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Celestron 6/8SE and Autoguiding - n00b questions

astrophotography equipment imaging
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#1 DVE

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Posted 23 October 2016 - 05:35 AM

Hi all,

 

I am new in this forum, so I'm sorry if it was discussed, I tried to make a search but didn't find the complete answer.

So, yesterday I've got my telescope, Nexstar 6SE, and I want to figure out, what setup I need for autoguiding.

 

What I have now:

- Nexstar 6SE. It has autoguide port, so I think, it should work.

- ASI290MC camera, will arrive to me at the middle of the week.

- Sony NEX5, can be connected to a telescope also, I saw T-adapters on Ebay

 

And some of noobs questions, I have:

 

1) I need a second small tube for autoguiding. Which one to choose, and how to connect it to the scope? Are there some adapters/connectors on ebay?

I saw "Celestron Guidescope Package", is it what I need? Its pretty expensive, btw. And I don't understand yet how to place it on my tube (duct tape will be not enough? ;) ).

"ZWO 60MM F/4.6 Guidescope" looks also pretty nice, but I don't understand how to mount it on the tube too.

 

Or maybe the "Celestron off-axis guider" is better? I like that it's pretty compact.

 

I live in the city and the telescope will be placed on the balcony, so I'm not going to use very long shutters anyway - too much light in the city, and 6/8SE mount, I think, is not mechanically perfect.

 

2) Do I need a wedge, or with small shutters (less tham a minute) it does not matter? I rent a flat, so I don't want to buy a lot of heavy things. And its $379, expensive for the piece of metal, btw.

 

3) ASI290MC, it has the autoguide port too. Can I connect it directly to the 6SE mount, or the pinout is different? Do I need to buy the additional cable? After I connect it, can I autoguide through the camera USB connecton only?

And it looks stupid to use 500$ camera for autoguiding only, maybe there are cheap alternative ways? 

 

I'll appreciate the ebay (or other shop) links to the stuff, I need to buy.

Thanks.


Edited by DVE, 23 October 2016 - 07:22 AM.


#2 Tel

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Posted 23 October 2016 - 05:53 AM

Hi DVE,

 

Welcome to CN and to this forum !  :bow:  :bow:

 

The first thing, unfortunately, to note is that you cannot auto-guide from the original 6SE  Alt./Az. mount. Your scope needs either to be wedge mounted, (personally not recommended), or its tube, (OTA), placed on a German equatorial mount (GEM).

 

The basic reason for this is that in trying to use the existing Alt./Az. mount for any exposure times much in excess of say, 30 seconds, your images will be subjected to field rotation, an effect which in essence will cause star trailing. This however does not apply to taking images of the Moon or the planets via a high frame rate video camera several of which are available.

 

Best regards,

Tel


  • Augustus, Noah4x4 and DVE like this

#3 DVE

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Posted 23 October 2016 - 06:00 AM

Thanks, I know this, thats why I wrote in "2" about short shutters, not more than 30s. Or you think, it will not work anyway?

I cannot put German eq.mount on the balcony now, its too small. Maybe later, on a new apartment :)

 

I was hoping, I can make 10-30s shutter photos and stack tham with a software, its better than nothing.



#4 Tel

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Posted 23 October 2016 - 06:25 AM

Hi DVE,

 

Yes you can deep sky image from your standard 6SE mount so long as you keep each frame exposure short, (say <30secs). You will just have to experiment but obviously stick to those deep sky objects which are relatively bright, (for example, the Orion Nebula M42).

 

Stack and process your images in something like DSS (DeepSky Stacker), and for further processing, Adobe Photoshop CS2 is now freely available to you.

 

Here's the link to down load it if you so wish.

 

http://www.techspot....toshop-cs2.html

 

Best regards,

Tel

.


Edited by Tel, 23 October 2016 - 06:26 AM.


#5 lenrabinowitz

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Posted 23 October 2016 - 06:28 AM

You can get ok photos of DSOs from an alt-az mount, but you are limited to the brighter ones and to 20-30 second exposures max.  Stacking will help, but you will never get the kind of results a GEM will get.  You might look at the 8HD Nexstar Evolution.  Easy to set up, and the HD design is photography oriented.



#6 DVE

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Posted 23 October 2016 - 07:31 AM

Thanks all, guys, for the hints.

I appreciate this, but software for me is a not a problem (I'm a software developer and work in image processing area btw).

