From: TerryMoselaol.com
Date: Thu, 9 Dec 2004 17:28:24 EST
Subject: Lidl Binocs, IAA lecture, Dunsink, Geminids

Hi all,

Some people have been asking me about the binoculars featured in the next 
Lidl Special Offer, available from Monday 13 December.
   These are 8-24 x 50 zoom, costing 19.99 pounds in N.I., and according to the 
website euro 19.99 in ROI (not fair!).
   I obviously haven't seen them yet, but I'm not sure that they would be 
good for astronomy. For a start, zoom binocs are generally not ideal for 
astronomy, as the extra zoom lens elements degrade the image by the extra internal 
reflections and scatterings. Secondly, it costs more to produce the zoom elements 
& mechanism, so if they are still keeping the price low, the quality must be 
suffering somewhere! (Although I must say that the quality of all their other 
optical items has always been quite good. I've had various good reports on 
their two bargain telescopes, recently featured.) Third, the zoom mechanism is 
one more part to go wrong, although they are of course covered by guarantee.
   The glass type (I presume for the prisms) is quoted as BK7, which isn't 
quite as good as the usual BAK4 (but it's still acceptable). It says that the 
lenses are 'blue', which I presume is an anti-reflection coating, but it doesn't 
indicate if it's multi-coating, or broadband, or full multi-coating, etc, 
etc. You would need to read what's on the box to be sure.
   But my most serious reservation is the small field of view, which is 78m 
at 1000m, or just about 4.5 degrees, at 8x. Most 8x binocs would have a FOV of 
about 8 degrees; my 10x50's have a 7 degree field. So 4.5 degrees is really 
quite small, giving the impression of 'looking down a tunnel'. And the FOV will 
decrease considerably with higher zoom magnification.
   They do have a tripod socket at the front of the centre bar, but it 
doesn't say whether a tripod adaptor is included. 
   They look well enough made from the photo, but it's impossible to say 
until you actually see & hold & try them. A case, strap, & lens caps are included.
   So my advice would be not to rush to buy them first thing on Monday - if I 
get a chance I'll check out a pair 'in the flesh', and report further if I 
think they're worth considering.
   They might be OK for birdwatching, especially at the ROI price of euro 19,
but 
you would need a tripod to use them at x15 or more.
   Or at that price you might like to split them into two high-power finders 
for your telescopes! If the zoom elements are not actually integral with the 
eyepieces, you could dispense with them and probably get a larger FOV. But 
attempt that at your own risk!

2.  The next Irish Astronomical Association Public Lecture will be on Wed 
December 15, when Dr John Butler of Armagh Observatory will give a talk entitled 
"The 2003 Restoration of Armagh Observatory" (If you haven't visited the 
Observatory recently, you should do so - quite a few changes, including one 
completely new dome, a unique 'Human Orrery', and major refurbishments! But first, 
come & hear this lecture, to get the full story.) It will be at 7.30 p.m., 
Lecture Room 5, Main Building, Stranmillis College, Belfast, with plenty of free 
parking. Free admission as usual and there will be some free seasonal 
refreshments as well!

3. I hope you've all replied to Brian McBreen as per the email letter to save 
Dunsink, featured in my last email notice?

4. And don't forget the Geminids on Monday night! (details in last email)

Clear Skies,

Terry Moseley

Last Revised: 2004 December 9th WWW contact:webmaster@arm.ac.uk

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