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Getting Started with a Nexstar 8SE

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#1 Adge87

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Posted 12 January 2019 - 02:10 AM

Hi all, sorry if this is in the wrong place.

I received a Celestron Nexstar 8SE for Christmas (with standard single arm Alt-Az mount) and having stuck to visual thus far, I am interested in dipping my toes in the pool that is A.P.

Now, I am under no illusions as to what can be achieved with what I have (an F/10 on a single arm Alt-Az), so I'm not expecting to be able to produce the stunning images taken with faster scopes on GEMs, but I'd still like to take a few tentative steps into the world of A.P. regardless.

I already have a DSLR camera (A Canon EOS 4000D) and a T-Ring and barrelled adapter that fits into the Star diagonal, but I have a few questions:

Most importantly, what should I be looking to acquire/upgrade first? I have my eye on a GEM (https://www.rotherva...mer-return.html) but with three young kids and a 4th due in the summer, 'luxury' purchases such as new mounts have to wait while I save a little so as not to impact finances quite so much.

I also have a focal reducer on the wishlist, too. But as above, it isn't something I can go out and realistically grab straight away, but it is something I'm aware I will need.

In the mean time, is there anything else one would need? Id like to grab both DSO and SS images, even if DSOs are not (currently) suitable for my set up. As I said, I'm aware of the limitations, and I'm certainly not expecting magazine standard quality images.

Also, do people use eyepieces when imaging? If so, do you require spacers or such like to provide the 'room' so that the EP doesn't impact/touch the camera mirror?

Lastly, any general tips or guidance that can help me squeeze as much as possible from my (limited) set up?

Thanks all! Sorry if a newbie looking to use unsuitable set ups for AP causes some brains to explode ;) :D

#2 james7ca

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Posted 12 January 2019 - 03:06 AM

You probably don't want to use your diagonal when imaging so you'll need to get Celestron's t-adapter that will replace the visual back on the 8SE. That combination will work best for DSOs and wide-field pictures of the moon.

 

Here is the t-adapter I am talking about:

 

 https://www.celestro...rain-telescopes

 

Beyond that and for planetary and high-magnification lunar work you probably want to get a barlow which means that you are most likely going to have to go back to the "barrelled adapter" that fits your diagonal (but, you still want to avoid using the diagonal if possible).

 

So, for the barlow the image train MIGHT look like the following:

 

8SE -> visual back -> barlow -> your "barrelled adapter" -> your T-Ring for the camera -> DSLR

 

There are multiple ways to do this setup so the above is not your only option.

 

The "visual back" is the adapter that attaches directly to the back of the 8SE and that is where your diagonal is inserted when using an eyepiece. I'm assuming that your "barrelled adapter" has either a 1.25" or 2" male eyepiece tube on one end and a male t-thread on the other (the latter connecting to your camera's t-adapter). But, I don't know if that is what you are talking about.

 

The only other thing you might want right away is a dew shield and perhaps even a dew heater. But, that will depend upon how much humidity you have and whether you ever have dew in the evenings or mornings.

 

As for the diagonal, you can use it if you like but it would be better to connect things as directly as you can.


Edited by james7ca, 12 January 2019 - 03:06 AM.


#3 Dynan

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Posted 12 January 2019 - 03:57 AM

Great advice from James above!

 

I might add:

 

A hair dryer will help control dew until you can get dew strips and controllers (surprisingly expensive).

 

The 8SE (also my first scope) is mounted almost to its limit with the OTA (optical tube assembly alone weighs 11 lbs, where the capacity of the 8SE is listed at 12 lbs.), so don't try and add too much gear.

 

If you're going to attach the DSLR, be careful about slewing toward zenith. There isn't much clearance between the lower mount and the OTA.

 

Imaging with the stock Atl/Az mount causes images to 'rotate', so keep your exposures short...30 seconds or less. Experiment and you'll find your sweet spot. You might want to get an Intervalometer to keep the scope from shaking when you press the shutter button. Here're some ideas (I didn't see the 4000D listed, but you can look into if it fits your camera:

 

https://www.amazon.c...d=1R79R0MIVS4GC

 

Image in RAW mode if possible. You'll then need to 'stretch' the image to get the full color and detail. There are some free programs you can download that will do this stretching for you. Shoot JPEG if you don't want to go through this immediately.

 

Let us know how it's going! And Welcome to Cloudy Nights!