 

Main issue for me now, is a hardware - how to connect all this stuff together? How can I put the guide cam on my 6" scope? Which adapters/mounts I need?



#7 lenrabinowitz

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Posted 23 October 2016 - 08:32 AM

You'll have to have a wedge.  Without a wedge, no autoguiding.



#8 CharlesC

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Posted 23 October 2016 - 08:50 AM

I have 6SE too.  The 6SE mount is to crude for autoguiding.  I've made a time lapse video and objects bounce around 5arcmin in half hour.  That is huge.  I've seen somewhat successful attempts at autoguiding using a wedge, but difficult.

 

The 6SE can take up to 30 second exposures okay without autoguiding.  Its ideal for Video Astronomy (or EAA) which use high sensitivity low resolution video cameras.  The OTC Revolution2 camera is ideal and only $99 in non-kit form.  I use a LN300-PAL camera which is based on the same CCD sensor, the ICX811.  Here are my best 6SE pics.



#9 Tel

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Posted 23 October 2016 - 12:43 PM

 

 

Main issue for me now, is a hardware - how to connect all this stuff together? How can I put the guide cam on my 6" scope? Which adapters/mounts I need?

As explained by those above in their respective posts, you cannot guide an Alt.AZ. mount unless you either place it on an equatorial wedge or the tube, (OTA) on a GEM.

 

I would additionally reiterate that having had past experience with a wedge, I would never recommend its use : one reason being that the single arm mount's balance with the OTA in place is one of an ever changing nature depending on whether the OTA is resting on or hanging from the arm.

 

Placing your tube on a GEM is an entirely different matter and will doubtlessly bring DSO imaging success.. BY this means, your guide scope and camera can be attached to the OTA and its subsequent guiding be monitored on LT screen by making use of something like Craig Stark's PHD2 software.

 

Best regards,

Tel



#10 DVE

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Posted 23 October 2016 - 01:02 PM

Ok, thanks all guys, I undersood :)

The first thing for putting in my future shopping list, is "Celestron 6se equatorial wedge". £350, omg...

What I need more? (I have a feeling, that its only the start of the route :) )

 

CharlesC, thanks for sharing photos, looks nice.


Edited by DVE, 23 October 2016 - 01:02 PM.


#11 lenrabinowitz

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Posted 23 October 2016 - 08:43 PM

I found the wedge frustrating and confusing also.  Ended up just going with a cgem mount.



#12 Tel

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Posted 24 October 2016 - 01:51 AM

Notwithstanding the necessary use of inferior spur gearing rather than almost backlash free worm drive, as dictated by the 6SE/8SE mount.



#13 DVE

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Posted 24 October 2016 - 06:48 AM

It looks like, the wedge can be done from the wood, btw who knows the proper bolts/nuts size at the bottom of the mount?

And it would be definitely cheaper than £350.



#14 CharlesC

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Posted 24 October 2016 - 09:01 AM

I'm only aware of one person, Jeff, that managed to do astrophotography with the 6SE.   I don't think he kept at it for long as its just not accurate enough to use this way.  The 6SE is great at short exposure times used with Video Astronomy cameras using real-time stacking software such as SharpCap.  I'd advise you look into that route in the EAA forum here.  Even then, I don't think the 6SE is a good fit for anything but the fastest EAA video cameras such as;  Revolution1/2,  LN300,  Lodestar X2c.  My LN300 can go to 20 seconds exposures, but I find that difficult on 6SE, and so limit its use to 10 second exposures.  These fast EAA cameras can capture a lot of faint detail in those short exposures, but astrophotography cameras and DSLR require much longer exposure times requiring far better EQ mounts such as AVX or CGEM.



#15 DVE

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Posted 25 October 2016 - 01:31 AM

Thanks for sharing.

Something like this http://s15.photobuck...to0616.jpg.html on his page, I think to make the wooden wedge is not too hard, and will cost 10-20$ in the local shop.

(But the center of gravity looks scary a bit, btw :) )


Edited by DVE, 25 October 2016 - 01:33 AM.


#16 Nicole Sharp

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Posted 24 July 2018 - 05:54 PM

While I agree that the wedge and spur gears may not be good for autoguided long-exposure deep-sky astrophotography, what about autoguiding for short-exposure planetary astrophotography?  Normally, autoguiding isn't necessary for planetary imaging, but it can still be useful.  Has anyone had any success with this for the 6SE or 8SE?




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