colour "fringing" with HR66+30x (1 Viewer)

Hi,

I recently (sort of - about 6 months ago actually) replaced my aging (&, lets face it, rubbish) spacemaster with an Opticron HR66Ga c/w 30x HR eyepiece. Generally I'm very pleased with the 'scope, but in certain conditions (I.E. looking into the light or high contrast views) I get a colour fringe in the image. In retrospect, I'm not sure why I chose such a high magnification! maybe it would've been better to have stepped down a notch or two to 23x or 20x, but thems the breaks!
Has anybody else experienced this with Opticron?
(the 'scope was bought from Warehouse Express as a package with a slik D3 tripod btw)

Simon

I think you'll get this to a greater or lesser degree with any scope that doesn't have a glass element in its construction made from what is called "extra-low dispersion glass" (often called ED or fluorite).

It's caused by the way glass lenses tend to focus incoming light. Instead of just acting as a lens, the glass also acts as a prism and splits some of the light into its various colours, focusing these in slightly different positions - hence you see a colour fringe around the edge of an object. This seems to happen especially when viewing into a bright light source.

The HR66 is very highly regarded and shouldn't be worse than other good quality scopes. It is available as an "ED" version but for a good deal more money. I doubt it has anything to do with the 30x objective - which is pretty near ideal for bird watching in most people's books.

Next time you're at Amwell lookout for me and you can look through my Opti ES80.

A superb scope. No colour fringes with that, eh, Pete? Where's Amwell by the way?

pduxon said:

Next time you're at Amwell lookout for me and you can look through my Opti ES80.

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Cheers Pete!

The next time I'm likely to be there is probably 1st Jan.
Though if looking through a better 'scope does the same this time as it did a few years ago when I tried a friends optolyth APO 100 (whilst I still owned the Bushnell!) then my wife's not going to forgive you (not to mention my bank manager!!)

Simon

scampo said:

Where's Amwell by the way?

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Dis-used gravel workings nr. Ware, Hertfordshire (guaranteed Smew every winter, Osprey nearly every spring & supposedly resident Hawfinch, though I think the latter is just a rumour spread so people taking part in the Lea Valley bird race can lie!!)

Simon

BTW, I forgot to add, re: Osprey, If you actually want to see them @ Amwell, you need to be there "5 minutes ago"!! (which is where my sig comes from - amongst others!)

I was going to ask you about the alleged Hawfinch. The Smew I can testify to. There were Little Egret there a week or so ago, or so some of the better birders tell me.

I think Amwell is the most Northerly part of the Lea Valley complex. It has one hide, and no other facilities, but most of the birding is in the open. Makes it pretty nippy this time of year. In Summer it would make a very pleasant stroll. Its about 3 miles or so from RSPB/HMWT Rye Meads.

Pete,

I'm Hijacking this thread now but I started it so it don't matter

I've never personally seen the Hawfinches at Amwell but I know people who have. When you're looking over the water there's a large wood yes? That's where they're supposed to be.
Walk down the path on your left as you come over the first bridge (on the way to to the hide) then veer right when you come to the bridge on your left. Carry on this path, over the footbridge (excellent spot for Kingfisher if you're patient - they'll fly right under your feet!).
Keep going 'til you reach the spot where the road goes over the path. Now you can either go up the steps on your right, to the road & continue along it or continue under the bridge (I favour this route as I've normally got my kids with me) either way will bring you to likely habitat (but like I've said, I've not been lucky yet!)
Good luck, & if you do see them, let us know? (definately a bird I've got to get on my life-list - & if I can get it on my Herts list too that'd be a bonus!!)

Little Egret are slowly getting more frequent. (there was also a Cetti's there for most of last winter - didn't have a car at the time though - so I'm hoping another will turn up!)
Simon

I'm Hijacking this thread now but I started it so it don't matter

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Simon, do not apologise for hijacking - it is all part and parcel of the enjoyment of this forum, with it's relaxed attitude (most of the time!) and very interesting viewpoints and observations. Everybody - carry on the good work.

Happy birding New Year!
Roger

rogerscoth said:

- it is all part and parcel of the enjoyment of this forum, with it's relaxed attitude

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Relaxed? Who's relaxed? It's only my stress that's holding me together!! :eek!:

Relaxed? Who's relaxed? It's only my stress that's holding me together!!

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Now then Diane, perhaps you still are too young to be thinking about relaxing, unlike "over(the hill) sixties" like me!
Happy New Year!
Roger