Blue spots

KlaasK

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Just before a short vacation to Italy, I upgraded my canon 350D to a 60D, but decided to keep using my old Tamron lens 18/200 mm for now. I did buy a 50 mm f1.8 with the camera. Most pictures were made with the Tamron. I used the 50 mm lens (plus UV filter!) a few times at low light conditions, without flash. Almost all these pictures (and only those taken with this lens!) had some light blue spots. I have no idea where they come from. They are not always on the exact same spot. Could something be wrong with the lens. Who can explain me what is causing these spots?









Klaas
 
Some optical aberrations can be the result of the filters attached to the lens rather than the lens itself. Did you take any with the 50mm without UV filter on?
 
The spots are lens flare, caused by a bright light source either within or just outside the picture. Flare is a result of light reflecting back and forth from the various lens surfaces, as well as the filter surfaces.

This will be most visible in these sort of low-light shots, as the main subject is relatively dim compared with the bright lights.
Solutions:
  • remove the UV filter
  • use a lens hood - this won't help if the light source is within the frame, but for bright lights outside the shot, a lens hood will help.
Also, the problem may be worse at wider apertures, as typically used in low-light conditions.

Anyway, this effect is normal, and does not mean there is anything wrong with the lens (but to repeat, using a filter on the lens will probably make matters worse).

edit : I just looked again at the photos, and this is almost certainly caused by the filter. Note that the spots exactly match the real lights in the picture, but rotated by 180 degrees. That's typical of the effect of a filter under these conditions.

Regards,
Peter
 
Draw a line from each blue spot through the image center to a point equidistant from the center. You will find the source of the blue spot: a bright spot of light. In fact drawing a line backwards from some bright sources of light can show blue spots you may have missed. This indicates internal reflection in the lens, or from an UV filter (most likely), or from the sensor surface itself. A good practice is to remove all filters when shooting directly into bright light sources such as you have here.









--
Severinson

 
I was gonna do what you did, but you get there first. Good job!

To the OP: Remove the UV filter. Put the UV filter in a drawer at home. Never take the UV filter out of the drawer. Put on a lens hood. Never take the hood off.

--
Charlie Davis
Nikon 5700, Sony R1, Nikon D50, Nikon D300
HomePage: http://www.1derful.info
"He had a photographic memory which was never developed."
 
Charlie is mostly right. I'd say to put the filter in the trash so you are less likely to use it again.

I think this is the third time in the past few days we've had filters degrading an image. Yet, there will still be people who swear they've never heard of it, that filters just don't degrade enough to be able to detect, they say.

--
Cheers, Craig

Equipment in Plan via Profile
 
Charlie is mostly right. I'd say to put the filter in the trash so you are less likely to use it again.
Or after he convinces himself that we are right, he can rummage through that drawer and reclaim the UV filter and sell it on eBay for $1 then invest that...soon he will be able to buy a good , $100 UV filter, which he can carry around in his camera bag, looking for some venue that really needs a "protective" filter...something like blowing sand or salt water or glowing metal flying off welding or grinding operations. Of course, when he understands that those venues are likely to ruin his $100 UV filter, he will either put it back in the drawer or throw it away. :-)
I think this is the third time in the past few days we've had filters degrading an image. Yet, there will still be people who swear they've never heard of it, that filters just don't degrade enough to be able to detect, they say.
There are all manner of people. Some can't see. Others can't think. Most not write a propers entence...and the wrest can't spel! ;-)

--
Charlie Davis
Nikon 5700, Sony R1, Nikon D50, Nikon D300
HomePage: http://www.1derful.info
"He had a photographic memory which was never developed."
 
There are all manner of people. Some can't see. Others can't think. Most not write a propers entence...and the wrest can't spel! ;-)
I was huked on fonix a long time ago. ;)

--
Cheers, Craig

Equipment in Plan via Profile
 
Draw a line from each blue spot through the image center to a point equidistant from the center. You will find the source of the blue spot: a bright spot of light. In fact drawing a line backwards from some bright sources of light can show blue spots you may have missed. This indicates internal reflection in the lens, or from an UV filter (most likely), or from the sensor surface itself. A good practice is to remove all filters when shooting directly into bright light sources such as you have here.







