LUNT O-ring for Pressure-Tuner at LS50THa solar telescopes

Universal 60mm viewfinder and guide telescope with a focal length of 250mmExcellent 10x60 viewfinder telescope with removable eyepiece unit and crosshairs with adjustable red illumination. The larger aperture and focal length, provide an even brighter field of view and more accurate tracking due to the higher resolution. The precise helical focuser and the 1.25 inch /31.7mm plug-in connection, as well as the T2 camera connection thread (M42x0.75mm), allow the autoguiding required for long time exposure to obtain a point-shaped star image. It can also be used as a mini travel telescope.High quality 10x60 viewfinder telescope with adjustable crosshair illuminationImage sharpness and viewing characteristics lift this viewfinder well above the level of the usual 10x60 viewfinder scopes. The visible image is bright and crisply sharp. Furthermore, this viewfinder has a very large field of view (FOV) of 6.0 degrees. This makes finding and adjusting objects much easier. The existing scale markings (pitch=0.85 degree) on the crosshair are a good reference for estimating distances, and the open centre markings also make it easier to centre objects precisely. All lens surfaces are protected against weathering by multi-coating and guarantee a bright viewfinder image due to the high light transmission values. The adjustable red LED illumination unit is powered by two LR41 coin batteries. The main lens and the crosshairs can be focused independently of each other, giving you perfect focus for your eyes.Compact tracking unit for autoguidingOne of the main applications for this telescope is the so-called autoguiding. Here the usually larger photo-taking optics are actively corrected by a smaller guiding telescope with a second tracking camera. This means that the mechanical fluctuations in the tracking accuracy, which are present in all astronomical telescope mounts, are measured by the tracking camera and compensated accordingly. This is necessary in order to obtain a point-shaped star image on the astrophotos during long time exposures and to avoid unwanted star trails. For this purpose, the guiding telescope is inserted into the existing viewfinder shoe of the photo-taking optics and aligned parallel. If the existing viewfinder shoe is not compatible, a suitable viewfinder shoe is also included. With the 1.25 inch / 31,7mm plug connection at the rear end or via T2 thread connection (M42x0,75mm), a tracking camera can be mounted afterwards. This is held securely by a brass ring clamp and 3 clamping screws. Please note the required back focus for your tracking camera. The focal plane (backfocus) is approx. 22mm behind the T2 thread. The sensitive focusing on the guiding star is done by a large knurled wheel of the mechanically precise manufactured helical focuser. For easy reproduction of the point of focus, this has a white millimetre scale from 0 to 28mm, which is attached by laser engraving. After the tracking camera has been connected directly or via computer to the telescope mount and the necessary basic settings have been made, the first astrophotos with long time exposure can be taken.Use as mini travel telescopeThis viewfinder and guide telescope can also be used quite simply as a mini travel telescope. With the optional eyepieces, a magnification of 9x to 50x can be achieved. Nearly all eyepieces with a focal length of 5 to 26mm and 1.25 inch/31.7mm plug connection are suitable. Especially recommended are the EXPLORE SCIENTIFIC eyepieces of the 52 degree (Art. 02195xx) and 62 degree (02196xx) LER series. Note: Only straight view use is possible.Metal viewfinder holder and viewfinder shoeThe mount of this viewfinder and guide telescope is completely made of aluminium and is a stable base. The viewfinder mount is suitable for many common types of telescopes, such as EXPLORE SCIENTIFIC, BRESSER MESSIER etc. If the existing viewfinder shoe is not compatible, a matching viewfinder shoe is also included. This can be attached to the telescopic tube by means of four M5 screws. The bore distances of the viewfinder shoe are 31.7mm on the longitudinal and transverse axis. The six large adjustment screws with non-slip knurling make it easy to align the viewfinder, even with clammy fingers. All adjusting and clamping screws have plastic tips that effectively prevent the viewfinder housing and viewfinder mount from being scratched.FEATURESExcellent 10x60 viewfinder and guiding telescopeCan also be used as mini travel telescopePerfect image sharpness and good viewing comfortFMC Multi-coated lens surfacesLens focal length: 250mmMax. possible camera weight: 550gRemovable eyepiece/cross hair unitCamera connection via 1.25 inch / 31.7mm plug connection or T2 threadT2 thread: M42 x 0,75mmPrecise helical focuser for focusing the visible imageFocuser travel range: 28mmClose focus distance: 3 mLaser engraved millimetre scale from 0 to 28mm on the focuserFocal plane (backfocus) is approx. 22mm behind the T2 threadSeparate focusing of the crosshair at the eyepieceVery large field of view FOV of 6.0 degreesWith adjustable red cross-hair iillumination Scale markings crosshair with 0,85 degree graduationPower supply of illumination unit: coin battery type LR41 (2pcs)Brass ring clamp and 3 clamping screws on the 1.25 inch plug connectionWith optional eyepieces magnifications from 9x to 50x can be achievedSuitable are almost all eyepieces with 1.25 inch/31,7mm shaftMounting of the viewfinder telescope is completely made of aluminiumViewfinder mount with 6 large adjustment screws with knurled head for easy gripFinder shoe suitable for EXPLORE SCIENTIFIC, BRESSER MESSIER etc.Additionally a suitable viewfinder shoe is includedBore distances of the viewfinder shoe are 31.7mm on the longitudinal and transverse axisAdjusting and clamping screws have plastic tipsWHAT'S INCLUDED10x60 viewfinder/guiding telescopeEyepiece unit with crosshairCrosshair illumination unit incl. batteriesViewfinder holder with viewfinder shoeInstruction manual