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shyam    8

hello

i have attached a image , even i have the same problem like coma with light spreading toward the tail. need help . I am using a celestrone astromaster 114 eq

ggg.tiff

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shyam    8

hello

This is not the picture i have taken, this is just to show that  my telescope also gives this kind of image exactly . kindly help to resolve this machine

 

regards

shyam menon

Sggg.jpg

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Shibby    454

Do you see sharp stars in the centre of the view, with fan-shaped stars around the edges? If so, that'd be normal Newtonian coma, which can be resolved with a coma corrector.

If the stars are like this across the whole field, then the problem could be a number of things - most likely the optics need collimating or the focuser is wonky.

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Louis D    888
1 hour ago, shyam said:

I am using a celestrone astromaster 114 eq

First off, that's a Jones-Bird design since the focal length is roughly double the length of the physical tube.  They are notoriously difficult to collimate thanks to the corrector lens below the focuser.

I'm with Shibby that you've probably got a collimation or alignment issue.  Something is definitely tipped in that optical train.

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NGC 1502    721

Hi Shyam. As posted already, could you please let us know if the stars look like the image you sent, in the centre of the field of view, or only towards the edges ?  If they are ok in the centre, but not at the edges, that could possibly be normal.

Folk here will try to help, Ed.

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shyam    8

hello

its like an inverted coma kind of thing with star being like a smal half moon . when i look to the star defocussed i dont see a round with cross inside rather sees a distorted round with top portion a bit elongated and down ok .

 

best regards

shyam menon

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shyam    8
13 hours ago, NGC 1502 said:

Hi Shyam. As posted already, could you please let us know if the stars look like the image you sent, in the centre of the field of view, or only towards the edges ?  If they are ok in the centre, but not at the edges, that could possibly be normal.

Folk here will try to help, Ed.

it looks somewhat the same as i sent like an inverted coma with star like a half moon

 

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shyam    8
18 hours ago, Shibby said:

Do you see sharp stars in the centre of the view, with fan-shaped stars around the edges? If so, that'd be normal Newtonian coma, which can be resolved with a coma corrector.

If the stars are like this across the whole field, then the problem could be a number of things - most likely the optics need collimating or the focuser is wonky.

hi

it looks like the photo , how do i correct it, and what is a comma corrector. I would prefer not to buy comma corrector at least for a time due to short of fund , i had removed the focusser corrector lens to insert laser to correct the path . i dont know whether the corrector lense position and primary and secondary mirror position . Moon looks ok only issue is stars

regards

shyam menon

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happy-kat    3,167

I wouldn't use the laser until you have tested the laser is true, it may need collimating itself.

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shyam    8

agree, mistake done how do i correct it. cause in my part of the world here we have no one interested in astronomy. Now need to correct it ,also this mistakes do teach us how to come out of it with a good support from this amazing team here on stargazer lounge . Also to remind that here till last week was a rainy season. So may to Nov never touched the telescope and i forgot  Lol... Now its a action time

regards

shyam menon

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happy-kat    3,167

There is only a mistake if the laser is out. First you need to test the laser, this has been covered so you will probably find a thread to help with a search, I'm only using a small phone so can't easily get it for you.

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Shibby    454

So it does sound like collimation is your issue. Sorry, but I don't know anything about Bird-Jones reflectors, but this video may help? 

 

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Stu    15,217

When you say you removed the corrector lens, did you refit it correctly?

It does not look like classic collimation because it seems to radiate from the centre, implying a star in the centre would look ok. Could you show us an image with a defocused star in the centre?

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shyam    8
2 hours ago, Stu said:

When you say you removed the corrector lens, did you refit it correctly?

It does not look like classic collimation because it seems to radiate from the centre, implying a star in the centre would look ok. Could you show us an image with a defocused star in the centre?

hi

looks like the one i have drawn elongated .. ignore the round one.

 

hhh.jpg

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shyam    8

defocussed star dont look round with cross rather looks elongated on top as seen in the picture

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Ricochet    536

I would suggest getting a Cheshire/sight tube to recollimate the scope. If the scope is one supplied without a primary centre spot you may also have to add one. 

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