Bookmarked this thread so that the excellent diagrams of Severinson can be referred to, next time it comes up. Thanks to Severinson.

Thanks also to original poster, Klaask, for providing such excellent examples to Severinson.
--
Regards,
Baz

"Ahh... But the thing is, they were not just ORDINARY time travellers!"
 
Thank you for being brave enough to say it on a public forum. :D

--
Rob.

Free advice, freely given. If you don't like it, I'll refund you twice the amount you paid.
 
I think this is the third time in the past few days we've had filters degrading an image.
degrading? I think in this case the blue spots are about the only thing that makes these pictures look interesting, so I´d say they are upgrading! ;-)
Yet, there will still be people who swear they've never heard of it, that filters just don't degrade enough to be able to detect, they say.
That´s just half the truth. They will say "they don´t degrade enough to be able to detect if used in an appropriate suitable lighting situation. "

And this low light scence we see here with some small strong light sources is everything else but an appropriate lighting situation for the use of a UV filter! So this is absolutely not a kind of proof that all UVs are an idea born in the empire of evil and will always degrade an image, but that there are situations when their use is not appropriate. That´s the conclusion you can draw from these shots.

A second conclusion could be that this must have been a rather lousy and cheap low-quality UV filter! Can´t imagine a B+W MRC would have shown the same results!

René
 
I think this is the third time in the past few days we've had filters degrading an image.
degrading? I think in this case the blue spots are about the only thing that makes these pictures look interesting, so I´d say they are upgrading! ;-)
@#$%! We were avoiding that comment. I'm sure Klaas is pleased to find out his picture is worthless, had he not put that cheap UV filter on the lens.
Yet, there will still be people who swear they've never heard of it, that filters just don't degrade enough to be able to detect, they say.
That´s just half the truth. They will say "they don´t degrade enough to be able to detect if used in an appropriate suitable lighting situation. "

And this low light scence we see here with some small strong light sources is everything else but an appropriate lighting situation for the use of a UV filter! So this is absolutely not a kind of proof that all UVs are an idea born in the empire of evil and will always degrade an image, but that there are situations when their use is not appropriate. That´s the conclusion you can draw from these shots.
Let me guess: You like using UV filters?
A second conclusion could be that this must have been a rather lousy and cheap low-quality UV filter! Can´t imagine a B+W MRC would have shown the same results!
Let me guess: You have a B+W MRC UV filter?

;-)
--
Charlie Davis
Nikon 5700, Sony R1, Nikon D50, Nikon D300
HomePage: http://www.1derful.info
"He had a photographic memory which was never developed."
 
@#$%! We were avoiding that comment. I'm sure Klaas is pleased to find out his picture is worthless, had he not put that cheap UV filter on the lens.
well, let me say here it was never my intention to hurt Klaas´ feelings! I just followed the old rule "Say what you think (and do what you say)", lol! Really wouldn´t call it worthless, but I still must say I would have preferred to see that street café shot taken a little earlier when there were still some people sitting outside as most of the nice atmosphere is gone once the people are gone; then these cafés always look a little sad.
Let me guess: You like using UV filters?
Correct, Charlie! :-) Mainly because I always prefer cleaning a (relatively) inexpensive filter and not the front element of a lens. And (this is for Monsieur Guidenet now), I use them most the time in combination with a sun hood! ;-)

And I do not expect these "paper-thin" filters (or how does he always say?) to give much protecion against mechanical impact! (G. always tries to make filter users look silly by saying they expect mechanical protection against impact from a filter!)

But what my filters do is protect the front element of my lenses from scratches or cleaning marks when cleaning them with my shirt, lol, happens about once a week when I´m on a walk and have forgotten once more to bring my micro-fibre cloth (or when I find it in my pocket after a week and it´s actually dirtier than my shirt, lol). Rural area here, everything is blooming at the moment, so ten minutes outside is enough to see some fine yellow dust on your lens and everything. And just trying to blow it off doesn´t really work.
Let me guess: You have a B+W MRC UV filter?
Good guess, Charlie, correct, once more! ;-) Actually it´s several of them. I really like their build quality, the brass rings, the good optical properties and the easy cleaning of B+W´s MRC coatings. But I would not use something B+W without these MRC coatings!

