OWL Astronomy

OWL Astronomy Products
Eyepieces, Telescopes, Binoculars, Microscopes
Barlow Lenses / Focal Reducer


Barlow Lenses and Focal Reducer


I. Barlow Lenses

Increase the power of your eyepieces without ending up with a short eye relief.

2 Inch 2X ED Barlow
New Ultra-Black Design - Brand New!
Coating on 2 Inch 2X ED Barlow
View of coating on new Knight OWL 2" 2X ED Barlow
Includes 1.25" adapter and compression rings
A Barlow lens is used to increase the power of an eyepiece. To use a Barlow you place the Barlow into the focus tube of your telescope. You then may put any of your eyepieces into the end of the Barlow. This will allow you to reach the highest useful range of powers with your telescope.

Barlow lenses are rated by the amplification factor. A 2X Barlow increases the magnification 2 times, a 3X increases it 3 times, etc. We have Barlow lenses for both 2 inch and 1-1/4 inch eyepieces. You also may use a 2 inch Barlow with your 1-1/4 inch eyepieces if you have an adapter. This adapter is included with the 2X 2" barlow.

In addition to getting higher power with any eyepieces, a Barlow lens also has the advantage of keeping the same eye relief as the original eyepiece. This is a great value to people who want to use eyepieces while observing. A Barlow makes the telescope act as if it had a higher focal length. This may actually aid in improving how the telescope works. In this fashion Barlow lenses are good for photography where you want a larger image from an object.

With many advantages, there are disadvantages. Although Barlow lenses have only a few elements (usually 2), the extra glass may cause some slight loss of light or color correction. This is usually very, very minor and the increased eye relief makes the image easier to see at many powers. There are some eyepiece/telescope combinations that do not do well with a Barlow lens. This is rare but you should be aware that it may occur.

Contrast in very important to bring out faint deep-sky features and fine planetary detail. Our 1-1/4 inch and the 2 inch 2X and 3X Barlows have edge-blackened and advanced multi-coated optics. These additional steps in the manufacturing process result in better contrast with your telescope. In any view through a telescope, especially where a bright star or planet is present, their is some light scatter. With standard optics some of this light may be reflected back into the eyepiece and results in decreased contrast. With edge-blackened optics, this reflection is eliminated. Coupled with the advanced multi-coating on these Barlows, you have a great product. The fully multi-coated optics on these eyepieces appear green at small angles and magenta (purple) at large angles. Multi-coating is more difficult to produce but results in increased contrast and light transmission.

Check out our new dual power barlow listed below. This 2X barlow will also give you a 1.4X power. The finish of these new barlows was made to match our new Ultrablack Plossl and Ultrawide eyepieces.

New ED Glass Barlows

The ED design barlows are a new and more advanced design. The ED stands for "Extra-Low Dispersion." Lens elements of the exotic ED glass are more expensive to make but yield apochromatic performance. The false color seen on bright objects using standard achromatic glasses is virtually eliminated. Even with super color correction, we have introduced these advanced 2 inch ED barlows at below the price some companies charge for an apochromatic 1-1/4" barlow. Our new 2 inch 2X ED barlow is now part our new Ultra-black series!

 

II. Focal Reducer

A focal reducer may be thought of as just the opposite of a barlow lens. Barlow lenses increase the power and focal length of a telescope. These focal reducers reduce the power and effective focal length. An f/10 SCT becomes an f/5 SCT telescope. An f/6 reflector becomes an f/3. It does not change the apparent field of view of an eyepiece, but increases the true field. It doubles the true field of view and decreases the required photographic exposure for an object by a factor of 4.
NOTE: There are some similar products available. In our testing these will not achieve a true 0.5X focal reduction without using an extension tube. This model, which was designed in our shop, will achieve the 0.5X directly. It will get even more reduction with an extension tube.

To use a focal reducer, you screw the lens onto the filter thread of your eyepiece. You may also use this with our C-mount adapter to adapt you C-mount video camera to your telescope. This focal reducer effectively divides the focal length (and f/ratio) of the telescope by 2. This will allow you see a wider true field of view with any eyepiece. You may use any of your standard 1-1/4" (31.75 mm) eyepieces with this as long as they have the standard filter thread. If you want to look at it the other way, it doubles the focal length of the eyepiece.

