AP130GTX Question

[Hans Tucker]

Any owner of a AP130GTX imaged, without any reducer, at the native f6.3. Does the scope need the Prime Focus Field Flattener or do people opt to go faster and use the QUADTCC?

[gregbradley]

Depends on the size of the sensor.

A full frame sensor will need the flattener. An APSc sensor probably also but these smaller sensors like the ASI533 may not.

Quad TCC gives F4.5 and a wider field of view with excellent correction. Its very sensitive to spacing. The flattener is more forgiving.

I have and use both. My 130GT is essentially the same performance as the GTX per Roland. The GTX has a bit wider colour correction but mainly it was to
make all lenses spherical and easier to make as opposed to the GT which has an aspherical lens element.

Greg.

[DavidTrap]

I have the both. Haven't yet used the flattener, but thought it might give me the option of a slightly longer focal length that might suit some objects.

I assume that the flattener will be needed for the full frame sensor I have.

DT

[Peter Ward]

I have both the FFC and QUAD reducer. The faster f-ratio is moot, it's more a case of wider field.

As for edge correction, in native format at F6.3 neither of will 35mm or APS_C cut it.

In either case stars look like small comets at the edges.

A hairy eyeball won't notice. Royal Greenwich might. The Malin's certainly will. ;)

[gregbradley]

Yes defintely.

Also the spacing for the Quad is extremely sensitive. I spent another couple of hours on it last night and got it to ideal. But just a few mm wrong gives you rather bad corner stars with the QHY600.

Those 1mm thick spacer rings AP sells are essential.

Expect to take a while.

Greg.