Edited by Dynan, 12 January 2019 - 04:51 AM.


#4 BQ Octantis

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Posted 12 January 2019 - 04:00 AM

No worries at all, mate. Welcome to Cloudy Nights!

 

Since you already have a DSLR and a T-thread adapter, an EQ mount with an autoguider is your biggest bang for the buck for DSO AP. You can probably already experiment with your Alt/Az with 8-30 second subs (at IS0 1600-3200)—as James already mentioned, just bypass the diagonal and plug the nose directly into the visual back. The continuous field rotation produced by the Alt/Az will mean you have to rotate your images in processing—this is significantly reduced with the EQ mount. A focal reducer will reduce edge coma, thereby increasing the size of the usable field.

 

From a budget perspective, you don't have to go with a fancy expensive mount—if you're good with a soldering iron, you could get a dumb tracking mount and hack the controller to get autoguiding. The cheapest setup I could muster would be

 

$297 - Orion SkyView Pro Mount

$145 - Dual-axis Drive Motors

$315 - Orion Magnficent Mini Autoguider

$757 - Total

 

Note that the focal length of the Magnificent Mini is only long enough for imaging through your C8 with the focal reducer. Otherwise, you'll need the Starshoot Autoguider Pro ($500)

 

Cheers,

BQ


Edited by BQ Octantis, 12 January 2019 - 04:58 AM.


#5 Adge87

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Posted 12 January 2019 - 05:39 AM

Hey, thanks for the advice and tips! I've ordered (and sanctioned with the wife!!) The adapter mentioned, so look forward to getting stuck I with that.

I never realised the mount left so little room for extra weight, so thanks for that heads up. For the time being it will just be the OTA and camera, so should hopefully be ok.

With regards to the mount, the wife has said a EQ mount will be coming my way in March (birthday) so I'm only looking at being stuck with the AltAz for a few months, and given UK skies (clouds!) that's pretty bearable and I don't feel I'll be missing loads while I wait!

At the minute I'm operating the camera via the laptop to reduce shaking with taking a picture - in your collective experiences, is it better to add the intervalometer to the shopping list, or is laptop control just as good?

Lastly, I've seen mentioned Hyperstar as an alternative to a EQ mount. Is this true that it's an alternative, or is EQ still the better choice? Id guess it is personal preference, but before I confirm either mount of Hyperstar, I'd naturally want to research both and pick afterwards. From what I have read, Hyperstar almost seems like a silver bullet, and will make AP much easier. As weird as it may sound, I quite like the thought of extra challenge, within reason of course, for a greater sense of reward/satisfaction. Odd, I know...

Sorry for all the questions! Had I known before Christmas I'd get the AP bug, I'd have looked at a different scope and mount :D well, live and learn. Plus I still get a chill from visual astronomy, so it isn't a massive problem:D

#6 james7ca

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Posted 12 January 2019 - 05:56 AM

As BQ said, you could just remove the diagonal and "plug the nose directly into the visual back" instead of getting Celestron's t-adapter for imaging. However, if you eventually get a reducer it would be nice to have the t-adapter and besides I prefer to have as few slip-fit connections as possible (keep everything threaded).

 

As for the Hyperstar, well, that makes for a very "fast" system but it is also pretty expensive and it's not the easiest optical system to master. Image quality can be a concern and it requires very good collimation and VERY good focusing.

 

I've considering getting a Hyperstar for my C6 but the price gives me pause and besides I already have some relatively fast refractors which are much easier to use.

 

As for the intervalometer that's kind of up to you. If you want to go completely without a computer then you'll obviously need it. Otherwise, there is nothing wrong about using a computer to control the image sequence (and it can offer some advantages). Is your Canon supported by software like BackyardEOS?


Edited by james7ca, 12 January 2019 - 06:07 AM.

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#7 PETER DREW

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Posted 12 January 2019 - 06:35 AM

I don't think the 8se is compatible with Hyperstar, mine certainly isn't.



#8 BQ Octantis

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Posted 12 January 2019 - 07:47 AM

Hey, thanks for the advice and tips! I've ordered (and sanctioned with the wife!!) The adapter mentioned, so look forward to getting stuck I with that.

 

At the minute I'm operating the camera via the laptop to reduce shaking with taking a picture - in your collective experiences, is it better to add the intervalometer to the shopping list, or is laptop control just as good?

