cam lens cleaning?

[ric1]

<p>Hi,</p>

<p>I have a second hand Samsung HMX H200. It is pretty cool, I have already tested it outdoors. It's actually got much more in terms of manual controls than I would have expected from a budget cam. But the first thing I noticed were some smudge marks on the lens - and the effect of course was of a light haze filter. I carefully removed these marks with breath vapour & a cotton bud, very, very, gently.</p>

<p>Think I got it, the shots look okay, considering I bought this for 'point + shoot' projects, my preferred medium is photographic emulsion. I also dig the SD card. Wonderful as mini dv tapes are, cam heads do soil up in time & although I have cleaned heads on an older camcorder in the past, the cam was never as good as it was when new. So SD are cards are cool with me - handy too, for shunting video files around :)</p>

<p>But I still wonder if I could do an even better job on the lens. I have pure alcohol which I use for various photographic cleaning jobs, but I don't know if it would be suitable for the HMX lens? Plus the cotton bud system is rather defeated by these new cam lens housings which pillar box the lens behind a cowling. All well & fine if the effect is for a miniature lens hood but rather silly if you can't remove it to get up close to the lens for maintenance, if needs be. I do not know at the moment if the cowling can be removed?</p>

<p>Whether or not I can remove the cowling, can I lightly go over the lens with pure alcohol on a damp lens cloth or should I use a commercial lens cleaner instead please?</p>

<p>Many thanks.</p>

[craig_shearman1]

<p>I use a clean white cotton T-shirt to clean lenses, from camcorders to professional still camera lenses. Sounds like maybe you're being overly gentle. Once you've blown away any dust so you're not grinding sand into the lens, it's OK to use a little pressure as you rub. I would not go anywhere near a lens with pure alcohol (what is "pure alcohol "?-- there are a bunch of different kinds of alcohol). If you need to use a liquid, use lens cleaner. And make sure it's photographic lens cleaner from a camera store, not eyeglass cleaner from the drug store. <br />Don't go taking anything apart. The risk of not being able to put it back together again, or getting something out of alignment, is far greater than any additional cleaning you might accomplish.</p>

[ric1]

<p>Thanks Craig,</p>

<p>Well the cleaning did the job - I zoomed in on a tv this evening and when I analysed the shot in the software I could even see a single hair blowing about on an actor's head - so the lens is okay. No, I haven't used the liquid, it is <em>isopropanol,</em> it cleans then evaporates without a trace. But there's nothing left to clean.</p>

<p>What I'm getting is 'light spill' in basic mode. Funnily enough I noticed this also on the tv presumably shot with HD cams. Maybe it's especially an HD thing though, I have never noticed this in SD?</p>

<p>There is a <em>spotlight</em> mode which loses light spill but I have no idea what will happen if I use this outdoors. Maybe I just have to get used to this cam, and light spill is one of its quirks?</p>

<p>Ric</p>

[craig_shearman1]

<p>What do you mean my "light spill"? Could you describe it more? Are you talking about lens flare when there's a bright light source in the picture?<br />Spotlight mode sounds like a metering mode. It is intended to recognize a scene where a performer is in a spotlight surrounded by a large dark area. Rather than seeing all the dark and opening up the aperture, which would wash out the person in the spotlight, it keeps the aperture closed down, giving correct exposure on the person and letting the black go black. But it should not have an effect on light spill/flare.</p>

[ric1]

<p>Hi Craig,</p>

<p>This is all rather confusing to me since I was raised on manul cameras but I have made some progress. No, not lens flare, rather this, the light spilling out either side of the flame:</p>

<p><a href="http://www.instructables.com/files/deriv/FXU/J7S9/GHX7NTS4/FXUJ7S9GHX7NTS4.LARGE.jpg">http://www.instructables.com/files/deriv/FXU/J7S9/GHX7NTS4/FXUJ7S9GHX7NTS4.LARGE.jpg</a></p>

<p>Yes, 'spotlight' is the wrong setting - but I found an EV setting 'exposure variation' which allows me to manually stop down the aperture, that reduces light spill from bright objects where there's a strong contrast involved. Trouble is, the cam doesn't tell you what the aperture of indeed the shutter speed is doing, but considering this is a budget camcorder I think it is amazing that there is so much manual control available?</p>

<p>EV -2: two stops below default:<br>

http://i124.photobucket.com/albums/p32/r_i_c_2007/EV-20.jpg</p>

<p>EV 0 (neutral) default settings:<br>

http://i124.photobucket.com/albums/p32/r_i_c_2007/EV_0.jpg</p>

<p>EV +2 two stops above default:<br>

http://i124.photobucket.com/albums/p32/r_i_c_2007/EV2.jpg</p>

<p>I still might give the lens a once-over with dedicated fluid though, it cannot do any harm.</p>

<p>Ric</p>

[craig_shearman1]

<p>Looking at the flame picture, that's what I would describe as flare, both around the flame and definitely toward the lower right over the pin that's sitting on the table. The area around the flame could also be described as "blooming," which is common in video going back to the earliest days of video. It can happen whenver there is a light source or even just a bright object in the frame. Can happen even with high-end cameras as you noted earlier.<br /><br />If you adjust the exposure to reduce the "light spill" what you're doing is giving the camera the correct exposure for the flame, but probably starting to underexpose everything else.<br /><br />In your shots of the TV screen, if you zoomed in to where the screen fills the frame you would probably get more accurate exposure.<br /><br /></p>

[ric1]

<p>Thanks Craig,<br />As I say, I find auto cameras very confusing & they make me lazy - also this is a cheap (actually it's not cheap in that sense) camcorder and my veteran Canon cam records those scenes with minimal if any glare, flare, boom or light spill - but I did notice the background automatiacally went into underexpose. That said, the HD definition on the Samsung is superior to the SD Canon. I really think for the money the Samsung represents good value considering the manual controls at your disposal. Couple of years ago I picked up a Sony Handycam which was fully auto with no manual settings at all, bit of a nightmare in fact.</p>

<p>Best thanks ;)</p>

<p>Ric</p>

<p>ps. "In your shots of the TV screen, if you zoomed in to where the screen fills the frame you would probably get more accurate exposure"</p>

<p>Do you mean an exposure lock? That might be pushing the boat out a little way for the Samsung though - I'll have a look.</p>

[craig_shearman1]

<p>TV screen -- Not necessarily exposure lock. Just that in the current framing of those shots, the video camera is trying to find a compromise between the relatively dark area surrounding the set and the relatively bright image of the screen. Neither is coming out well -- the surrounding area is too dark and the screen is too bright. If you fill the picture with the screen, it would average out the same as a normal scene and look about right. If you're shooting a scene where the TV is going to be part of the scene and needs to be properly exposed, you could do an exposure lock on the screen, then zoom back out. But you probably need to increase the light level in the room to get the screen and surrounding level to balance out.</p>

[ric1]

<p>Thanks. I don't think the Samsung has an <em>exposure lock</em> as such, but you can tweak the default exposure by four stops - 2 either way - which ought to be enough for most situations. I am unlikely to encounter such extremes of contrast outdoors, but now if I do I know where the Exposure Value setting is.</p>

<p>The <em>Indoor</em> as opposed to <em>Auto</em> mode setting also stopped the diaphragm down which helped on the tv test :) Possibly similar gains in overall picture quality might be expected in selecting an outdoor mode when videoing landscapes, instead of the auto default.</p>