Les instructions d'Andrew Lunt pour LS 60

[Jean Louis]

Internal etalon systems have a few compromises when compared to external front

mounted etalons.

The main reason for an internal system is the reduced cost of the solar scope

while providing a larger aperture which will allow for better resolution.

As I have stated in a few previous tech notes, the internal etalon will

compromise slightly from a few issues.

 

The collimation system in our LS60T is optimized to the best of our ability at

the 656nm wavelength.

However, there are always some off axis light rays that can never be brought

perpendicular to the etalon.

The optimization is done such that the field is collimated at about 70-80% of

the aperture of the etalon.

This has the effect of a slight bird shape (with regard to contrast) across the

field.

As etalons improve, this bird effect will become more apparent for the internal

system. Hence the reason we general try to keep internal etalons at about 0

.7-0.8 angstroms.

We have optimized for as flat a field as physics will allow.

 

The other issue is due to the fact that our internal etalons are tiltable.

 

Competitive products do not allow for any internal tilt. The etalon is fixed at

the factory and there is no additional tuning capability by the customer.

Etalons are air spaced. The air inside the gap of the etalon has a refractive

index tied to barometric pressure and altitude. As these things change, the

center wavelength of the etalon will change. The design of an etalon is tied to

the refractive index of the gap. In our case the gap is air. In solid etalons

the gap is glass.

 

I have replied to many e-mails from customers who state that the tuner does very

little.

They are absolutely correct.

The internal etalon is tuned very precisely at the factory to a position that is

as perpendicular to the optical train as possible. Thus reducing the off axis

errors that may be created across of the field to a minimum.

The tilt mechanism does not work like the tilt mechanism on the front of a

system.

 

The tilt mechanism is there to allow for very minor changes to the center

wavelength to compensate for changes in air pressure and altitude. Some Doppler

shifting can be done but due to the fact that Doppler shifting is done by

tilting the etalon plane at an angle you will notice a "banding" effect across

image. As you tilt more, the banding effect will tighten.

 

When the tilt of the LS60T internal etalon is all the way to the right when at

the eyepiece, the mechanism will be loose. This is the point where the tilt rod

is disengaged from the etalon housing to assure that the etalon is sitting flat

with no mechanical influence.

As the tilt knob is moved to the left, it will engage the etalon housing. The

etalon should be, or come on band, within 1 turn of the knob. If you are using

the system between 1500 and 3500 feet, no tilt may be needed. We provide far

more range than necassary due to mechnical tolerances of the tilt parts.

The tilt will allow the user to fine tune the center wavelength and flatten the

field. This works well at lower magnifications.

At higher magnifications, tilting the etalon will tighten that band I talked

about earlier. I cannot explain the physics of the ray tracing in an e-mail but

the result is a slight improvement of the contrast in a band across the etalon

which is parallel to the etalon pivot point. This may allow for a slightly

better view of small surface detail. At higher magnifications the system can be

tweaked to look at small surface detail. The lost contrast will not be visible.

 

When the system is being used for full disk images and the tilt is adjusted the

Sun will have a very good flat field of ~<0.75 angstroms overall. Tweaking of

the system outside these parameters will increase contrast at what people refer

to as a sweet spot at the loss of contrast elsewhere.

 

Double Stacking.

 

If you doublestack the LS60T, you are reducing the bandpass to about 0.55

Angstroms.

When doublestacked, the proms generally fade and the surface has more contrast

and has better detail.

 

If the field was flattened well in single mode, the field should be fairly flat

in DS mode.

 

There are a few subtle things that can be done to improve the system's

performance.

 

Make sure the area you wish to observe is in the center of the eyepiece.

Tune the LS60T to the furthest to the right position possible with the tilt

knob.

Place the LS50F on the front and tune for the best surface detail.

Very VERY slowly move the LS60T tilt knob to the left. It will not take much

(<1/4 turn)

Now rotate the LS50F on the front by unscrewing it a little. (Don't let it fall

off! It doesn't have to go more than 1/2 a turn).

An O-ring or some felt may help if it goes more than 1/4 turn.

 

You will note the surface contrast will alter. Getting better and then worse as

you turn.

There will be a point where the surface should pop a little better and the

"band" almost eliminated.

 

Because the etalon on the front is tilted and the etalon inside is tilted we do

have some ray angles to deal with. It is possible to re-optimize the system with

a little rotation.

 

Lunt Solar are moving forward on a patent pending design for an internal

pressure tuned system.

This system is currently available on our LS100T and really works well.

 

Because we place the etalon internally in the normal position we can really

optimize the rays with the collimating system.

