Now I'm confused and bewildered (80mm 'Fracs)

[gsjag]

My understanding is that you can make an Apo out of any quality lens.

The Apo is a design using 3 lens (elements) to bring the 3 primary colours to a common focal point. The achro., using 2 lens to focus only 2 of the primary colours gives us some false colour information.

I don’t recall there ever being a mandate (commercial, physical or other) that says an Apo must use high quality lens in its configuration, just that it must have 3 of them. Therefore, optical quality and lack of false colour aren’t necessarily the same thing.

From my view, having tried many type of binoculars, I was eventually happy only with Leica and Zeiss; not always the most powerful and not always having the largest objective, but shear quality reveals details that higher power or larger aperture optics would miss (yeah, I know, before anyone says it, I run a Meade ETX and not a Questar or APQ, but needs must).

[OXO]

Cheers Steve :D

James

[Kaptain Klevtsov]

My understanding is that you can make an Apo out of any quality lens.

The Apo is a design using 3 lens (elements) to bring the 3 primary colours to a common focal point. The achro., using 2 lens to focus only 2 of the primary colours gives us some false colour information.

I don’t recall there ever being a mandate (commercial, physical or other) that says an Apo must use high quality lens in its configuration, just that it must have 3 of them. Therefore, optical quality and lack of false colour aren’t necessarily the same thing.

The number of lens elements should have nothing at all to do with how well the colours focus together. The visible spectrum is continuous so by that reasoning there ought to be an infinite number of lenses, one for each shade of each colour, or at the very least a red, orange, green, blue indigo and a violet correction lens. The reason that we are able to use only three primary colours to make things appear to be any visible colour is to do with the fact that our eyes use three kinds of sensor in the same way that a colour webcam or DSLR does.

The skywatcher ED80 Pro reviewed in the first issue of Practical Astronomer has two elements and is described as an APO telescope by the manufacturer and as a near-apochromat (whatever that means) by the reviewer.

Captain Chaos

[GazOC]

As CC says the number of elements is irrevant, apos can have 2, 3 or even 4 elements (Petzvals.)

[gsjag]

OK, learning all the time; thanks guys.

However, my assertion that there is no substitute for quality stands. If its important to you, buy the best you can afford (without running the risk of the wife breaking your neck).

[GazOC]

However, my assertion that there is no substitute for quality stands. If its important to you, buy the best you can afford (without running the risk of the wife breaking your neck).

[Ambermile]

Ah now here's a thing. My 102mm APM triplet (not apo) has 4 elements... octarine perhaps?

Arthur

[Kaptain Klevtsov]

OK, learning all the time; thanks guys.

However, my assertion that there is no substitute for quality stands. If its important to you, buy the best you can afford (without running the risk of the wife breaking your neck).

What has "your neck" got to do with it? It's not my neck that I'm worried about.

Captain Chaos

BTW she would get more annoyed if I bought "another just the same" so I'm going for just one, hopefully upgrade free option. Just working out now if I think I need it and how much I need it.

Captain Chaos

[gsjag]

The result of the “how much you need it” calculation will be zero (if you do the sums properly), but then you have to factor in the “how much do I want it” part of the equation and that’s when it all goes to pot! Anyway, now we know you’re getting one, we’re all waiting to see some spectacular astro images! Good luck matey…

Gary

ps Ask the wife to give the neck a quick, merciful break rather than a slow painful one. :?

[FLO]

.... then you have to factor in the “how much do I want it”

Wouldn't life be dull if we only bought what we 'needed' rather than what we 'wanted'.

Boys need toys to stay sane

[gsjag]

Here here to that!

[iancandler]

frac wise Id give rob at bcf a ring and book one of the new revelation apo 80mm its identical to the willams optics scope of the same spec.. £399 is a steal..*please let me win the lottery tonight* add a good 2" diagonal and a sturdy mount and your sorted..

[GazOC]

The new Moonfish semi-apos look the biz...

[Tinkerbell]

frac wise Id give rob at bcf a ring and book one of the new revelation apo 80mm its identical to the willams optics scope of the same spec.. £399 is a steal..*please let me win the lottery tonight* add a good 2" diagonal and a sturdy mount and your sorted..

The new Moonfish semi-apos look the biz...

TH and MoonFish 80mm Apo = Same Scope. Unfortunately nothing at all to do with WO scopes.

Still very good scopes though.

[GazOC]

Ah, sorry MP. Nice scopes....