Esprit 100 Pinched optics?

[Adam J]

I received a Esprit 100 from FLO a few weeks back and have just this week managed to take some test images. 

I am thinking that this looks like pinched optics. Star Halos are looking Hexagonal to my eye, the Esprit 100 has 6 lens adjustment screws for each lens element, so more than the usual 3 and hence I assume this is resulting in hexagonal stars when pinched as opposed to triangular. 

Here is a close up on a star using my scope in with a UV/IR filter and an ASI1600MM Pro. I would say it was not that cold and the dew heater was running. 

Here is a star from my friends Esprit 100 also using a ASI1600mm pro (exactly the same image scale). More integration mind you. 

Here is the full test image:

I would appreciate opinions on this and if I should be returning the scope on this basis.

But its not the only problem with the scope, the focuser is also giving me issues as the tension is not consistent over the entire length of its movement and when delivered was so poorly adjusted that you could feel it wiggling at one end of its travel due to the pinion not engaging with the rack while at the other end of its travel it seemed fine. I managed to adjust it so its not too bad but it is less than ideal as i cant tighten it as much as i would like without it becoming too tight at one end. 

On the focuser FLO have agreed to return it and have a look at the focuser it. But it would be good to confirm if people think that there is a problem with the optics too before I send it as I have not discussed that issue with them yet. 

Originally I had tilt but that seems to have vanished now without me changing anything, just the scope sat in the obsy un touched between two sessions, so no idea what to think about that. 

I feel I should note that I did opt to have the scope checked and tuned by ES Reed. 

thanks

Adam

 

Edited December 14, 2019 by Adam J

[ollypenrice]

Shame you're having issues. Sorry to hear it. I certainly do think your brighter star looks hexagonal and the smaller ones don't somehow look quite right, though I can't see them as hexagonal myself. Your 'six clips' theory also strikes me as making sense. I'm sure FLO will look after you, though.

Olly

[Davey-T]

IIRC there was a problem like this when they were first introduced, there was a YT video by a telescope mechanic showing how they corrected it.

Dave

[Adam J]

3 minutes ago, ollypenrice said:

Shame you're having issues. Sorry to hear it. I certainly do think your brighter star looks hexagonal and the smaller ones don't somehow look quite right, though I can't see them as hexagonal myself. Your 'six clips' theory also strikes me as making sense. I'm sure FLO will look after you, though.

Olly

Probably not enough pixels sampling the smaller stars to see it. 

I am sure they will I just don't want to waste their time over nothing. So thought I would get opinions first. 

[FLO]

Hi Adam, looking at our helpdesk I see you are already in discussion with my colleague Ian King about focuser alignment. If you let him know you would also like Es to look again at your telescope’s optics we will happily arrange that 🙂

HTH, 

Steve

[souls33k3r]

Ouch! Sorry to hear about your troubles. Did you opt for check and tuned service when buying this scope? Just curious.

[alan potts]

That is not so good news but if it were to happen to me, there is no business that I feel would deal with you better than FLO, they sent me a spare cable even though I told them it was another fault which no one had ever heard of to do with our electric system which can't actually happen with the UK's.

Alan

[henry b]

I do not believe as  a  customer receiving a new product delivery from a supplier that you should have  the need to have it checked by a  third party!  However i am sure FLO will resolve the issues.       Henry B.

[Adam J]

5 hours ago, FLO said:

Hi Adam, looking at our helpdesk I see you are already in discussion with my colleague Ian King about focuser alignment. If you let him know you would also like Es to look again at your telescope’s optics we will happily arrange that 🙂

HTH, 

Steve

Steve, thanks I did not see Ian had replied on Friday night but had not gotten back to him yet as I figured it was the weekend and you guys would not get my reply until Monday anyway, Ill get back in touch with him.

4 hours ago, souls33k3r said:

Ouch! Sorry to hear about your troubles. Did you opt for check and tuned service when buying this scope? Just curious.

Yes I did get the ES check and tune service with the scope.