Lastly, I've seen mentioned Hyperstar as an alternative to a EQ mount. Is this true that it's an alternative, or is EQ still the better choice? Id guess it is personal preference, but before I confirm either mount of Hyperstar, I'd naturally want to research both and pick afterwards. From what I have read, Hyperstar almost seems like a silver bullet, and will make AP much easier. As weird as it may sound, I quite like the thought of extra challenge, within reason of course, for a greater sense of reward/satisfaction. Odd, I know...

By "adapter", you mean you ordered the focal reducer?

 

If you've got the money, get the Hyperstar! Nothing makes up for for good tracking, but turning your f/10 optic into an f/2 is tough to beat. But at US$1000, it's not exactly a cheap option.

 

As for camera control, I just use the built-in Canon camera functions for convenience. I often use an IR release for my T3i, but it looks like you can do wireless remote via WiFi on your 4000D—just shoot the shutter while in Live View to prevent mirror shake. But there's no end to options (intervalometers abound), and your experience will ultimately be your guide…

 

BQ


Edited by BQ Octantis, 12 January 2019 - 07:57 AM.

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#9 CharlesC

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Posted 12 January 2019 - 09:28 AM

8SE is not adequate for astrophotography, but fine for EAA.  Get a ASI224 EAA camera and visit the EAA forum here.


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#10 Dynan

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Posted 12 January 2019 - 09:32 AM

I don't think the 8se is compatible with Hyperstar, mine certainly isn't.

I have an 8SE purchased in March of last year. AFAIK all new Celestron Schmidt-Cass are labeled "Fastar Compatible" directly on the secondary housing. Mine is. Hyperstar is the new name for the discontinued Fastar. You should check for that before purchasing a Hyperstar. And Hyperstar needs the camera mounted where the secondary is, so a DSLR will take up a lot of room in an 8SE's field of view (FOV). A small cmos/ccd camera is best for Hyperstar, which may not be too expensive depending on the model, but you're talking some serious $$$ once you get into cooled cameras, but that's for farther down the road.

 

Operating the camera from the computer eliminates the 'shake' problem when taking an image. That works perfectly.

 

And a +1000 for BackYard EOS if you're going to use a Canon DSLR!!! (Nikon users use BackYard Nikon, essentially the same program.) You can try BYEOS for free for 30 days. I absolutely LOVE the program.

 

https://www.otelesco.../2-backyardeos/

 

There are great tutorials on YouTube. This one is by the creator of BYEOS:

 

https://www.youtube....h?v=z3gkw8bx7Aw


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#11 BQ Octantis

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Posted 12 January 2019 - 05:55 PM

I have an 8SE purchased in March of last year. AFAIK all new Celestron Schmidt-Cass are labeled "Fastar Compatible" directly on the secondary housing. Mine is. Hyperstar is the new name for the discontinued Fastar. You should check for that before purchasing a Hyperstar. And Hyperstar needs the camera mounted where the secondary is, so a DSLR will take up a lot of room in an 8SE's field of view (FOV). A small cmos/ccd camera is best for Hyperstar, which may not be too expensive depending on the model, but you're talking some serious $$$ once you get into cooled cameras, but that's for farther down the road.

Hyperstar is an f/2 conversion kit made by Starzona, an astrophotography outfit in Tucson. It's based on Celestron's discontinued Fastar system, but they built the system to work on any SCT.

 

Here is Celestron's knowledgebase article on the matter:

https://www.celestro...ow-do-they-work

And here is Starizona's Hyperstar page:

https://starizona.com/hyperstar/

 

And here's Starizona's order page for the C8 f/1.9 variant:

https://starizona.co.../hyperstar-8-v4

Cheers,

BQ



#12 Kendahl

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Posted 12 January 2019 - 07:40 PM

Your 8SE is fine for visual observing as well as lunar and solar photography. (You need a filter made of Baader visual film for solar which you can make yourself.) It's questionable for planetary photography with your 4000D because of image scale. (Jupiter will span only 100 pixels.) It might be adequate for photographing DSOs but you would be limited to exposures of only a few seconds at a very high ISO due to the alt-az design and plastic gears.

 

The Advanced VX mount has a checkered track record. Some are fine; others aren't. A more reliable choice is the Orion Sirius / Skywatcher HEQ5. Another one to consider is the Bresser EXOS-2GT with PMC-8 electronics. In the United States, the distributor is Explore Scientific. The mount should have a payload rating at least 50% higher than the total weight of your optical tube, camera, etc. Double is preferable.

