NexStar 8SE
« on: September 28, 2021, 10:35:26 PM »
I have been huge space fan since...well, forever. Never got to actually order a proper tool.

So, now I did and can't wait to get it

https://lovethenightsky.com/celestron-nexstar-8se-review/

My question is, do any of the FE people have telescopes? You can get a decent one for like 600$, cheaper second hand.

Many of FE speak about that there is no space, or how to explain moons around other planets if UA was in play, or why does whole universe move up at 1G, constantly, moving almost at speed of light - are telescopes also fake? Like movie cameras?

Anyway, can't wait! Movie or not, it's gonna be a lot of fun!

Re: NexStar 8SE
« Reply #1 on: October 22, 2021, 06:13:35 AM »
You can get a decent scope for well under $600. Any cheap equatorial mounted scope will demolish the notion of a sun/moon/stars going in a circle above a flat plane.

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Offline Tom Bishop

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Re: NexStar 8SE
« Reply #2 on: October 22, 2021, 06:29:02 AM »
You can get a decent scope for well under $600. Any cheap equatorial mounted scope will demolish the notion of a sun/moon/stars going in a circle above a flat plane.

Have you ever used an equatorial mounted scope? They only work for a few minutes before drifting off of the target star.

-----

$700 Equatorial Mount - https://www.amazon.com/gp/product/B07NY44782/

https://www.amazon.com/gp/product/B07NY44782/ref=ask_ql_qh_dp_hza

"Question: When polar aligned north, can you use a ball head mount to rotate your camera 180* to capture the southern sky without trailing?

Answer: Hi Doyle, YES! Once the head is aligned, move your camera wherever and it will track the object for up to 5 minutes when using a wide-angle the lens. A telephoto (200mm) can only go about 2 minutes."

---

In this one, on a page called "Equatorial Mount Tracking Errors" the author shows stars which drift out of shot within a short amount of time on an EQ mount.

http://www.pk3.org/Astro/index.htm?astrophoto_mount_errors.htm

Quote
Equatorial Mount Tracking Errors

~

"Capture Selected Frames capture mode was selected with period 1 second (exact period was 1.11s)."


---

Other types of advanced EQ mount packages are computerized with multiple motorized axis' and have cameras for optical guide tracking and following of a target star, and are more reliable, but this isn't what you're referring to.

Unguided mounts can only track for short amounts of time:

https://starizona.com/blogs/tutorials/exposure-times



https://web.mit.edu/wallace/instruments.html


« Last Edit: October 22, 2021, 06:46:47 AM by Tom Bishop »

Offline SteelyBob

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Re: NexStar 8SE
« Reply #3 on: October 22, 2021, 09:04:48 AM »
I have been huge space fan since...well, forever. Never got to actually order a proper tool.

So, now I did and can't wait to get it

https://lovethenightsky.com/celestron-nexstar-8se-review/

My question is, do any of the FE people have telescopes? You can get a decent one for like 600$, cheaper second hand.

Many of FE speak about that there is no space, or how to explain moons around other planets if UA was in play, or why does whole universe move up at 1G, constantly, moving almost at speed of light - are telescopes also fake? Like movie cameras?

Anyway, can't wait! Movie or not, it's gonna be a lot of fun!

We've been here before - see https://forum.tfes.org/index.php?topic=17660.msg232068#msg232068

After a long thread with lots of really interesting evidence, including some fantastic videos, discussion about periodic and cumulative errors which seemed to pass some people by completely, we ended up with the go-to get out clause: 'all the videos and photos could be faked'.

It's entirely true, of course - they could be faked. It's just that there is a much more likely explanation...

Re: NexStar 8SE
« Reply #4 on: October 26, 2021, 06:07:41 AM »
You can get a decent scope for well under $600. Any cheap equatorial mounted scope will demolish the notion of a sun/moon/stars going in a circle above a flat plane.

Have you ever used an equatorial mounted scope? They only work for a few minutes before drifting off of the target star.

-----

$700 Equatorial Mount - https://www.amazon.com/gp/product/B07NY44782/

https://www.amazon.com/gp/product/B07NY44782/ref=ask_ql_qh_dp_hza

"Question: When polar aligned north, can you use a ball head mount to rotate your camera 180* to capture the southern sky without trailing?

Answer: Hi Doyle, YES! Once the head is aligned, move your camera wherever and it will track the object for up to 5 minutes when using a wide-angle the lens. A telephoto (200mm) can only go about 2 minutes."

