Skywatcher Esprit 150 field Flattener mirror question

[bluesilver]

Hi,  I have a Skywatcher Esprit 150,  I am referring to the part they call the Field Flattener that comes as part of the scope,  not the optional focal reducer.

It is listed in the online manual  https://inter-static.skywatcher.com/upfiles/en_download_caty01416868668.pdf page 12 3rd item from the left

I removed both lens for some cleaning, but lost the orientation on which way around they come out, 

Now by that i mean, I know which one goes closest to the camera,  but not sure which way around they are suppose to be,  weather it is convex or concave.

So the first mirror that goes closest to the camera,  is the camera side concave or convex?  so is the camera side shaped like this ) or like  this (

And then the same for the second mirror furthest away from the camera, is the camera side concave or convex?  so is the camera side shaped like this ) or like  this (

I hope all that makes sense.

 

 

 

 

[inFINNity Deck]

According to this image, the last lens before the camera is convex towards the camera: [PS: this is a diagram of the reducer/flattener, it comes from https://manuals.plus/sky-watcher/esprit-150-ed-super-apo-3-element-ed-apochromatic-refractors-manual#axzz7pVHdakQL]

And the other side appears to be convex towards the scope:

Here you can see what it should look like when everything is mounted. If you mount one of the lenses the wrong way around you may be able to see that it is different:

I do have a flattener on my Esprit 150ED, but that is currently mounted with camera and all, so I will keep it that way... 😉

Nicolàs

 

Edited January 6, 2023 by inFINNity Deck
diagram is of reducer/flattener instead of flattener

[inFINNity Deck]

I have checked several drawings of other manufacturer's flatteners, and the first and last element should be convex in the same direction:

In the last of above images a faint reflection on the uppermost surface can be seen, indicating that indeed that surface is nearly flat.

But best thing to do is to mount the lenses and check if the reflections of and view through the lenses compare to the images in my first reply.

Nicolàs

 

 

[bluesilver]

Thanks for the detailed reply there,  I searched a fair bit and couldn't find any diagrams,  so very much appreciated.

Just to add to the confusion,  well for me anyway and to help myself see what is going on in those diagrams

So basically the first and last elements are  convex in the same direction?

So this means that both elements should be installed so they look like this:  (  (

It is just in the first diagram,  the last lens before the camera is convex towards the camera which is like this :  )

So it is kind of saying two different things here,  one is saying that both elements should be in the same direction, which is convex,  and then the next it is saying that it should be concave.

You can possibly see why I have gotten myself a little confused here.

 

I am guessing the last diagram may be the one to reference to,  both elements to be Convex,  So with the Flattener installed on the scope looking through it,   Both elements facing the telescope the will be both Convex,  like this:  (  (

So the end facing back to the camera is Concave  like this:  )  )

 

I think that is what you were saying,  just talking me a little while to work it all out.

Cheers.

[inFINNity Deck]

Hi Bluesilver,

yes, it is quite confusing, and it is a pity that I am in the middle of an imaging project, so I do not want to open mine to check it out for you.

I went back to where I found that diagram: https://manuals.plus/sky-watcher/esprit-150-ed-super-apo-3-element-ed-apochromatic-refractors-manual#axzz7pVHdakQL

As you can see it is a messy site. What I missed, is that the diagram is of the reducer/flattener instead of the flattener... So we have to ignore that drawing.

That means we are left with the images and diagrams of other flatteners, and those seem to be "scope ( ( camera". Now, I do also have an Esprit 80ED with flattener on my rig (which is not being used at the moment), so I opened that one and that confirms "scope ( ( camera". But it would be good to compare what you create from your parts to that last flattener-photo I posted.

Nicolàs

 

[bluesilver]

Thanks for the reply,  it is very much appreciated.

I will put it all back together as  "scope ( ( camera"

Bit of luck this should be correct,  I have sent Skywatcher an email a few days ago,  but no reply yet as i think they are still on their Christmas break.

Next time i will pay a bit more attention before things get messy.

 

 

[windjammer]

Ooops