Air pressure allows us to increase and decrease the refractive index of the air

gap without tilt. This allows for true Doppler shifting toward and away from the

user instead of up and down.

 

I hope the above explains a little of what is going on.

We have worked very hard to optimize an internal system in order to bring it to

a price point where people can enjoy a 60mm aperture. Alternate front mount

systems do cost more due to the larger etalon, but as I have described above,

most of the compromises are gone. Air tuning, off course, will take internal

systems to a whole new level of performance.

 

Andrew Lunt

Lunt Solar Systems LLC

2520 N. Coyote Drive. Suite 111

Tucson, AZ 85745

USA

Si quelqu'un peut traduire:)

 

Merci,

 

Jean Louis

[Will]

Ben oui, merci Jean-Louis, mais c'est tout en anglais...

[Leimury]

Internal etalon systems have a few compromises when compared to external front

mounted etalons.

The main reason for an internal system is the reduced cost of the solar scope

while providing a larger aperture which will allow for better resolution.

As I have stated in a few previous tech notes, the internal etalon will

compromise slightly from a few issues.

 

The collimation system in our LS60T is optimized to the best of our ability at

the 656nm wavelength.

However, there are always some off axis light rays that can never be brought

perpendicular to the etalon.

The optimization is done such that the field is collimated at about 70-80% of

the aperture of the etalon.

This has the effect of a slight bird shape (with regard to contrast) across the

field.

As etalons improve, this bird effect will become more apparent for the internal

system. Hence the reason we general try to keep internal etalons at about 0

.7-0.8 angstroms.

We have optimized for as flat a field as physics will allow.

 

The other issue is due to the fact that our internal etalons are tiltable.

 

Competitive products do not allow for any internal tilt. The etalon is fixed at

the factory and there is no additional tuning capability by the customer.

Etalons are air spaced. The air inside the gap of the etalon has a refractive

index tied to barometric pressure and altitude. As these things change, the

center wavelength of the etalon will change. The design of an etalon is tied to

the refractive index of the gap. In our case the gap is air. In solid etalons

the gap is glass.

 

I have replied to many e-mails from customers who state that the tuner does very

little.

They are absolutely correct.

The internal etalon is tuned very precisely at the factory to a position that is

as perpendicular to the optical train as possible. Thus reducing the off axis

errors that may be created across of the field to a minimum.

The tilt mechanism does not work like the tilt mechanism on the front of a

system.

 

The tilt mechanism is there to allow for very minor changes to the center

wavelength to compensate for changes in air pressure and altitude. Some Doppler

shifting can be done but due to the fact that Doppler shifting is done by

tilting the etalon plane at an angle you will notice a "banding" effect across

image. As you tilt more, the banding effect will tighten.

 

When the tilt of the LS60T internal etalon is all the way to the right when at

the eyepiece, the mechanism will be loose. This is the point where the tilt rod

is disengaged from the etalon housing to assure that the etalon is sitting flat

with no mechanical influence.

As the tilt knob is moved to the left, it will engage the etalon housing. The

etalon should be, or come on band, within 1 turn of the knob. If you are using

the system between 1500 and 3500 feet, no tilt may be needed. We provide far

more range than necassary due to mechnical tolerances of the tilt parts.

The tilt will allow the user to fine tune the center wavelength and flatten the

field. This works well at lower magnifications.

At higher magnifications, tilting the etalon will tighten that band I talked

about earlier. I cannot explain the physics of the ray tracing in an e-mail but

the result is a slight improvement of the contrast in a band across the etalon

which is parallel to the etalon pivot point. This may allow for a slightly

better view of small surface detail. At higher magnifications the system can be

tweaked to look at small surface detail. The lost contrast will not be visible.

 

When the system is being used for full disk images and the tilt is adjusted the

Sun will have a very good flat field of ~<0.75 angstroms overall. Tweaking of

the system outside these parameters will increase contrast at what people refer

to as a sweet spot at the loss of contrast elsewhere.

 

Double Stacking.

 

If you doublestack the LS60T, you are reducing the bandpass to about 0.55

Angstroms.

When doublestacked, the proms generally fade and the surface has more contrast

and has better detail.

 

If the field was flattened well in single mode, the field should be fairly flat

in DS mode.

 

There are a few subtle things that can be done to improve the system's

performance.

 

Make sure the area you wish to observe is in the center of the eyepiece.

Tune the LS60T to the furthest to the right position possible with the tilt

knob.

Place the LS50F on the front and tune for the best surface detail.

Very VERY slowly move the LS60T tilt knob to the left. It will not take much

(<1/4 turn)

Now rotate the LS50F on the front by unscrewing it a little. (Don't let it fall

off! It doesn't have to go more than 1/2 a turn).

