My dirty $55 secret & a question

<p>Okay, its ancient, with slow AF BUT, it only cost me £37 ($55 USD) including postage.<br>

What is it?<br>

A clean working 70-210 f4. Now I have some nice glass, Ls included, but none were cutting the mustard for me when it came to video zooming. And for practicality: it holds focus through a zoom! (if you zoom in and focus first before doing a live zoom in)<br>

Push Pull lenses just may have a new lease of life.<br>

I am already wondering how much I could get a 100-300 f3.6L or 80-200 f2.8L for.<br>

I still fully intend to get a 70-200 f2.8L non-IS for stills, but on my video days push pull is going to be far more friendly than twist zooming.<br>

One question, which if I get the wrong answer is going to see me shouting and bawling at Canons R&D folks.<br>

Can you enable a counter in video mode which will warn you when the card will run out of space?<br>

This would be very very useful, especially for people like me who don't trust massive cards (and who have found that 4x4gb is cheaper than 1x16gb)</p>

<p>I reckon the push-pulls are going to be sought after by the video users.. dig yours out and dust it down now!</p>

<p> </p>

<p>Well, some zoom lenses are parafocal (hold focus when zooming) and some not: the construction of the zoom mechanism (push-pull or rotating) has nothing to do with the lens being parafocal. But yes, if you intend to zoom on a stationary object while videoing then a parafocal lens is more useful.<br>

As for push-pull zoom being "better" for video, I dunno...Most people, including yours truly, think opposite, i.e. either turn the rings manually or, better, employ two follow focus mechanisms - one being for zooming. Push pull sucks for video IMO.</p>

<p>Don't know which camera are you using but 1D4 displays remaining/elapsed time, and turns the display red if there is no room on the card.</p>

<p> </p>

<p>Yeah I saw the follow focus mechs for the 5D and nearly fell off my chair laughing. Not what you would call compact or inexpensive. If I need that level of control I'll just make do with my broadcast camera with tripod follow focus and zoom demand.<br /> Compared to a twist zoom there is far less resisitance and shake with the push pull zoom, shake which will be a big issue on a 50" plasma.<br /> Its the 7D I use and it shows the remaining capacity before you hit record, and it shows you the elapsed recording time as you record, but it only warns you that you are out of space, not that you are about to run out of space (my camcorders have either a remaining time indicator or a tape meter) so if canon are reading, that would be a nice firmware upgrade.<br>

I know that not all lenses are parafocal. I thought it might be useful for somebody to know that the 70-210 f4 is!</p>

<p>Canon has this to say about zoom lenses in their lens book, pg 175:</p>

<blockquote>

<p>A zoom lens allows the focal length to be continuously varied over a certain range and can <em>maintain focus during zooming</em> . (Zoom lenses in which the focus changes wit the focal length are known as "vari-focal lenses.")</p>

</blockquote>

<p>I normally and almost always use AF so I haven't paid attention to parfocal performance on any of my lenses.</p>

<p>Pick up a cheap combo follow focus for zoom and focus, a push pull is way to jerky. Waste a few dollars on a cheap follow focus. Example of one not requiring gears etc.: http://www.idcphotography.com/kart/index.php?p=product&id=126&parent=31 <br>

From Vincent Laforet blog showing his IDC follow focus:<br>

<img src="http://img176.imageshack.us/img176/6285/screenshot20100306at117.png" alt="" width="497" height="330" /></p>