UV or Not UV

[boojum]

OK, I am not quite as bright as the average bear. But I thought that a good UV filter would be "clear" imparting nothing to the captured image. However I was poking about in the fog today on the Washington side of the Columbia and took a shot that looked kind of bluish when compared to what my naked eye saw. So I took off the UV filter (B&W) and re-shot the simple scene and it was the proper grey that I saw, again with my naked eye. Is this normal? UV first, followed by not UV. Do you see it?


Leica M9, Canon 50mm LTM f/1.4, f/1.4, 1/1000, ISO 160

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Leica M9, Canon 50mm LTM f/1.4, f/1.4, 1/750, ISO 160

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[Retro-Grouch]

Actually, it looks like a slight difference in exposure. Was the camera on "auto", or are the exposures the same? Seems odd that the shot without the filter looks more bluish to you. A UV filter would have a very slightly warming effect, normally. You might try shooting an 18% gray card with and without the filter, with exposure set manually and the same for each exposure.
UV filters are not clear; they are meant to eliminate UV light, which can register as an excessive bluish cast with film (and, I assume, digital). There are clear filters meant solely for protection, often marked "NC" for example. I don't know how common they are now in the digital era, since I'm a filmosaurus.

 

[boojum]

Actually, it looks like a slight difference in exposure. Was the camera on "auto", or are the exposures the same? Seems odd that the shot without the filter looks more bluish to you. A UV filter would have a very slightly warming effect, normally. You might try shooting an 18% gray card with and without the filter, with exposure set manually and the same for each exposure.
UV filters are not clear; they are meant to eliminate UV light, which can register as an excessive bluish cast with film (and, I assume, digital). There are clear filters meant solely for protection, often marked "NC" for example. I don't know how common they are now in the digital era, since I'm a filmosaurus.

Yes, it was on "Auto." I am sorry that I was not clearer, it is the UV that seemed bluer to me which is why I took a second shot without filter. The exposure difference I am ascribing to the increased darkness of the trees and land by there being more of it there in the captured image. I should try it again committing one of the two major "Leica Sins", a tripod. The other sin is, of course, a flash. LOL Maybe I'll try both sins. ;o) I'll be lucky to get off with Purgatory.

 

[Rob-F]

It is puzzling that the shot with UV filter should look bluer. All UV filters are not identical, but none of them should be adding blue. The result ought to be either neutral (as you were expecting), or slightly warmer. And yet you got cooler, not warmer. What did you have white balance set to?

 

[boojum]

It is puzzling that the shot with UV filter should look bluer. All UV filters are not identical, but none of them should be adding blue. The result ought to be either neutral (as you were expecting), or slightly warmer. And yet you got cooler, not warmer. What did you have white balance set to?

Yes. I am surprised also. The white balance is Auto. I will go out again with a dreaded tripod and see what happens. I can use a white balance card to get a reading just to be safe and scientific. I just went back and reviewed the images and sequentially in order taken the blue one precedes the less blue one. The blue one is the one which got my notice and caused me to try the next image without the UV filter. And B&W is a good house to my understanding so I am confused. Maybe I will try a different lens, the CV 40mm /f.1.2 Asph would be good. Andthe same lens as the test above, the Canon 50mm LTM f/1.4

 

[former member]

No Leica sin using a Tripod. Anyone that tells you this is more into Fashion than Photography. Tell them that.

The exposure is different- the shot with the UV filter is at 1/1000th, without the filter is 1/750th. The under-exposed image will show more Blue, as it is dominant. Repeat the experiment on a Tripod and set the exposure manually.

Also: Not all UV filters are equal. Nikon made the L37 and L39, the latter being more aggressive. 3700Ansgtom and 3900Ansgtrom respectively.

The M9 CCD is very sensitive in the UV region, a UV filter makes a difference, Lenses that show Purple Fringing on the M9- use a UV filter to cut down. I used to think this was IR contamination, did a quick test- was UV.

 

[james.liam]

Breakthrough Photography, Heliopan SH-PMC and Leica appear to be the clearest. I've seen some light transmission graphs and B+W tends to impair transmission a tad more than the others.

 

[Retro-Grouch]

If you do a more tests, just make sure that all variables other than filter/no filter are identical. Shooting under natural light outdoors can throw in undesired variables; I've seen the color temperature of outdoor light change from one frame to another in much less than a minute. Your eye adjusts to the change, so it's invisible to you, but the film or sensor sees it.
And make sure no one sees you put the Leica on a tripod. Someone might notify LPS (Leica Protective Services); they will come and take you away, and your Leica will be sent to a good home.

 

[boojum]

If you do a more tests, just make sure that all variables other than filter/no filter are identical. Shooting under natural light outdoors can throw in undesired variables; I've seen the color temperature of outdoor light change from one frame to another in much less than a minute. Your eye adjusts to the change, so it's invisible to you, but the film or sensor sees it.
And make sure no one sees you put the Leica on a tripod. Someone might notify LPS (Leica Protective Services); they will come and take you away, and your Leica will be sent to a good home.

God forbid a tripod, and eternal Hell and damnation for a flash attachment! LOL I enjoy the "Leica Culture Dance" as it is as silly as the thread dancers in Lilliput. That said, I enjoy how the M9 handles bad weather. The A7M III kind of cleans it up a bit but the M9 puts an honest photo out. That said, here is the latest UV, Not UV test. AWB was set to "Daylight" and both photos were with the Canon 50mm LTM f/1.4, f/5.6, 1/1000, ISO 160. As those wiser than me have suggested a static indoor pair of photos I'll do that. And I expect a damned Nobel Prize for all this serious work! Get your votes in now. ;o)

UV

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Not UV

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Yes, I will do another set with a tripod and a 5600K LED flood light. And no one better rat me out about the tripod. I have a bunch of dolls I can stick pins in, so you are warned. ;o)

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