I do think the optics are showing signs of being slightly pinched and a few people here seem to agree? Although to be fair to ES pinched optics can often be temperature dependent. In itself that does make me worry though as depending on temperature it may or may not show up if he looks at it again.

2 hours ago, alan potts said:

That is not so good news but if it were to happen to me, there is no business that I feel would deal with you better than FLO, they sent me a spare cable even though I told them it was another fault which no one had ever heard of to do with our electric system which can't actually happen with the UK's.

Alan

Yes I purchased from FLO because of their reputation and if it was some other shops I would be much more worried right now, not that I aren't worried. Guess I am left feeling more than a little down about it though as this was a major purchase for me and I was very much looking forward to using it over my Christmas leave.

Adam

 

[FLO]

4 hours ago, henry b said:

I do not believe as  a  customer receiving a new product delivery from a supplier that you should have  the need to have it checked by a  third party!  However i am sure FLO will resolve the issues.       Henry B.

The third party QC is optional, not compulsory. We offer it because Es Reid’s reputation in the UK is second-to-none and people repeatedly requested it. It also means in situations like this Es will handle any necessary optical work, not the UK distributor. 
 

2 hours ago, Adam J said:

Yes I purchased from FLO because of their reputation and if it was some other shops I would be much more worried right now, not that I aren't worried. Guess I am left feeling more than a little down about it though as this was a major purchase for me and I was very much looking forward to using it over my Christmas leave.

You are welcome to continue using it through your Christmas leave period (if as we suspect it is temperature related then a dew heater should provide a good short-term solution) and we can send it to Es in the new year. If you wish 🙂

Steve 

[henry b]

The suggestion of a dew heater as an Elastoplast in this case is noted as a poor show,   a very poor show!   Henry b.

[FLO]

5 minutes ago, henry b said:

The suggestion of a dew heater as an Elastoplast in this case is noted as a poor show,   a very poor show!   Henry b.

Was only looking for a way that would enable Adam to continue using the telescope through his Christmas hols. If you know of a better solution please say? 🙂 

Steve 

[david_taurus83]

Can it be adjusted at home? 16th of a turn back on each screw?

[FLO]

39 minutes ago, david_taurus83 said:

Can it be adjusted at home? 16th of a turn back on each screw?

I think Henry b would like that suggestion even less 😄 

That might be all that is required but it isn't something we would expect an end-user to do. Indeed we would prefer they did not. Besides, the telescope is only a few weeks old. I think it best we collect it then let Es' check it on his bench. It tested well first time around so we are especially interested to know why it is now misbehaving. We are assuming Adam is happy for Es to have a second look - he might prefer a replacement. 

HTH, 

Steve 

[Adam J]

11 minutes ago, FLO said:

I think Henry b would like that suggestion even less 😄 

That might be all that is required but it isn't something we would expect an end-user to do. Indeed we would prefer they did not. Besides, the telescope is only a few weeks old. I think it best we collect it then let Es' check it on his bench. It tested well first time around so we are especially interested to know why it is now misbehaving. We are assuming Adam is happy for Es to have a second look - he might prefer a replacement. 

HTH, 

Steve 

Thanks for giving me some options Steve I am considering them, ill let you know what I want to do by Monday.

24 minutes ago, david_taurus83 said:

Can it be adjusted at home? 16th of a turn back on each screw?

Thanks for the suggestion but fortunately I know better lol. I would not touch the colimation screws on a triplet with a barge pole. The tolerances are incredibly fine.

1 hour ago, henry b said:

The suggestion of a dew heater as an Elastoplast in this case is noted as a poor show,   a very poor show!   Henry b.

It is worth remembering that if anyone is at fault its Skywatcher not FLO and that pinched optics can only show themselves at certain temperatures I doubt ES's optical bench is in a fridge freezer. In the end though I still think the Esprit 100 is the scope for me, looking at other peoples results I have just had some bad luck.

Adam

[FLO]

No problem 🙂 

Whatever you decide, please let Ian know when you reply to his email. 

