Potential Pam Cyclops

[HauteHippie]

Those that have worked on or are working on PAM cyclops projects, please let me know what you think of these specs for a 6mm cyclops that I have found.

Round sapphire, 6mm diameter.

Total height with edge 0.95mm

Central thickness 0.55mm

Radius of curvature 5.21mm

Magnification roughly 1.4x to 1.5x depending on distance.

[Watchmeister]

Any of Archibald, Sssurfer or Finepics can best answer that question.

[Finepics]

will try to answer this tomorrow as it's my bedtime now!!

[sssurfer]

Chieftang, in my PM to you I missed it was sapphire. Apologies.

I too have to make some new calculations before replying.

[sssurfer]

Here I am (hi Chief, I see you are reading right now! ).

Central Thickness is supposed to be the total thickness of a lens.

Instad, your source seems to use the term 'Central Thickness' to mean what we can call 'Active Thickness', i.e.: Central Thickness minus Edge Thickness.

In this case 'your' cyclops has:

Central Thickness = 0.95 mm

'Active Thickness' = 0.55 mm

Edge Thickness = 0.4 mm

These figures give:

Radius Of Curvature = 8.4 mm (NOT 5.21)

Focal Length = 16 mm if glass, 12 mm if sapphire

Mag: 1.2-1.3x if glass, 1.3-1.4x if sapphire

1.2-1.3 is the usual mag we have on our reps.

I personally recently experimented a lens with Focal Length = 12 mm (i.e. Mag = 1.3x at 3 mm, 1.4x at 3.5 mm) and I can assure you that its mag was just a tiny bit higher than that by our 'original' rep cyclops.

In order to go to Mag 1.4x - 1.5x, we need Focal Length = 10 mm, that corresponds to:

With glass:

Radius Of Curvature = 5.15 mm (5.21 is ok as well)

'Active Thickness' = 0.96 mm (0.95 is ok as well)

Edge Thickness: the lower, the better. Any companies that Finepics, archibald and I asked in the past declared unable to go below 0.3 mm. So we can say, if we are lucky:

Edge Thickness = 0.3 mm

and (therefore):

Central Thickness = 1.25 - 1.26 mm

With sapphire:

Radius Of Curvature = 7 mm

'Active Thickness' = 0.67 mm

Edge Thickness = 0.3 mm

and (therefore):

Central Thickness = 0.97 mm

If, on the other hand, the info from your source are to be intended as 'Active Thickness' (i.e. CT minus ET) = 0.95 mm, then WITH GLASS it would have exactly ROC = 5.21 mm as they said, and this would led to Focal Length = 10 mm and (therefore) Mag = 1.4x at 3 mm, 1.5x at 3.5 mm, again as they said.

If they can provide such a lens with an Edge Thickness = 0.3 mm or less, then this is our ideal cyclops and no better can be done with mineral glass.

Hope this helps. Please keep us informed.

[tech]

PANNY cyclops upgrades would be sweet...my two reps are screamin' for this upgrade....

[HauteHippie]

Hope this helps. Please keep us informed.

Well my source has come back and said he miscalculated... He now says the real R value is approximately 8.2.

[sssurfer]

Well my source has come back and said he miscalculated... He now says the real R value is approximately 8.2.

As I supposed. Very close to my calculated value of 8.4, with that 0.2 difference surely imputable to roundings.

Well, ROC = 8.2 is not so bad.

It gives FL = 10.52 - 10.82 (depending on the quality of sapphire).

Assuming FL = 10.7, then mag is 1.39-1.48x.

Almost as my 'best glass lens', but with a very smaller thickness.

Not bad at all. You may want to give it a try.

The only problem we 'Watchmen' found on our first try was that sapphire has scandalous price, especially when not in massive production (100+ pieces). On single pieces we have been asked 100+ USD for custom lenses like those we needed. But if your company has them readily available then price may drop.

May I ask you how much they asked you for it?

[HauteHippie]

As I supposed. Very close to my calculated value of 8.4, with that 0.2 difference surely imputable to roundings.

Well, ROC = 8.2 is not so bad.

It gives FL = 10.52 - 10.82 (depending on the quality of sapphire).

Assuming FL = 10.7, then mag is 1.39-1.48x.

Almost as my 'best glass lens', but with a very smaller thickness.

Not bad at all. You may want to give it a try.

The only problem we 'Watchmen' found on our first try was that sapphire has scandalous price, especially when not in massive production (100+ pieces). On single pieces we have been asked 100+ USD for custom lenses like those we needed. But if your company has them readily available then price may drop.

May I ask you how much they asked you for it?

So it sounds like you are saying this might work? I will let you know a price. I'm guessing around $25USD or less though, and probably better in quantity.

I don't know the equations to do the calculations, but originally you were saying FL would be 12mm for ROC of 8.4 but now you're saying it's 10.52-10.82... Why the discrepancy?

Another question... how is sapphire quality specified? I can try to get information about the sapphire if I know what quesitons to ask.

