Urgent help needed to explain flares

<p>Hello, I'm hoping to get some expedited feedback as to what might be causing the flare/streaking/star-type effect coming off the light sources in the attached pics. It's not usual and it ruined a bunch of shots from last nigh there in Mumbai. Parameters for most of the shots are 5dII, 24-105 at 24-70mm @ f4, no flash, ISO 1250-3200.<br /> I've done tons of this kind of shooting over the years and never experienced anything like this and it's freaking me out as the next 8 nights are all critical. At first I though camera movement given than some exposures were as slow as 1/10th, using the IS, but the subjects are sharp, there is no appreciable movement.<br /> The one with the balloons is a throwaway but shows the problem well, and its at a 125th<br /> Thanks very much for input.</p><div></div>

<p>Weather? I often have similar problems when the lens <em>starts</em> to get fogged up (but I don't notice due to the darkness), some of the lenses will fog on the internal elements (which are slower to acclimate)</p>

<p>Was it particularly humid, or was there a drastic temp difference between your equipment and the ambient?</p>

<p>If this is part of the problem, I'd suggest using properly acclimated primes (lens internal air movement and usually less optical mass)</p>

<p>Hi Marcus, thanks, it was humid, but I had been out all day shooting in hot humid temps, no inside/outside, no AC in play, and this was the onset of darkness, so temp was dropping, and humidity was not terribly high, probably 40%, which is pretty low for Mumbai in monsoon. I was thinking the same, but I think I would have likely seen the telltale signs of fogging in the images, as in large, smoothly gradated flares and reduced contrast/washed out-quality across sizable portions of the images. Which I don't. There's actually no sign of foggy lens type flare or side effect in any of the images. This seems to be just as if I had been using a star filter.</p>

<p>BTW I don't post much here, and I couldn't determine whether this was really the most appropriate place to post this. If anyone has any thoughts please suggest. Thanks.</p>

<p>If the temp was dropping, then the relative humidity was increasing. Certainly it's possible that it's completely unrelated, but given that:<br>

1) you were out shooting in the heat prior, 2) the temperature was changing, and 3) it was temporary, and 4) it was mumbai, I'd hesitate to come to any other conclusion.</p>

<p>Remember the air in your camera (and lenses) hold it's own moisture @ a given temp, and if the warmer air inside has a lower RH, then moisture will get sucked in (concentration gradient), yielding a higher amount of moisture inside... as the temperature (inside) falls that moisture precipitates on ...well, everything... <br>

Sometimes (IME) the <em>amount</em> of fogging will vary across the surface of the lens (thicker at the center, or edges, depending on the temp gradient)... <br>

Sometimes a very fine (especially on some of the coated and flourite elements) fog occurs that only really catches sharp contrasting light (such as candles)....</p>

<p>Like I said, I don't know for certain what is causing this (I'm in the states, not Mumbai ;-) ), but that'd be my first, and best educated guess. I shoot all year round in Savannah, so I'm familiar w/ ALL the effects RH has on my eqp. I can't count the number of images I've got which have <em>very similar</em> effects (and I don't use star filters ;-) )</p>

<p>If this is causing the problem, as I said, pulling out a small prime may help, but more than that, pulling off your lens and waving it around (to swish out the air, and equalize surface temps), while leaving the camera open is the best 'fix' I've ever found for this, but even<em> I</em> would hesitate in an extremely dusty environment...</p>

 

<p>Fog/water droplets on the lens, due to the increase in humidity/lower temp after the sun goes down. You should have seen it in the viewfinder too.</p>

<p>Can you see it in tests? Like with candles in a dark room, and the camera on a tripod?</p>

<p>Does the lens look clean? Front and rear glass? Also remove any filter you're using.</p>

<p>Does the problem diminish when you stop down the lens? Is it better at f/8, f/16?</p>

<p>Ok, thanks guys, I will keep an extra eye out for this. I have been out shooting from 3pm-9pm almost every day (i.e. transition from afternoon to night) for the past month and a half, and this has never happened, and the weather/light change is pretty gradual and consistent from one day to the next.<br>

I like the idea that this is the cause, at least it wouldn't be a mystery. Sounds like it was probably a very thin, even frosting of condensation across the whole filter surface, not enough to manifest in a washed out quality in the images, but enough to tweak the light sources. I<br>

I should mention that I am using a B+W clear filter, regular thickness.<br>

I appreciate the responses.</p>

<p>A couple of thoughts.<br>

I have had flare problems with this lens in the past with filters - do you have a protective filter on the lens? If so, it would be worth removing it and seeing if things improved.<br>

In very early models of this lens, a very bright point-light source positioned in the corner of a full frame viewfinder with the lens set to 24mm and not stopped down much was prone to flare. <br />Canon has posted a Service notice acknowledging the flare problem and will repair <br />any affected lenses (Control number less than UT1000)</p>

<p>Thanks Alan, these are good tests. Had some of the same thoughts but have just a bit too wiped out today to run them, but will do so soon. Sorry, I missed your post there.</p>

