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Fl of a 25mm cctv lens


Bottletopburly

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Is the focal length of a 25mm cctv lens 25mm , being a tad lazy after doing PA in sharpcap and not swapping over to my qhy mini guide scope fl 130mm only just realised phd is set up for the qhy mini guide scope so thinking ? this not helping my getting to grips with guiding , mind the 25mm does pick up stars nicely.

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Yes, that refers to the focal length. The aperture would normally be 25mm divided by the focal ratio though the lens could look bigger if it had some internal baffles.

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25 minutes ago, Tweedledee said:

Yes, that refers to the focal length. The aperture would normally be 25mm divided by the focal ratio though the lens could look bigger if it had some internal baffles.

Cheers Pete  I’ve will swap over next time anyway me just being lazy , not sure what effect this has with phd2 not having the correct focal length obviously won’t be helpful  .

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