eyepiece arrangement

[tesla2002]

hello , I bought today a bst  1.25" 16 mm 60 degree eyepiece and I accidentally opened it which made all the lenses come out , I need help in putting the back the way they were can anybody help me ?

 

[faulksy]

how did you accidentally open it

[wookie1965]

First who did you buy it from, I got mine from skies the limit I took my 18mm apart to clean it and messed up the lens I emailed Alan and sent him a picture he emailed back with the picture labelled with the right configuration. Secondly I did not think BST did a 16mm. 

[ollypenrice]

You can often find schematics of EP design on the maker's website. It would be worth a look. Failing that you could ask them if they could show you one.

Olly

[Ricochet]

Assuming you mean a BST Starguider (which isn't avalable as a 16mm) then the lens arrangement should be like below. 

[ollypenrice]

3 minutes ago, Ricochet said:

Assuming you mean a BST Starguider (which isn't avalable as a 16mm) then the lens arrangement should be like below. 

Yes, I just found something similar. https://www.google.fr/search?q=bst+explorer+technical+diagram&source=lnms&tbm=isch&sa=X&ved=0ahUKEwij6sDJsIHVAhUHmbQKHRxvBw0Q_AUIBigB&biw=1280&bih=660#imgrc=S37cu_px0Zy9KM:

Olly

[ronin]

The image as Ricochet shows is the Starguider/Explorer/Paradigm arrangement:

https://www.astronomics.com/astro-tech-paradigm-dual-ed-eyepieces_c52.aspx

Page has maybe other information on it. Not sure which bit is the top or the bottom.

If it is one of the other BST's then tell us which one, but cannot see a 16mm in any of the BST offerings on Alan's site of Sky's the Limit.

If it is a Starguider then "accidently" and "opened it" are a difficult pairing.

[Alien 13]

The general layout for most eyepiece types is given in this chart.

As a very general rule of thumb the flater parts of the lenses face both ends.

Alan

[tesla2002]

@wookie1965  can you send me the configuration ?

 

[rwilkey]

Here is a diagram showing the lens structure with spacers: 

 

[tesla2002]

thank you all guys , I finally managed to fix it after a couple of hours , you were all very helpful which is why I love this website

[Charic]

 

2 hours ago, tesla2002 said:

I finally managed to fix it after a couple of hours

 Well done......can you still  confirm it was a 16mm.

Not only that, and for others too, use your mobile to video the process, eyepieces just don't fall apart or open up, without several turns of the barrel
One clue is to listen! the more you loosen, the greater the rattle?

[wookie1965]

This is what I received from Alan at Sky`s the limit.

Thanks for the picture.  I have amended it with some numbers to help with reassembly.  This is the order to put them into the body facing the silver nosepiece.

 

No 1 - convex face facing out (towards the silver nosepiece)

Nos 2, 3 and 4 have to go together to make a sandwich.  With the one I took apart the lens was actually in the metal part so this one might end up the wrong way round - still a 50-50 chance of getting this one right.  Once assembled the open metal end faces the silver nosepiece.

No 5 goes in with convex side down (flatter side up towards your eye)
No 6 is the securing ring - holes up so that you can tighten it - use a bent paper clip if you haven't got pointy nose tweezers

No 7  Wind the eyepiece out a bit then fit securing ring 7.

Pop the rubber eyecup back on and job done.

 

If it doesn't work try the 2, 3, 4 sandwich the other way round.

 

If you do it in daylight you will soon find out if you have done it correctly.

[Red Dwarfer]

6 hours ago, Alien 13 said:

The general layout for most eyepiece types is given in this chart.

As a very general rule of thumb the flater parts of the lenses face both ends.

Alan

Handy guide ! Did a screen cap for future reference ... from this guide the Kellner has three elements and one less than the Plossl design , so does that automatically make the Plossl one rung higher up the lens ladder ? 

[John]

1 hour ago, Red Dwarfer said:

Handy guide ! Did a screen cap for future reference ... from this guide the Kellner has three elements and one less than the Plossl design , so does that automatically make the Plossl one rung higher up the lens ladder ? 

Kellners are not as well corrected in faster scopes as the Plossl is (or can be, if it's well made). Kellners can work well in F/10 or slower scopes (ie: F/12, F/15 etc). The number of elements is not always a guide to how well corrected an eyepiece is though - it's complicated by many factors such as the glass types used, the figuring and polish of the lenses, the coatings used, etc, etc etc.

The wonderful world of eyepieces is a complex and sometimes confusing place !

 

[Louis D]

21 hours ago, John said:

Kellners are not as well corrected in faster scopes as the Plossl is (or can be, if it's well made). Kellners can work well in F/10 or slower scopes (ie: F/12, F/15 etc). The number of elements is not always a guide to how well corrected an eyepiece is though - it's complicated by many factors such as the glass types used, the figuring and polish of the lenses, the coatings used, etc, etc etc.

The wonderful world of eyepieces is a complex and sometimes confusing place !

 

Add to that list the use of aspheric surfaces (figuring in your list, possibly).  Adding a single aspheric surface can sometimes take the place of at least one additional element.

[tesla2002]

@Charic yes it is a 16 mm one  http://agenaastro.com/bst-16mm-flat-field-eyepiece.html it is this one

[tesla2002]

@Charic I wanted to clean it because it had something inside it and I realized that it was an extremely idiotic move the second I opened it

[Ricochet]

32 minutes ago, tesla2002 said:

@Charic yes it is a 16 mm one  http://agenaastro.com/bst-16mm-flat-field-eyepiece.html it is this one

Ah, one of those. I hadn't realised they were also being sold under the BST brand. The lens diagrams supplied were for a different eyepiece so you'll have to test the eyepiece and see if the lenses are in the right order and orientation based on the view through them. Unfortunately, I haven't found a schematic for that eyepiece design to compare. 

[Charic]

2 hours ago, tesla2002 said:

@Charic I wanted to clean it because it had something inside it and I realized that it was an extremely idiotic move the second I opened it

Sometimes its the only way to learn.

What back then may have felt idiotic, has now made you better aware and better prepared for the next time?

[tesla2002]

@Ricochet I tested it and it works fine , thank you very much

[tesla2002]

@Charic that's very true

 

[Dave In Vermont]

For those who like charts and designs, here's another chart of designs to file, print, hang-on-wall, or all-of-above:

 

 

That'll do it -

Dave

[Stargazer McCabe]

On 11/07/2017 at 14:26, faulksy said:

how did you accidentally open it

A classic case of "if all else fails; read the instructions or research fully" by the sounds of it... ?

[Alien 13]

5 minutes ago, Dave In Vermont said:

For those who like charts and designs, here's another chart of designs to file, print, hang-on-wall, or all-of-above:

 

 

That'll do it -

Dave

Interesting chart, I am surprised at the age of some of these deigns and makes you wonder what will be achieved with modern glass and computer aided design/manufacturing.

Alan