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Celestron 6se, astrophotography

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#1 Abzmouse

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Posted 19 June 2017 - 10:49 AM

Can anyone help me with this,I'm using a celestron nexstar 6se telescope, I haven't had the chance to get a vx mount,I find that I can't do astrophotography because of the standard mount that came with it and only get exposures upto 40 seconds before pictures get blurry and messy.would a celestron autogider work and keep the object in view and work for astrophotography, because I read a few reviews from users doing this, and are very pleased with the results their getting but I still haven't seen how the pictures come out,if this is true should I buy a autogider or buy the vx mount instead, if the if the autogider does the job I'd rather use that because of the weight of a vx mount.any suggestions or advice please on best options.

#2 Augustus

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Posted 19 June 2017 - 10:53 AM

It will need an autoguider and the VX.

 

The SE mount is alt-azimuth and thus won't be good for over 40s exposures even with an autoguider due to field rotation. The VX mount needs an autoguider at 1500mm focal length due to tracking errors.



#3 GaryCurran

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Posted 19 June 2017 - 10:55 AM

You really need to post this in the Basic and Intermediate Imaging forum.  But, I'll answer your question for you.

 

An Alt/Az mount like the one on the 6SE does not have the ability to compensate for the Earth's rotation.  There are two ways to combat that.  One, you can mount the telescope on a 'Wedge', which is a device that sits between the tripod and the actual mount, and the wedge will tilt the entire mount up at an angle equal to your latitude.

 

Secondly, and the better solution, is to purchase an German Equatorial Mount, like the AVX.

An Autoguider will not stop field rotation, which is what is causing your problems.  If you purchase a wedge, OR, the AVX, an Autoguider will help to keep your target centered, but will not, can not, overcome the inherent design limitation of an Alt/Az mount.

 

You can click on the 'Notify Moderator' link at the bottom of the post and ask this to be moved to the BI&I forum.


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#4 mistateo

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Posted 19 June 2017 - 01:38 PM

You really need to post this in the Basic and Intermediate Imaging forum.  But, I'll answer your question for you.

 

An Alt/Az mount like the one on the 6SE does not have the ability to compensate for the Earth's rotation.  There are two ways to combat that.  One, you can mount the telescope on a 'Wedge', which is a device that sits between the tripod and the actual mount, and the wedge will tilt the entire mount up at an angle equal to your latitude.

 

Secondly, and the better solution, is to purchase an German Equatorial Mount, like the AVX.

An Autoguider will not stop field rotation, which is what is causing your problems.  If you purchase a wedge, OR, the AVX, an Autoguider will help to keep your target centered, but will not, can not, overcome the inherent design limitation of an Alt/Az mount.

 

You can click on the 'Notify Moderator' link at the bottom of the post and ask this to be moved to the BI&I forum.

I am going to reiterate that Gary said 'better solution' is the EQ mount.  It may be tempting to go the cheaper route with a wedge, but I would definitely advise against it.  Just some quick googling will revel many conversations of frustrated budding astrophotographers dealing with wedges.  I am not saying it can't be done, or done well, but as a beginner the less variables you have to deal with, the better.



#5 Ken Sturrock

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Posted 19 June 2017 - 02:05 PM

Moving to B&II. Thanks.



#6 poobie

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Posted 19 June 2017 - 08:40 PM

 

I am going to reiterate that Gary said 'better solution' is the EQ mount.  It may be tempting to go the cheaper route with a wedge, but I would definitely advise against it.  Just some quick googling will revel many conversations of frustrated budding astrophotographers dealing with wedges.  I am not saying it can't be done, or done well, but as a beginner the less variables you have to deal with, the better.

 

 

I've got a 6SE and the SE wedge, and I'll vouch for this as well.  I've shot some stuff with it that came out OK, but mostly it's just been frustrating.  polar alignment, while not impossible, is non-trivial.  Even when you do get it well polar aligned, the geartrain is going to limit your guiding performance.  IIRC, the best I've gotten out of it is 2" RMS. 

 

All that said, I still use it from time to time because it's lighter and uses less power than my AVX.  It's perfectly manageable for short exposure work, but you have to work within its limitations.  

 

I got the AVX because it was on sale, and at that price, significantly cheaper than anything else in its class; if I had to do it over, I'd probably get the PMC-8 version of the EXOS-2GT that ES is selling now.



