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GSO 1.25" Plossl Eyepiece - 4mm
| Brand | GSO |
| Part Number | GSP04 |
| Availability | available |
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Product Info
Manufacturer Description
GSO's Super-Plossl eyepieces have been some of our most popular sellers over the years. Users will experience incredible views without breaking the bank or impinging on your telescope's balance. They represent what is perhaps the best buy today for astronomers on a budget or for beginners. But don't be fooled by their low prices - these might well turn out to be all the eyepieces you will ever need!
The GSO Super-Plossls are available in a 1.25" barrel size and 9 different focal lengths ranging from 4mm to 40mm. The 4mm, 6mm and 9mm models are great for high power planetary and lunar observation. The 12mm and 15mm are perfect intermediate focal lengths, performing well on both deep-sky and planetary subjects. The 20mm and 25mm models would be excellent choices for low power scanning of open star clusters and viewing larger galaxies. The 32mm and 40mm models offer a wide field and are superb for wide field scanning, detailed observations of large diffuse subjects or as a finder eyepiece.
Features:
- All eyepieces are fully multicoated (FMC) for maximum light transmission
- High quality lenses provide the best-possible sharpness all over the field of view
- Blackened lens edges reduce light scattering and improve contrast
- Fold-down rubber eyecups to keep out stray light
- Barrel features a safety undercut for added security
- Comfortable eye relief at all but the shortest focal lengths (As in all Plossl eyepieces, eye relief can get tight at the shorter focal lengths but this is design constraint, not a fault of these eyepieces)
- Includes two end caps. We also include a free bolt case with each eyepiece (a $2.75 - $5.50 value!)
Important note: Depending on your telescope, this eyepiece may provide magnifications that are too high! While it can be very useful for viewing the Sun, Moon, brighter planets and terrestrial objects, it is not for everyone or for common viewing conditions.
Before buying, please make sure that you are using realistic magnifications with your telescope. A good rule of thumb is that under very good conditions and with a very good telescope, the maximum power you will be able to use is about 50x of magnification per inch of telescope aperture. With average telescopes and/or average conditions, you might be limited to 30x of magnification per inch of telescope aperture. So for example, if you have a 5" telescope, under typical conditions you might typically use 5x30 = 150x of magnification, and 5x50 = 250x of magnification at best. If your telescope has a focal length of, say, 1200mm, then this eyepiece will result in a magnification of 1200 / 4 = 300x which is probably too much for this telescope.
Also, when you magnify an object, its light is spread over a larger area. Since the brightness of the object being viewed hasn't changed, this means that the image you see will be fainter. Double the magnification and the image will get 4 times fainter. This is a basic law of physics, but people often forget this and complain that the "image is not bright enough" when they increase the magnification to very high powers.
Boosting the magnification beyond the recommended maximum for your telescope aperture is not realistic. This is bound to result in image break-down, causing faint, fuzzy images, focusing difficulties, increased color around objects and general disappointment. Use the eyepiece in the right settings and with the correct expectations, and you will enjoy it.
Reviews
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Jan 6, 2014
Quality eyepiece
Pros:Lightweight,Compact
Cons: Comments:Good quality eyepiece for a Plossl but does not measure up to a well made orthoscopic at this focal length of 4mm.
Bottom Line: Would you recommend this item? NoThis review was provided courtesy of AgenaAstro.com
Dec 20, 2011Excellent quality and value
Pros:Compact,Strong Construction,Accurate,Easy to Use,Quality Lenses
Cons: Comments:The usual high quality lens from this supplier, excellent value.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Dec 16, 2011Great Eyepiece for those perfect nights!
Pros:Quality Lenses,Strong Construction,Lightweight,Easy to Use
Cons: Comments:This is a great eyepiece to have in your collection. Perfect for those evenings when the seeing is perfect and you are examining planetary objects. We love ours!!!
