Triplet vs Doublet (FPL53) AP&vis

[kriss13]

Hi

I have a short list of two OTAs I for my new AP rig, both 80mm, both FPL53, but one is triplet , one is doublet.

It will also serve as an GnG for visual.

Astro-Professional (same as Orion)

and the doublet

TS APO80

I know triplet is the way to go for AP but wouldn't an extra lens block some of the light for visual use (or not)?

Should I go for a doublet and a fringe killer for an all rounder?

I would appreciate any feedback about a triplets used for visual (occasionally)

[ronin]

Forget the idea of a fringe killer.

If they are done right they are an apodisation filter and they need to be matched to the scope, they basically operate by filtering out the light that causes the problem, this is usually that around the outer section of the lens so they mainly reduce the aperture of the lens. Which for AP is not a great deal of use.

Much arguement but assuming either lens is designed right a triplet will out perform a doublet. It simply controls 3 wavelengths whereas the doublet can only control 2.

Some will say a well designed doublet will/can out perform a poorly designed triplet but that is pretty obvious.

These days the design will be done by computer and very likely by an external software house, so I would assume that either are equally well designed.

I presume that the TS TLAPO804 is the same as the AP one but in an aluminium tube

Do you nedd carbon?

Think aluminium would cool quicker and the TS scope comes with tube rings not a L foot, which is a bit more versatile.

As the doublet is f/6.25 I would say that the triplet is the better option, for a doublet f/6.25 is fast enough to show CA.

If you read the APM TS description it says: "The chromatic abberation is surprisingly low"

[kriss13]

Carbon because I will use it with Astrotrac, so I want to be as light as possible.

I'm even considering a 70mm as it is even lighter, triplets are heavier due to 3rd lens.

But 70 mm for visual is too small.

On the other side a triplet will spare me some port processing time removing the CA.

The L foot will be replaced with rings.

[kriss13]

There is a new kid on the block..

http://www.omegon.eu/omegon-apochromatic-refractor-ap-80-500-ed-carbon-ota/p,14738

Triplet, FPL53, carbon, rail.. cool.

A bit longer FL (less CA).

Almost the same as Orion And Astro Pro, but with rail focuser which is more ropust.

A bit heavier because of rings I think.

I will sleep over over it a bit, but I "feel" this is it.

[kriss13]

Just ordered this one
http://www.optical-systems.com/astroprofessional-apo-80480-carbon-telescope-p...
Identical to Orion 80CF but less expensive + a small discount for paying in advance
Cant wait to look at/thru it, only if the 2 month fog will let me...
My first triplet.
I have another AstroPro (signature)and I enjoined it, but CA in photos is too strong (it is up for sale now).