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Abbe value for Specsavers/Pentax/Reactions 1.67 lenses
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Tony Houghton
Apr 9, 2013, 1:22:15 PM4/9/13
to
I had an eye test today specifically because I wanted a new pair of
photochromic lenses. Specsavers use Pentax branded lenses in general
and "Reactions" for their photochromic range.
I wanted 1.6 plastic lenses because I find it's a reasonable compromise
between thickness and chromatic aberration. I have tried higher index
lenses before (might have been polycarbonate) and can't get on with
them, and I think it's the chromatic aberration that's the problem. I
certainly felt as if I was being forced to look straight ahead all the
time.
I asked to be reminded of the Abbe values (Vd) before deciding what to
buy, and none of the staff were able to log in to the staff-only
section of their website and in the end one of them looked it up on the
web with her iPhone. To my surprise it was 42, compared to 40 for 1.6
and 30 for polycarbonate, so I thought that would be good enough and
went ahead and ordered.
I've tried looking up the value myself and now I think the optician
must have read the wrong row/column or something because of the small
screen. Everything I can find says 1.67 plastic has a Vd of 32. So
who's right? Can anyone confirm whether or not 1.67 lenses with a Vd of
40 exist? If they don't I'll know to be more assertive about
cancelling/changing my order and avoid some annoying back and forth
phone calls or something.
photochromic lenses. Specsavers use Pentax branded lenses in general
and "Reactions" for their photochromic range.
I wanted 1.6 plastic lenses because I find it's a reasonable compromise
between thickness and chromatic aberration. I have tried higher index
lenses before (might have been polycarbonate) and can't get on with
them, and I think it's the chromatic aberration that's the problem. I
certainly felt as if I was being forced to look straight ahead all the
time.
I asked to be reminded of the Abbe values (Vd) before deciding what to
buy, and none of the staff were able to log in to the staff-only
section of their website and in the end one of them looked it up on the
web with her iPhone. To my surprise it was 42, compared to 40 for 1.6
and 30 for polycarbonate, so I thought that would be good enough and
went ahead and ordered.
I've tried looking up the value myself and now I think the optician
must have read the wrong row/column or something because of the small
screen. Everything I can find says 1.67 plastic has a Vd of 32. So
who's right? Can anyone confirm whether or not 1.67 lenses with a Vd of
40 exist? If they don't I'll know to be more assertive about
cancelling/changing my order and avoid some annoying back and forth
phone calls or something.
Mike Tyner
Apr 9, 2013, 11:48:30 PM4/9/13
to
I don't know the Abbe value for Pentax lenses but you said "I think it's the
CA that's the problem and this seems unnecessarily vague.
Chromatic aberration produces rainbows off-axis. If edges didn't separate
into rainbow fringes in your high-index lenses, then CA wasn't the problem.
The "horrors" of CA are often overstated.
-MT
"Tony Houghton" <h...@realh.co.uk> wrote in message
news:20130409182...@realh.co.uk...
CA that's the problem and this seems unnecessarily vague.
Chromatic aberration produces rainbows off-axis. If edges didn't separate
into rainbow fringes in your high-index lenses, then CA wasn't the problem.
The "horrors" of CA are often overstated.
-MT
"Tony Houghton" <h...@realh.co.uk> wrote in message
news:20130409182...@realh.co.uk...
Tony Houghton
Apr 10, 2013, 8:30:33 AM4/10/13
to
On Tue, 9 Apr 2013 22:48:30 -0500
"Mike Tyner" <mty...@mindspring.com> wrote:
> I don't know the Abbe value for Pentax lenses but you said "I think it's the
> CA that's the problem and this seems unnecessarily vague.
>
> Chromatic aberration produces rainbows off-axis. If edges didn't separate
> into rainbow fringes in your high-index lenses, then CA wasn't the problem.
>
> The "horrors" of CA are often overstated.
I was definitely aware of the colour separation, and not being able to
"Mike Tyner" <mty...@mindspring.com> wrote:
> I don't know the Abbe value for Pentax lenses but you said "I think it's the
> CA that's the problem and this seems unnecessarily vague.
>
> Chromatic aberration produces rainbows off-axis. If edges didn't separate
> into rainbow fringes in your high-index lenses, then CA wasn't the problem.
>
> The "horrors" of CA are often overstated.
see properly off-axis, but there are other reasons they can "feel
wrong". On two occasions I've tried to stick with high index lenses as
advised, but couldn't get used to them, and the problem was resolved by
switching to a lower index material. I've just remembered another
occasion when I was aware of CA immediately and it turned out the wrong
type of lens had been fitted. So I think I understated my sensitivity to
CA in my first message rather than overstating it.
