Bright spot on macro's

**eccs19** · 05-02-2010, 04:11 PM

Today with my K7, I was playing with macro / extension tubes. As you can see from the picture, I am getting bright spots in the center of the photo. It is not being caused by the flash, as I tried a couple without flash. Also tried a couple different lenses, but it's there. It doesn't appear (that I can see) under normal situations, only when playing with macro. I've used this exact combo on my *istD, and never seen this. Is there something in the settings on this camera that I need to adjust? It's also there in Live View.

yeatzee · 05-02-2010, 04:16 PM

looks like you have something infront/inside the lens.... atleast thats what it looks like.

**eccs19** · 05-02-2010, 04:46 PM

Originally posted by yeatzee

looks like you have something infront/inside the lens.... atleast thats what it looks like.

Except that it was there on 2 different lenses.

yeatzee · 05-02-2010, 04:47 PM

Right, im just saying what it looks like. i had a similar effect when a dog slobbered on the inside element of one of my lenses. I thought I cleaned it all but there was a thin film like layer left which caused the same effect.

Wheatfield · 05-02-2010, 04:52 PM

Most likely, that is a reflection off the sensor to the rear lens element and then back to the sensor as image forming light.
If this is the case, the cure, such as there is one, is to use a less bright background for your macro shots.

**eccs19** · 05-02-2010, 05:17 PM

Just tried again, and background was not a light color, but it's still there. It almost seems like there is some sort of light bouncing around in there. If I move my hands about between the lens & the object, I can somewhat change it. It's also more noticeable when closed all the way. When I open the aperture , it does go away at some point. Just seems strange that I never noticed it with my other camera.

JeffJS · 05-02-2010, 07:59 PM

How about light entering through the viewfinder? You say it isn't caused by flash, what is your actual setup?

**Just1MoreDave** · 05-02-2010, 08:19 PM

Originally posted by Wheatfield

Most likely, that is a reflection off the sensor to the rear lens element and then back to the sensor as image forming light.
If this is the case, the cure, such as there is one, is to use a less bright background for your macro shots.

I agree with this explanation. I see this when I try to turn the FA 35/2 into a DA 35/2.8 by using a 25mm extension tube. It doesn't show in the viewfinder at all. I tried a lot of shading and hood techniques without affecting the problem.

creampuff · 05-03-2010, 12:16 AM

Could be a light leak from that extension tube or some form of internal reflection.

distudio · 05-03-2010, 02:28 AM

Originally posted by Just1MoreDave

I agree with this explanation. I see this when I try to turn the FA 35/2 into a DA 35/2.8 by using a 25mm extension tube. It doesn't show in the viewfinder at all. I tried a lot of shading and hood techniques without affecting the problem.

I concur with this explanation too, when you're shooting macro there is a lot of light which doesn't hit the sensor due to the large mag factor, this can get reflected off the wall of the mirror box and of the surfaces of the lens and sensor.

**eccs19** · 05-03-2010, 04:14 AM

Originally posted by JeffJS

How about light entering through the viewfinder? You say it isn't caused by flash, what is your actual setup?

I thought about light entering the viewfinder, and covered that up, but that didn't make a difference. I know it wasn't cause by the flash, as the last batch I tried, I didn't use the flash at all, just to make sure that wasn't causing the issue.

**eccs19** · 05-03-2010, 04:17 AM

Originally posted by creampuff

Could be a light leak from that extension tube or some form of internal reflection.

Don't think it's an extension tube leak. I made sure everything was tight. Internal reflection may make more sense. It's almost like the camera is shining a light down the middle. Does it use some sort of light to confirm the focus? Not sure how that works, but being as the bright spot is right in the middle, makes me wonder if it's something to do with that or not.

distudio · 05-03-2010, 05:06 AM

Originally posted by eccs19

I thought about light entering the viewfinder, and covered that up, but that didn't make a difference. I know it wasn't cause by the flash, as the last batch I tried, I didn't use the flash at all, just to make sure that wasn't causing the issue.

