Yes , its a near infra red filter. I thought that it transmitted most of the colour specrum but cut down on IR - thats why its used on achromatic scopes with CCD to stop flaring of ir transmitting stars. Its a Sirius optics filter and from their spectral data it should be OK but may also gve me a slight colour bias towards blue. From their data "The NIR1 blocking filter all but eliminates this near infrared (700-950 nm wavelength) radiation, while keeping transmission levels very high across the visible spectrum". Dont tell me I have to do some sort of testing to see what is the best. I had imaged without the filter and it seems better with it.
Allan
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Originally Posted by Robert_T
Hi Allan,
Second one looks much better with the balance. The NIR filter, is that a near infra-red filter - if so wouldn't that exclude much of your R,G,B?
I had the scope out cooling last night, but after seeing the Jetstream prediction decided to pack it in without so much as a look at what the seeing really was like - at least I got some sleep 
cheers, |