#7 GaryCurran

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Posted 19 June 2017 - 10:57 PM

In regards to what Matt said about the AVX, as an AVX owner, I've had to do considerable work to it to make it function the way I think it should.  If you are going to buy new, I agree that the Explore Scientific EXOS-2 GT with PMC-8 is the way to go.  It's the same class mount, based on the older, reliable Meade LXD75, except it has updated motors and a belt drive system.

 

https://www.optcorp....lectronics.html

 

At the same price as the AVX, right now, it's a no-brainer, at least to me.

 

https://www.youtube....mNPajsd9H4&t=7s

 

However, if you purchase an used AVX, you usually can rebuild it to make it work pretty well, much better than what it was before.  You can find my thread on rebuilding the AVX in this forum, somewhere.



#8 Cajundaddy

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Posted 19 June 2017 - 11:06 PM

Short exposures less than 30 sec, the SE mount will work.  It is light and convenient to use but the wrong tool for long exposure AP.  For that you will want the biggest, heaviest, most precise mount you can get.  Anything less will bring disappointment and frustration with long exposures.  Yes we have all tried to do it.  No the pics didn't turn out the way we planned.


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#9 mistateo

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Posted 20 June 2017 - 01:33 PM

Short exposures less than 30 sec, the SE mount will work.  It is light and convenient to use but the wrong tool for long exposure AP.  For that you will want the biggest, heaviest, most precise mount you can get.  Anything less will bring disappointment and frustration with long exposures.  Yes we have all tried to do it.  No the pics didn't turn out the way we planned.

I even attempted to do guided long exposures on a cg4 with dual axis motors, it wasn't worth the time, especially since the minimum speed was 2x.



#10 mikefulb

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Posted 20 June 2017 - 02:25 PM

If you have a local astronomy club then go and meet with some established imagers and you will see what a solid imaging setup looks like.



#11 rigel123

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Posted 21 June 2017 - 01:29 PM



Can anyone help me with this,I'm using a celestron nexstar 6se telescope, I haven't had the chance to get a vx mount,I find that I can't do astrophotography because of the standard mount that came with it and only get exposures upto 40 seconds before pictures get blurry and messy.would a celestron autogider work and keep the object in view and work for astrophotography, because I read a few reviews from users doing this, and are very pleased with the results their getting but I still haven't seen how the pictures come out,if this is true should I buy a autogider or buy the vx mount instead, if the if the autogider does the job I'd rather use that because of the weight of a vx mount.any suggestions or advice please on best options.

It all depends upon what kind of images you want to get, I don't see an autoguider making that much of a difference with an Alt/Az mount, but you can use your set up to learn some basics about collecting lights, darks, flats and basic processing skills.  I started out with a Meade LS6, basically the same set up you have.  I was able to get decent shots using lots of 30 second exposures and learned processing this way.  Of course, like so many others, I wanted better and ended up with a big EQ mount with a small scope and the images got much better.  But below are some images I took with a setup similar to yours with 30 second exposures and no guiding.

 

get.jpg

get.jpg

get.jpg



#12 Lead_Weight

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Posted 21 June 2017 - 03:31 PM

I have personally been down this exact route with my 6SE. See here an issue you will face with the wedge. I wouldn't want to dissuade you from using your 6SE for imaging, as it can capture some cool images. For starting out it's great. Over time, I personally grew frustrated at some of it's limitations (poor coma being one one of them). It starts to get costly trying to correct out optical problems from this scope and you'll eventually want one that doesn't have the issues to start. But it's still great to learn with. Because of it's increased focal length, you will want an auto guider. I didn't use one in a lot of my early images, and it shows. It took me a year to get really comfortable doing astrophotography, and I eventually went to an APO to get higher quality images than I couldn't get with the 6SE. Check out the site in my signature for photos and info on this particular scope and why I switched to the AVX. I don't have a ton of info on there yet, but you can see some images I've taken with it.



#13 bobzeq25

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Posted 21 June 2017 - 03:56 PM

Can anyone help me with this,I'm using a celestron nexstar 6se telescope, I haven't had the chance to get a vx mount,I find that I can't do astrophotography because of the standard mount that came with it and only get exposures upto 40 seconds before pictures get blurry and messy.would a celestron autogider work and keep the object in view and work for astrophotography, because I read a few reviews from users doing this, and are very pleased with the results their getting but I still haven't seen how the pictures come out,if this is true should I buy a autogider or buy the vx mount instead, if the if the autogider does the job I'd rather use that because of the weight of a vx mount.any suggestions or advice please on best options.

Best option.  Get an AVX and put a camera and a lens on it.  When you can do nice images (ie ones you like) that way, move up to a small refractor.  Nothing longer than 600mm.