An O-ring or some felt may help if it goes more than 1/4 turn.

 

You will note the surface contrast will alter. Getting better and then worse as

you turn.

There will be a point where the surface should pop a little better and the

"band" almost eliminated.

 

Because the etalon on the front is tilted and the etalon inside is tilted we do

have some ray angles to deal with. It is possible to re-optimize the system with

a little rotation.

 

Lunt Solar are moving forward on a patent pending design for an internal

pressure tuned system.

This system is currently available on our LS100T and really works well.

 

Because we place the etalon internally in the normal position we can really

optimize the rays with the collimating system.

Air pressure allows us to increase and decrease the refractive index of the air

gap without tilt. This allows for true Doppler shifting toward and away from the

user instead of up and down.

 

I hope the above explains a little of what is going on.

We have worked very hard to optimize an internal system in order to bring it to

a price point where people can enjoy a 60mm aperture. Alternate front mount

systems do cost more due to the larger etalon, but as I have described above,

most of the compromises are gone. Air tuning, off course, will take internal

systems to a whole new level of performance.

 

Andrew Lunt

Lunt Solar Systems LLC

2520 N. Coyote Drive. Suite 111

Tucson, AZ 85745

USA

Si quelqu'un peut traduire:)

 

Merci,

 

Jean Louis

 

Tu paie combien la ligne ?

 

Tiens, c'est gratuit mais quelquefois bizarre

http://fr.babelfish.yahoo.com/

 

Bon ciel

[Jean Louis]

:DLeimury

Je m'étais fait une traduction perso avec Reverso.C'est vrai que c'est bizarre mais on saisi le sens général.

[Leimury]

:DLeimury

Je m'étais fait une traduction perso avec Reverso.C'est vrai que c'est bizarre mais on saisi le sens général.

 

Bonjour,

 

J'ai lu, il parle du doublet dont la couche d'air est une lentille également qui peut varier légerement suivant la pression atmosphérique et bla bla bla et bla bla bla.

Chap plan et bla bla bla et bla bla bla

 

If you are using

the system between 1500 and 3500 feet, no tilt may be needed.

De 500 à 1200m d'altitude, le réglage usine conviendra parfaitement.

 

En fait, il parle tout simplement de la collimation de la lunette et de l'ajustement de l'espace et pression d'air entre les lentilles.

En insistant bien sur le fait que le réglage d'usine a été fait avec le plus grand soin possible et qu'un réglage ultérieur apportera un gain négligeable et pas vraiment quantifiable.

 

En plus, pour réduire les couts et proposer ce formidable engin à un prix abordable, le réglage de collim est pas vraiment accessible et tout à été fait pour qu'on en ai pas besoin.

 

Double filtration:

Là, je te le traduis parce quee ça pourrait te servir

 

There are a few subtle things that can be done to improve the system's

performance.

 

Make sure the area you wish to observe is in the center of the eyepiece.

Tune the LS60T to the furthest to the right position possible with the tilt

knob.

Place the LS50F on the front and tune for the best surface detail.

Very VERY slowly move the LS60T tilt knob to the left. It will not take much

(<1/4 turn)

Now rotate the LS50F on the front by unscrewing it a little. (Don't let it fall

off! It doesn't have to go more than 1/2 a turn).

An O-ring or some felt may help if it goes more than 1/4 turn.

 

You will note the surface contrast will alter. Getting better and then worse as

you turn.

There will be a point where the surface should pop a little better and the

"band" almost eliminated.

 

Vous pouvez néanmoins optimiser le système.

 

Observez bien au centre du champ.

Réglez la LS60T au mieux avec la vis de réglage d'inclinaison.

Placez le LS50F devant et réglez pour voir au mieux les détails de la surface du soleil.

Tournez vraiment très doucement le réglage d'inclinaison de la LS60T; il ne devrait pas avoir besoin de plus d'un quart de tour.

Maintenant tourner le LS50F devant la lunette en le dévissant légèrement, ne le faites pas tomber !, il ne devrait pas nécessiter plus d'un demi tour.

An O-ring or some felt may help if it goes more than 1/4 turn.

Apparement, il faudrait un bidule en plus (O-Ring: sorte de rondelle entretoise ?) si plus d'1/4 de tour est nécessaire.

 

Vous noterez un changement dans le contraste au fur et à mesure de la rotation.

Vous devriez atteindre le réglage qui vous assurera meilleurs netteté et contraste.

[Invité astrobruxelles]

merci Leimury pour la traduction...

[Leimury]

merci Leimury pour la traduction...