Two of my old AIS Nikkors came with Nikon filters, I think they are o.k., too. Still have to find out about the quality (or not) of a 72mm Soligor DHG UV filter, that I found relatively inexpensive (compared to B+W) some weeks ago.

René
 
@#$%! We were avoiding that comment. I'm sure Klaas is pleased to find out his picture is worthless, had he not put that cheap UV filter on the lens.
well, let me say here it was never my intention to hurt Klaas´ feelings! I just followed the old rule "Say what you think (and do what you say)", lol!
I should have put a winkie at the end...I was attempting some humor.
Really wouldn´t call it worthless, but I still must say I would have preferred to see that street café shot taken a little earlier when there were still some people sitting outside as most of the nice atmosphere is gone once the people are gone; then these cafés always look a little sad.
I didn't really care...for all we know, Klaas knew it wasn't very good...he just posted it to show the flare.
Let me guess: You like using UV filters?
Correct, Charlie! :-) Mainly because I always prefer cleaning a (relatively) inexpensive filter and not the front element of a lens. And (this is for Monsieur Guidenet now), I use them most the time in combination with a sun hood! ;-)
Good for you. A hood should be on a lens 24/7.
And I do not expect these "paper-thin" filters (or how does he always say?) to give much protecion against mechanical impact!
Good again. They are almost worthless as physical protection..."almost" because they work with small missiles, like sand.
(G. always tries to make filter users look silly by saying they expect mechanical protection against impact from a filter!)
Unfortunately, Craig and I are 100% in agreement...you UV filter users are silly. Sorry. ;-)
But what my filters do is protect the front element of my lenses from scratches or cleaning marks when cleaning them with my shirt, lol, happens about once a week when I´m on a walk and have forgotten once more to bring my micro-fibre cloth (or when I find it in my pocket after a week and it´s actually dirtier than my shirt, lol). Rural area here, everything is blooming at the moment, so ten minutes outside is enough to see some fine yellow dust on your lens and everything. And just trying to blow it off doesn´t really work.
Let me offer a different paradigm...

I don't need a filter to protect the front element of the lens from cleaning abuse, because I rarely clean it! Like perhaps once a year? Your obsession with cleaning is problem that should be addressed with a psychiatrist. Did you know that dust on a lens doesn't cause any observable IQ loss? There is a well known series of pictures of a lens that is seriously cracked due to an impact...pieces of glass are missing! Yet the images produced by that badly damaged lens look OK...if you didn't know before hand what the lens looked like, you would have never guessed it was seriously damaged.

My advice is to stop cleaning so much. If you occasionally blow off the front of the lens, the few dust particles that remain should be left alone. And cleaning a good filter every week will ruin it! Just stop it!
Let me guess: You have a B+W MRC UV filter?
Good guess, Charlie, correct, once more! ;-) Actually it´s several of them. I really like their build quality, the brass rings, the good optical properties and the easy cleaning of B+W´s MRC coatings. But I would not use something B+W without these MRC coatings!
Again, you have chosen wisely. BTW, Craig is a B+W fan.
Two of my old AIS Nikkors came with Nikon filters, I think they are o.k., too. Still have to find out about the quality (or not) of a 72mm Soligor DHG UV filter, that I found relatively inexpensive (compared to B+W) some weeks ago.
Perhaps you should start collecting UV filters? I would be glad to send you some that I have in a drawer somewhere. As you reach retirement age, you could put them in a Museum of Worthless Things. Give me some time and I'll make you a list of other "Worthless Things"...

--
Charlie Davis
Nikon 5700, Sony R1, Nikon D50, Nikon D300
HomePage: http://www.1derful.info
"He had a photographic memory which was never developed."
 
Perhaps you should start collecting UV filters? I would be glad to send you some that I have in a drawer somewhere. As you reach retirement age, you could put them in a Museum of Worthless Things. Give me some time and I'll make you a list of other "Worthless Things"...
As we reach retirement age, we go into the museum of worthless things. I don't want no filters cluttering up the place when I get there.