 

Whatever your mount, you will need a source of 12 volt DC power. The 8SE will run off internal AA cells but not for very long. An external power source works much better. That can be a deep cycle battery or a 12 volt power supply fed from an extension cord to your house. Estimate the total current draw for the mount (0.5 ampere), dew heater (up to 1 ampere) and computer if you use one for photography. Buy a power supply with at least that output capability. If you choose battery power, multiply the total current by longest time you expect to observe before recharging and buy a battery with double that many amp-hours capacity. (I use a 100 amp-hour marine battery to run everything.)

 

You will need both a dew shield and a dew heater. Astrozap sells a controller and a dew shield with an embedded heater. US price for both is $180. You could make a shield yourself and, if you're handy with a soldering iron, a dew heater. DewBuster, another manufacturer of controllers, has plans for a heater (http://dewbuster.com...-resistors.html). You could save yourself the price of a controller by building three heaters -- two with 1/4 power and one with 1/2 power. Use switches to turn them on selectively to provide zero, 1/4, 1/2, 3/4 and full power. (You wouldn't need to insulate the outside of the heaters because they would be covered by the shield.)

 

You will definitely want a 0.63x reducer-corrector for photography even more than visual observing. It reduces effective focal length from 2,032 mm to 1,280 mm and cleans up optical problems at the edge of the field. (Tracking at long focal lengths is so difficult that novice photographers are usually advised begin with a focal length well under 1,000 mm.)

 

I'm puzzled by advice for using a Barlow (or focal length extender) for photography. My wife's Evolution 8 uses the same optical tube as your 8SE. The visual back is threaded for either a reducer-corrector or a diagonal. A photo back is threaded for the T-adapter specific to your camera. Either way, to use a Barlow, you need a 1¼" or 2" barrel, not threads. I suggest you discuss this with your vendor's tech support people.

 

There are many options for camera control. If you store images in the camera, you can get by with an intervalometer. The EOS utility software that came with your camera will work for exposures up to 30 seconds. Beyond that, you need specialized astronomy software. Backyard EOS, which I use, is very good and inexpensive. Eclipse Orchestrator is designed for solar eclipses but the exposure sequence can be tweaked for general use. (I plan to use it for the upcoming total lunar eclipse if the clouds go away.)

 

DSO photography works better with exposures several minutes in duration rather than several seconds. Long exposures let you use lower ISO settings which aren't as noisy. To track with sufficient accuracy, you need an autoguider. Orion sells complete autoguiding systems but you can save money by buying the guide scope and camera separately. I use this scope (https://www.astronom...-refractor.html) and this camera (https://optcorp.com/products/qhy-5l-ii-monochrome-cmos-telescope-camera) with PHD2 software. An off axis guider is a better choice for Schmidt-Cassegrain optical tubes because it eliminates the possibility of flexure between autoguider and optical tube. For wide field photography, the mount's inherent tracking accuracy is good enough that you don't need to autoguide. Put your camera and lens directly on your mount using a dovetail.



#13 james7ca

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Posted 12 January 2019 - 11:04 PM

...I'm puzzled by advice for using a Barlow (or focal length extender) for photography. My wife's Evolution 8 uses the same optical tube as your 8SE. The visual back is threaded for either a reducer-corrector or a diagonal. A photo back is threaded for the T-adapter specific to your camera. Either way, to use a Barlow, you need a 1¼" or 2" barrel, not threads. I suggest you discuss this with your vendor's tech support people...

I suggested the barlow for planetary work and for high magnification shots of the moon. The barlow should be able to be attached in the same way that you mount the diagonal (in the visual back's 1.25" eyepiece holder). But, I don't know how the diagonal attaches to the 8SE. Does it need to be threaded to the back of the scope or is there a 1.25" eyepiece holder? It's hard to tell from the pictures on Celestron's website. I know that my C6 came with a small adapter that has female SCT threads on one side (to connect to back of the scope) and a female 1.25" eyepiece holder on the other (to hold a diagonal or any other 1.25" tube). This is what is commonly called the visual back (see picture below, the one for the 8SE may not look exactly like this).

 

If using a DSLR with pixels about 4 microns in size you want to be imaging at about f/20 to get the maximum resolution from the scope/camera system. That would mean using a 2X barlow.

Attached Thumbnails

  • Visual Back for C6.jpg



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