What is a Series 7 adapter exactly?

<p>Hi folks,</p>

<p>I remember buying a series 7 adapter ring years ago to attach a cheap wide angle conversion lens to my camera lens. But... what exactly is a series 7 adapter? I know it converts a "series 7" thread to a specified filter thread e.g. Series 7 to 58mm adapter ring etc.</p>

<p>But what size and type is the series 7 thread? Can a standard stepping ring be used instead?</p>

<p>The reason I need to know is because I get a lot of customers contacting me for advice about attaching conversion lenses to their cameras. I stock every possible size of stepping ring but I do not have series 7 rings.</p>

Series 7 rings are intended to hold that particular series size filter to a lens. If they fit a WA or TEL conversion lens it's by coincidence.

<p>Look <a href="http://silverbased.org/series-filters/">here </a>for an explanation of series filters. The screw thread diameter you want is probably 2 1/8", which is very close to 54mm. I don't know what the thread pitch is. This would actually correspond to the Series VII retaining ring or hood.</p>

 

<p><em>If they fit a WA or TEL conversion lens it's by coincidence.</em></p>

<p>Not necessarily. They may well have made the conversion lens to attach by a Series VII thread on the front of the camera lens. </p>

<p>(Fine print: some camera lenses were like this, although I have no personal experience of it. They had a series thread right on the lens, so you could drop on a series filter, and then screw a hood or retainer right on the lens.)<em><br /></em></p>

<p>

I know it converts a "series 7" thread to a specified filter thread e.g. Series 7 to 58mm adapter ring etc. But what size and type is the series 7 thread?

<br>

A series VII filter (or V or whatever) has no thread. Itś a drop-in thatś held in place by a retaining ring that screws into the adapter.</p>

<p>Thanks all. It sounds as though I need to get a stock of some series 7 rings then. I was hoping the series 7 thread was a standard size thread. Never mind.</p>

<p>You can buy many different size adapters that will adapt to series 7. Here are some on Ebay. http://www.ebay.com/sch/i.html?_nkw=series+7+adapters.&_sacat=0&_odkw=seried+7+adapters.&_osacat=0&_trksid=p3286.c0.m270.l1313</p>

<p>This ought to be somewhat helpful: http://randomphoto.blogspot.com/2007/04/serious-about-series.html</p>

<p>Michael, a small point, but if you click on "cameras..." in the eBay box to the right of "series 7 filters" it avoids the similarly named car parts.</p>

<p>There is a partial explanation of series filters in general at http://www.marriottworld.com/pieces/pieces21.htm of which the main part is:</p>

<blockquote>

<p>Series filters are glass or plastic mounted in a metal or plastic rim. There is no screw thread or other mounting; instead, the filter is designed to be held in place by a retaining ring. This retaining ring would either be part of the lens or be part of a lens hood/filter holder. <br>

<a name="series"></a>Series filters are usually referred to using Roman numerals (except Series 4.5). </p>

</blockquote>

<table border="0" bgcolor="#FFFF99">

<tbody>

<tr>

<td>

<blockquote>Series Number</blockquote>

</td>

<td>

<blockquote>Diameter, mm.</blockquote>

</td>

<td>

<blockquote>Rim Thickness, mm.</blockquote>

</td>

</tr>

<tr>

<td>

<blockquote>IV (4)</blockquote>

</td>

<td>

<blockquote>20.8</blockquote>

</td>

<td>

<blockquote>4.06</blockquote>

</td>

</tr>

<tr>

<td height="12">

<blockquote>4.5</blockquote>

</td>

<td height="12">

<blockquote>25.4</blockquote>

</td>

<td height="12">

<blockquote>-</blockquote>

</td>

</tr>

<tr>

<td>

<blockquote>V (5)</blockquote>

</td>

<td>

<blockquote>30</blockquote>

</td>

<td>

<blockquote>4.31</blockquote>

</td>

</tr>

<tr>

<td>

<blockquote>VI (6)</blockquote>

</td>

<td>

<blockquote>41.3</blockquote>

</td>

<td>

<blockquote>4.82</blockquote>

</td>

</tr>

<tr>

<td>

<blockquote>VII (7)</blockquote>

</td>

<td>

<blockquote>50.8</blockquote>

</td>

<td>

<blockquote>5.33</blockquote>

</td>

</tr>

<tr>

<td>

<blockquote>VIII (8)</blockquote>

</td>

<td>

<blockquote>63.5</blockquote>

</td>

<td>

<blockquote>5.58</blockquote>

</td>

</tr>

<tr>

<td>

<blockquote>IX (9)</blockquote>

</td>

<td>

<blockquote>88.9</blockquote>

</td>

<td>

<blockquote>5.58</blockquote>

</td>

</tr>

</tbody>

</table>

<p>There are some series filters that do have threads. Most notable of these is some Series VIII threaded filters, which happen to be the same as 67mm screw-in filters.</p>

<p>Yep, to flog a dead horse: the series filter itself is a standard-sized disk with an unthreaded metal rim. However, a series adapter also has a standard-size thread for its retaining ring. This thread size is what we mean implicitly, when we say something like "Series VII thread".</p>

<p>FWIW, <a href="http://medfmt.8k.com/bronaux.html">this page</a>, on the old medium format site, talks about WA and tele adapters in Series thread, which was the original topic. It talks about using Series VIII-threaded adapters on Bronica lenses, which conveniently have 67mm threads, like JDM said. </p>