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10-24-2014, 09:54 AM   #16
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QuoteOriginally posted by bm75 Quote
Hi all.
I've already brought a M 20mm f/4 in perfect conditions. I've taken some photos during a mountan trip with my k-5 and results were strange.. .There's a light blue dominance in the pictures. I tought it could be really high UV radiation in mountain (altitude not higher than 1950mt) or WB ( I controlled it: was ok on auto and "natural"
no custom settings, no digital filters) and I had to shoot compensating -0,3 -0,5 ev .The same pictures taken with DA 17-70 are much better , but settings are the same.
Had anyone noticed the same behaviour of the lens? I'll be grateful for any suggestion.
Best Regards.
Matteo
Having to adjust towards underexposure is normal, because since the lens IS NOT an "A" lens, the camera is switching to centerweighted metering instead of matrix. Due to high altitude and wide angle of coverage, it is normal to get a lot of light in frame that can throw the meter towards overexposure.

About the blue tinting.. hmmm that is strange. Of course, high altitudes and clean skies are two strong reasons for excess UV radiation, but that should not affect nor shift the color balance on digital. It was normal on film. That is why "Skylight" filters were slightly pink.

Before doing any changes in camera or chasing the "blue ghosts" around lens and camera, I suggest checking first the color balancing of your computer monitor. Maybe photos are fine but your monitor is overadjusted to to high color temp.

Let us know your findings.

---------- Post added 10-24-2014 at 11:06 AM ----------

QuoteOriginally posted by wtlwdwgn Quote
Although filters are not supposed to have an effect on digital sensors, I use Skylight filters which were designed to control the Kodachrome blue skies which were unnaturally dark blue. Worth a try.
Right, filters are not supposed to do any effect on digital sensors, except polarizers of course. Any color shifting that is needed can be done by white balance adjustment or digital custom filtering... but (big BUT HERE):

Filters DO have an effect on digital cameras. Not by shifting color. Instead, they create lots of ghosting and double images, especially at night when you have bright lights in frame. This is more noticeable with medium to long telephoto lenses. On wide angles, filters do produce a loss of contrast and lots of glaring inside lens. Low cost filters like old Tiffen, Hoya or such are very prone to this ghosting and flaring. The worst I've seen are Cokin's Optilights (plastic) and Kenkos. Even old B&W filters have this flaw. Just newer super multi coated (both faces) filters can reduce this ghosting and flaring a little better.

Check this examples of ghosting:


10-24-2014, 10:20 AM   #17
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I noticed the blue dominant on camera screen, and that was confirmed viewing pictures at home with two different monitors. I noticed the difference towards same pictures taken with Da17-70 that didn't performed the same way the M 20 did (much better). I look the histograms and blue curve was at the right Side of the graph , much more than green and red . There's no question it could be fixed in PP, but if I can avoid it while shooting, this will be my first choice, just not to loose colour detail . I Will try different color temperature on camera WB or a stronger filter. Best regards. Matteo
10-24-2014, 12:36 PM   #18
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QuoteOriginally posted by bm75 Quote
I noticed the blue dominant on camera screen, and that was confirmed viewing pictures at home with two different monitors. I noticed the difference towards same pictures taken with Da17-70 that didn't performed the same way the M 20 did (much better). I look the histograms and blue curve was at the right Side of the graph , much more than green and red . There's no question it could be fixed in PP, but if I can avoid it while shooting, this will be my first choice, just not to loose colour detail . I Will try different color temperature on camera WB or a stronger filter. Best regards. Matteo
Then, it is confirmed: color shift is lens related. But unless you can clearly see a bluish color cast through the lens, the camera's auto WB should take care of this.