--
Leonard Migliore
 
Good for you. A hood should be on a lens 24/7.
Would it be o.k. with you when I put the lens back in its case to take the hood off and mount it reverse, lens cap still on? LOL
(G. always tries to make filter users look silly by saying they expect mechanical protection against impact from a filter!)
Unfortunately, Craig and I are 100% in agreement...you UV filter users are silly. Sorry. ;-)
Tiny correction : ...WOULD be silly (if we expected significant protection against mechanical impact)! And tolerance is not really your thing, right?
I don't need a filter to protect the front element of the lens from cleaning abuse, because I rarely clean it! Like perhaps once a year? Your obsession with cleaning is problem that should be addressed with a psychiatrist.
Good for you if there is no need to clean it more often!

Do you know how often I clean which lens or filter? Do you know what would be called normal/necessary and where obsession begins without knowing anything about the environmental conditions? I doubt it!
Did you know that dust on a lens doesn't cause any observable IQ loss?
Did you know that a very good filter on a lens doesn´t cause any observable IQ loss? Unless when used in a not so appropriate lighting sitution?
My advice is to stop cleaning so much.
Again, you don´t know how often I clean which lens/filter, so you can´t say it´s too much.
If you occasionally blow off the front of the lens, the few dust particles that remain should be left alone.
Really would like to see you blow off the pollen of certain plants that are blooming here right now! If it was just about a few dust particles, I really wouldn´t care! It always depends on where you live, rural area, forest, city, near the sea, etc. and it also depends on the time of year.
And cleaning a good filter every week will ruin it! Just stop it!
I still have to ruin my first B+W MRC by cleaning, no idea how to do this!
Again, you have chosen wisely. BTW, Craig is a B+W fan.
Good for him, so not all hope is lost, lol! Schneider at Bad Kreuznach is about an hour from where I live, would be stupid for me to use anything else!
Perhaps you should start collecting UV filters? I would be glad to send you some that I have in a drawer somewhere.
In your case I assume they were never used, never cleaned, so if they are B+W MRC just go ahead! Just make sure they will fit on my lenses, could send you a list of diameters!
;-)

René
 
Good for you. A hood should be on a lens 24/7.
Would it be o.k. with you when I put the lens back in its case to take the hood off and mount it reverse, lens cap still on? LOL
Your laughter is that old paradigm fighting for survival! It's faster to just leave the hood facing out . You can store those lens caps in the same drawer where your UV filters hide.
(G. always tries to make filter users look silly by saying they expect mechanical protection against impact from a filter!)
Unfortunately, Craig and I are 100% in agreement...you UV filter users are silly. Sorry. ;-)
Tiny correction : ...WOULD be silly (if we expected significant protection against mechanical impact)! And tolerance is not really your thing, right?
Yes, that improves things...
BTW, my tolerances are tight...well within spec. ;-)
I don't need a filter to protect the front element of the lens from cleaning abuse, because I rarely clean it! Like perhaps once a year? Your obsession with cleaning is problem that should be addressed with a psychiatrist.
Good for you if there is no need to clean it more often!
Do you know how often I clean which lens or filter?
Yes...at least if you can be believed. You wrote that you cleaned them each week!

" But what my filters do is protect the front element of my lenses from scratches or cleaning marks when cleaning them with my shirt, lol, happens about once a week when I´m on a walk and have forgotten once more to bring my micro-fibre cloth... "

I underlined the cleaning interval, to help you find it... ;-)

