Filter Question

[Alex Corn]

Hi,

I was browsing through the various filters where I work and came across a Tiffen Photar +1 filter. I am assuming that it is similiar to proxar or close up filters? I popped it on one of my cameras and it did adjust the close focus to what a proxar would do at the same distance, but I just wanted some more clarification or to see if there is some other purpose along with that of the close focus adjustment. I looked on the tiffen site, to no avail, and a google search yielded only ebay auctions. Thanks guys.

[Leo Anthony Vale]

...and a google search yielded only ebay auctions. Thanks guys.

 

---Doesn't it always.

 

Tiffen doesn't own the trade name Proxar. So it has to make up it's own trade name.

 

---LV

[Alex Corn]

---Doesn't it always.

 

Tiffen doesn't own the trade name Proxar. So it has to make up it's own trade name.

 

---LV

 

 

 

What is the exact effect of the various grades of these types of filters? When it says +1, that halves the distance of close focus? For instance, if the lens close focuses at 3'6", will it now close focus at 1'8"? What would +3 do?

[Leo Anthony Vale]

What is the exact effect of the various grades of these types of filters? When it says +1, that halves the distance of close focus? For instance, if the lens close focuses at 3'6", will it now close focus at 1'8"? What would +3 do?

 

---They're lenses, not filters.

The numbers are their focal lengths in dioptres. A dioptre is 1/focal length in meters.

 

Thus a +1/2 has a focal length of 2 meters. a +1 is one meter, a +3 is 1/3 meter.

 

Put one on a lens focused at infinity, the system will focus at the focal length of the cu lens.

 

Adding the diopters together gives the combined focal length of the system

 

 

OOPS, gotta go. More later.

 

---LV

[Leo Anthony Vale]

---They're lenses, not filters.

The numbers are their focal lengths in dioptres. A dioptre is 1/focal length in meters.

 

Thus a +1/2 has a focal length of 2 meters. a +1 is one meter, a +3 is 1/3 meter.

 

Put one on a lens focused at infinity, the system will focus at the focal length of the cu lens.

 

Adding the diopters together gives the combined focal length of the system

 

---Adding two +1 dioptres together gives you +2, which makes that the equivalent of a single +2.

 

One can also express the distance the cameram lens is focused on in dioptres.

So if it is focused at infinity it is 0 (zero) dioptres.

If at one meter it is focused at +1 dioptre. Put a +1 dioptre on that and , it now focuses at +2 dioptres, 1/2 meter.

 

Hopefully thats not too unclear.

 

Also some lens manufacturers, such as Nikon give an arbitrary model number to their close up lenses.

The above will not apply to those numbers, but the actual dioptre ought to be listed.

 

---LV

[Alex Corn]

---Adding two +1 dioptres together gives you +2, which makes that the equivalent of a single +2.

 

One can also express the distance the cameram lens is focused on in dioptres.

So if it is focused at infinity it is 0 (zero) dioptres.

If at one meter it is focused at +1 dioptre. Put a +1 dioptre on that and , it now focuses at +2 dioptres, 1/2 meter.

 

Hopefully thats not too unclear.

 

Also some lens manufacturers, such as Nikon give an arbitrary model number to their close up lenses.

The above will not apply to those numbers, but the actual dioptre ought to be listed.

 

---LV

 

So what you're saying is that by putting a +1 on a lens that its infinity mark would now focus at one meter? And by putting a +2 on a lens its infinity mark focuses at 1/2 meter? Just trying to get it through my head. Thanks.