I dunno, I'm taking a wild guess here, but I would check the preset and custom color balances (in camera) that are set in shooting parameters and filters (neutral, vivid, custom, etc.) when this specific lens is mounted and when the DA 17-70 is mounted. This is about the only reason to believe the camera is actually shifting to a different color balance in capture mode, when this lens (as any lens with no electronic communication with body, such as any original K or M lens.
10-24-2014, 12:46 PM   #19
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QuoteOriginally posted by bm75 Quote
Without UV filter the situation is really worse and pictures have a lack of contrast - they look "washed" and I have problems with metering ( I noticed a huge overexposure)
I think you may have a problem with your lens that is not design-related. A "washed" look may indicate internal contamination and/or separated element and/or internal hazing. Any of the above may also cause a color cast.


Steve

10-25-2014, 12:23 AM   #20
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Thanks all.
My intentions are: 1- make more pictures with M20 in different conditions with standard AWB; 2- using WB bracketing to see what changes ; 3 - understanding how to manage the blue dominant with correct custom WB setting (if needed); 4 - if anything of that doesn't work....take the lens to a laboratory for a better internal control. I'm not worried, the condition of the lens is really good with no signs of damage, so perhaps I only need to know how to menage the lens behaviour. I have huge respect towards those "old" lenses and I wish I can use them for a long time more.
I'll post an exemple of what I'm talking about (the bluish tint in the pictures).
Best regards.
Matteo
11-02-2014, 08:59 AM   #21
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QuoteOriginally posted by bm75 Quote
Hi all.
I've already brought a M 20mm f/4 in perfect conditions. I've taken some photos during a mountan trip with my k-5 and results were strange.. .There's a light blue dominance in the pictures. I tought it could be really high UV radiation in mountain (altitude not higher than 1950mt) or WB ( I controlled it: was ok on auto and "natural"
no custom settings, no digital filters) and I had to shoot compensating -0,3 -0,5 ev .The same pictures taken with DA 17-70 are much better , but settings are the same.
Had anyone noticed the same behaviour of the lens? I'll be grateful for any suggestion.
Best Regards.
Matteo
A caveat with "auto" WB: it's not based on a fixed value, the camera will analyze the scene and try to find the optimal WB (which thus varies), but it can (and will) be fooled...
I was shooting the temple of the 5000 gates in Kyoto and had all this orange wooden gates that threw my WB off kilter and all pics came out very washed out, with bluish shades and desaturated oranges.
Best thing in those circumstances is to set WB for daylight (5500K) or shade, this way you ensure consistency.
That's of special importance if you're performing a test.
11-02-2014, 01:25 PM   #22
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Hi. This is what I'm talking of (look at the second pic: the first is there just for a comparison in "normal" conditions, same clear blue sky). No PP just saving as resized ( shoot the original jpeg in ****, here it is 1200*700 just * ). Square - non original - lens hood on , Uv filter on. Sun about 45-60 on the right. Ok, I know...not the best composition here!!! but just to show the problem. As you will see also geens are really "washed" . FFor the first pic: it seems quite "soft" but I assure it isn't, if viewed in its original filesize.
In PP using PDCU 4 I've seen using 5560 K as custom color temperature helps fixing "blue haze" in most of the pictures (NOT THIS!!), as You said. I'm thinking this would be my standard WB with this lens in same conditions.
Many thanks for suggestions. Best regards.
Matteo

Last edited by bm75; 12-24-2016 at 06:32 PM.
11-02-2014, 03:35 PM   #23
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QuoteOriginally posted by bm75 Quote
Hi. This is what I'm talking of (look at the second pic: the first is there just for a comparison in "normal" conditions, same clear blue sky). No PP just saving as resized ( shoot the original jpeg in ****, here it is 1200*700 just * ). Square - non original - lens hood on , Uv filter on. Sun about 45-60 on the right. Ok, I know...not the best composition here!!! but just to show the problem. As you will see also geens are really "washed" . FFor the first pic: it seems quite "soft" but I assure it isn't, if viewed in its original filesize.
In PP using PDCU 4 I've seen using 5560 K as custom color temperature helps fixing "blue haze" in most of the pictures (NOT THIS!!), as You said. I'm thinking this would be my standard WB with this lens in same conditions.
Many thanks for suggestions. Best regards.
Matteo
Well, pictures look very different... was the angle of the sun exactly the same for both? I bet the altitude was higher for the second one, maybe the UV filter isn't doing much after all...
If you're comparing two different lenses I'd suggest you try to do the same shoot with both.