[sssurfer]

I don't know the equations to do the calculations, but originally you were saying FL would be 12mm for ROC of 8.4 but now you're saying it's 10.52-10.82... Why the discrepancy?

You are right, I have been excessively pessimistic. I rounded the refraction index of sapphire down to 1.7, and this resulted in FL = 12 mm.

Instead, sapphire refraction index ranges from 1.757 to 1.779, that results in FL around 11 mm for ROC = 8.4.

Taking ROC down from 8.4 mm to 8.2 mm accounts for the remaining 0.28-0.48 mm difference towards the FL I said.

The equation is the so-called 'thin lens equation':

FL = ROC / (RI - 1)

(where RI is the Refractive Index)

Finally, here are your complete figures on ROC = 8.2 mm:

If Refraction Index = 1.757 then: FL = 10.82, Mag = 1.38x @ 3 mm, 1.48x @ 3.5 mm

If Refraction Index = 1.779 then: FL = 10.52, Mag = 1.4x @ 3 mm, 1.5x @ 3.5 mm

As you can see, Mag differs only for 0.02x on the quality of sapphire. I think that 0.02 is negligible, but if you want to be sure then ask your company about the refractive index of their sapphire, or - even simpler and better - the effective FL of that lens.

So yes, I think that that lens may work. At 25 USD or less, it definitely is worth a try.

Such a thin lens might also sustain a little increment in thickness, so to work in 7 mm diameter (for more recent PAM models), without interfering with the watch hands. If you are interested and if your company also manufactures 7 mm lenses then let me know and I'll make the calculations for you (thin lens equation alone will not suffice).

[HauteHippie]

So yes, I think that that lens may work. At 25 USD or less, it definitely is worth a try.

Such a thin lens might also sustain a little increment in thickness, so to work in 7 mm diameter (for more recent PAM models), without interfering with the watch hands. If you are interested and if your company also manufactures 7 mm lenses then let me know and I'll make the calculations for you (thin lens equation alone will not suffice).

I should have pricing and more info on 7mm version (if he can produce it) tomorrow (Monday).

[HauteHippie]

What do we believe the correct mag (per genuine PAMs) for 6mm cylopses should be? I've heard up to 1.6x? ssurfer, you've been talking about 1.4x-1.5x. Is that just because it's the best you can do with glass?

Thanks.

[sssurfer]

What do we believe the correct mag (per genuine PAMs) for 6mm cylopses should be? I've heard up to 1.6x? ssurfer, you've been talking about 1.4x-1.5x. Is that just because it's the best you can do with glass?

Exactly. It is just because it is the best I can do with glass.

And it is also very close to what I now suspect to be the best possible without incurring in problems from distortion and brightness decreasing, i.e. 1.5x - 1.55x.

Noone knows what the hell genuine mag is. Measuring pixel-wise several pictures of gens one would bet that it is 1.8x. And 1.7-1.8x was the mag we (the self-named 'watchmen') made on our first cyclopses.

But now we are almost sure that Officine P. heavily retouch their pics on their website instead. This suspicion has also been supported by experts, I have been told.

To make the things even more complicated, different PAM models have different cyclopses -- differing both about diameter and magnification. And some members here assured that they may witness that even different exemplars of a same model may have different cyclopses.

I think this is due to the different rehauts in different models. And, actually, one of the greatest difficulties we found on our first try was to find a tradeoff that could work on most models.

Personally, I now think that OP can go up to 1.7 (maybe even 1.8, no more than that) just because they may optimize their cyclopses on the different models, they may use aspheric (which, alone, multiplies by 4 the cost of a lens), and they have gorgeous bright datewheels.

But if we want a cyclops that can go on almost all models, at a reasonable price, we have to stay at 1.5-1.55x (just consider that even at as low as 1.5x, brightness would be less than a half of the unmagnified).

The great advantage of sapphire is that, on 6 mm diameter, it can reach 1.5-1.55x even with a lens less than 1 mm thick (while glass needs 1.3 mm just to go to 1-4-1.5x). 1 mm thick means NO PROBLEM ABOUT TOUCHING THE WATCH HANDS ON ANY MODELS... and there is even some more room left to think about 7 mm cyclopses.

Personally, I am an aficionado of 7 mm cyclopses too, because of 3 reasons:

1 - that is the diameter found on the most recent models;

2 - I think it looks better... something like the 2.1 mm thick Palp crowns, that people here even prefer to the gen crowns (1.9 - 2.0 mm thick);

3 - especially because, at a same mag, larger diameter means lower distortion.

But in order to get a same mag (i.e., same focal length) with a larger diameter one needs to also raise the ROC (i.e., the thickness).

On sapphire one has the room to do that.

[HauteHippie]

Update - no off the shelf 7mm cyclops available from this supplier but custom work can be done for a 100 piece minimum order. Pricing yet to come.

I'm also talking with them about a custom 6mm job with altered specs, but again, that'll be subject to a 100 piece min.