The mirror totally obscures light entering through the finder when it's up and resting below the focus screen. And focus determination is all passive, cap the lens and the spot will go away ;-)

JeffJS · 05-03-2010, 09:33 AM

Originally posted by distudio

The mirror totally obscures light entering through the finder when it's up and resting below the focus screen.

Then why does Pentax tell us to cover the viewfinder for long exposures?

**Lowell Goudge** · 05-03-2010, 10:06 AM

Originally posted by Wheatfield

Most likely, that is a reflection off the sensor to the rear lens element and then back to the sensor as image forming light.
If this is the case, the cure, such as there is one, is to use a less bright background for your macro shots.

Originally posted by Just1MoreDave

I agree with this explanation. I see this when I try to turn the FA 35/2 into a DA 35/2.8 by using a 25mm extension tube. It doesn't show in the viewfinder at all. I tried a lot of shading and hood techniques without affecting the problem.

Originally posted by distudio

I concur with this explanation too, when you're shooting macro there is a lot of light which doesn't hit the sensor due to the large mag factor, this can get reflected off the wall of the mirror box and of the surfaces of the lens and sensor.

I'll add my 2 cent's worth, and agree with you three.

I have an old Rikenon 135 F2.8 screw mount that has the same issue. It is the only lens I have that exhibits it out of 30 lenses in total.

05-02-2010, 04:11 PM	#1
eccs19 Site Supporter Join Date: Jul 2008 Location: Lisle, Ontario Photos: Gallery Posts: 1,510	Bright spot on macro's Today with my K7, I was playing with macro / extension tubes. As you can see from the picture, I am getting bright spots in the center of the photo. It is not being caused by the flash, as I tried a couple without flash. Also tried a couple different lenses, but it's there. It doesn't appear (that I can see) under normal situations, only when playing with macro. I've used this exact combo on my *istD, and never seen this. Is there something in the settings on this camera that I need to adjust? It's also there in Live View.

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05-02-2010, 04:16 PM	#2
yeatzee Veteran Member Join Date: Feb 2009 Location: Temecula Photos: Gallery \| Albums Posts: 3,675	looks like you have something infront/inside the lens.... atleast thats what it looks like.

05-02-2010, 04:46 PM	#3
eccs19 Site Supporter Join Date: Jul 2008 Location: Lisle, Ontario Photos: Gallery Posts: 1,510 Original Poster	Originally posted by yeatzee looks like you have something infront/inside the lens.... atleast thats what it looks like. Except that it was there on 2 different lenses.

05-02-2010, 04:47 PM	#4
yeatzee Veteran Member Join Date: Feb 2009 Location: Temecula Photos: Gallery \| Albums Posts: 3,675	Right, im just saying what it looks like. i had a similar effect when a dog slobbered on the inside element of one of my lenses. I thought I cleaned it all but there was a thin film like layer left which caused the same effect.

05-02-2010, 04:52 PM	#5
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,975	Most likely, that is a reflection off the sensor to the rear lens element and then back to the sensor as image forming light. If this is the case, the cure, such as there is one, is to use a less bright background for your macro shots.

05-02-2010, 05:17 PM	#6
eccs19 Site Supporter Join Date: Jul 2008 Location: Lisle, Ontario Photos: Gallery Posts: 1,510 Original Poster	Just tried again, and background was not a light color, but it's still there. It almost seems like there is some sort of light bouncing around in there. If I move my hands about between the lens & the object, I can somewhat change it. It's also more noticeable when closed all the way. When I open the aperture , it does go away at some point. Just seems strange that I never noticed it with my other camera.

05-02-2010, 07:59 PM	#7
JeffJS Inactive Account Join Date: Aug 2008 Location: Michigan, USA Photos: Gallery \| Albums Posts: 7,484	How about light entering through the viewfinder? You say it isn't caused by flash, what is your actual setup?