11-02-2014, 04:34 PM   #24
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What I notice is a bluish cast all over that indeed washes out greens or any "warm" color. I've seen such "wash outs" in optics with some fungi inside or wth very bad or uncoated UV filters.

Have you tried this type of photography with and without the UV filter? (same lens and shooting conditions) It wouldn't surprise me id it shows a big difference...
11-03-2014, 01:42 PM   #25
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Hi.images are shot with the same lens and Uv filter on (Hoya UV C).
In the washed image something went wrong....but I don't know what!! The bluish cast was visible in every image I shot that day in these conditions with that lens.
But in pictures taken the day after (the sanctuary, first image) the cast is quite invisible.
My first tought was the UV filter has some damage...It seems that You confirm my thinking. I have got some B+W UV filters(old from '98) but the smallest is 52mm sized (M 20 f/4 fits 49mm) so I used the Hoya branded. Honestly I don't know how better or worse or more effective UV filters could be depending on brand and construction ...I only know they're built to stop UV wave lenght radiation...any suggestion would be precious in this matter...I'm not a phisician. Perhaps a better filter would fix problems. By the way: the two pictures aren't taken in the same light conditions: sun was placed differently in the first picture,check the shadows; the place was different and altitude also. It wasn't the same day and hour.
Thank You all for your attention.
Best regards . Matteo
11-03-2014, 03:22 PM   #26
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QuoteOriginally posted by bm75 Quote
Hi.images are shot with the same lens and Uv filter on (Hoya UV C).
In the washed image something went wrong....but I don't know what!! The bluish cast was visible in every image I shot that day in these conditions with that lens.
But in pictures taken the day after (the sanctuary, first image) the cast is quite invisible.
My first tought was the UV filter has some damage...It seems that You confirm my thinking. I have got some B+W UV filters(old from '98) but the smallest is 52mm sized (M 20 f/4 fits 49mm) so I used the Hoya branded. Honestly I don't know how better or worse or more effective UV filters could be depending on brand and construction ...I only know they're built to stop UV wave lenght radiation...any suggestion would be precious in this matter...I'm not a phisician. Perhaps a better filter would fix problems. By the way: the two pictures aren't taken in the same light conditions: sun was placed differently in the first picture,check the shadows; the place was different and altitude also. It wasn't the same day and hour.
Thank You all for your attention.
Best regards . Matteo
That is exactly what I mean.

You need to take some pictures WITH and WITHOUT the filter (any filter) attached to lens. IMHO, the general bluish cast, most visible in the shadow areas of both pictures, IS NOT ultraviolet light. It seems more like a general inside glare from lens or filter.

Remember, old filters (pre-digital era) were uncoated (cheap ones), single coated and multicoated, BUT ONLY ON THE EXTERIOR SURFACE. Almost none were coated in the interior surface, which is the one producing all the ghosting, glares and contrast loss due to sensor reflection back through the lens. (check my examples of ghosting at the beggining of this thread).

This glares and loss of contrast is not visible through viewfinder, because at that moment, the shutter is closed and the mirror is down, so no light is being reflected back from the sensor through the lens- towards the back of the filter.

You can to this tests tomorrow. Wait untill sun is at highest point and shining through. You need big shaded areas to evaluate the bluish cast over this areas. Shoot some frames with filter, then remove filter and shoot a couple more. Compare. You should be able to see a big difference if the filter is the culprit here. Otherwise, it could be the lens itself, that due to its old age, maybe some elements lack coating on one side or both.

Let us know your results.
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