<p>As Alan said, I would try removing the filter.</p>

<p>Hi Rick, yes, It has a B+W F-Pro 010 UV Haze 1x, regular thickness. I thought it was clear but it's a haze. It's very clean. I'm hesitant to take it off as the places I"m shooting have millions of people milling around and constant bumping into each other, but if it's a fix I will. Lens date is Y, 2010</p>

<p>The humidity here (and it's sometimes unpredictable side effects) is one reason I don't use filters anymore. I didn't realize you had a filter on, but the thinner filter glass can cool rapidly (much faster than the lens elements), and if the air behind it (in front of the front element) is warmer, condensation sometimes forms - only a smidge because there is only a small pocket of air, but certainly enough to cause (sometimes) the flare you are seeing especially given the high contrast.</p>

<p>Thanks for all the input guys.</p>

<p>Things that can caused flares flares in the past for me....</p>

 

<ul>

<li>High Humidity</li>

<li>Bringing a camera from a cool air conditioned environment out to a hot / humid one causing some fogging on the lens and / or sensor.</li>

<li>Cheaper lens filters</li>

<li>Dirt build up on the inside of the lens</li>

<li>Though it hasn't happened to me - just read up on fungus issues with lenses.</li>

</ul>

<p>How to track down the issue</p>

<ol>

<li>Remove all filters, see if the issue goes away</li>

<li>If it is a high humidity area, make sure you let your camera acclimate to the new temp for about an hour or so</li>

<li>Get the lens / body / sensor cleaned by Canon</li>

</ol>

<p> </p>

<p>FYI - Here is a shot I took a few days ago (5D2 / EF 24-105L) which shows significant flare. Hood used, no filter, no problem with other shots (ie not condensation issue). There was a spotlight off to the top right which was the problem. Once I shaded the front of the lens with my hand the problem was solved. Conclusion: the EF 24-105L is susceptible to flare under certain circumstances.</p><div></div>

<p>It seems this lens is no worse for flares than others (http://www.lenstip.com/240.9-Lens_review-Canon_EF_24-105_mm_f_4L_IS_USM_Ghosting_and_flares.html).</p>

<p>Steve: I think the photos you uploaded are quite good actually. The flares enhance the pictures and give atmosphere. Maybe not what you intended but hardly 'throw-aways'?</p>

<p>Filters should be used only when absolutely necessary (and never when there are light sources in a frame) but that goes against the popular "protect the lens with a filter" movement.<br>

Yes, it is somewhat susceptible to flare but you may also wish to read about the "recall" in 2005 of some 24-105/4 L IS lenses because of the flare issue.<br>

<a href="http://www.dpreview.com/news/2005/10/28/canon24105svc">http://www.dpreview.com/news/2005/10/28/canon24105svc</a></p>

<p>Thanks everyone, population density here is as much as a million people per square mile in some of the areas where I work (Dharavi or example) hence you are always being bumped into, and my camera is out on my shoulder 24/7, so a filter is a good idea in that regard. It's also super dusty and dirty, you come back from each day with a layer of grime on you and everything you own. Also during Ganesh festival there are millions of additional people and even more dense crowds. Point being I'd like to keep the filter on, but if I see this happening again through the viewfinder I know something's up, and filter removal will be my first line of defense. Thanks for all the input.<br>

Michael, what's the thinking with filters and light sources in-frame? I've taken many thousands of such images over the years with no issues in terms of flare, including countless images with candles at night like the one I posted. </p>

If you need to protect the lens against dust,

water, etc., a clean, high quality glass filter is

OK, but a filter (which adds two extra glass/air surfaces) does Increase a chance of

distortions, flares and reflections if you

photograph light sources. But that depends

on many factors, such as the angle of the

light source in relation to the lens/filter

surface, its location in the frame, etc.

In my book only blowing sand/dust and

water justify a filter: everything else can be

cleaned off the lend surface.

<p>Hi Steve, I just checked weather report on Mumbai and its currently showing 79% RH. I live further down south in coastal area and I have seen RH cross 85%. I wouldnt rule out humidity.<br>

That said, once I got flare from my 28-105 mm lens and I was surprised. On checking my equipment, I realised that I had not attached my lens hood properly and it was not completely turned in. In case, you plan to service the lens, please avoid the centers in India, even if they are canon authorized. I had a bad experience with fungus cleaning for my lens and it's not worth the risk.</p>

<p>Thanks Sanjay, I dd some more testing tonight at Chowpatty and I think it must be a very fine coating of sea mist, although taking off my filter didn't change anything. I have to do some more tests, will report back.<br>

Ganpati Bappa Morya!</p>

 

The 24-105 is particuly bad for flare, a filter or doesn't make any diffidence (unless really cheap)

http://www.zen20934.zen.co.uk/photography/LensTests/Flare/EF%2024-105mm%20f4L%20at%2024mm.htm

 

Having said that I have yet to see a problem in real life shots.

 

The original op posting does look like fog due to humidity.

 

The point about a filter having less thermal mass than a lens element: shouldn't that mean it settles to ambient FASTER

and any misting clears faster?