Letters and photos
Tell us what you think. Write to:
The best small binoculars and nestbuilding Goldfinches have you writing in this month.
Rebecca Armstrong, Editor, at: Birdwatch, Warners Group Publications plc, The Maltings, West Street, Bourne, Lincolnshire PE10 9PH or email letters@birdwatch.co.uk www.facebook.com/birdwatchmagazine @BirdwatchExtra
Pocket sized
I have been involved with several types of optics for most of my long life and was looking forward to your review of the Swarovski CL Pocket bins (Birdwatch: 346: 48-49). I was puzzled as to why you chose the 10x25 model instead of the 8x25 which, with its wider field of view, brighter image and being easiest to hold steady, will surely be a much better seller.
Modern 10x32 and 10x42 bins are excellent (I am a fairly recent convert to 10x42), but the 10x25 has a very small exit pupil size. A side-by-side with the Swarovski 10x42 Pure is a bit like putting a glider up against an F16.
The review itself was excellent; I just feel it would have been better the other way round. Mr M ‘Mac’ McInnes, Cockenzie
Birdwatch Optics Editor Mike Alibone replies: “You are absolutely correct in your argument for the choice of a lower magnification in the Swarovski CL Pocket binocular. The field of view in the 8x is 119 m at 1,000 m, as opposed to a rather narrower 98 m at 1,000 m of the 10x. Additionally, with all other things being equal, the image of the 8x will, in theory, be brighter in low light conditions, as the exit pupil is greater, although they both have the same figure of 88% light transmission.
“The 10x was chosen because it was a representation of the ‘smallest binocular packing the biggest punch’ in terms of magnification. Personally, I found the small size and low weight of the binocular contributed positively to my being able to hold it steady enough to use successfully with the 10x magnification.”