SIEBERT  TELESCOPE OPTICS


This Web page will list all of the Telescope optical eyepieces that I have made and a little about them.  Thanks for looking.


I have been an amateur astronomer for many years and have owned a great many lenses.  Meade Plossl, Kellner, and some fairly inexpensive lenses.  But instead of spending a tremendous amount of money, over the years I have experimented and assembled my own lenses from sources such as Edmond Scientific and various suppliers of high quality optics.  These are handmade eyepieces and the cosmetics are not perfect.  But the optics are high quality.

Here is a  link to some feedback from people who now possess some of these  eyepieces.  It shows how happy they are with my eyepieces. I am very proud of the eyepieces and the feedback from others and want to show them off.

http://cgi2.ebay.com/aw-cgi/eBayISAPI.dll?ViewFeedback&userid=siebert

12.5mm wide angle

               

In the picture to the left is my homemade 12.5mm wide angle eyepiece.  The picture to the right has a comparison of  a 6.7 Meade eyepiece (left);  the 12.5mm eyepiece that I made(center); and  a 12.5mm Kellner type eyepiece (right).  Notice that the aperature size of my eyepiece is much larger than the ordinary 12.5mm while at the same time they both have a postive focal distance of 12.5mm hence producing the same magnification. This is a 12.5mm fully coated 3 filament eyepiece which produces extremely wide angle at all magnifications for 1.25" diameter.  At 80x magnification when viewing the moon not only does it produce an extremely sharp and crystal clear view with perfect color quality, but takes in the entire view of the moon with room to spare.   The optics are very high quality and coated for maximum light transmission.  Also using the 3 filament lens system it fully corrects for color aberrations.     This eyepiece has a 65 degree field angle and eye relief of 7mm.

18mm wide angle

In this picture you see a 1.25" 18mm fully coated 4 element eyepiece which produces extremely wide angle at all magnifications depending on your focal length.  This is almost identical in every respect to the 12.5mm above.  The only difference is that this eyepiece adds a 4th element, a glass achromat type doublet that is placed to increase the focal distance to 18mm.  Also being an achromat type doublet it maintains extremely sharp image quality and maintains perfect color quality.  Its field angle is roughly 65 degrees and eye relief of 7mm.

21mm superwide angle

This is a 1.25" 21mm fully coated 3 filament eyepiece which produces extremely wide angle at all magnifications depending on your focal length.  At 900 mm  focal length it produces 43x magnification.  Most seasoned astronomers appreciate what that means.  the lower the magnification the more field of view you have.  But this lens goes a step further.  Even though it has a 21mm positive focal length, the clear aperature of this eyepiece is about 5/8" or 16mm wide.  The field angle is 80 degrees and the eye relief is 8mm..  When you look through this eyepiece you can barely see the end of the field of view.  But no color distortion.  Dense and wide star fields are a pleasure to view.  Ordinary Kellner type eyepieces cannot compare when it comes to field of view.

29mm good eye relief

This is a 1.25" 29mm fully coated 6 element eyepiece which gives good eye relief.  It has a 29mm positive focal length and the clear aperature of the eyepiece is about 17mm wide.  It has no color distortion and no discernable image distortion even around the extreme outter edges.  The reason for this is because it uses two achromat type doublets (crowns facing each other) lenses and an additional magnifier making this a 6 lens system.  A similar set used by Meade Plossl.  This produces exceptionally sharp images, as anybody familiar with the achromat lens knows.  This lens configuration fully corrects for color and image aberrations.  But it also does something else.  This type of lens configuration gives incredibly long eye relief.  In this case over 25mm or 1".  This one trades wide (65 degrees) and superwide (80 degrees) for a much longer eye relief.  But it still offers a respectable field of view.  The field angle is 52 degrees.  The total height of this eyepiece is 3".  You can see from the picture the wide aperature of this eyepiece.  A light filter snaps neatly into the bottom.

32mm  and 35mm superwide aperature

This is the 32mm superwide aperture, high eye relief eyepiece.  The eye relief is 25mm and has a field angle of 52 deg.  It is a 6 element eyepiece consisting of  two achromat doublets and a field of view expansion lens.



Also shown is the  35mm superwide aperature, high eye relief eyepiece.  The eye relief is a little over 1 inch.  You can see the complete field of view without ever taking off your glasses if you wear any.  This is the most comfortable lens I have ever used.  It is very bulky, as you can see in the above picture.  It is made with two 30mm achromat doublets of high index glass and a field of view expansion lens.  This makes this a 6 element eyepiece.  It also has provisions on the bottom for a light filter.  It snaps in very firmly and will not fall out.  It has just under  50 deg. fov and 27mm of Eye Relief (ER).

45mm ultra-wide aperature

This is a 1.25" 45mm ultra-wide aperature high eye relief eyepiece.  It uses two 30mm achromat lenses (crowns facing each other) along with an additional 30mm magnifier to produce this incredible effect.  The lens is actually inset almost 2/3" before the aperature and  yet your eye relief is roughly 29mm outside the aperature.  This means extremely long, comfortable viewing times.  Even though the field is about 42 degrees, which is understandable for a high eye relief eyepiece, it takes in an enormous section of sky.   An example of the field of view is the Orion Belt.  There are 3 stars right at the heart of the Orion Belt called Alnitak, which is a 1.8 magnitude star; Alnilam, 1.7 magnitude; and Mintaka, 2.2 magnitude.  The field of view allows you to see either Alnilam and Mintaka or Alnilam and Alnitak at the same time.  Now these stars are pretty far apart.  There are not too many eyepieces that would group these stars together in the same field of view.  But this eyepiece almost gives you what you would expect to see in a pair of 8 x 35 binoculars with a 370' per thousand yards field of view.  Now this may be exaggerating a little bit, but not much.  This lens is an attempt to achieve the widest field with the highest high eye relief.  Now if you wear glasses I suggest you wear them at all times with this lens.  This gives 100% crystal clear super sharp images with no distortion in the field of view.  A light filter fits very snugly and securely to a neopreme gasket fashioned securely to the bottom.  Light filters will not fall out.  This eyepiece is not recommended for short tube newtonians of 500mm or less.  You would be able to see the secondary obstruction or secondary mirror.