|
Hi Stu,
Some companies that make binoviewers also produce an Optical Correction System (OCS) that will allow the binoviewer to reach focus with a newtonian. The Denkmeier OCS has been advanced to "power switch" status. Historically a lot of people just used a barlow to bring the focal plane in to allow the binoviewer to reach focus. Shortening your poles or not fully extending them will also enable the binoviewer to reach focus. Depending on the sizing of the secondary mirror it could introduce vignetting as moving the secondary closer to the primary will inherently cause the secondary to be undersized. That having been said the secondary mirrors on the Chinese/Taiwanese scopes tend to be a tad oversized in any case, so with these particular scopes it should work fine. If it does vignette this will be evident by a dimming of the image brightness towards the edge of the FOV.
Also keep in mind that binoviewers work best on brighter objects only because they work by "splitting" the available light into two, which will cause a dimming of the image, which is very noticeable on the dimmer targets. I have used them a bit and to be honest I much prefer the single eye views to using a binoviewer. However, I have been very spoilt with ready access to an excellent 12.5" binocular telescope and a pair of 25 x 150 Fujinon binoculars. By comparison these blow any binoviewer into the weeds and probably causes me to be a little harsh in real terms, on what a binoviewer can achieve.
Cheers,
John B
Cheers,
John BS
|