On the subject of cleaning lenses, I'm not a fan of "microfiber cloths"...I use cleaning paper and a drop of proper cleaning fluid on the paper.
Do you know what would be called normal/necessary and where obsession begins without knowing anything about the environmental conditions? I doubt it!
I live on the edge of W. Texas. We have lots of blowing dust and lots of pollen, too. Is your environment any more hostile?
Did you know that dust on a lens doesn't cause any observable IQ loss?
Did you know that a very good filter on a lens doesn´t cause any observable IQ loss? Unless when used in a not so appropriate lighting sitution?
Yes and yes.
My advice is to stop cleaning so much.
Again, you don´t know how often I clean which lens/filter, so you can´t say it´s too much.
Again, you said " once a week " and that's too often.
If you occasionally blow off the front of the lens, the few dust particles that remain should be left alone.
Really would like to see you blow off the pollen of certain plants that are blooming here right now! If it was just about a few dust particles, I really wouldn´t care! It always depends on where you live, rural area, forest, city, near the sea, etc. and it also depends on the time of year.
I agree...but leave the pollen on the lens...never try to remove pollen with a dry cloth! A few pollen grains don't affect the pix any more than a good UV filter does.
And cleaning a good filter every week will ruin it! Just stop it!
I still have to ruin my first B+W MRC by cleaning, no idea how to do this!
It's probably "toast" already. Have you tested the AR coatings to see if they are intact and functioning?
Again, you have chosen wisely. BTW, Craig is a B+W fan.
Good for him, so not all hope is lost, lol! Schneider at Bad Kreuznach is about an hour from where I live, would be stupid for me to use anything else!
Agreed.
Perhaps you should start collecting UV filters? I would be glad to send you some that I have in a drawer somewhere.
In your case I assume they were never used, never cleaned, so if they are B+W MRC just go ahead! Just make sure they will fit on my lenses, could send you a list of diameters!
My old filters are for your museum...I don't intend you to actually use them. Most are 52mm, since every Nikkor lens I had used that size. Sorry...

You assume incorrectly. In my early years, I was like you...I bought expensive UV filters for all my lenses...I cleaned them excessively...I was paranoid about "dirt". We didn't have good AR coatings back then, so they occasionally caused issues, but we didn't know better and, besides, "everybody did it"...

Then I had an epiphany: UV filters are a silly idea!

I'm on a mission...

--
Charlie Davis
Nikon 5700, Sony R1, Nikon D50, Nikon D300
HomePage: http://www.1derful.info
"He had a photographic memory which was never developed."
 
chuxter wrote:
.
Do you know how often I clean which lens or filter?
Yes...at least if you can be believed. You wrote that you cleaned them each week!

" But what my filters do is protect the front element of my lenses from scratches or cleaning marks when cleaning them with my shirt, lol, happens about once a week when I´m on a walk and have forgotten once more to bring my micro-fibre cloth... "
I underlined the cleaning interval, to help you find it... ;-)
I know where and when I wrote what, lol! I just "kept a little door open" for you to come back to this thread. ;-) Knew you would.

I think you will agree that "once a week" actually doesn´t say anything, unless you also know about how many lenses we´re talking here! If it was about the same lens all the time, yes, once a week would be quite a bit too much! But - I´m more than "knee deep" into old manual lenses, lol, (maybe I should block ebay from my computer!), means I could shoot a different lens each week from January at least until early fall, lol! So for some lenses it would be more correct to say "once a year" and not "once a week". And from late fall until spring there is usually not much reason at all for me to clean any lens or filter.
I agree...but leave the pollen on the lens...never try to remove pollen with a dry cloth! A few pollen grains don't affect the pix any more than a good UV filter does.
It´s what I usually do. it´s just that there are some that can´t be blown off as they are almost sticky, but don´t ask me now what tree/plant they come from, no idea.
And cleaning a good filter every week will ruin it! Just stop it!
I still have to ruin my first B+W MRC by cleaning, no idea how to do this!
It's probably "toast" already. Have you tested the AR coatings to see if they are intact and functioning?
I "use" filters on some of my lenses, Chuxter, but that doesn´t mean I´m on some kind of "filter mission" and even test them, lol! If I would visually detect scratches or other cleaning marks they would go; but so far I haven´t seen a need to do so.
Most are 52mm, since every Nikkor lens I had used that size. Sorry...
Would fit (among on some others) on my two 105/2.5 AIS, lol! Lovely lens, btw; on the 520 they´re stabilized 210/2.5! (But both came with filters, not B+W, but Nikon).

