Be extra careful and get a very high quality coated filter. I have had a direct light source sneak in past the lens hood and hit the front lens element. Not that big of a deal normally. But with a UV filter on the illuminated lens now reflected back at itself on the back of the UV filter. So now I have a shot of the talent and half of it is obscured by a reflection of the lens! Now....it was transparent but as I panned and moved you could clearly see that there was something in the frame screwing up the clarity.

You will find a few guys on this board who swear that you should not put any extra glass in front of your lens unless absolutely necessary. I believe Charles Papert is one of them and he is a highly respected DP if I am not mistaken. So he knows a thing or 2 about optics and quality.

Personally I agree with him and only use filters for effects or to protect the lens when in some extreme environment like the beach, desert or a pit full of scorpions.

thanks :)
 

thanks guys for the advice. I just called Glaziers in Seattle, and they do have the UV filter I guess I can purchase. I will be using it with discretion, depending on the environment like you said Marty, but will be doing tests with it on to see if I do notice any problems. More than likely I wouldn't even have it on if I'm doing interview shots inside somewhere.

<<<-- Originally posted by Marty Hudzik :
Personally I agree with him and only use filters for effects or to protect the lens when in some extreme environment like the beach, desert or a pit full of scorpions. -->>>

The latter of which is typically a daily occurance for my filming needs.

Joseph,
You mainly need to look for this issue when there is a light source in the frame (or just outside of it) that causes lens flares. It is possible that the light can creep in, not cause a flare but still reflect back. I used with a UV on there for 6 months and had no problems but then one shoot the sun was in just the right spot and wham! Ruined my shot! Nothing like having a ghost image of a transparent semicircle in the bottom half of the frame! The lenshood was shading the top half of the lens for me.

Oh!!! If you are using a professional Matte Box this issue may not occur at all or only when the light source is in the frame. Good Luck!

The main problem I've noticed with them is when there is light from the front or side I'll often see a spot from where water has dried and left mineral residue. The bad news is the picture is not as nice as it might be without the spot. The good news is that the spot is on the filter - not the front element of the lens.

Question: The 20X has elements which are coated with calcium fluoride. Is the front element one of these? Is calcium fluoride softer than glass?

Interesting twist (discovered while researching CCD's for another thread): Silicon CCDs are the opposite of film in that they naturally have reduced response to shorter wavelengths and increased response to longer ones. Thus the traditional UV filter isn't doing us any good in terms of haze reduction. An IR filter would be required for that.

Great post Mark. I was wondering this exact thing.

Zoom and focus presets on 20x lens. Impossible to use???
 

Hi all

just a simple question for those of you that use the zoom and focus presets. I find them very useful for slow crawls where I can remove my hands from the camera.

But anyway, how do people use these features if at all because I find that unless under very controlled situations it's impossible to use these switches on the lens without moving the camera, even on a tripod with some zoom on. Is there any magic tricks or methods to use these switches and not end up with a jerk in the footage when you flick the switch?

Also does anybody find the slow focus speed way too fast when using these features, almost too fast to bother using it to slow focus change from foreground to background? Even then, anytime I've used it I shake the camera making the effort a waste of time. Maybe I'm using it wrong?

Anyway, anybody got any comments?

Donie

Hi all

Anybody use this feature at all? Is it just tripod that is the problem?

Thanks
Donie

Donie - I experience the same problem as you with a jerk in the footage when flicking the switch.
I recently got a better and more stable tripod (Libec T58 with H55 head), and the jerk is not so noticeably as with my first tripod, even if you can still see a small jerk. I think more practice will help me a lot!

- Per Johan

With the preset Focus/Zoom being a slider switch, I think having the camera move when sliding the switch is virtually impossible to avoid. I wish Canon had made the preset a simple push button or even better something you can activate using the remote. Wouldn't that be cool. I use the preset for doing slow pull outs on a golf show, so I get in as tight as the lens will go and just accept that the first 15 or so frames are uselss.

The 1.6x extender works on the 20x lens?
 

I still see the 1.6 extender from Canon advertised for the x16 lens and am wondering if it also works ok on the 20x lens.

Also, can the century tele lens be used with the 20x lens?

See http://www.dvinfo.net/canonxl2/artic...e10.php#xl20ex

Greg, I use the 1,6 extender with my 20x lense. I am taking lots of wildlife footage. If you would like to take a look at some footage were I use the 1.6 extender, take a look at one of my previous thread at this forum:
http://www.dvinfo.net/conf/showthrea...threadid=40780


- Per Johan

wrangler note: edited link to make it active -gb-

Re: The 1.6x extender works on the 20x lens?
 

<<<-- Originally posted by Greg Jacobson : I still see the 1.6 extender from Canon advertised for the x16 lens and am wondering if it also works ok on the 20x lens.

Also, can the century tele lens be used with the 20x lens? -->>>

Thanks, but I guess you can't also use the Century tele lens on the 20x as you can on the 16x?

Also, if you use the EF adapter I would imagine that you could also use the 2x extender for the Canon lenses on the XL2. Right?

Those photos of the tractor are amazing. Nice reach.

I don't see any reason why you could not have both the 1.6x extender plus the Century teleconverter both on at the same time.

Greg, have you seen this? http://www.dvinfo.net/canon/images/images17.php