4/3/2023 0 Comments Delete cammaskUnfortunately, they are also discontinued and difficult to get. Unfortunately, Computar has discontinued this series of asperical lenses, and also at EBAY they are difficult to catch.Ī similar series of aspherical 1/2″ c-mount lenses was manufactured by Panasonic. Especially the 3.8 mm, 6 mm and 8 mm lens are frequently used by meteor observers. 3.8 mm, 6 mm, 8 mm, 12 mm) with a fast f-stop of f/0.8. They come at different focal lengths (e.g. Particularly popular among video meteor observers is a series of asperical 1/2″ c-mount lenses by Computar. However, a vari-focal 1/3″ lens will also work out, if you do not choose the shortest possible focal length. Most cameras use a 1/2″ CCD chip, so you normally also need a 1/2″ c-mount lens to avoid vignetting. Also the astrometric quality is getting insufficient.įixed-focues lenses are the first choice for video observers, but also zoom lenses may do a good job if you ensure that the focal length does not change during observation.Īn auto-iris lens is sometimes helpful, but not a must either. Here the image distortion becomes so strong, that it cannot be modeled properly anymore with third order plate constants as used by MetRec. Furthermore the spatial resultion of the camera and therefor accuarcy of the astrometric measurement improves significantly.Ī short focal length is advised if you want to cover a large field of view in single station mode, whereas longer focal lengths are advised for double-station observations.Ī focal length short than about 3 mm is not advised. The image distortion becomes small and the measurement of the reference stars becomes easier. The field of view at 8 mm focal length is only 1/4 in size, but the gain in limiting magnitude typically more than compensates this. A camera with 4 mm focal length will give a large field of view with about 100 deg diagonal and a limiting magnitude of up to 4 mag. The focal length decides about the size of your field of view. Vertical stripes that shows up if the contrast is set to max in recordings of Mintron (and possibly other) cameras are caused by the camera itself and cannot be avoided.Īny c/cs-mount lens can be used with non-intensified surveilance cameras. Horizontal stripes that slowly move upward or downwards are caused by low-quality power supplies of the camera, bad shielding of the video cable (or interchanged signal/shield cable) or bad connectors. Two types of inteferences are sometimes observed with non-intensified cameras. The reason might be that the readout electronics is more noisy. It is cheaper than Mintron and Watec, but in practice also clearly less sensitive. It is more sensitive (we measured a limiting magnitude gain of almost 0.5 mag compared to the Mintron 12V6-EX), but also about twice as expensive.Īlso the Supercircuits PC164CEX-2 uses the Sony CCD chip. The Watec 910HX-RC is the “big brother” of the 902H2 Ultimate. It is slightly cheaper that the Mintron, has about the same sensitivity, but does not offer the frame integration function. The Watec 902H2 Ultimate is the second most frequently used camera among video observers. The gain should be set to manual and increased to the maximum. The V6 is more sensitive than earlier version of the Mintron (V1 to V5), probably because the readout electronic was further improved. If more frames are integrated, MetRec cannot handle the video stream properly, because two or more subsequent frames will be identical. For meteor observation, you should integrate two frames, which will give an effective integration time of 1/25s (PAL) resp. It has a special feature that allows to integrate up to 128 frames internally. The Mintron camera Mintron 12V6-EX is probably one of the best cameras available. In the following we describe a number of cameras which are frequently used by video meteor observers. B/W cameras are typically more sensitive than color cameras, and a 1/2″ CCD chip gives better performance than a 1/3″ chip. In practice, cameras that use a Sony ExView HAD CCD detector have given the best results. If no image intensifier is used, you should take the most powerful video camera you can get. When you think about the camera, you first have to decide between an image-intensified or non-intensified camera. 3.3.4 Adapt the MetRec configuration file.3.3.2 Update your reference star file after first run.3.3.1 Create your first reference star file.
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