Autoguiding with QHY5

[damo_Melbourne (Damian)]

Hi All,

Currently Im using and ED80 and heq5pro unguided (and having a ball I might add!) and want to extend my exposures now with guiding as Im now totally addicted!

Rather than purchase another OTA such as an ST80.... can I utilise my 6" newt as a guide scope with the QHY5 and I will pop the ED80 on top to image with my 450d?

Weight shouldnt be a problem the weight of the ED80 + 450D is a smidge over 4kg but Im wondering if the QHY5 will be able to get focus on the newt?
I have used a phillips 900nc without any focus problems on the newt (its a celestron c6-N) but thought I had better check first.

Any ideas or do you think Im kidding myself and get something like an ST80?

One final question I have been debating QHY5 or DMK21 mono and doing alot of reading here... The DMK would be better for planetary but more expensive. but one thing I cant work out is how do you hookup the DMk21 on the heq5pro for guiding? Does it have a guide port like the qhy5?
Im currently running a serial cable from my lappy for Sky6 into the handcontroller which is working a treat.

Any advice would be greatly appreciated

Damian

[multiweb (Marc)]

For sure. That is exactly what I'm doing. I have one ED80 and one Celestron Newtonian 5". I swap the guider or imaging camera on both scopes. Here's a pic of my setup. If you can focus on the newt with your DSLR you'll have no problem focusing the QHY5

http://www.multiweb.com.au/astro/QHY8_piggyback.jpg

[pjphilli (Peter)]

Hi Damian
I have an ED80 piggybacked on a Mak 150mm and like Marc I can use the scopes alternately as imager or guider. The setup works fine but I can make the following comments. I was disappointed with the performance on the QHY5 on the Mak 150mm until I;
- focal reduced the Mak150 to f6 to get a wider fov and brighter stars
- made sure I focused the QHY5 accurately
- use a dark frame facility (such as I can with my PHD guiding program)
Having done all this I now find that I can nearly always find good guiding stars within the fov of the Mak 150. Of course, the other way around using the ED80 as a guider works fine also.
Cheers Peter

[damo_Melbourne (Damian)]

Wow Marc
Your setup is identical to what I'll be doing! Thanks also Peter
(Im posting my 2nd light pics in the Deep Space section now for comments so please have a look and let me know what you think).

The only issue I now have is the common one which guide QHY5 or DMK21 mono
If I dont need another OTA I will quite happily get the DMK at the extra $ as I would like to do some lunar/solar imaging too.

How do you hookup the DMK? to the heq5pro?

many thanks again

Damian

[Barrykgerdes]

Originally Posted by pjphilli

Hi Damian
I have an ED80 piggybacked on a Mak 150mm and like Marc I can use the scopes alternately as imager or guider. The setup works fine but I can make the following comments. I was disappointed with the performance on the QHY5 on the Mak 150mm until I;
- focal reduced the Mak150 to f6 to get a wider fov and brighter stars
- made sure I focused the QHY5 accurately
- use a dark frame facility (such as I can with my PHD guiding program)
Having done all this I now find that I can nearly always find good guiding stars within the fov of the Mak 150. Of course, the other way around using the ED80 as a guider works fine also.
Cheers Peter

Interested in your set up. I have a 150mm Mak I got as part of a deal when I sold my LX200. It looks pretty good but an 1900MM FL but I also have a reducer I have never used. I was also thinking of piggy backing and ED 80.

I just tried the reducer and it works OK. 1200 mm looks a lot better for a FL

Barry

[pjphilli (Peter)]

Hi Barry
Thanks for your input. I would like to ask you about another point, not directly on your enquiry Damian but perhaps of interest to you too.
I have tried piggy backing my ED80 on the Mak 150 and also built a sturdy platform for side by side mounting. However, in each case I get thdreaded flexure. When operating the Mak150 focal reduced to about 1000mm this flexure it at about 0.7 pixels per minute in the RA direction. This is not enough to spoil single images which I normally take up to a max of 6 minutes but it does cause an annoying slow drift of successive images across the screen during long imaging session say up to an hour. Any comments? Some say that this drift may be cause by movement in the Mak mirror but since it is so consistent I am inclined to think that it is caused
by the relative shift of my imaging and guiding scopes. Incidentally, my guiding is usually rock solid using PHD software with RA and DEC movement kept withing less than + or - pixel.
Cheers Peter

[marki]

Damien, the QHY5 is a dedicated autoguider which is why it has the ST4 port on the back. The DMK camera's are planetry imagers which is why they do not have a ST4 port on the back. That said if you used the DMK as a guider you will need to direct the correction signal via a laptop and GUSB to convert the signal into a langauge the mount understands. You do not need this with the QHY5 which can be plugged directly into the mounts autoguider port.

Mark

[damo_Melbourne (Damian)]

Thanks for explaining Mark,
Ive put an order in for the QHY5
cheers
Damian

[marki]

They are good little autoguiders and do the job well

Mark