05-02-2010, 08:19 PM	#8
Just1MoreDave Site Supporter Join Date: Feb 2007 Location: Aurora, CO Photos: Gallery \| Albums Posts: 6,339	Originally posted by Wheatfield Most likely, that is a reflection off the sensor to the rear lens element and then back to the sensor as image forming light. If this is the case, the cure, such as there is one, is to use a less bright background for your macro shots. I agree with this explanation. I see this when I try to turn the FA 35/2 into a DA 35/2.8 by using a 25mm extension tube. It doesn't show in the viewfinder at all. I tried a lot of shading and hood techniques without affecting the problem.

05-03-2010, 12:16 AM	#9
creampuff Veteran Member Join Date: May 2007 Location: Singapore Photos: Gallery Posts: 3,953	Could be a light leak from that extension tube or some form of internal reflection.

05-03-2010, 02:28 AM	#10
distudio Veteran Member Join Date: Jul 2007 Location: Sydney Photos: Albums Posts: 450	Originally posted by Just1MoreDave I agree with this explanation. I see this when I try to turn the FA 35/2 into a DA 35/2.8 by using a 25mm extension tube. It doesn't show in the viewfinder at all. I tried a lot of shading and hood techniques without affecting the problem. I concur with this explanation too, when you're shooting macro there is a lot of light which doesn't hit the sensor due to the large mag factor, this can get reflected off the wall of the mirror box and of the surfaces of the lens and sensor.

05-03-2010, 04:14 AM	#11
eccs19 Site Supporter Join Date: Jul 2008 Location: Lisle, Ontario Photos: Gallery Posts: 1,510 Original Poster	Originally posted by JeffJS How about light entering through the viewfinder? You say it isn't caused by flash, what is your actual setup? I thought about light entering the viewfinder, and covered that up, but that didn't make a difference. I know it wasn't cause by the flash, as the last batch I tried, I didn't use the flash at all, just to make sure that wasn't causing the issue.

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05-03-2010, 04:17 AM	#12
eccs19 Site Supporter Join Date: Jul 2008 Location: Lisle, Ontario Photos: Gallery Posts: 1,510 Original Poster	Originally posted by creampuff Could be a light leak from that extension tube or some form of internal reflection. Don't think it's an extension tube leak. I made sure everything was tight. Internal reflection may make more sense. It's almost like the camera is shining a light down the middle. Does it use some sort of light to confirm the focus? Not sure how that works, but being as the bright spot is right in the middle, makes me wonder if it's something to do with that or not.

05-03-2010, 05:06 AM	#13
distudio Veteran Member Join Date: Jul 2007 Location: Sydney Photos: Albums Posts: 450	Originally posted by eccs19 I thought about light entering the viewfinder, and covered that up, but that didn't make a difference. I know it wasn't cause by the flash, as the last batch I tried, I didn't use the flash at all, just to make sure that wasn't causing the issue. The mirror totally obscures light entering through the finder when it's up and resting below the focus screen. And focus determination is all passive, cap the lens and the spot will go away ;-)

05-03-2010, 09:33 AM	#14
JeffJS Inactive Account Join Date: Aug 2008 Location: Michigan, USA Photos: Gallery \| Albums Posts: 7,484	Originally posted by distudio The mirror totally obscures light entering through the finder when it's up and resting below the focus screen. Then why does Pentax tell us to cover the viewfinder for long exposures?

05-03-2010, 10:06 AM	#15
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,886	Originally posted by Wheatfield Most likely, that is a reflection off the sensor to the rear lens element and then back to the sensor as image forming light. If this is the case, the cure, such as there is one, is to use a less bright background for your macro shots. Originally posted by Just1MoreDave I agree with this explanation. I see this when I try to turn the FA 35/2 into a DA 35/2.8 by using a 25mm extension tube. It doesn't show in the viewfinder at all. I tried a lot of shading and hood techniques without affecting the problem. Originally posted by distudio I concur with this explanation too, when you're shooting macro there is a lot of light which doesn't hit the sensor due to the large mag factor, this can get reflected off the wall of the mirror box and of the surfaces of the lens and sensor. I'll add my 2 cent's worth, and agree with you three. I have an old Rikenon 135 F2.8 screw mount that has the same issue. It is the only lens I have that exhibits it out of 30 lenses in total.