Filter sizes all the same ?

[Hyena]

Ok this is a real n00b question:

I currently gave a 67mm UV filter on my D70 kit lens. If I'm looking around at other filters to use in addition am I looking only at 67mm as well ? That probably sounds dumb, but I wanted to make sure the thread at the front was the same at the one at the back (ie printed on the side ?)

I have a smaller filter on my video camera and it looks like the front thread size is a few mm different to the back, but it could be just an over-active imagination

Cheers

Jay

[gstark]

Jay,

The question is a very good one, but it's not quite clear, so I'll address it in a couple of different ways.

The question that I think you're seeking the answer to is whether the threads on the front and reat of the filter are the same.

The answer to this question is yes, but implicit in that question is the probability that you're thinking of running more than one filter on the lens at the one time. As a general guide, you probably don't want to do this. Just replace filter A with filter B and you'll be fine.

The other way that your question might be interpreted is that you're asking about using the one single filter across a variety of lenses. This and does work, but you need to accept that different lenses do have differing specifications, including their front thread.

But if, for instance, you have a 67mm CPL, that will fit on any lens you have that accepts a 67mm thread, but if you also have a lens with a 72mm thread, and/or another with a 77mm thread, those lenses won;t accpt the filter without an adapter.

If you're wanting to share filters in this manner, it's best to buy the largest filter you're likely to use (think ahead to future lens purchases you may wish to make) and buy adapters to bring them down to fit the lenses you have. Bear in mind with this approach that you may also induce some vignetteing in your images.

[phillipb]

The front of the lens is a female thread, the back is male. That may be the reason for the optical illusion.

[Hyena]

the probability that you're thinking of running more than one filter on the lens at the one time. As a general guide, you probably don't want to do this

Thanks Gary, despite my less than clear post you managed to answer my first question and prevent me needing to ask the 2nd

I was thinking of adding a 2nd filter when needed, but I might just leave one filter on each of the lenses and plan for them to be interchangable (getting the largest necessary and using an adapter as you've suggested)

Thanks

[gstark]

Jay,

My pleasure.

[Steffen]

What Gary said is correct, in general. One notable exception to the rule (that front and rear threads are the same) are Nikon's own circ/pol filters.

In order to avoid vignetting on wide lenses, Nikon built a step-up ring into those. The 52mm polariser, for example, is 52mm at the rear but a totally odd 60mm at the front. Nikon even make special screw-in lens hoods to fit their polarisers' front threads.

Cheers
Steffen.