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Selected as a Star Product of 2014 by Astronomy Magazine.

INTRODUCTORY PRICE FOR LIMITED TIME! Note: The image shows the front OCS-A45 optic as well as the spacer tubes and our patented Power Switch system. This product includes ONLY the front OCS-A45 Optic in cell, capped with a beautifully machined aluminum engraved dust cover. 

Recommended For All Dobs
Wow! So many users of new large FAST dobs have asked if I could make a full aperture OCS Lens that would grab peripheral rays to the max. Well, this optic is not only of super optical quality, fully multi-coated and the same focal length as our lowest power OCS optic but it is 45mm clear aperture. You can see from the photo that we could not make it any larger! We do need to house it in a beautiful precision anodized cell and it still must enter a 2" focuser. Because this optical lens transfers the image plane through the light path of the binoviewer and is of a very low power in order to keep magnifications to the minimum, the lens needs to be set inside of the focal plane more deeply than say a single eyepiece. Therefore, a converging cone of light formed by your primary mirror and redirected by your sceondary is still wide when the OCS Optic receives it. The fact is that the larger the clear aperture of this lens, the more efficient it is at capturing those exterior rays.

We check every single mounted lens on our own flourite refractor for optical performance and any aberrations, Suffice to say that these optics are absolutely beautiful in appearance and performance! available starting in Mid August. Order NOW! I have tested this optic with my own 20" Dob using the power switch at 1.3X/2.3X3X under the sky and am totally psyched at how beautiful the images are. I have told many callers that I'd try my best to produce the largest possible clear aperture front optic for our binoviewers when the fast mirrors started showing up. Well, here it is! shippiung is additional and varies according to your location. We can ship Priority mail in USA for $10 insured. Overseas, small box priority will run approximately $20 insured.

First Customer Feedback:

"I have noted that on the Catseye Nebula, that I could not see the center star before with the D21s in the Bino before the OCS-A45 and now I can see the center star with the OCS-A45!!!  That is proof positive that it has expanded what you can now see and it is definitely an improvement.  Great job Russ." - Victor  

"HEY RUSS...CONGRATULATIONS ON A NICE NEW UPGRADE. THE NEW 45MM OCS IS TERRIFIC. I POSTED THIS ON CLOUDY NIGHTS TONIGHT! We were able to run some tests with the new Denk 45mm OCS at Chiefland tonight using two large scopes of different focal ratios...a 16" f/4.3 and my 28" f/3.66. Tomorrow night, we'll add some longer focal ratios.

FIRST - the image is noticeably brighter in both scopes than with the 'standard' OCS. This was verified both visually and photographically.

We're not talking about a BIG difference...but it is definitely noticeable.

On an extremely faint object, such as Comet 168P, using the 28" scope, the visible tail was perhaps 30% longer and the coma ahead of and around the nucleus was perhaps twice as large using the 45mm OCS vs.the 'standard'.

Understand that these differences were not immediately apparent to a casual observer but were able to be detected with diligent observation.

M-31 was obviously brighter and, in quick DSLR imaging at identical settings, with the same camera, faint details were much easier to detect. All observers agreed that the star images were much sharper and nebulosity more contrasty with the 45mm.

In the f/4.3 scope, the field of view SEEMED larger but we were not able to put a number to it. In the f/3.66 there was no doubt. Images confirmed a REAL increase of ~15%.

More testing will follow but it is readily apparent that, for 'fast' scopes, the new 45mm OCS is a definite improvement and, in my opinion, something you should seriously consider as an upgrade to your Denk BinoViewer". -Mike Harvey

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