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Author Topic: Spot on inside of lens  (Read 5017 times)

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« Reply #25 on: April 19, 2014, 06:53 »
+1
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« Last Edit: May 11, 2014, 21:54 by tickstock »


Phadrea

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« Reply #26 on: April 19, 2014, 06:56 »
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It certainly is not a wind up. I can clearly see a mark inside the glass. When i look thorough the viewfinder I can see a spot. Why would I lie about this ? 

Phadrea

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« Reply #27 on: April 19, 2014, 06:57 »
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I think he's winding us up. He says he saw it clearly inside the lens, but it obviously isn't there,  it's clearly a sensor spot; then he said he saw it in the viewfinder after changing lenses. It's all either imagination or nonsense - except for the spot which means the sensor needs a clean.
Like I said earlier he could have some dust in the lens another piece in the viewfinder and another one on the sensor.   Only the one on the sensor will cause a spot but if you don't know it's easy to think that a big chunk of dust in the lens will do that.

Thanks for your confidence at least. That could be the very thing. It could also be on the mirror.
« Last Edit: April 19, 2014, 06:59 by Herg »

« Reply #28 on: April 19, 2014, 07:01 »
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If it's on the mirror it wouldn't show up on the picture. If it's on the sensor it wouldn't show up on the lens, if it's on the lens it wouldn't be there when you change lenses.

But maybe you have sensor dirt, a dirty mirror and lens fungus all at once, quite possible.

« Reply #29 on: April 19, 2014, 07:02 »
+2
I don't think he is winding us up. A lot of people just don't have good troubleshooting technique. Root cause analysis is part of my job.

Herg, if this is a viewfinder issue (I'm thinking DSLR, no other) then you would not get it in the captured photo. The spot you show appears like sensor dirt. A lens swap is the quickest way to separate if the spot in is the lens (goes away with the lens swap), or stays (must be with the camera body).

If viewfinder issue (DSLR) but not the captured image, then the flip-up mirror, the focusing plate, the pentaprism, the eyeglass are all in the light path and could have dirt. In a DSLR the sensor is not used for the viewfinder.

If in the viewfinder and the captured image then the dirt must be in a common light path to both. In a DSLR this is the lens.

If the dirt is visible in the captured image, but not the viewfinder (DLSR), then the dirt is most likely on the sensor. Pixels are so small that this dirt is not able to be seen by the naked eye on the sensor. It takes significant magnification, such as the aforementioned lighted magnifying loop, to see the specs. Dirt can still be small in the magnifying loop.

Small apertures often make the dust more defined in a captured image. Try f22 or f32 and take a photo of blue sky or a white monitor screen. Long shutter time and subsequent blur is OK.

If you are NOT using a DSLR, and ARE using some body with an electronic viewfinder, then the sensor is used to create the electronic viewfinder image. This section also applies if you ARE using a DSLR in LIVE VIEW mode (e.g. sensor is feeding live image to the back screen of the camera body). The light path to an electronic viewfinder is via the sensor. A lens swap is the best way to determine if the dirt stays with the lens or the body. If the dirt stays with the body it is almost certainly sensor dirt.

There are a multitude of methods for sensor cleaning but we won't discuss the pros and cons of each until it is decided the sensor needs cleaned (sensor dirt is still my best guess of the day for your problem).

Phadrea

    This user is banned.
« Reply #30 on: April 19, 2014, 07:46 »
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The spot I can see through the viewfinder seems to be coming out in the same spot of the captured image. Hmmm,m

« Reply #31 on: April 19, 2014, 08:15 »
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DSLR? Or Electronic viewfinder?

shudderstok

« Reply #32 on: April 19, 2014, 09:25 »
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If it's on the mirror it wouldn't show up on the picture. If it's on the sensor it wouldn't show up on the lens, if it's on the lens it wouldn't be there when you change lenses.

But maybe you have sensor dirt, a dirty mirror and lens fungus all at once, quite possible.

