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Panasonic 20mm Light flare spikes

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  • #46
    Re: Panasonic 20mm Light flare spikes

    I do think that the chemical coating on the lens that is meant to suppress this light effect has something to do with it.

    But I am unsure as to what the chemical actually consists of or where it is applied

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    • #47
      Re: Panasonic 20mm Light flare spikes

      Looking at your before and after photos.

      Flare
      The Before shot has a diffuse patch of light around the street lamp which I would call lens flare - lens coatings can reduce it, but shooting into the light it is always going to be there to some extent. The After shot has the same diffuse patch of light. Similar diffuse patchiness can be caused by condensation on the front lens element or within the lens. But I would say you have pretty much the same amount of flare both before and after. Unless you have rubbed at your lens i can;t imagine the coatings changing significantly in the few days you have owned this lens

      Diffraction spikes
      These are obvious in the After image but less so in the Before. In the Before there is a vertical spike originating from the right tip of the lamp-post - maybe there is a shiny bit of reflector there that is providing a point source specular highlight. Diffraction spikes are most obvious where the light is a point source (see earlier Patrick's shots - the one across the water has the most distinct spikes because the lights are point sources - the spikes are there in the others but are more blurry and fat because the light sources are fat so it looks more like reduced contrast or flare). In your Before picture there are signs of diffraction spikes if you look closely around the 7 or 8 oclock position - but they are quite diffuse and blurred because the light source is so big.

      The Before and After shots are not taken from exactly the same spot - it could be that the After shot picked up more specular highlights from the lamp than did the before shot.

      Generally - diffraction spikes are caused by the non-circularity of the diaphragm. Unless the aperture is a perfect circle (which needs lots of blades) you will get diffraction spikes from light sources. I can tell that Patrick's lens has six diaphragm blades because there are six spikes. The Panny 20mm according to the specs has seven blades so i would expect to see 14 spikes (uneven number of blades causes double the spikes but half as bright - google this if you want more info). Looking at your After shot - if you were to draw in further spikes at the same spacing as the six that are there I reckon you would get to 14.

      Can you try taking a shot of a distant or point source of light and see what you get - I'll bet you get 14 spikes and I would say that is normal and to be expected.

      My view is that your After lamppost shot is what I would expect to see in terms of flare and diffraction - I would say it is different from the Before because you are shooting from a slightly different position and you have picked up a bright highlight that you missed in the Before.

      And Finally
      I expect (but cannot be sure as i don't have one) the GF1 does have a B setting - switch to Manual mode and set the shutter speed to B. The aperture will shut down for as long as you have your finger pressed on the shutter button so will allow you to get a good long detailed look at the diaphragm blades

      Comment


      • #48
        Re: Panasonic 20mm Light flare spikes

        You raise a couple of points.

        I did think there might have been condensation formed on the lens. But I thought it might have caused the spikes not the glow. Taking it from a warm place into the open into the cold may cause condensation. The camera is metal and is cold to the touch outside.
        But I thought if that was a problem, wouldn't it show on other shots ? , wouldn't Panasonic pack the lens with a small silicone pack to draw away moisture if it was a common problem ? I mean warehouses are pretty cold places.

        If it is condensation, would it react with the coating ? Which is why I would want to know what sort of chemicals are used in it.

        The streetlight was not taken at pinpoint exactly the same place, they are also days apart, but the light glowed through the viewfinder at all angles before and now I can not even achieve a glow now no matter what angle I move the camera to, same goes for traffic lights. I will try to post some more shots later

        But to be honest, it's like I'm using a different lens.

        By the way, on manual mode on the gf1 there isn't a b shutter setting, but I did take pictures using the camera on the slowest shutter speed to have a look at the blades. And they work as I would expect. However, the blades aren't used on its widest aperture (f1.7) they stay where they are and both before and after were taken at that aperture.

        Comment


        • #49
          Re: Panasonic 20mm Light flare spikes

          Condensation is not an unusual problem at night in my experience - just breathing with the camera up to my eye can be enough to fog eveything. I wouldn't associate condensation with spikes though - more with the diffuse low contrast mistyness. Condensation would be more obvious problem when shooting into the light - same as when the car windscreen is misty and an oncoming car has its headlights on and suddenly you can;t see a thing.

          Maybe you were misted up on the "Before" shots and now the mist has gone the reduced diffusion is causing you to get diffraction spikes. Hard to say. You could maybe try breathing on your lens to fog it up, try taking the lamppost shot again and see what happens.

          I don;t think I would worry about the coatings unless there are obvious signs of damage. I think lens coatings are pretty tough - most lens cleaning fluid is based on isopropyl alcohol diluted with water. So I would have thought it pretty unlikely that coatings would be damaged by a bit of water/condensation in the short term.

