Adrian Taylor
Member
As I prepared to go off to work on 8th June the sun shone brilliantly clear through my east-facing window. I was perfectly placed to observe the start of the 2004 transit of Venus – except for one thing (I still kick myself) – for the first time in my life I had no optical instrument with which to project an image of the sun's disc.
Better late than never, as I passed a camera shop in Bognor Regis some months afterwards I saw in the window a Bausch & Lomb (Bushnell) 7x50 Legacy binocular offered at a discount. I bought it, winced as the lady scrubbed the objectives with a microfibre cloth, and carried it home with ideas of reawakening my interest in birds butterflies and bees together with a bit of stargazing.
I noticed that the prisms in my binocular were undersized, which will have contributed to their weighing in at below 1kg, so it was essential to stop down one of the 50mm lenses before projecting an image of the sun. The baffle I used was a plastic lens cap into which I cut a central hole of 28mm around a £2 coin. It worked very well for the right-hand scope. The left-hand one showed colour fringes on my screen.
What interested me more was the effect of the pre-objective baffle on an image when viewing normally through the eyepiece. The field angle was, so far as I could tell, unaltered at about 7 degrees. Colour fringes were reduced and depth-of-focus seemed to increase making it a very friendly instrument to handle. I cut a second baffle for the left-hand scope, after which I much preferred using my 7x50 in 7x28 mode for daytime viewing, especially in summer when the 50mm lenses might capture more radiation than was safe for my eyes.
Since I retired from work I have acquired three more binoculars, each claiming its own merits or specialised uses, but I am loth to part with the old B&L. It is not waterproof, it fogs, and in bright sunshine it gives an impression of there being a thin layer of dust over the image due, I presume, to its minimal coatings. At about ten metres, the closest focus will hardly impress a birder. However, one learns to discount optical defects which appear to greater or lesser degrees through all binoculars with severely compacted focal ratios.
I must confess a certain mistrust of optician's claims. Prices rise steeply in pursuit of unattainable perfection while, with each additional optical element, comes a risk of introducing further problems. In practice definition may not increase with aperture, it may in fact decrease, making smaller binoculars a better choice. Again, in twilight the eye loses its discrimination and the major advantage comes with a larger aperture's light grasp. As for distortion, only flat lenses produce flat images! One day the present multitude of binoculars may be replaced by digital versions which will offer a choice of corrective algorithms but, in my opinion, they will do little to diminish the pleasure of exploring nature through one of these traditional glasses.
Better late than never, as I passed a camera shop in Bognor Regis some months afterwards I saw in the window a Bausch & Lomb (Bushnell) 7x50 Legacy binocular offered at a discount. I bought it, winced as the lady scrubbed the objectives with a microfibre cloth, and carried it home with ideas of reawakening my interest in birds butterflies and bees together with a bit of stargazing.
I noticed that the prisms in my binocular were undersized, which will have contributed to their weighing in at below 1kg, so it was essential to stop down one of the 50mm lenses before projecting an image of the sun. The baffle I used was a plastic lens cap into which I cut a central hole of 28mm around a £2 coin. It worked very well for the right-hand scope. The left-hand one showed colour fringes on my screen.
What interested me more was the effect of the pre-objective baffle on an image when viewing normally through the eyepiece. The field angle was, so far as I could tell, unaltered at about 7 degrees. Colour fringes were reduced and depth-of-focus seemed to increase making it a very friendly instrument to handle. I cut a second baffle for the left-hand scope, after which I much preferred using my 7x50 in 7x28 mode for daytime viewing, especially in summer when the 50mm lenses might capture more radiation than was safe for my eyes.
Since I retired from work I have acquired three more binoculars, each claiming its own merits or specialised uses, but I am loth to part with the old B&L. It is not waterproof, it fogs, and in bright sunshine it gives an impression of there being a thin layer of dust over the image due, I presume, to its minimal coatings. At about ten metres, the closest focus will hardly impress a birder. However, one learns to discount optical defects which appear to greater or lesser degrees through all binoculars with severely compacted focal ratios.
I must confess a certain mistrust of optician's claims. Prices rise steeply in pursuit of unattainable perfection while, with each additional optical element, comes a risk of introducing further problems. In practice definition may not increase with aperture, it may in fact decrease, making smaller binoculars a better choice. Again, in twilight the eye loses its discrimination and the major advantage comes with a larger aperture's light grasp. As for distortion, only flat lenses produce flat images! One day the present multitude of binoculars may be replaced by digital versions which will offer a choice of corrective algorithms but, in my opinion, they will do little to diminish the pleasure of exploring nature through one of these traditional glasses.
