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Message: <blockquote data-quote="Binastro" data-source="post: 3141835" data-attributes="member: 111403">. Regarding using test charts to assess the difference between a tripod mounted and handheld binocular.David states that the loss of resolution is probably between 8% and 35%.So the gain using tripod mounted binoculars compared to hand held binoculars will be between about 9% and perhaps 53%.An arithmetic mean of about 31% and a geometric mean of about 22% roughly.But I don't think this is the whole story.When a binocular is tripod mounted one can see the fine detail almost continuously.When binoculars are handheld the finest detail is only seen momentarily or for a very short period of time.These differences do not equate to how one observes in the real world, however, either astronomically or in birdwatching.In astronomy it is well known that if a discovery is made with say a 16 inch (40 cm) telescope, the object will then be able to be seen it in a 10 inch telescope and eventually in a 6 inch telescope by the same observer in each case under the same conditions.There is a vast difference between finding unknown detail and seeing well-known detail such as an intimately known test chart.I was really quite amazed when looking at the aircraft at 2 1/2 miles. With the 8×25 binocular with the stabiliser off it was  a nice looking side on view of the aircraft.When I pressed the stabiliser button the aircraft carrier's name magically appeared in large letters on the side of the fuselage. I had noticed nothing on the side initially.Once I knew there was writing on the side I could just see there might be writing on the side with the stabiliser off but it was quite impossible for me to read it.Getting back to astronomical observations, I used to use something called Astro cards for finding very faint objects in the sky. These showed exactly where the object was and I could see objects four time fainter using the cards than using a normal sky map. If one knows exactly where something is it is very much easier to find.The same goes with seeing the planet Venus in the daytime. It can be seen easily with unaided eyesight on a transparent day but only if you know exactly where it is. It is almost impossible to find just by scanning the sky.I think that I am about average in being able to handhold binoculars. I do have pain in my hands but this does not affect the steadiness of my hands although I do try to limit the time that I use binoculars.My rest pulse is 58 per minute and my blood pressure 125/75, which is not bad for an antique.I don't know what causes handshake, whether it is ones pulse or breathing or both or something in addition.Obviously it varies from person to person.I don't think the Canon would have produced a range of image stabilising binoculars if there were not very real benefits to users, although obviously not everybody gets on with them.They would not make complex binoculars that are heavier and bulkier than non-stabilised binoculars if they did not give considerable gains.But the real gains are in steadiness, resolution, small star images and very good edge performance with the better models.I stick with my figures for the 8×25 of gain for myself of 50% to 70% and sometimes more with static objects and at least 100% for a moving object like an aircraft.It is not as if I am unfamiliar with aircraft, I have made well over 200,000 aircraft observations, although I am not as up-to-date as I should be.Also, I have been observing astronomical objects daily for longer than I would like to admit.I'm not, however a birdwatcher and only have a rudimentary knowledge of birds.</blockquote>

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