101 yawn
[/quot

firstly, there is no mention of the lens he is using - wide or tele? even then hyper focal distance most likely would not create a spot on the final image if it was on the lens, soft focus in certain areas for sure especially if it was mold and shot at f/11 ++, but not a visible dot on the final image. there is also no mention of what aperture he is using to see the dot, though 101 tells me it is f/8 and onward.

is the so called dust spot on the front or rear element, yes it could possibly make a difference but not likely.

if it's on the mirror then nope it won't show on the final image.

do a real test that is the standard test to see if you have dust on your sensor, it eliminates a lot of guess work.

baldricks trousers is absolutely correct in what he is saying, and that is 101. who woulda thunk?

if you really want to find out if it is on your sensor (most likely) then put on any lens, go to the smallest aperture f/16 or f/22 or f/32 and use a white piece of paper or a white wall to fill the frame. with luck you will get a long exposure of a 1 sec or 2, 3 or even 4 seconds, move/shake your camera body around for this time. now take that shot, and put it into photoshop or whatever you use and dial up the contrast as much as you can, that should show you every sensor dot/spot you have - you will even find ones you did not know you have. clean your sensor and do it again, then if you have different results, then it is definitely your sensor.

chances of a dot on your lens or mirror showing up in your image is next to none as paul said.

good luck!



 


« Reply #33 on: April 19, 2014, 14:42 »
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This is the spot magnified. Not had chance to swap the lens yet but will report back when done.

That is dust on the sensor. Take the lens of and blow into the hous, best with clean air.
If the spot goes away, or moves, it is dust on the sensor.
I have had thousands of these. Some bigger than rats.

« Reply #34 on: April 19, 2014, 14:44 »
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Herg, thanks for opening this thread. I have the same issue. I hope you dont mind me posting my example.

I know its a dirt spot, but I cant find it anywhere, its not on the glass, no on the mirror and as far as I can see its not on the sensor either. No idea where this is coming from.

Canond 6D+24-70L II

That is dried in snot, cough or tea drops on your sensor. The sensor needs cleaning with a cleaning pad and some solvent.
We owners of d 600 know all about these.
I have had millions of these, with all kinds of cameras.

« Reply #35 on: April 19, 2014, 16:16 »
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I clean my sensor every couple of days when I'm working in dusty environments with one of these and a rocket blower:

https://www.lenspen.com/?resultType=category&params=17&tpid=0&tpid=323

The blower should shift dust out of the mirror box if you've got stuff in there. I've seen insects crawling around in mine before now, so it's not uncommon.

Keep your sensor clean you dirty boy!

Batman

« Reply #36 on: April 21, 2014, 07:24 »
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Herg, thanks for opening this thread. I have the same issue. I hope you dont mind me posting my example.

I know its a dirt spot, but I cant find it anywhere, its not on the glass, no on the mirror and as far as I can see its not on the sensor either. No idea where this is coming from.

Canond 6D+24-70L II

Why would a spot on the mirror show on photos.

Phadrea

    This user is banned.
« Reply #37 on: August 23, 2014, 08:03 »
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Herg this is a sensor spot!

Managed to get my D200 working again (dead battery syndrome) and get the mirror up to clean the sensor as advised on youtube tutorial using blower. Ditto the mirror also. Suffice to say the spot is still there in the same place despite cleaning twice to make sure. This tells me the spot is indeed on the inside of the lens :-(

« Reply #38 on: August 23, 2014, 08:23 »
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I have a 5D MK 11 which is a real dust magnet but Arctic butterfly soon removes sensor spots, just need to be careful and ignore the fear mongers who would have us believe that using anything on a sensor would be as damaging as running over the camera with your car.

Photominer

« Reply #39 on: August 23, 2014, 09:09 »
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I get similar spots on one lens. It''s not there when I switch lenses. I get the spots on my 70-300 but not on my 17-55.

« Reply #40 on: August 23, 2014, 13:05 »
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If a spot is inside the lens it should be easy to see.

take the lens off and look through the lens in a bright location, pointing the lens towards a solid colour.

I have just been through examining all my lenses for mold and fungus.... and finding it.   :(

Using a adjusting focus and zoom can help pinpoint which element the dirt is on.

Goofy

« Reply #41 on: August 23, 2014, 18:16 »
0
I have a 5D MK 11 which is a real dust magnet but Arctic butterfly soon removes sensor spots, just need to be careful and ignore the fear mongers who would have us believe that using anything on a sensor would be as damaging as running over the camera with your car.

or using fine grit sand paper  8)



 

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