Please Note: Using the focal reducer on your eyepiece requires you to focus inward on most telescopes about 20 mm. This is not usually a problem but could cause you to be unable to focus the telescope in the few telescopes that do not allow this inward travel. This will be NO PROBLEM on SCTs and similar telescopes. The exact amount of inward focus depends on the eyepiece. The 20 mm is based on our Plossl eyepieces using our reflector telescope that we used for most tests.

 

Barlow Lenses

Inexpensive Meade Barlow Lens
(Unused surplus product)

2X Meade Barlow Meade Instrument Corporation has manufactured a number of different barlow lenses for their various products. For sale with their lower priced telescopes, Meade has produced this low priced barlow. OWL Astronomy Products (OWL Services) was able to purchase a number of these barlows on the surplus market. This is an unused product in new condition.

This barlow model is a short form and will work fine in all telescopes. The achromatic lens used in this product has a good anti-reflection coating. This lens is housed in a light plastic case. While this barlow is inexpensive because it was purchased surplus, it was manufactured to Meade quality standards.
2X Meade Barlow 1-1/4 Inch
Fully Coated
Price: $9.95
(Limited time only!)

Brand New Dual Power Barlow Lenses

2X Barlow 3X Barlow
2X Barlow 1-1/4 inch
Fully Multi-coated
(Dual power as 1.4X barlow - See below) 		3X Barlow 1-1/4 Inch
Fully Multi-coated
(Dual power as 1.8X barlow - See below)
Price: $19.95.
 Price: $21.95
Lens cell of barlow
Barlow lens cell removes from the base
of the barlow barrel.
Note: Eyepiece is not included. 		Lens cell of barlow on eyepiece
Lens cell screws onto the bottom of the eyepiece
filter thread to make the 2X a 1.4X barlow
Note: Eyepiece is not included.
3X Barlow and Caps
Both new 2X and 3X barlows are fully multi-coated and come with
top and bottom caps, removable lens cell, and a deluxe bolt type case.

Quality Barlow Lenses from Parks (Lumicon)


2X APO Barlow		 2X Shorty Barlow
Parks Gold Series 2X Barlow
Three Element APO Design
Fully Multi-coated
Clear aperture of 26 mm for wide-field viewing 		Parks Silver Series 2X Barlow
Fully Multi-coated
T-thread adapter for Astrophotography use
Price: $89.95. NEW!
 Intro Price: $49.95 NEW!

2 Inch ED Barlow Lens with Brass Compression Ring

2X 2 Inch ED Barlow
New Ultra-black design.
Comes with 1.25 inch adapter and bolt-type case		 New Ultra-Black Design - Brand New! Coating on 2 Inch 2X ED Barlow
View of coating on new Knight OWL 2" 2X ED Barlow

Includes 1.25" adapter and compression rings
2X ED Barlow 2 Inch - Knight OWL
Fully Multi-coated - ED Glass
Apochromatic Performance
Bolt-type case
Sale! Price: $56.95
(For a limited time only)

Focal Reducer

New Knight OWL Focal Reducer
New Knight OWL MC 0.5X Reducer

Fully Multi-coared
Fully Multi-coated
Fits any 1.25 inch eyepieces with standard filter thread

0.5X and Eyepiece
Attaches to the bottom of your eyepieces.
0.5X and Eyepiece
Focal Reducer on our Plossl Eyepiece.
(Eyepiece shown above in NOT included with the focal reducer. Use any 1.25 inch eyepiece)
Price: $29.95.

C-Mount Adapter for OWL Focal Reducer
C-Mount Adapter for OWL Focal Reducer
OWL Focal Reducer screws into the bottom of the adapter. 		C-Mount Adapter for OWL Focal Reducer
C-mount at top fits standard C-mount video cameras.
C-Mount Adapter for OWL Focal Reducer
OWL Focal Reducer mounted on the C-mount adapter.
(The focal reducer and the adapter are sold separately) 		This adapter will adapt the OWL Focal Reducer to a standard C-mount video camera. The threads at the bottom of the adapter fit the threads on the focal reducer. The threads at the top fit the C-mount on your camera. The unit then fits into a standard 1.25" focus tube. This adapter and our focal reducer give you a much faster system with a larger field of view. These are made for us in the United States.

Please note: This adapter would not work with your C-mount camera without the focal reducer. A longer one is required without the focal reducer. We also carry a C-mount adapter for this purpose.

Price: $16.49.


Last Updated February 18, 2010