind places havoc with it.

Just an idea but I'm taking some great images of widefield nebula with my Megrez 72 and you can pick an ED80 up for about £200 I think you would get more enjoyment out of a smaller scope on that mount OR sell the eq5 and get at least a HEQ5 for your 200p.

Clear skies

Matt.

[chemtom24]

To be honest mate you are pushing the limits of the eq5 with a 200p for astro-photography and if a gnat farts within 10 meters of the mount it's going to show on subs!

I know because I used to have the same platform. You may get some decent guided subs in the best conditions but to be honest even with my 200p mounted on a HEQ5 the wind places havoc with it.

Just an idea but I'm taking some great images of widefield nebula with my Megrez 72 and you can pick an ED80 up for about £200 I think you would get more enjoyment out of a smaller scope on that mount OR sell the eq5 and get at least a HEQ5 for your 200p.

Clear skies

Matt.

I was thinking about getting a 2nd hand 130 or 150 newt for imaging as i realise the 200 is pretty heavy.

would a 130 be big enough aperture?

also, if i wanted to piggyback my dslr on the scope ( eg for a 200mm shot of the andromeda galaxy) instead of prime focus, coud i still use the OAG to guide the scope and therefore the piggybacked dslr?

[Catanonia]

I was thinking about getting a 2nd hand 130 or 150 newt for imaging as i realise the 200 is pretty heavy.

would a 130 be big enough aperture?

also, if i wanted to piggyback my dslr on the scope ( eg for a 200mm shot of the andromeda galaxy) instead of prime focus, coud i still use the OAG to guide the scope and therefore the piggybacked dslr?

All is possible that you suggested, just watch the weight. As a rough rule of thumb I use, if you have more than the 2 standard counterweights on your counter balance I would say you are overloading and will struggle with guiding.

The ed80 route is a good suggestion, or go to a HEQ6 mount for that extra capacity.

[chemtom24]

trying to keep the cost down so a new mount is pretty much out the question im afraid

As a newbie to astro pics, will i notice a major difference in aperture? will i get godo results with a 130 newt? or a smaller achromat? cheap cheap cheap

[Stephen]

trying to keep the cost down so a new mount is pretty much out the question im afraid

As a newbie to astro pics, will i notice a major difference in aperture? will i get godo results with a 130 newt? or a smaller achromat? cheap cheap cheap

Here's a thought:

Sell EQ5 - don't buy new scope - buy S/H HEQ5 (basic model) - fit DIY guide port - save money and image with 200P

[riklaunim]

If achromat has good flat field then it will be good for narrowband images. 130 Newtonian like the SkyWatcher PDS version with nice 2" focuser is also good for at least "cheap" astrophotography - light and rigid.

[chemtom24]

Here's a thought:

Sell EQ5 - don't buy new scope - buy S/H HEQ5 (basic model) - fit DIY guide port - save money and image with 200P

a lovely thought indeed arent heq5's ~£400 ?

[Stephen]

a lovely thought indeed arent heq5's ~£400 ?

A S/H PRO one would be a shade more than that, a lesser spec S/H one would be less

[chemtom24]

A S/H PRO one would be about that, a lesser spec S/H one would be less

oh really? so would i just need to mod the handset or wouldnt it come with one? synscan syntrek pro goto ARGHGHH i have no idea what these mean lol.

Basically if im gonna be spending say 150 for a smaller newt, + at least 100 for the OAG, + 70-80 for the usb guider. so its lookin like 350 with bits and bobs.

but then if i get a heq5 for what, 300? i will still need the OAG for 100 and the usb guider for 80 so itl be more liek 500 all rounded.

150 quid more but i would have a better mount both for imaging and visual. it would be false economy to not buy it, but is it really that simple?

[Stephen]

You forgot to subtract the value from the sale of your EQ5 Makes it even closer doesn't it?

You also don't have to go OAG + usb guider. You could for example start with finder scope + webcam + adaptor + PC.

Now that's pretty cheap isn't it?

[riklaunim]

Small scopes can be guided through finderscopes - no need for OAG or extra guidescope (although some finderscope modding required). Syntrek doesn't has GoTo and can't be directly connected to a computer (needs EQDir for that). SynScan has goto and can be connected. If you guider will have ST-4 port then it's only goto difference as such guider connects to mount directly.

[Stephen]

Oh and I forgot to add, for less than a tenner you can add a guide port to the basic HEQ5 that doesn't have one.

Just the same mod you were going to make to your EQ5.

[chemtom24]

Oh and I forgot to add, for less than a tenner you can add a guide port to the basic HEQ5 that doesn't have one.

Just the same mod you were going to make to your EQ5.

kheldar, you are a naughty man! lol

can we just clarify something... a basic heq5 will have motors and a handset to control these motors, but no guideport and no 'guider' inbuilt into the mount. therefore i wuold need to modify the handset and buy a simple usb guider which will sit between the modded guideport and the laptop, which will allow a prog on laptop to guide the mount.

if i buy a better version of the heq5, i wont need the usb guider as it will already be inbuilt and will also come with a guide port, so its just one cable i need from mount to laptop?

on top of all this, i need a imaging device and a guide scope or off axis guider.

Originally i was going to use a finderscope with a webcam but i got put off the idea cos people said it wasnt too good.

All i want is a simple (yea right!) guided setup which wont cost me the bleedin earth!

kh3ldar if you could give me a quick run down of equipment and price id be very grateful

[Stephen]

kheldar, you are a naughty man! lol

can we just clarify something... a basic heq5 will have motors and a handset to control these motors, but no guideport and no 'guider' inbuilt into the mount. therefore i wuold need to modify the handset and buy a simple usb guider which will sit between the modded guideport and the laptop, which will allow a prog on laptop to guide the mount.

All correct. (for webcam guiding. For decent guide cam [QHY5] you don't need the guider either.)

if i buy a better version of the heq5, i wont need the usb guider as it will already be inbuilt and will also come with a guide port, so its just one cable i need from mount to laptop?

I'm not sure for webcam guiding, but I think you may still need the guider. (no direct experience.) Again, QHY5 won't need a guider.

on top of all this, i need a imaging device and a guide scope or off axis guider.

Correct unless you ....

Originally i was going to use a finderscope with a webcam but i got put off the idea cos people said it wasnt too good.

It's not the best in the world I grant you, but it's a cost saving initially that you can add later You maybe don't need to get ALL the kit right away, start with the basics and grow it.

All i want is a simple (yea right!) guided setup which wont cost me the bleedin earth!

You and me both What I'm trying to say at the end of all this is that for not much more you can get the better mount. This is going to be the most effective investment in the long run.

[Stephen]

OP : I just PM'ed you a bargain I found

If you don't want it, let me know so I can post it in Heads Up.

[chemtom24]

thanks kh3ldar, ive sent a message to the seller, if its still going il take it! will post again with an update soon

[chemtom24]

got a reply this morning, its mine :D veyr happy, thanks so much kh3ldar

[Stephen]

got a reply this morning, its mine :D veyr happy, thanks so much kh3ldar

You're most welcome

Another imager saved from the EQ5 rofl

[Catanonia]

So comon then, spill the beans, what have you bagged

[chemtom24]

i dont want to count my eggs just yet, but playing email tennis and its been sold to me so i guess its mine, but until ive got it i wont sleep easy!

heq5, 127 sw mak - £200