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GSO Parabolic Primary and Secondary Mirror Set - 8" f/4
| Brand | GSO |
| Part Number | PATM-GS-P8F4SET |
| Availability | available |
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Product Info
Manufacturer Description
For years, GSO has made dobsonian telescopes sold under various labels. Users of these scopes know the excellent quality of the optics included, and they have a well-deserved reputation for being the finest mirrors in their price range. We are now pleased to offer virtually the entire line of GSO's Newtonian optics in the US market.
GSO's parabolic primary mirrors are perfect for those who want to build their own telescopes or replace mirrors in older ones. Ranging in aperture from 6” to 16” and offered in various f-ratios, these mirrors are made from optical grade BK-7 glass. All mirrors have a reflective aluminum coating with a reflectivity of 92-93%. The aluminum coating is protected by a silicon oxide (SiO2) over-coating. GSO's elliptical flat mirrors have the same high quality as their parabolic primary mirrors.
GSO uses high-volume, state-of-the-art, high quality manufacturing and test lines. GSO guarantees diffraction limited performance, but their mirrors typically have a mirror surface quality of 1/16 wave RMS at least, and often better. This very smooth mirror surface results in excellent optical performance with practically no light scatter.
Please Note:
Most parabolic mirrors will have 2-4 minor uncoated areas along the edge of the mirror. See photo 3 above for an example. These are caused by the clips used to hold the mirrors in the coating chamber. Note that these are not defects. A couple of these uncoated edge strips will typically be covered up by the clips in your mirror cell anyway.
Additional Information:
Q. Is a test report included with each mirror?
A. No. GSO tests each mirror via laser interferometry before shipping, but does not provide individual test reports.
Q. Is the primary center-dotted?
A. Sometimes yes but mostly no. It just varies from batch to batch.
You can easily center-dot the primary yourself if the mirror you receive is not dotted. Instructions to do this are readily available on the internet. If you want a center-dotting sticker, just request one from us at the time you place your order.
If you want a mirror that does not have this center dot, please check with us before your purchase. Removing the center dot is not easy or recommended. If the mirror already has a center dot but you do not want it, we recommend that you not purchase this item.
Reviews
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Jun 15, 2017
Parabolic mirror 8" f/4
Pros: Cons: Comments:I am using this mirror for astrophotography and even being a fast telescope I have observed no pronounced signs of coma aberration. It provides a sharp and bright image.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
MJC2 New Member
- Skill Level
- Unknown
- Time with Product
- Unknown
- User Notes:
- Review by Old Man Mark of ChicagoLand, IL.
Dec 1, 2012Good quality at a fair price
Pros:Nice Thickness,Quality Lenses,Good Coating Figure
Cons: Comments:I tested the mirror, both with a knife edge tester and in a telescope. The figure looks to be at least 1/4 wavefront quality (that means 1/8 surface), as advertised. Price was very fair and delivery was prompt. Thank you, Agena.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
MJC2 New Member
- Skill Level
- Unknown
- Time with Product
- Unknown
- User Notes:
- Review by MJC of ChicagoLand, IL.
Oct 15, 2012Excellent mirror at good price.
Pros:Fast Low Cost Mirror
Cons:Coating Gaps At Clips
Comments:Very nice mirror at good price. Quick shipment as well. I tested the mirror on my mirror tester and it came in at least as 1/4 wave front quality, which for the price is very respectable. Imaging with a coma corrector produced excellent results over an APS-C (DSLR type) chip the first time I used it. After imaging I viewed Jupiter. The satellites were nice and sharp at 100X and the belts were very distinct. Given the cost of coatings and mirror blanks/abrasives, why make your own? Only con is the way (apparently) the mirror was mounted in the coating chamber. This produced three small (1/4 x 1/8 inch or less) gaps in the coatings at the edge. Two of them were covered by the mirror cell clips. One was not. This has no measurable effect on viewing or imaging with it. Purely asthetic. Again, for the price, a very good product. Highly recommended.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
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