base/ic question

[apaul]

Hi All!

Glass PBX 1.6 (yes available in UK)

RX +7.50/-1.25

Thin as possible required!

What base woiuld you use?

8 or 10 ?

Thanks

Alan

[ziggy]

What type/size of frame are you using?

[apaul]

Hi Paul

To be honest px is wearing an 8 base
I ordered a pair thin as possible but forgot to specify
base and they sent me a 10
which px picked up on
basicaly if u order thin as possible in a + lens
shouldnt they give u as shallowest base as possible?

thanks

Alan

[Clive Noble]

My advice would be to make up the 10 base lenses, the Pt might just thank you for the extra bit of concave surface at the back, far less reflections and more natural curve than the almost flat surface of the 8.

Visually, yes, it may look thicker in the 10 but there's hardly any real thickness difference.... and you may save yourslf a redo!

[ziggy]

Hi Paul
basicaly if u order thin as possible in a + lens
shouldnt they give u as shallowest base as possible?

thanks

Alan

Most labs will have a base curve slection chart that they use, and according to the chart a 10+base curve would be in order. I like my plus lens to be as thin and flat as possible. Clive is right about the reflections make sure you have a good AR Coating.

[apaul]

Hi Paul

So basically because i asked for as thin as possible and didnt ask for flat as possible I have to purchase new lenses

alan

[ziggy]

Allan,Check with the lab,, most have a "RE-DO" policy

[Laurie]

Hi,

I hope, that if you are going outside Vogel's Rule for Base Curve selection (which would require a very steep base (+10.00 to +12.00), you are adding asphericity.

Otherwise, they will have a ton of spherical aberration, marginal error, sagittal/tangential errors, etc. in the peripheri.

: )

Laurie