[B0SC0]

Okay, came across two different BESELER 18" EF SERIES III lenses

#1 dimensions = 4" x 6"

#2 dimensions = `5.375" x 6.125" (heavy)

What's the difference in these two other than size?

TIA

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[tgreenwood]

I think #1 has the aspheric optical acrylic lenses. It can have the same field of view and focal length in a smaller size.

#2 has glass lenses, so it is heavier.

Tgreenwood

PS. Of course I could be totally wrong. Aspheric lens explanation

[B0SC0]

Verrrry interestinnng.

How does one clean the inside of the lens?

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[B0SC0]

Of the Beseler, which one would be more suitable for a 15.4" WUXGA lcd?

I would think #2, having a wider diameter for better fov.

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[B0SC0]

B0SC0, on Jul 6 2007, 07:26 AM, said:

Of the Beseler, which one would be more suitable for a 15.4" WUXGA lcd?

I would think #2, having a wider diameter for better fov.

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bump

[B0SC0]

Can anybody address my last 2 questions?




TIA

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[ndnjoeh]

I think Tgreenwood told you they are the same

FOV will be the same

Shape of lens different but producing same FL


I have not cleaned mine yet but if I do I will make sure that I gather all the info I can about the procedure.


If you are buying these from someone and they have remarked that they need cleaning I would look for one that is in better shape. It will more than likely be about the same price.

I would go with the glass one just because it is glass

This post has been edited by ndnjoeh: 10 July 2007 - 04:02 AM

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ndnjoeh, on Jul 9 2007, 10:54 PM, said:

I think Tgreenwood told you they are the same

FOV will be the same

Shape of lens different but producing same FL
I have not cleaned mine yet but if I do I will make sure that I gather all the info I can about the procedure.
If you are buying these from someone and they have remarked that they need cleaning I would look for one that is in better shape. It will more than likely be about the same price.

I would go with the glass one just because it is glass

I am puzzled about fov of two lenses that are suppose to be the same.

One has a smaller diameter, so I would think it could not handle the larger lcd's

as the larger diameter lens.

Am I missing something here?


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[NinHowFritz]

Field of view is relatively independant of lens diameter(from what I understand). Since the one lens is asphirical, it can be smaller and still have the field of view reach out as far.

It may not catch as much light if you are using a long arc though. Maybe that is what you are thinking of?

[B0SC0]

NinHowFritz, on Jul 10 2007, 07:58 AM, said:

Field of view is relatively independant of lens diameter(from what I understand). Since the one lens is asphirical, it can be smaller and still have the field of view reach out as far.

It may not catch as much light if you are using a long arc though. Maybe that is what you are thinking of?

Yes, light, that was it. thanks

[ndnjoeh]

Asphirical lens by design have a better field of view passing a clear and cleaner image than a standard lens setup, same goes for light passed through it. A ray trace would show what is done to keep standard lens and asphirical lens the same, although they be different sizes and weights. Production practices are all that are different in this case. To produce this lens more than likely cost more with the larger one than the smaller one. Grinding glass cost more than molding plastic no matter quality of the materials. I would still go with the #2 something to do with the male pychi bigger is better LOL