•

# Skywatcher LET 2" 28mm???

15 replies to this topic

### #1 Dubreuil

Dubreuil

Explorer 1

• topic starter
• Posts: 58
• Joined: 29 Sep 2007

Posted 05 August 2012 - 03:32 PM

This eye piece came with my telescope and I am trying to find out more information about it. I am trying to find out the AFOV of this eye piece. Would anybody know what the AFOV is on the Skywatcher LET 2" 28mm?

http://ca.skywatcher...ail.php?sid=161

If it is greater than 50 degrees then I do not see the need to get a 32mm Plossl

Thanks,

### #2 Jim Nelson

Jim Nelson

Apollo

• Posts: 1006
• Joined: 10 May 2005
• Loc: SE Michigan, USA

Posted 05 August 2012 - 03:56 PM

They appear to have a 55 degree AFOV. LINK

### #3 Dubreuil

Dubreuil

Explorer 1

• topic starter
• Posts: 58
• Joined: 29 Sep 2007

Posted 05 August 2012 - 04:41 PM

Thank you very much. Looks like another eye piece is in my future.

Thanks again.

### #4 Jon Isaacs

Jon Isaacs

ISS

• Posts: 54413
• Joined: 16 Jun 2004
• Loc: San Diego and Boulevard, CA

Posted 05 August 2012 - 07:02 PM

According to the link Jim provided, the field stop of the 28mm LET is 31mm, that would mean it should exceed the TFoV of a 1.25 inch 32mm Plossl. The field stop of the Plossl is less than 28mm.

You could actually measure the diameter of the field stop. When you look through the eyepiece, you see the edge of the field of view as a dark boundary, that's the field stop.

If you turn the eyepiece around and look through it backwards, you should see the field stop as a ring part way down the barrel. If you can measure the diameter of the ring, you can calculate the TFoV.

Jon

### #5 Michaelo

Michaelo

Lift Off

• Posts: 2
• Joined: 21 Dec 2012

Posted 11 January 2013 - 03:07 PM

What exactly is a LET eyepiece and how do they differ from normal eyepieces?

### #6 denis0007dl

denis0007dl

Vendor (Binoviewer Supercharging)

• Posts: 680
• Joined: 17 Apr 2012
• Loc: Umag, Croatia

Posted 11 January 2013 - 04:57 PM

It is a Kellner with 3 elements, he is good for f/10 scopes and slower, but in fast scopes, like f/5, not good at corrners!

### #7 Andy Johnson

Andy Johnson

Lift Off

• Posts: 8
• Joined: 07 Aug 2012
• Loc: Shropshire, UK

Posted 30 May 2013 - 04:56 PM

I have one of these that came with my 300PDS f/5, I have to admit it's pretty good when used with either a Revelation Astro (GSO) 2" Barlow or Baader MPCC. My only criticism (apart from comma towards the edges) is that the background sky is quite light (blue rather than black) Would a 2" Plossl maybe in the 26-32mm range produce better contrast, does anyone have any recommendations that are not in the Nagler price range. I have been wondering if the Revelation 2" Plossls from Telescope house are any good for the price.

### #8 SeattleScott

SeattleScott

Surveyor 1

• Posts: 1851
• Joined: 14 Oct 2011

Posted 31 May 2013 - 01:06 AM

For fast scopes a 4 element plossl should perform better than a 3 element Kellner. But good luck finding a 2" plossl 26-32mm. For 2" wide field eyepieces for a F5 scope you are really in the super wide or ultra wide territory. You could get a 26mm or 32mm Q70. Wide field and they should outperform the LET for sharpness, although not by much.

### #9 Messyone

Messyone

Apollo

• Posts: 1177
• Joined: 02 May 2012
• Loc: Down Under

Posted 31 May 2013 - 04:18 AM

There is a good reason these are free with scopes. They are complete rubbish....The 'T' stands for trash....Long Eyerelief Trash, or LET.
Better to get a decent plossl and use this as a paperweight.
• jgroub likes this

### #10 bdcmd

bdcmd

Ranger 4

• Posts: 396
• Joined: 14 Mar 2008
• Loc: Glen Rose, Texas

Posted 31 May 2013 - 08:38 PM

. . But good luck finding a 2" plossl 26-32mm.. .

Smart Astronomy Sterling plossls are available in 2" 30mm and 40mm versions. I particularly like the 30mm, but the fastest scope I have used it in is f/6.7, so not sure how well it would perform at f/5, but, . . . it's a plossl, so it probably wouldn't be too bad. For my money, the Agena 32mm SWA would be a better choice. Anything much better will be a lot more expensive.

### #11 csrlice12

csrlice12

Hubble

• Posts: 16114
• Joined: 22 May 2012
• Loc: Denver, CO

Posted 24 August 2015 - 10:53 AM

There is a good reason these are free with scopes. They are complete rubbish....The 'T' stands for trash....Long Eyerelief Trash, or LET.
Better to get a decent plossl and use this as a paperweight.

Have to disagree here.  While they have their limitations, with the 102 f10, it works fine.  Wouldn't mind trying out the short fls....mechanically, they're well built (except for that Televue style undercut) and others would do well to use that twist up eyecup idea.  These aren't the NLV type twist cap, but are finely threaded like an XW.

### #12 skyward_eyes

skyward_eyes

Vendor - Sky-Watcher USA

• Posts: 4134
• Joined: 12 Dec 2006
• Loc: California

Posted 24 August 2015 - 10:57 AM

They are excellent for solar observing because of their simple design.

### #13 Jacques

Jacques

Messenger

• Posts: 478
• Joined: 11 Aug 2002
• Loc: Belgium

Posted 24 August 2015 - 12:21 PM

Mine came with the ED 120. I think it's actually quite good with a long FL scope, good sharpness on axis, good clarity, good contrast. But...it really suffers with shorter focal lengths. Distortion is pretty severe even at moderate FL like F7.5 (like the ED). I suspect it to be quite nice with a long focal length scope though.

### #14 CCC

CCC

Explorer 1

• Posts: 88
• Joined: 28 Nov 2010
• Loc: Northern Manitoba

Posted 24 August 2015 - 12:35 PM

This eyepiece came with my scope as well. It doesn't get much use at night, but I use it all the time for solar viewing. It seems to be excellent for that activity. I've never tried it in my f4.7 dob.

### #15 russell23

russell23

Fly Me to the Moon

• Posts: 6417
• Joined: 31 May 2009
• Loc: Upstate NY

Posted 07 September 2015 - 11:23 AM

They are excellent for solar observing because of their simple design.

Is the 20mm eyepiece that comes with the SW120ED an LET?

Are all the elements in these glass?

Dave

### #16 CCC

CCC

Explorer 1

• Posts: 88
• Joined: 28 Nov 2010
• Loc: Northern Manitoba

Posted 08 September 2015 - 10:29 PM

They are excellent for solar observing because of their simple design.

Is the 20mm eyepiece that comes with the SW120ED an LET?

Are all the elements in these glass?

Dave

According to Skywatchers USA webpage both eyepieces are LET's. I can only speculate that all the lens's are glass.

## CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

 Cloudy Nights LLC Cloudy Nights Sponsor: Astronomics