> <dementia1***@gmail.com> wrote in message
> news:1142829752.018791.102970@e56g2000cwe.googlegroups.com...
> Hello. I was wondering if lenses follow any standard for threading? I
> want to mess around with filters and lenses, but can't figure it out.
> The lens on my cam now says "Zoom lens 1:1.8 f=4.5-45mm" then at the
> bottom, "Ø30 Japan". Does that mean it's 30 or 30.5 mm? Does the mm
> have to do with thread measurement at all? If you have no way to find
> out the thread size, is there a way to measure it? This is really
> confusing.
> --------------------
>
> I'm surprised that you didn't say what make your camcorder is.
> My Sony TRV22 uses 30mm filters.  The OD over the threads of the Sony
> labelled filter is around 29.8mm - it varies slightly as I rotate the
> filter.
> HTH
> --
> M Stewart
> Milton Keynes, UK
> http://www.megalith.freeserve.co.uk/oddimage.htm

> Malcolm Stewart wrote:
>> <dementia1***@gmail.com> wrote in message
>> news:1142829752.018791.102970@e56g2000cwe.googlegroups.com...
>> Hello. I was wondering if lenses follow any standard for threading? I
>> want to mess around with filters and lenses, but can't figure it out.
>> The lens on my cam now says "Zoom lens 1:1.8 f=4.5-45mm" then at the
>> bottom, "Ø30 Japan". Does that mean it's 30 or 30.5 mm? Does the mm
>> have to do with thread measurement at all? If you have no way to find
>> out the thread size, is there a way to measure it? This is really
>> confusing.
>> --------------------
>>
>> I'm surprised that you didn't say what make your camcorder is.
>> My Sony TRV22 uses 30mm filters.  The OD over the threads of the Sony
>> labelled filter is around 29.8mm - it varies slightly as I rotate the
>> filter.
>> HTH
>> --
>> M Stewart
>> Milton Keynes, UK
>> http://www.megalith.freeserve.co.uk/oddimage.htm
>
> Hi, I didn't specify the type because I thought someone may say to buy
> lenses made for this camera, which there aren't any available. It is a
> Sharp VL-SD20, and it has threading for UV, flourescent and polar
> filters, so maybe a lens will fit into that threading. If any lenses
> aren't available to fit this cam, I will probably try to thread a piece
> of alminum tubing and make a lens.

> dementia1***@gmail.com writes:
> >Hello. I was wondering if lenses follow any standard for threading? I
> >want to mess around with filters and lenses, but can't figure it out.
> >The lens on my cam now says "Zoom lens 1:1.8 f=4.5-45mm" then at the
> >bottom, "Ø30 Japan". Does that mean it's 30 or 30.5 mm? Does the mm
> >have to do with thread measurement at all? If you have no way to find
> >out the thread size, is there a way to measure it? This is really
> >confusing.
>
> Yes, the "30" is the filter thread diameter.  The thread is actually 30
> mm nominal diameter, 0.75 mm thread pitch, 60 degree thread included
> angle.
>
> The *actual* measurement of the outside of the male thread will be
> somewhat less than 30 mm, because the thread is cut to allow some
> clearance, and because the peaks of the thread are normally not sharp.
> If you want to know how to convert the nominal "30 mm" diameter into
> actual measurements that you can make, you'll need to look at a
> machining text that explains threading and tolerances.  But the intent
> is that a "30 mm" male thread will screw into a "30 mm" female thread
> without binding and have good strength - the exact measurements don't
> matter unless you are machining threads or making taps and dies.
>
> So you want filters marked 30 mm diameter.
>
>     Dave