---

In this one, on a page called "Equatorial Mount Tracking Errors" the author shows stars which drift out of shot within a short amount of time on an EQ mount.

http://www.pk3.org/Astro/index.htm?astrophoto_mount_errors.htm

Quote
Equatorial Mount Tracking Errors

~

"Capture Selected Frames capture mode was selected with period 1 second (exact period was 1.11s)."


---

Other types of advanced EQ mount packages are computerized with multiple motorized axis' and have cameras for optical guide tracking and following of a target star, and are more reliable, but this isn't what you're referring to.

Unguided mounts can only track for short amounts of time:

https://starizona.com/blogs/tutorials/exposure-times



https://web.mit.edu/wallace/instruments.html



You misunderstand the difference between “a few minutes before drifting off the target star” and “maximum exposure time” before a star starts to blur in an image/the background becomes too bright for usable images.
Apart from these misunderstandings, a proper alignment, not just a rough alignment on the star Polaris, is extremely important. Also important is getting your latitude correct, very precisely. Likewise, gears and cogs can only be so accurate. Any slop or play will affect tracking.

Disregard all this, and take a time lapse photograph of the night sky. You will see each star makes a concentric circle in the night sky. This is impossible With overhead stars circling around a flat plane.

We are getting off topic. I hope OP  enjoys his new telescope. I suggest looking at Jupiter and it’s moons while it’s in the sky! Just after dark is probably the best time!

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Offline Tom Bishop

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Re: NexStar 8SE
« Reply #5 on: October 26, 2021, 06:49:18 PM »
Quote from: Astronomer
You misunderstand the difference between “a few minutes before drifting off the target star” and “maximum exposure time” before a star starts to blur in an image/the background becomes too bright for usable images.

You misunderstand the difference between providing an argument with appropriate sources and pulling something out of one's rear end. You have provided no sources for this, and therefore it is the later.

If the limitation is the camera exposure then on the MIT telescope why, exactly, is the limit for an unguided mount max exposure only up to 5 minutes, while the exposure for guided mount is listed as 60 minutes plus?

This is a catastrophe of an argument. But really, it is obvious that this argument is no mistake. You clearly just came here to make things up and lie to us.
« Last Edit: October 26, 2021, 07:14:09 PM by Tom Bishop »

Re: NexStar 8SE
« Reply #6 on: October 26, 2021, 08:09:20 PM »
Quote from: Astronomer
You misunderstand the difference between “a few minutes before drifting off the target star” and “maximum exposure time” before a star starts to blur in an image/the background becomes too bright for usable images.

You misunderstand the difference between providing an argument with appropriate sources and pulling something out of one's rear end. You have provided no sources for this, and therefore it is the later.

If the limitation is the camera exposure then on the MIT telescope why, exactly, is the limit for an unguided mount max exposure only up to 5 minutes, while the exposure for guided mount is listed as 60 minutes plus?

This is a catastrophe of an argument. But really, it is obvious that this argument is no mistake. You clearly just came here to make things up and lie to us.

Tom, I don’t need to cite the sources you yourself have already provided. Your citations only prove what I’m trying to say.

I’m going to say something that I should have made clear in my first response to you. When you’re talking about astrophotography, which your sources are, the “max exposure time” is the maximum time you can shoot before the start begins to visibly drift in frame, resulting in non ideal photographs. It does not mean that the stars or planets just fly out of frame within seconds or minutes, as you seem to imply.


http://www.pk3.org/Astro/index.htm?astrophoto_mount_errors.htm
As per your first source, and so there is no confusion -
“Telescope mounted on equatorial mount is rotating in opposite direction of Earth rotation, thus no trails should appear. The word SHOULD is used intentionally, because there are several factors which affect perfect tracking:
The mount should be perfectly aligned with Earth's polar axis. Any deviation of mount's polar axis from Earth's axis causes tracking errors.
Even quality machined mount parts like worms, worm gears, shafts are not absolutely perfect. The parts are machined in micrometer precision at best. We must realise that in astrophotography we require tracking precison up to arcseconds. That means, that e.g. teeth of teeth on perimeter of wheel with diameter of 8cm must be machined with accuracy of hundreeds of nanometers!
As mount's shaft rotates, any error in its surface and shape and also in worm and worm gear surfaces and shapes causes a periodic bump in tracking. The most observable is so called periodic error of the mount which is caused by inaccuracy of of worm. The period of this error takes one revolution of gear (usually 5-10 minutes for common mounts).
More expensive mounts has possibility to suppress this error by means of electronics - Periodic Error Correction (PEC). The principle of PEC is based on recording tracking corrections made by observer by star tracking during one period. This tracking corrections are then applied during normal mount use.
Atmospheric refraction causes that stars are not moving exactly according to their calculated trajectories.
Further effects - tripod, scope, focuser and other parts firmness, vibrations, thermal changes agffect the result tracking accuracy.”


https://starizona.com/blogs/tutorials/exposure-times
And for your second source, a blog, discussing exposure time -
“For deep sky imaging, suffice to say that longer is always better, at least until light pollution starts to overwhelm the image.”



