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Antares 2" 0.5x Focal Reducer

4.4 (8 Reviews) Read Reviews Write Review
Brand Antares
Part Number FR2
Availability available

Product Info

Manufacturer Description

Antares' 2" 0.5x focal reducer screws on to any accessory (such as eyepieces, camera adapters, etc.) that accepts standard 2" threaded filters and provides a nominal reduction of 0.5x. Use of this focal reducer effectively halves the focal ratio of your telescope, resulting in a wider field of view and significantly shortened exposure times for astrophotography. For example, use of this reducer will convert an f/10 telescope into an f/5 scope.

The 2-element reducer features fully multi-coated optics in a black-anodized aluminum filter cell. This focal reducer will work well for visual use too when coupled with the right kind of eyepieces and telescopes (it is not recommended for very fast scopes or very wide angle eyepieces for visual applications). This new, improved version also features a 2" female thread so you can screw/stack additional 2" filters on to this reducer.

The actual reduction will vary a little over or under 0.5x depending on exactly where the focal reducer is placed in the optical path. The focal length specification of this reducer is 158mm. Hence, the "working distance" of this specific reducer is 79mm, i.e., this reducer will provide a reduction of 0.5x when the center of its lens assembly is placed 79mm from the focal plane of the eyepiece or imaging device. Move the focal reducer closer to the eyepiece/camera and its reduction factor will increase. Move it away and the reduction provided will decrease.

By using additional spacers or extension tubes (sold separately), you can vary the amount of reduction you obtain with this reducer as follows:

Extra Spacer Length
Nominal Reduction Provided
0" / 0mm
0.50x
0.25" / 6.4mm
0.46x
0.5" / 12.7mm
0.42x
0.75" / 19.1mm
0.38x
1" / 25.4mm
0.34x

Note that the use of any optical element like barlows and focal reducers changes the focus point of your telescope, requiring additional in-focus or out-focus travel. The exact amount of focus travel required will depend on the optics and mechanics of your specific set-up (telescope, diagonal (if used), barlow/reducer, and eyepiece). Hence, be aware that you may not be able to reach focus with all eyepieces or in all configurations with a given barlow/reducer.

Total length (including external thread) = 19.4mm (0.76"); Total length (excluding external thread) = 16mm (0.63"); Clear Aperture = 38.5mm (1.52"); Weight = 2.3 oz.; Made in Canada.

Reviews

4.4 (Based on 8 Reviews) 100% of reviewers recommended this product.
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    1. Guest

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      Review by Al of Near Paris France.
      1453680000
      Jan 24, 2016

      5.0 Excellent

      Pros:

      Compact,Easy to Use

      Cons:

      Comments:

      Wonderful as for visual as photo far field objects observations

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    2. Guest

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      Review by animotion of NY.
      1435363200
      Jun 26, 2015

      4.0 Reduce you focal length

      Pros:

      Strong Construction,Easy to Use,Lightweight,Accurate,Compact,Quality Lenses

      Cons:

      Comments:

      Very useful for getting wider views with good optics.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    3. crsrs

      crsrs New Member

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      Review by crsrs of San Tan Valley, AZ.
      1385769600
      Nov 29, 2013

      5.0 Fantstic option for a reducer

      Pros:

      Lightweight,Easy to Use,Quality Lenses,Strong Construction,Compact

      Cons:

      Comments:

      This focal reducer works great with my eyepieces in my Nexstar 9.25 SCT telescope. I have plenty of back focus to work with, and I love the way this lens simply threads onto my eyepieces. I use it on my ES 100 degree 20mm eyepiece to acheive the the focal length of a 30mm eyepiece. The view is very nice with a somewhat corrective effect yeilding a flat field and no coma. This is a great option, and I like it very much.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    4. Guest

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      Review by Jeff of Fort Collins, CO.
      1381536000
      Oct 11, 2013

      4.0 Works as intended

      Pros:

      Compact,Easy to Use,Strong Construction,Lightweight

      Cons:

      Comments:

      I used to have the SCT reducer but returned that since screwing and unscrewing from the back of the OTA of my Nexstar 8se got annoying after a while. I use this everytime I do my short exposures AP. The only downside of this item is that it doesn't flatten the field. Otherwise, works great for what I need for.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    5. Guest

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      Review by SunBlack of Rome, IT.
      1272672000
      Apr 30, 2010

      4.0 Nice product

      Pros:

      Cons:

      Comments:

      Nice product

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    6. Guest

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      Review by rray of Houston, TX.
      1243382400
      May 26, 2009

      5.0 I would buy this product again

      Pros:

      Quality Lenses,Accurate,Strong Construction

      Cons:

      Heavy

      Comments:

      It was exactly what I ordered

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    7. AstroGuy1

      AstroGuy1 New Member

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      Review by prk9h of Virginia.
      1228176000
      Dec 1, 2008

      4.0 Antares 0.5x 2" FR

      Pros:

      Wider true FOV

      Cons:

      Lens can be scratched

      Comments:

      I've used this piece a few times visually with my Celestron C6-S and some 2" EPs. I really like the wider field views it gives with my 2" 30mm EP, and it also sharpens up the edges of the FOV. With it I can see the whole of Orion's sword. It's a great buy for the money. The only problem is that because of the design you have to be careful not to scratch the lens

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    8. prk9h

      prk9h New Member

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      User Notes:
      1193406600
      Oct 26, 2007

      4.0 Antares 0.5x 2" FR

      Pros:

      Wider true FOV

      Cons:

      Because of the design you have to be careful not to scratch the lens

      Comments:

      I've used this piece a few times visually with my Celestron C6-S and some 2" EPs. I really like the wider field views it gives with my 2" 30mm EP, and it also sharpens up the edges of the FOV. With it I can see the whole of Orion's sword. It's a great buy for the money.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No
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