Steve 

[Adam J]

Ok just posting this now for interest as if there was any doubt that the stars are hexagonal take a look at what they look like when I combine LRGB as opposed to just Lum, not much data but I think its still very telling:

First this red star, I think that the shape is much clearer here:

But the real nail in the coffin is this, I see 6 x while dots in the star halo:

Full LRGB image here, like I say not much data at all but its sufficient to show the issue:

 

Adam

Edited December 14, 2019 by Adam J

[henry b]

I can now see a customer with a fully operational scope over the festive holidays, I have used some harsh words for which I will apologise openly, Skywatcher products have served our hobby very well and I will always acknowledge this fact.    Henry B.

[WanderingEye]

Forgive my ignorance, but what exactly are pinched optics, by that I mean what has to wrong with the scope to have this happen, as I find it intriguing... 

[Mr Spock]

1 minute ago, WanderingEye said:

Forgive my ignorance, but what exactly are pinched optics, by that I mean what has to wrong with the scope to have this happen, as I find it intriguing... 

It's when the optics are held too tight in the cell and become distorted. 

[WanderingEye]

5 minutes ago, Mr Spock said:

It's when the optics are held too tight in the cell and become distorted. 

Ok, thanks, hmmm so the screws would have to be pretty darn tight to distort pieces of glass that thick....or is it more of a tilt to the glass... ..?

[vlaiv]

3 minutes ago, WanderingEye said:

Ok, thanks, hmmm so the screws would have to be pretty darn tight to distort pieces of glass that thick....or is it more of a tilt to the glass... ..?

Not really that tight - just a bit tighter than just holding in place can distort mirror for example.

Remember, optical surface precision is measured in fractions of wavelength of light - and that is order of hundred or so nanometers. You simply can't perceive bending on that scale by eye - and most items flex that much when you apply even slight pressure on them. Clips holding mirrors and lens in position are in perfect place to cause pinching if too much force is applied (again too much force means anything more than what is barely needed to hold it in place).

Btw pinched optics can be consequence of different thermal expansion coefficients. If two different materials are used to hold the lens in cell at proper spacing and there is significant temperature drop compared to temperature when scope was put together - there will be different contraction of said materials and that can be enough to cause needed pressure to twist optics out of shape.

[Gasman]

I know it's a pain Adam but Flo will sort it👍. Been enjoying my Flo bought Espirit 120 for years now without a scrap of bother!.

Steve

[WanderingEye]

1 minute ago, vlaiv said:

Not really that tight - just a bit tighter than just holding in place can distort mirror for example.

Remember, optical surface precision is measured in fractions of wavelength of light - and that is order of hundred or so nanometers. You simply can't perceive bending on that scale by eye - and most items flex that much when you apply even slight pressure on them. Clips holding mirrors and lens in position are in perfect place to cause pinching if too much force is applied (again too much force means anything more than what is barely needed to hold it in place).

Btw pinched optics can be consequence of different thermal expansion coefficients. If two different materials are used to hold the lens in cell at proper spacing and there is significant temperature drop compared to temperature when scope was put together - there will be different contraction of said materials and that can be enough to cause needed pressure to twist optics out of shape.

Ok, now that is an explanation....thanks 👍

[FLO]

41 minutes ago, henry b said:

I can now see a customer with a fully operational scope over the festive holidays, I have used some harsh words for which I will apologise openly, Skywatcher products have served our hobby very well and I will always acknowledge this fact.    Henry B.

That is gracious of you but we aren’t out of the woods yet...

If Adam chooses to return his telescope now, rather than after Christmas, then a collection must be arranged and the telescope, or replacement telescope, must be assessed by Es (Adam purchased an Es Ried test). We would arrange this as quickly as possible but during the festive period cannot guarantee to have it back in Adam’s hands in time for his Christmas hols (the couriers struggle at this time of year). We will of course do our best. This is why Adam is concerned and why I suggested he might choose to use the telescope with a dew-heater tape (prevents cold weather induced pinching) until after Christmas then return it. 

Ultimately Adam purchased the telescope, not you, so it is Adam we must serve. He will let us know Monday how he wants us to proceed and we will work with him to achieve a good outcome. We always do 🙂

HTH, 

Steve