Again, these sources, the ones you have provided, prove my claim. Being able to accurately track a body through the night sky depends on the mechanical precision of the equipment, which can never be prefect, and the accuracy of the alignment on the celestial poles.


https://web.mit.edu/wallace/instruments.html
Your third source, the MIT telescope.
It appears the professional telescope is accurate enough to track(for astrophotography purposes), unguided to compensate for inevitable mechanical inaccuracies, longer than most amateur setups can while guided. Not surprising.


I’ll say it again as you ignored it in my last reply. Time lapse photography of the night sky reveals concentric circles around the celestial pole, proving my point about EQ mounts while removing the problem of their inherent mechanical errors.
I’ll repeat that this is impossible on a flat plane with objects circling around overhead. The only place that would work is on the North Pole of a flat earth map, and that’s quite clearly not the case.
« Last Edit: October 26, 2021, 08:17:53 PM by Astronomer »

Trillion

Re: NexStar 8SE
« Reply #7 on: October 28, 2021, 10:24:01 PM »
Quote
Have you ever used an equatorial mounted scope? They only work for a few minutes before drifting off of the target star.
Yes I have and I can absolutely tell you that this is completely untrue. Why would something that is designed specifically to track the stars only work for a few minutes before drifting off?

Quote
If the limitation is the camera exposure then on the MIT telescope why, exactly, is the limit for an unguided mount max exposure only up to 5 minutes, while the exposure for guided mount is listed as 60 minutes plus?

Nothing to do with the camera exposure. Everything to do with tiny errors with polar alignment or mechanical errors in the mount drive system. Self-explanatory I would have thought. That's the purpose of guiding. So software can compensate for those tiny errors by sending small correction signals to the mount.

If it helps to convince you Tom I can post an image I have taken with my mount lasting several minutes and which shows pinpoint stars. The image includes a label showing the exposure time. 10,20,30 minutes it makes no difference. You might be interested to see a 10 minute guided and 10 minute unguided image of the same field of stars so you can see the difference?

Quote
I’ll repeat that this is impossible on a flat plane with objects circling around overhead. The only place that would work is on the North Pole of a flat earth map, and that’s quite clearly not the case.
Impossible unless you invent some completely unproven theory of light bending called electromagnetic acceleration (and unmentioned outside of the FE community since it doesn't actually exist). Better that though than to admit your beliefs are wrong eh?!? But the evidence does tend to support the Earth being a globe doesn't it. This is where flat Earth believers lose any credibility they might once have had in my view. The fact that they need to re-invent physics to keep their beliefs alive.
« Last Edit: October 30, 2021, 03:08:14 PM by Trillion »

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Offline Tom Bishop

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Re: NexStar 8SE
« Reply #8 on: October 30, 2021, 09:51:35 PM »
Quote from: Astronomer
https://starizona.com/blogs/tutorials/exposure-times
And for your second source, a blog, discussing exposure time -
“For deep sky imaging, suffice to say that longer is always better, at least until light pollution starts to overwhelm the image.”

Wow, you continue to double down on your falsity and lie to us.

From your source, the next sentence after the one that you quoted says:

https://starizona.com/blogs/tutorials/exposure-times

Determining the proper exposure time is as much an art as a science. For deep sky imaging, suffice to say that longer is always better, at least until light pollution starts to overwhelm the image. From a very dark location, or with a narrowband light-pollution filter (such as a Hydrogen-Alpha filter), the only limit may be the camera software, which usually limits exposures to 3600 seconds (1 hour).

Why did you cut this out? Is it because it implies that the five minute max wasn't because of the limitations due to the sky?

It doesn't say that the camera exposure limit is 5 minutes here. It says that exposures could be limited to 1 hour, limited by the camera software.