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Nov 8, 20114mm plossl
Pros:Compact,Easy to Use,Quality Lenses,Strong Construction,Accurate,Lightweight
Cons: Comments:I like the views I get of Saturn on my Starhopper 8.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Nov 4, 2011Very Good Performer
Pros:Lightweight,Strong Construction,Easy to Use,Compact,Accurate,Quality Lenses
Cons: Comments:This is an excellent eyepiece for that price. Ordered mainly for fine collimate an SCT, found out later it was a aberrations free ,no false color,great performer planetary epc . The first one I received it was awful though and practically
Bottom Line: Would you recommend this item? Yes
useless, Agena arranged an immediate exchange and the defective one replaced in the shortest shipping time I ever noticed as an e-buyer ever!!!!
Agena is A VERY TRUSTWORTH AND OUTSTANDING SERVICE company with high level PROFESSIONALISM staff.This review was provided courtesy of AgenaAstro.com
Jan 18, 2010Good eyepiece, great price
Pros: Cons: Comments:Great high-power eyepiece at a low price. We use it with the Edmund Astroscan. Make sure you have a steady mount.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Sep 2, 2009Great addition for small price
Pros:Strong Construction,Accurate,Quality Lenses
Cons: Comments:This is great addition for my Meade DS2090 refractor telescope which come with 5 MA eyepieces. Compare to its 6mm MA f/l this 4mm plossl outperforms in brightness and visibility, although it's giving more magnification.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
May 26, 2009YES
Pros:Quality Lenses,Accurate,Compact,Strong Construction
Cons: Comments:I use this with my 10 inch Zhumell Dobsonian Telescope, and the 4mm eyepiece shows excellent detail of the Moon, and great detail of Saturn and its rings. But what is really fascinating is that you can see the different colors of the poles on Saturn because the contrast of the poles is a different color than the color of Saturn's middle equator.
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
AstroGuy1 New Member
- Skill Level
- Unknown
- Time with Product
- Unknown
- User Notes:
- Review by jeepizoid of Arizona.
Nov 27, 2008Great eyepiece for the money!
Pros:Blackened lens edges,Good eye relief for a 4mm,Fully multi-coated lens,Security recess barrels
Cons:None
Comments:The 4mm GSO plossl is a great high power eyepiece, at 250x with my Orion 120 mm f/8.3 refractor (which is pushing my scope to the limits), and good seeing. I was able to see much detail in Saturn including the Cassini division and color banding along with 4 moons.I have 2 Orion Sirius plossl EPs, the 10mm and the 25mm and I can tell you that the GSO Super Plossl EPs are a step above them. The GSO's are fully multi-coated with blackened lens edges also with security recess barrels. Being a machinist I can say that the diameters of the barrels are machined with close tolerances and fit my diagonal with a feel of quality. As for eye relief the GSOs have more than either the Orion Sirius or the Orion Highlights on any given eyepiece ... my 15mm GSO has as much eye relief as the 20mm Orion Highlight and my 4mm GSO has more than the 7.5mm Orion highlight . Oh yeah, let's not forget the price, the free bolt case, and the free shipping so maybe just try one!
Bottom Line: Would you recommend this item? YesThis review was provided courtesy of AgenaAstro.com
Sort bySpecifications
Apparent Field of View 52° Barrel Size 1.25" (31.7mm) Bolt Case Included Yes - Free Agena Eyepiece Container Bolt Case Size Agena 42x60mm Coatings Fully Multi-Coated Design Plossl Height (with Eye Guard) 52mm End Caps 2 Eye Relief by Design 6mm Filter Threads Standard 1.25" Filter Thread (M28.5 x 0.6) Focal Length 4mm Lens Elements 4 Rubber Eye Guard Yes Blackened Lens Edges Yes Manufacturer GSO Eyepiece Focal Length 5mm and Under Eyepiece Field of View 51 - 60 degrees Eyepiece Series GSO Plossl Barrel Type With safety undercut Eyepiece Weight 2.60oz (73.71g)
