FS7: Nasty flare in lens hood on the 28-135mm kit lens

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dhart1949

Well-known member
I was shooting some FS7 test footage outside this am that involved a number of moderately back lit scenes. When I was reviewing my footage on my edit system I noticed a small but rather nasty lens flare in a number of the shots. This was not readily apparent in the FS7 EVF at the time of shooting.

I've used a number of other broadcast lens in similar situations with no flare problems like this.

I will not venture out again with this lens without a proper matte box or french flag. IMO, something is seriously wrong with the design of the sun shade. Perhaps it is not deep enough or the plastic is too shiny and reflects light back into the lens.

Anyone else experience this?
 
This lens can be barely called a "broadcast lens". It is not optimized for Super 35. It is a full frame lens and as such it creates a much bigger image circle which causes problems of internal reflections (in the sensor "box", olpf, ND's, etc).
 
Upon closer examination I've discovered that the sun shade is rather shiny internally. I believe the flare I discovered is actually the reflection of the internal corner of the sun shade. I'm going to try spray painting the internal portion of the sun shade with a black matte paint to see if that cures the problem.
 
The way the aberration fluctuates even though the camera's still, & there seems to be little-to-no wind, makes me suspect that something other then lens flare is going on here.
 
Bern Caughey said:
The way the aberration fluctuates even though the camera's still, & there seems to be little-to-no wind, makes me suspect that something other then lens flare is going on here.
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Thats why the IS question was valid, if the internal elements are 'vibrating' indepenent of the front element you would expect this..
 
If you examine the internal corners of the lens shade they are extreme shiny. My theory is that sun reflected off a corner and back into the lens (the corner is the same shape as the "flare"). I've coated the internal sides of the sun shade with a coat of flat black. Wait a day for it to completely dry and then test in similar conditions and see what happens. I'll double check to make sure steady shot is off.
 
Sorry to hear (and see) you have an issue.

I've been using the 28-135 lens for about 3 months in a variety of exterior environments, some extreme, without problem. The first thing I did when I received my FS7K was to purchase the Vocas MB255 Matte box (using the eyebrows) - I have never shot without it, nor have I had problems with flare, glare or grid flaring shooting into, aside, behind and through to sunlight.

It looks like you had sunlight through trees (hence the shimmer movement) and/or an unfortunate reflection. Would you go into a studio and shoot similar when there are high positioned keylights or other multiple light sources using that plastic lend hood? I certainly wouldn't.

As for someone calling the lens "non-broadcast" is silly. Most lenses are capable of producing broadcastable material - even plastic GoPro ones; whether you would match it with a cinematic type lens is another matter. Perhaps you would be more specific in your critique?

Claire
 
morgan_moore said:
Thats why the IS question was valid, if the internal elements are 'vibrating' indepenent of the front element you would expect this..
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Understood.

I've used Canon, Nikon, & Panasonic, stabalized lenses extensively in backlight & never seen any such aberration, but that doesn't mean this Sony hasn't got an issue.

I'm renting the 28-135/4 this week for a gig but mostly as a backup. If I get a chance I'll try reproducing the scenario.
 
Better, but not up to my expectations. https://vimeo.com/128890354 I will not use this lens in sunny conditions (pretty common here in Arizona :-) without a french flag. As you can see flare does not disappear until the lens is perpendicular with ground. Not good. This was shot with Steady Shot off. Sony needs to address this issue in my opinion. Here is the same shot with french flag https://vimeo.com/128894253
 
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Viddovation said:
Could it be a defect with your unit as opposed to a problem with the model on whole?
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I don't think so. I believe the sun shade is too short for the size of the lens (flare is worse when lens is at its widest angle). French flag "cures" the unusual flare problem so it's not the lens, it's the sun shade.
 
A single "shape" or "depth" lens hood or sunshade cannot properly work with wide angle to telephoto zoom lenses. By the time you get enough depth to properly "shade" the medium and telephoto ranges of such a lens it will definitely vignette on the wide end.

Your only real solution is an adjustable depth (bellows type) lens shade with the capability to add a flag when collapsed to the proper depth to not vignette on the wide end.

I used to have the bellows lens hood for the Mamiya RB-67 and really appreciated it when I took that camera out of the studio for "environmental" portraiture. The hood was adjustable with marks on the rails for the different focal length lenses in the system, so it was easy to adjust the depth as needed. No "flag" but on occasion I held a clipboard in the right position to block unwanted flare (or had an assistant hold it).
 
dhart1949 said:
Upon closer examination I've discovered that the sun shade is rather shiny internally. I believe the flare I discovered is actually the reflection of the internal corner of the sun shade. I'm going to try spray painting the internal portion of the sun shade with a black matte paint to see if that cures the problem.
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Dang. That's unfortunate. You sure it's not sneaking in from behind? Maybe a donut around the shade might mitigate the hit.
 
If the lens is made to cover full frame, then the supplied lens shade is highly ineffective when the lens is used on Super 35 sensor camera. Not to mention that on a zoom lens a fixed size lens shade is always quite poor. That's one thing and the other is additional light scattered around the sensor when the image circle is bigger than necessary.
 
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