Talking about Nikon filters, maybe we could forget about our little "verbal ping-pong game" now and put it to sleep, ;-) here´s a serious question to you:

Different to other brand lenses I see it very often on ebay, that Nikkors come with a skylight L1Bc and not the usual UV L37c. Now when I leave this skylight on the lens, the results on my Oly always look a little wrong, thinking of color here. Just what I would expect from a skylight filter, a little less blue, changing everything a bit towards warm, away from what I´ve actually seen when taking the shot.

My question now: Is this any different when used on a Nikon body? Do Nikon images look closer to reality if a bit of blue is filtered out? Do Nikon OOC images tend a bit towards blue so this skylight filter makes sense here? Would be nice to hear your opinion on this!
I'm on a mission...
Thou shalt never try to stop a missionary if he´s on a mission, just wish him good luck! (when cleaning front elements, lol!) ;-)

René
 
Do you know how often I clean which lens or filter?
Yes...at least if you can be believed. You wrote that you cleaned them each week!

" But what my filters do is protect the front element of my lenses from scratches or cleaning marks when cleaning them with my shirt, lol, happens about once a week when I´m on a walk and have forgotten once more to bring my micro-fibre cloth... "
I underlined the cleaning interval, to help you find it... ;-)
I know where and when I wrote what, lol! I just "kept a little door open" for you to come back to this thread. ;-) Knew you would.
Far be it for me to walk away from a lively discussion...
I think you will agree that "once a week" actually doesn´t say anything, unless you also know about how many lenses we´re talking here! If it was about the same lens all the time, yes, once a week would be quite a bit too much! But - I´m more than "knee deep" into old manual lenses, lol, (maybe I should block ebay from my computer!), means I could shoot a different lens each week from January at least until early fall, lol! So for some lenses it would be more correct to say "once a year" and not "once a week". And from late fall until spring there is usually not much reason at all for me to clean any lens or filter.
This is working out even better than I thought. In addition to your museum collection of "useless" filters, you can have a collection of useless lenses! ;-)
I agree...but leave the pollen on the lens...never try to remove pollen with a dry cloth! A few pollen grains don't affect the pix any more than a good UV filter does.
It´s what I usually do. it´s just that there are some that can´t be blown off as they are almost sticky, but don´t ask me now what tree/plant they come from, no idea.
Me either...but what ever it is, it's everywhere... :-(
I "use" filters on some of my lenses, Chuxter, but that doesn´t mean I´m on some kind of "filter mission" and even test them, lol! If I would visually detect scratches or other cleaning marks they would go; but so far I haven´t seen a need to do so.
My point was that I don't believe that it's possible to detect damage to AR coatings w/o some instrumentation. Just because it looks good, doesn't mean it still functioning properly. Also, there are many different types of AR coatings...they have different characteristics... :-0
Most are 52mm, since every Nikkor lens I had used that size. Sorry...
Would fit (among on some others) on my two 105/2.5 AIS, lol! Lovely lens, btw; on the 520 they´re stabilized 210/2.5! (But both came with filters, not B+W, but Nikon).
Then my stack of filters could go into that museum...
Talking about Nikon filters, maybe we could forget about our little "verbal ping-pong game" now and put it to sleep, ;-)
Aw, shucks...I was having so much fun.
here´s a serious question to you:

Different to other brand lenses I see it very often on ebay, that Nikkors come with a skylight L1Bc and not the usual UV L37c. Now when I leave this skylight on the lens, the results on my Oly always look a little wrong, thinking of color here. Just what I would expect from a skylight filter, a little less blue, changing everything a bit towards warm, away from what I´ve actually seen when taking the shot.

My question now: Is this any different when used on a Nikon body? Do Nikon images look closer to reality if a bit of blue is filtered out? Do Nikon OOC images tend a bit towards blue so this skylight filter makes sense here? Would be nice to hear your opinion on this!
My opinion is that any color correcting filter is useless on a digital camera. Just do a custom WB or adjust it in PP. You can make it look any way you like.
I'm on a mission...
Thou shalt never try to stop a missionary if he´s on a mission, just wish him good luck! (when cleaning front elements, lol!) ;-)
Thanks.

--
Charlie Davis
Nikon 5700, Sony R1, Nikon D50, Nikon D300
HomePage: http://www.1derful.info
"He had a photographic memory which was never developed."
 

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