Quote from: Astronomer
http://www.pk3.org/Astro/index.htm?astrophoto_mount_errors.htm
As per your first source, and so there is no confusion -
“Telescope mounted on equatorial mount is rotating in opposite direction of Earth rotation, thus no trails should appear. The word SHOULD is used intentionally, because there are several factors which affect perfect tracking:
The mount should be perfectly aligned with Earth's polar axis. Any deviation of mount's polar axis from Earth's axis causes tracking errors.
Even quality machined mount parts like worms, worm gears, shafts are not absolutely perfect. The parts are machined in micrometer precision at best. We must realise that in astrophotography we require tracking precison up to arcseconds. That means, that e.g. teeth of teeth on perimeter of wheel with diameter of 8cm must be machined with accuracy of hundreeds of nanometers!
As mount's shaft rotates, any error in its surface and shape and also in worm and worm gear surfaces and shapes causes a periodic bump in tracking. The most observable is so called periodic error of the mount which is caused by inaccuracy of of worm. The period of this error takes one revolution of gear (usually 5-10 minutes for common mounts).
More expensive mounts has possibility to suppress this error by means of electronics - Periodic Error Correction (PEC). The principle of PEC is based on recording tracking corrections made by observer by star tracking during one period. This tracking corrections are then applied during normal mount use.
Atmospheric refraction causes that stars are not moving exactly according to their calculated trajectories.
Further effects - tripod, scope, focuser and other parts firmness, vibrations, thermal changes agffect the result tracking accuracy.”

None of that says that there is a maximum exposure time of five minutes "before a star starts to blur in an image/the background becomes too bright for usable images" as you stated.

If the sky created a limitation of five minute exposure time, why is the MIT mount getting 1 hour exposure times with guided mounts?

https://web.mit.edu/wallace/instruments.html



It clearly says that guided mounts are getting 1 hour+ exposure times.

This suggests that people are getting longer than five minute exposure times. Your fibs are beyond obvious. You clearly just came here to lie to us rather to engage in any honest discussion.
« Last Edit: October 30, 2021, 11:30:09 PM by Tom Bishop »

Trillion

Re: NexStar 8SE
« Reply #9 on: October 30, 2021, 10:32:10 PM »
Tom, do you understand the difference between tracking and guiding yet? Your original claims about equatorial mounts only working for a few minutes before 'drifting off' the target star seems to be the biggest error that has been made in this discussion so far.  I have explained why very clearly the difference. I have even offered to present you with two images of any exposure time you care to name and I can show you the difference between guiding and tracking.

An unguided exposure of 30 minutes for example would present some drift over time unless the mount was extremely accurate (and therefore expensive to the point of being beyond the budget of most amateurs) or very accurately polar aligned. Even then we are only talking about a few pixels which would mean the star is elongated rather than point like.  A guided image of 30 minutes would result in pinpoint stars. Dedicated guiding software will tell you what the maximum error is over the course of the exposure.

As I said before, what would be the point of an equatorial mount, which is after all a telescope mount designed for and used exclusively for astronomical purposes if it was only capable (according to you) of tracking stars successfully only for a few minutes?  I might as well use an alt-azimuth in that case.

The fact that equatorial mounts can be successfully used anywhere in the world as long as they are adjusted for the observers latitude does rather favour the view that we live on a globe and not on an Earth which is flat. If you can present any compelling evidence to the contrary, without having to resort to your old favourite of EA which has never been scientifically proven to exist (at least not in the way flat Earthers describe it as a way of conveniently getting around anything which cannot be explained in any other way) then please do.
« Last Edit: October 30, 2021, 10:41:30 PM by Trillion »

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Offline stack

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Re: NexStar 8SE
« Reply #10 on: October 30, 2021, 10:35:34 PM »
This suggests that people are getting longer than five minute exposure times. Your fibs are beyond obvious. You clearly just came here to lie to us rather to engage in any honest discussion.

What exactly is your argument here? Originally it seems like you were arguing that an equatorial mount would lose its target after a few minutes

You can get a decent scope for well under $600. Any cheap equatorial mounted scope will demolish the notion of a sun/moon/stars going in a circle above a flat plane.

Have you ever used an equatorial mounted scope? They only work for a few minutes before drifting off of the target star.

Now you're saying that's not true?

I'm not sure why you're hung up on camera exposure time limits. For instance, unbeknownst to me, my Canon 5D Mark IV can handle a whopping 99 hours with the shutter open:




Trillion

Re: NexStar 8SE
« Reply #11 on: October 30, 2021, 10:42:36 PM »
Quote
Now you're saying that's not true?
That's what I thought as well.  Seems like a bit of a U turn going on there somewhere.

Quote
It clearly says that guided mounts are getting 1 hour+ exposure times.

This suggests that people are getting longer than five minute exposure times. Your fibs are beyond obvious. You clearly just came here to lie to us rather to engage in any honest discussion.
Seems like the fibs or lies are being a bit misdirected here to me.

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Offline Tom Bishop

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Re: NexStar 8SE
« Reply #12 on: October 30, 2021, 11:45:36 PM »
This suggests that people are getting longer than five minute exposure times. Your fibs are beyond obvious. You clearly just came here to lie to us rather to engage in any honest discussion.