Mark A
Apr 12, 2013, 4:32:48 AM4/12/13
to
On Wed, 10 Apr 2013 13:30:33 +0100, Tony Houghton wrote:
> I was definitely aware of the colour separation, and not being able to
> see properly off-axis, but there are other reasons they can "feel
> wrong". On two occasions I've tried to stick with high index lenses as
> advised, but couldn't get used to them, and the problem was resolved by
> switching to a lower index material. I've just remembered another
> occasion when I was aware of CA immediately and it turned out the wrong
> type of lens had been fitted. So I think I understated my sensitivity to
> CA in my first message rather than overstating it.
Don't let anyone tell you that CA is overstated. For certain Rx's it is a serious problem and IMO most
> I was definitely aware of the colour separation, and not being able to
> see properly off-axis, but there are other reasons they can "feel
> wrong". On two occasions I've tried to stick with high index lenses as
> advised, but couldn't get used to them, and the problem was resolved by
> switching to a lower index material. I've just remembered another
> occasion when I was aware of CA immediately and it turned out the wrong
> type of lens had been fitted. So I think I understated my sensitivity to
> CA in my first message rather than overstating it.
people who dispense lenses are oblivious to the plight of their patients who have this sensitivity.
Mark A
Apr 12, 2013, 4:42:23 AM4/12/13
to
1.67 lens with a 42 abbe value, although the Pentax doc does claim that their 1.60 plastic is has abbe
value of 47, which is higher than normal.
http://www.svoplus.com/lenses/pentax/AFGuide.pdf
Tony Houghton
Apr 12, 2013, 10:12:56 AM4/12/13
to
information (BTW, they gave me the figure for 1.6 from the same table
for comparison, and that was 42, not 47), so I'll just have to wait and
see. They said they'll replace them if I have a problem, but my concern
is that I wanted them for a holiday and they won't be ready in time if
the first pair is no good. I've got a very nice spare frame (I was
originally going to get that reglazed at Specsavers, but it was cheaper
to get a new frame due to special offers) so I might as well put them to
use and get those reglazed by an online place that does 1.6
photochromics.
Mark A
Apr 13, 2013, 12:11:32 PM4/13/13
to
On Fri, 12 Apr 2013 15:12:56 +0100, Tony Houghton wrote:
> I rang the branch again and they told me that I was given the right
> information (BTW, they gave me the figure for 1.6 from the same table
> for comparison, and that was 42, not 47), so I'll just have to wait and
> see. They said they'll replace them if I have a problem, but my concern
> is that I wanted them for a holiday and they won't be ready in time if
> the first pair is no good. I've got a very nice spare frame (I was
> originally going to get that reglazed at Specsavers, but it was cheaper
> to get a new frame due to special offers) so I might as well put them to
> use and get those reglazed by an online place that does 1.6
> photochromics.
I would make sure about the manufacturer of the lens you will get, and then call them directly for abbe
> I rang the branch again and they told me that I was given the right
> information (BTW, they gave me the figure for 1.6 from the same table
> for comparison, and that was 42, not 47), so I'll just have to wait and
> see. They said they'll replace them if I have a problem, but my concern
> is that I wanted them for a holiday and they won't be ready in time if
> the first pair is no good. I've got a very nice spare frame (I was
> originally going to get that reglazed at Specsavers, but it was cheaper
> to get a new frame due to special offers) so I might as well put them to
> use and get those reglazed by an online place that does 1.6
> photochromics.
value information.
rea...@gmail.com
May 15, 2013, 11:09:01 AM5/15/13
to
On Friday, 12 April 2013 09:42:23 UTC+1, Mark A wrote:
> On Tue, 09 Apr 2013 18:22:15 +0100, Tony Houghton wrote:
[Specsavers told me their Pentax 1.67 lenses had a Vd of 40 and I was sceptical]
> On Tue, 09 Apr 2013 18:22:15 +0100, Tony Houghton wrote:
> According to this PDF, the Pentax 1.67 high index plastic has an abbe value of 32. Never heard of any
>
> 1.67 lens with a 42 abbe value, although the Pentax doc does claim that their 1.60 plastic is has abbe
>
> value of 47, which is higher than normal.
>
> http://www.svoplus.com/lenses/pentax/AFGuide.pdf
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