 

Y'a pas de quoi

[Jean Louis]

:)Merci,Leimury,sympa:cool:

[fredlarun]

O-Ring = Joint Torique?

[Jean Louis]

fred,il me semble que c'est ça.

[PierreH]

Je confirme la trad de O ring : j'en utilise à longueur de journée...

[manola]

However, there are always some off axis light rays that can never be brought

perpendicular to the etalon.

[titi et nini]

qu'entends tu par là?

[isym44]

Par là, je n'entends pas grand-chose, mais il me semble voir que :

Malgré tout, il y aura toujours un certain nombre de rayons lumineux non axiaux (des réflexions ?) qui ne pourront être perpendiculaires à l'étalon (le filtre FP, je suppose).

Ceci induit un léger défaut de contraste dans l'image.

Jean-Pierre

[titi et nini]

par là ,j'entends pas grand chose non plus(Pierre Dac!!!)

est-ce quelque chose comme ça, sur le bord droit de l'image?

[isym44]

Je ne saurai dire ne possédant pas de Lunt.

Il parle de défaut en travers du champ. Peut être une image fantome.

En tous cas si cette photo est faite avec un Lunt ça m'incite à investir.

Jean-Pierre

[Jean Louis]

:?:En visu,je ne constate pas ça.Il m'a semblé comprendre que ces instructions concernent surtout le nouveau système de tuner "air pressure".Le FP est enfermé dans une cavité étanche.Le gros bitognot à l'extérieur servant à affiner le contraste et les détails.Je n'en sais pas plus.

[Jean Louis]

Le Lunt Pressure Tuner

[titi et nini]

Je ne saurai dire ne possédant pas de Lunt.

Il parle de défaut en travers du champ. Peut être une image fantome.

En tous cas si cette photo est faite avec un Lunt ça m'incite à investir.

Jean-Pierre

 

Bonjour Jean Pierre,

et oui ç'est fait avec le Lunt LS 60 Bf 600,j'en ai posté quelques unes ces derniers temps .

Titi

[julouin]

Alors petite nouvelle de Galiléo pour l'achat de ma futur lunette, avec le Pressure tuner, qui est en fait une pompe.

 

Le nouveau modéle est 400€ plus cher que le modéle présenté sur le site de Galiléo, le nouveau modéle n'étant pas encore affiché sur ce même site.

 

Le délais de livraison est plus court que pour les anciens modéles.

Car Lunt, même si Galiléo a encore des reliquats d'acheteur d'anciens modéles, livre plus rapidement ses nouveaux modéles.

 

De plus si vous êtes interressé par un nouveau modéle, précisé le bien ; je l'avais fait il y à trois semaines et j'avais était clair, pour que l'on me dise aujourd'hui que la commande était prise pour un ancien modéle, donc surprise aujourd'hui votre Lunt passe de 1400€ à presque 1800€ (enfin j'attends encore la confirmation, mais quand même).

 

Heureusement que j'avais quelques brouzoufs de côté, mais maman ne va pas être contente, je le sent !!!

[Leimury]

Alors petite nouvelle de Galiléo pour l'achat de ma futur lunette, avec le Pressure tuner, qui est en fait une pompe.

 

Bonjour,

 

Pressure tunner ?

D'après le texte en anglais, ils parlent de la pression de la couche d'air du doublet optique qui influe sur l'optique.

Cette couche d'air est considérée comme une 3e lentille en fait.

Ils écrivent également que l'optique est réglée au mieux pour une altitude de 1500 à 3500 pieds -> 500 à 1200m.

 

Le Pressure tunner, c'est pour ajuster la pression de cette couche d'air là ?

 

Ca pourrait donner des idées à d'autres fabricants de doublets.

Cette partie là, c'est pas propre à l'observation solaire mais ça cause des caractéristiques d'un doublet en général.

 

Bon ciel

[julouin]

Alors à ce que j'ai compris, le Pressure tuner, interviendrais plus sur le FP comme le dit Jean Louis au message #17.

Et c'est pour cela que la pompe est utilisée, changer la pression sur le FP, la photo que nous a presenté Jean Louis.

[Jean Louis]

Apparament,c'est beaucoup plus souple que réglage par molette.Sur le FP les corrections sont micromètriques,un rien peut tout changer.Sur le site de Médas,ils le disent à propos des filtres Daystar.

[Jean Louis]

:)En tout cas ,Juloin,tu vas avoir une super Lunt.Je Précise que Andrew Lunt à travaillé 20 ans dans l'optique spatiale et qu'il est le fils de David Lunt,créateur de Coronado et concepteur des SM et PST.