What exactly is your argument here? Originally it seems like you were arguing that an equatorial mount would lose its target after a few minutes

You can get a decent scope for well under $600. Any cheap equatorial mounted scope will demolish the notion of a sun/moon/stars going in a circle above a flat plane.

Have you ever used an equatorial mounted scope? They only work for a few minutes before drifting off of the target star.

Now you're saying that's not true?

Nope. Unguided mounts can only track stars for a short amount of time measured in a few minutes. Guided mounts with the camera attachments can track stars for long periods of time, for an hour or longer.

It was claimed that the 1- 5 minute limitation of the unguided mounts was a result of cameras being unable to take exposure of the sky "before a star starts to blur in an image/the background becomes too bright for usable images".

Clearly, this was either ignorance or, most likely, abject deception, as the poster knew that guided mounts can take exposures for 60 minutes plus.
« Last Edit: October 30, 2021, 11:55:35 PM by Tom Bishop »

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Re: NexStar 8SE
« Reply #13 on: October 31, 2021, 12:08:35 AM »
This suggests that people are getting longer than five minute exposure times. Your fibs are beyond obvious. You clearly just came here to lie to us rather to engage in any honest discussion.

What exactly is your argument here? Originally it seems like you were arguing that an equatorial mount would lose its target after a few minutes

You can get a decent scope for well under $600. Any cheap equatorial mounted scope will demolish the notion of a sun/moon/stars going in a circle above a flat plane.

Have you ever used an equatorial mounted scope? They only work for a few minutes before drifting off of the target star.

Now you're saying that's not true?

Nope. Unguided mounts can only track stars for a short amount of time measured in a few minutes. Guided mounts with the camera attachments can track stars for long periods of time, for an hour or longer.

It was claimed that the 1- 5 minute limitation of the unguided mounts was a result of cameras being unable to take exposure of the sky "before a star starts to blur in an image/the background becomes too bright for usable images".

Clearly, this was either ignorance or, most likely, abject deception, as the poster knew that guided mounts can take exposures for 60 minutes plus.

So tracking versus guiding. With equatorial tracking, the polar axis of the equatorial telescope mount is accurately polar aligned with the north (or south) celestial pole, and it is now tracking the apparent movement of the night sky versus augmenting with guided. Guided using a secondary guide camera to communicate small adjustments (pulses) to the mount for improved tracking accuracy.

Either of which whether used for short or long exposures, still don't lend themselves to a non-globe referenced scenario. So I'm not sure what you're arguing. Is it that tracking has its best results with shorter shutter exposure durations and guided is better for longer exposures? If so, so what?

Trillion

Re: NexStar 8SE
« Reply #14 on: October 31, 2021, 08:13:21 AM »
Quote
Nope. Unguided mounts can only track stars for a short amount of time measured in a few minutes.
If what you say is true Tom how is it then that I can track the Sun during the day over a few hours without having to adjust the mount. As you will appreciate you cannot guide a mount on the stars during broad daylight and especially when the telescope is aimed at the Sun! All I have to do is change the tracking rate from sidereal for the stars to solar for the Sun. And yes, before anyone makes the point, I am using a solar telescope which is specially designed for observing the Sun in complete safety and which is equipped with the special filters needed for solar observing.

Equatorial mounts are specifically designed for astronomy and for tracking the stars. So I say again what would be the point of them if they could only track the stars for a few minutes at a time? I don't know what your experience is of using these mount or what mounts you have used but it is clearly very different to mine. Guiding is only needed for imaging, and even then the corrections needed are in the order of a few arc seconds at worst. Unguided tracking is perfectly adequate for visual use.

You will also note that the NexStar 8SE is designed around a computer controlled 'GOTO' alt-azimuth mount.

Quote
You misunderstand the difference between “a few minutes before drifting off the target star” and “maximum exposure time” before a star starts to blur in an image/the background becomes too bright for usable images.
There is no maximum exposure time before the background becomes too bright to produce a usable image. In the software that I use for actual imaging (Sequence Generator Pro) you have the ability to change the black and white levels on the histogram in order to create the correct balance between the stars and the background brightness. If the white level is set too far to the left then the image will be just white.

This of course has nothing to do with actual tracking or guiding. The latter in my case being through a separate guiding camera (SX Ultrastar) which is attached to the off-axis guiding port of my main camera (QSI 6120 wsg-8). I use PHD2 Guide which is dedicated autoguiding software. If I am using a short focal length telescopes then I don't need to use the autoguider since the tracking errors of my mount (AP 1200GTO) are less than the resolution of the system.
« Last Edit: October 31, 2021, 04:34:26 PM by Trillion »