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No wonder I can't see?

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#1 Danoglide63

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Posted 11 July 2018 - 04:13 PM

Hi, I have a Celestron Nexstar SE6 telescope with a 6.3 focal reducer and I'm trying to learn how to see Deep Space objects and maybe even capture a Nebulae or Galaxy with Sharpcap Pro. I started off just looking at planets with my 25mm EP while  waited on the ZWO ASI224MC camera to come in the mail. With the EP I did the Skyalignment on 3 different stars and looked at Jupiter and Saturn and took a few pictures with my Sony A6000 and a 2x Barlow.  I got the ZWO camera and right away I noticed that after alignment with the EP and switching over to the ZWO  I would be way off and had to re-center Jupiter and re-focus, no problem really I guess Jupiter's easy to find. Next I tried looking for Deep Space objects and I was striking out every time and not seeing anything. I know there's a lot of light pollution here but really? I'm using Sharpcap Pro and turned up and down everything trying to see something. Well...the other night I set up everything, aligned, focused on Vega with my Bahtinov mask and went looking for M57 Ring Nebulae, OMG there it was way up in the top left corner! This makes me wonder that alignment with the EP and switching over to the ZWO why I couldn't find anything? I always do the Precise Goto procedure and check focus on the star with the mask and hit Enter and go back to what DSO I was looking for.

 

I'm guessing if I intend to use the ZWO camera I should align with the ZWO camera? I'm using a 2x Barlow too so does it have to be included while aligning?

 

Thanks everybody,

Dano


Edited by Danoglide63, 11 July 2018 - 04:15 PM.


#2 Gipht

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Posted 11 July 2018 - 04:44 PM

Well I was trying to figure what eyepiece the ASI224MC would be equivalent too,  and I am guessing in the range of 15  to 20mm.  The field of view, because of the chip size would probably be much smaller then an equivalent eyepiece.  The ASI224MC is designed for solar system viewing,  so its default settings are set up for very bright objects in comparison with the ring nebula.  Here are some possibilities.

 

1)  The settings on the ASI224MC did not allow for enough light to pick up the very dim ring nebula.

 

2)  The ring nebula was not in the smaller field of view.

 

3)  The telescope was not properly focused for the ASI224MC.

 

You should not have to use the barlow, to bring the camera into focus.  What I would try is to align on Vega with just the ASI224MC, and focus with the Bahtinov mask.  Play with the settings on the camera by increasing the gain and exposure until Vega is reasonably bright.  Then try and find Deneb, also a bright star.  Then you might try to find M27, the Dumbell Nebula,  as a fairly easy target.  My guess is the ring Nebula could possibly be out of the range of the ASI224MC.  It won't hurt to try and find it though.



#3 bobzeq25

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Posted 11 July 2018 - 04:56 PM

Imaging DSOs is utterly different than planetary imaging.

 

Planets are sunlit, it's like taking a snapshot.  Even bright DSOs are orders of magnitude dimmer, it's like taking a telephoto picture at night, in the countryside.  From a moving car.  <smile>

 

It's complicated and expensive.  Your excellent scope is not suitable (DSO imaging is very far from intuitive).  Two recommendations.

 

This book.

 

http://www.astropix....bgda/index.html

 

Putting any further photography questions in the Beginner and Intermediate Imaging forum.  The moderators like to keep the Beginner forum uncluttered.

 

Minor point.  How I (and many other imagers) locate DSOs.  We GOTO the general vicinity, take an image, and platesolve it.   Computerized pattern recognition that tells us exactly where we're pointed.  Then we correct.


Edited by bobzeq25, 11 July 2018 - 04:58 PM.


#4 Gary Z

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Posted 11 July 2018 - 05:02 PM

With the ZWO Camera and a 2x barlow, you will certainly have higher magnification and even narrower FOV which could make alignment take you a little longer, but it can be done.  I've done alignment with my Canon using the grid display and it works wonderfully!

 

With the higher magnification, you will also encounter the shortcomings of the SE Mount, meaning, you'll encounter drift and away from the target.  When the 224 camera first came out, some folks on NSN used the 224 camera on equatorial mounts and it was amazing what they could pull from it.  But you are also talking about exposures lasting a few minutes.  The SE Mount, as much as I love mine, just can't do that. You'll be all over the place and even with the EVO Mount, the same applies. 

 

However, for planetary, lunar, and solar imaging, the 224 and the SE mount will do fine, and I've had considerable  success using the SE and EVO mounts with the 224. 

 

There are cameras like the Atik Infinity, that will give you a better chance of imaging the DSOs, but don't expect high quality imaging as you would with using an equatorial mount and guiding....still, its a fun time just in the effort. 

 

Take care,

 

Gary


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#5 xiando

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Posted 11 July 2018 - 06:04 PM

 

I'm guessing if I intend to use the ZWO camera I should align with the ZWO camera? I'm using a 2x Barlow too so does it have to be included while aligning?

if you're using a camera, as long as you've star aligned and centered your target using an eyepiece (or the camera "live view (one way if it doesn't have a "live view" mode is to use short 1-5 sec images and disable image save during the tuning process), you shoud be fine on that count.

 

As for barlows and imaging, especially when imaging with a long focal length scope like the SEseries, you're going to likely run into troubles unless you confine yourself to bright targets....the moon, bright starfields, bright globs like M13, a few bright DSOs like M42 when  it comes back, possible the ring nebula, and dumbell,  but if in alt-az mode, you're going to probably have to toss a lot of subs, and at a guess, even in eq mode it won't be "easy". (ime)

 

It's not that it "can't be done",  but having done similar things myself (I started out in imaging using an old Nexstar 130 SLT and a guide camera as my "main" camera, and 1-10sec exposures...hundreds and hundreds for each target) it's not easy even with a shorter focal length scope, and applying a barlow made my good-to-bad light-sub ratio drop to ~1:10 or 2:10 from it's normal alt-az ~5:10

 

It's the weeding of image sets before stacking that gets really tedious.


Edited by xiando, 11 July 2018 - 06:05 PM.

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