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          • #50
            Re: Panasonic 20mm Light flare spikes

            The thing is I originally asked if anyone who had a Gf1 with a 20mm lens attached to try the streetlight and traffic light test and comment what happens but so far no-one has

            "steaming up" would show up on the other pictures I took before the problem occurred and didn't so really I'm not convinced that that is what it is.

            I did contact Panasonic by email and didn't get a reply. And by phone I got a customer service type person who advised me to send it to a third party company for an engineer to look at and decide whether it was faulty

            I did think that a company the size of Panasonic would have decent technical support who could be contacted by email or even in a chat window. They would have a 20mm attached to a gf1 and could have said "yes it does this" or "no it doesn't do that"

            So, if anyone has a Gf1 with a 20mm lens attached try the streetlight and traffic light test and let me know if it glows or spikes

            Comment


            • #51
              I can't post the link directlyvas I don't have enough posts on this forum but if you can work it out here is something taken on the GX1 (not GF1) but with the 20mm

              wwwdotphotosigdotcom/go/photos/view?id=2540494&forward=browse

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              • #52
                Or here with gf1 this time...

                wwwdotflickrdotcom/photos/radimersky/5610784727/in/pool-1407670@N21

                Comment


                • #53
                  Re: Panasonic 20mm Light flare spikes

                  Originally posted by Camera View Post
                  The thing is I originally asked if anyone who had a Gf1 with a 20mm lens attached to try the streetlight and traffic light test and comment what happens but so far no-one has

                  "steaming up" would show up on the other pictures I took before the problem occurred and didn't so really I'm not convinced that that is what it is.

                  I did contact Panasonic by email and didn't get a reply. And by phone I got a customer service type person who advised me to send it to a third party company for an engineer to look at and decide whether it was faulty

                  I did think that a company the size of Panasonic would have decent technical support who could be contacted by email or even in a chat window. They would have a 20mm attached to a gf1 and could have said "yes it does this" or "no it doesn't do that"

                  So, if anyone has a Gf1 with a 20mm lens attached try the streetlight and traffic light test and let me know if it glows or spikes
                  Panasonic isn't on it's own using third party service companies, I know Canon do, its in Stoke on Trent.

                  Have you done further test shots, since the ones you posted? This will tell you what the lens will do concistantly as you may have had a one off effect due to conditions you were not aware off.
                  This will be cheaper than paying the post to send to have it checked (inside the warrranty period the official Panasonic repairer will do the actual check for free) then having to pay return post only to be told the lens is fine.

                  It is impossible not to get some star effect even at f1.7 the effect will intensify as you stop down. The cause already explained by Roger.
                  The glow round is I think more to do with exposure than anything else, its not flare as flare is a lens element effect creating a number of light discs shaped on the image in reducing size, the number usualy corisponding to the number of elements in the lens, zooms are more prone to this than prime lenses. Coating the lens elements helps, but does not eliminate this.

                  Coating on lenses don't change, the internal coating cannot change, the only way external coating can change would be with a powerful solvent, or something abrasive, not normal use in the wet. Or indeed using lens cleaning fluids, providing its used gently with a soft lint free cloth. handkerchieves are not recommended.

                  Patrick

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                  • #54
                    Re: Panasonic 20mm Light flare spikes

                    I think that I did ask earlier on if the lens works alright in daylight, no doubt a rhetorical question. If its alright then I cannot believe that Panasonic would have any reason to accept a warranty claim.

                    Comment


                    • #55
                      Re: Panasonic 20mm Light flare spikes

                      Originally posted by Patrick View Post
                      Panasonic isn't on it's own using third party service companies, I know Canon do, its in Stoke on Trent.

                      Have you done further test shots, since the ones you posted? This will tell you what the lens will do concistantly as you may have had a one off effect due to conditions you were not aware off.
                      This will be cheaper than paying the post to send to have it checked (inside the warrranty period the official Panasonic repairer will do the actual check for free) then having to pay return post only to be told the lens is fine.

                      It is impossible not to get some star effect even at f1.7 the effect will intensify as you stop down. The cause already explained by Roger.
                      The glow round is I think more to do with exposure than anything else, its not flare as flare is a lens element effect creating a number of light discs shaped on the image in reducing size, the number usualy corisponding to the number of elements in the lens, zooms are more prone to this than prime lenses. Coating the lens elements helps, but does not eliminate this.

                      Coating on lenses don't change, the internal coating cannot change, the only way external coating can change would be with a powerful solvent, or something abrasive, not normal use in the wet. Or indeed using lens cleaning fluids, providing its used gently with a soft lint free cloth. handkerchieves are not recommended.

                      Patrick

                      I should have mentioned, even the most advanced modern coatings do not eliminate any of the discussed issues in this thread they merely reduce them.

                      Patrick

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