 

Scroll down to the picture of the author of this (recommended) book.  That weird looking setup is _exactly_ what you want for getting into AP of DSOs.  Recommended by all the experts, and by many here who tried starting out with an SCT.  Quote below, not mine.  I have many more.

 

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

 

I'll disagree with the poster above.  With a lens or small scope, you can learn astrophotography.  With an SCT you'll learn how to fiddle with the scope.  Like driving nails with a crescent wrench, it's the wrong tool for the job.

 

"Of all the recommendations though, if you want to get into imaging then a short imaging refractor is probably the best one (IMHO).  I have a C8 and this was the scope I learned AP on.  It was a long, tough struggle and I have no good pictures to show for it.  I could have easily saved a year by starting with a more image-friendly scope."



#14 Lead_Weight

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Posted 21 June 2017 - 04:41 PM

I'll disagree with the poster above.  With a lens or small scope, you can learn astrophotography.  With an SCT you'll learn how to fiddle with the scope.  Like driving nails with a crescent wrench, it's the wrong tool for the job.

Since I did learn on an SCT, this exact one, I think I'm living proof it can be done. I think the quality of the results will be much better, if you start out with a shorter focal length, but the process is basically the same. But I do agree, it helps to have a proper mount.



#15 AstroPics

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Posted 22 June 2017 - 03:19 PM

A few additional complications of a SCT vs. a APO refractor based on my experience. Most are surmountable but I would say improved guiding accuracy is the major item to keep in mind. If you go with an SCT, just remember to run through your checklist each night with focus and collimation.

 

  • You'll need a coma corrector and probably want a focal reducer for good AP. I'd recommend Starizona but that alone is around $399. Otherwise, you will have bad coma in your images.
  • Guiding needs to be a lot more accurate. The camera pixel size will be a lot smaller than a small APO. Better guiding translates to either a higher quality EQ mount and auto-guiding (OAG recommended). Additional costs.
  • Mirror flop and focus. It is a lot harder to get good focus on an SCT (but if you do it, remember to always approach focus counter-clockwise). You should generally re-check your focus after a meridian flip as well to ensure you are still properly focused.
  • You need to collimate it. Not a big deal but something you will have to do initially and re-check periodically. I recommend checking it at the beginning of an imaging session just to make sure it is still collimated.


#16 overnight

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Posted 25 June 2017 - 09:33 PM

It will need an autoguider and the VX.

 

The SE mount is alt-azimuth and thus won't be good for over 40s exposures even with an autoguider due to field rotation. The VX mount needs an autoguider at 1500mm focal length due to tracking errors.

The mount doesn't decide the FL of the autoguider. The scope does. It should be roughly 1/3 of the scope's FL by a old rule of thumb which I may not follow...

 

A 1500mm FL guidescope would work with a 4500mm FL scope, which one shouldn't use for AP.


Edited by overnight, 25 June 2017 - 09:36 PM.


#17 GaryCurran

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Posted 26 June 2017 - 01:23 AM

 

It will need an autoguider and the VX.

 

The SE mount is alt-azimuth and thus won't be good for over 40s exposures even with an autoguider due to field rotation. The VX mount needs an autoguider at 1500mm focal length due to tracking errors.

The mount doesn't decide the FL of the autoguider. The scope does. It should be roughly 1/3 of the scope's FL by a old rule of thumb which I may not follow...

 

A 1500mm FL guidescope would work with a 4500mm FL scope, which one shouldn't use for AP.

 

I believe you'll find what Augustus was saying, and I'll agree with him, is that the AVX mount isn't accurate enough for unguided images with a scope above 1,500mm in focal length, hence an autoguider is necessary to keep it on target.


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#18 overnight

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Posted 26 June 2017 - 01:37 AM

 

 

It will need an autoguider and the VX.

 

The SE mount is alt-azimuth and thus won't be good for over 40s exposures even with an autoguider due to field rotation. The VX mount needs an autoguider at 1500mm focal length due to tracking errors.

The mount doesn't decide the FL of the autoguider. The scope does. It should be roughly 1/3 of the scope's FL by a old rule of thumb which I may not follow...

 

A 1500mm FL guidescope would work with a 4500mm FL scope, which one shouldn't use for AP.

 

I believe you'll find what Augustus was saying, and I'll agree with him, is that the AVX mount isn't accurate enough for unguided images with a scope above 1,500mm in focal length, hence an autoguider is necessary to keep it on target.

 

Oh, got it.

 

Its also dependent on weight.


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