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Stellarium and Field stops

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#1 SgtSluggo

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Posted 12 June 2019 - 06:05 PM

I have been trying to use Stellarium to plan my targets. I tried to put in my equipment but I cannot find field stops for my EP's.   Other people say that this doesn't matter, but it clearly affects FOV.  I was confused because my real view of Saturn didn't match Stellarium at all.  Am I doing something wrong or is there actually a place to get this info on cheap eyepieces?

 

My EP's are

Celestron 25mm Kellner (came with scope)

Celestron 10mm Kellner (came with scope)

Celestron Omni 6mm Plossl

 

They don't seem to sell the included lenses seperately so I am guessing on actual FOV as well. 

 

Thanks!


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#2 alexantos

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Posted 12 June 2019 - 07:27 PM

I believe by experience that Stellarium does that automatically, and it's pretty close.

 

But if you want to be more precise, you can try this site to figure out Eyepiece's field stop.

For example, a 25mm 52° aFOV has a field stop of around 23.

 

If you want Telescope Simulators, to find out approximately how an object appears on a determined power, you can try this ones:

 

Stelvision Telescope Simulator.

 

Astronomy Tools.

 

Telescopius (former DSO browser)

 

Take care

 

Alexandre



#3 JoeInMN

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Posted 12 June 2019 - 07:33 PM

Don't know whether this applies or not, and maybe it's just happening on my system (Linux Mint 19), but I'm seeing what looks like a bug in the Oculars plugin with the latest Stellarium (0.19.0)... When I select the telescope, the view doesn't show the correct power and field until I also switch the eyepiece to a different one and then back again. Here is the view through my 6" f/5, before and after I changed and then re-selected the 12mm Plossl:

 

190612_stellarium_ocular_issue.jpg

 

Edit: To clarify, the workaround eyepiece I switch to also appears to have the right field of view. So, changing the telescope throws the FOV rendering off somehow, and changing the eyepiece gets it back on track again, is how I experience it.


Edited by JoeInMN, 12 June 2019 - 07:42 PM.


#4 alexantos

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Posted 12 June 2019 - 07:40 PM

Fix the link on the second image so I can see more clearly.



#5 kathyastro

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Posted 12 June 2019 - 07:43 PM

Kellners usually have an AFOV of about 40 degrees.  Plossls are usually around 50 degrees.


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#6 t_image

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Posted 12 June 2019 - 07:48 PM

Maybe it's my personal operating tendency to not let computers do most of the thinking for me,

but the easiest method to have a good calibration between one's gear and the software view is to just do a visual calibration oneself.

I did this for my camera lenses and know my results to now be trustworthy as I set the FOV custom keys to their corresponding FL....

So it might not be ideal,

but if you find the numbers aren't quite matching up with eyepieces,

then an easy work around is to point towards a known target, notice recognizable stars at all the edges in the scope's view with said EP, and manually zoom in/out of Stellarium in small bits until the view matches the EP with field stop.. Then take note of the FOV for that particular EP.....



#7 JoeInMN

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Posted 12 June 2019 - 07:54 PM

Fix the link on the second image so I can see more clearly.

It's one image; clicking on it should bring up a full-size version.



#8 alexantos

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Posted 12 June 2019 - 07:57 PM

It's one image; clicking on it should bring up a full-size version.

Yeah, I see it now. Small screen of mine...wink.gif



#9 alexantos

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Posted 12 June 2019 - 08:08 PM

Don't know whether this applies or not, and maybe it's just happening on my system (Linux Mint 19), but I'm seeing what looks like a bug in the Oculars plugin with the latest Stellarium (0.19.0)... When I select the telescope, the view doesn't show the correct power and field until I also switch the eyepiece to a different one and then back again. Here is the view through my 6" f/5, before and after I changed and then re-selected the 12mm Plossl:

 

Edit: To clarify, the workaround eyepiece I switch to also appears to have the right field of view. So, changing the telescope throws the FOV rendering off somehow, and changing the eyepiece gets it back on track again, is how I experience it.

 

It shouldn't do that.

 

Changing eyepieces on the same telescope selected, should show magnification according to eyepiece's power.

Try to have different eyepieces, like 5mm 10mm 15mm 20mm, with the same FOV, and try if it works.

Then Alternate scopes and see.

Then change only the eyepice's FOV, like 50° 60° 70° 80°, and see what happens.

 

On my Stellarium version 0.18.3.1753 it works perfectly.



#10 alexantos

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Posted 12 June 2019 - 08:19 PM

My EP's are

Celestron 25mm Kellner (came with scope)

Celestron 10mm Kellner (came with scope)

Celestron Omni 6mm Plossl

 

They don't seem to sell the included lenses seperately so I am guessing on actual FOV as well. 

 

Thanks!

The celestron Omni 6mm has 52° FOV as you can see in here.

 

The Kellners have FOV between 40° and 50°

I'd stick to the minimum as kathyastro said.

 

Take care.



#11 alexantos

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Posted 12 June 2019 - 08:27 PM

Don't know whether this applies or not, and maybe it's just happening on my system (Linux Mint 19), but I'm seeing what looks like a bug in the Oculars plugin with the latest Stellarium (0.19.0)... When I select the telescope, the view doesn't show the correct power and field until I also switch the eyepiece to a different one and then back again. Here is the view through my 6" f/5, before and after I changed and then re-selected the 12mm Plossl:

 

Edit: To clarify, the workaround eyepiece I switch to also appears to have the right field of view. So, changing the telescope throws the FOV rendering off somehow, and changing the eyepiece gets it back on track again, is how I experience it.

 

Also check out my settings. Maybe it will help to clarify the problem.

 

 

gallery_304439_10528_203920.png




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