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Fact or fiction with Foveon Merrell sensors

Jim DE

New member
I read in one of the forums that the Foveon Merrell sensor responds favorably to using a UV filter and can actually reduce the random splotches some are seeing. Anyone here actually verify this statement?

I have not used a UV filter on a digital camera since my old AGFA 1280. Always thought it was unnecessary at the least and to the worse actually decreased IQ. Now, every digital up till now have been Bayer sensors so I am curious if that posters statement has any validity with the Merrell sensor. I am sure I have a 49mm UV filter somewhere I can use if this helps IQ with a Merrell sensor.
 

Kirk Candlish

New member
If you have the camera and the filter why not do some testing and see for yourself ?

Random splotches ? I've never seem them in anything I've shot with the DP2M, with or without a UV filter.
 

Hulyss Bowman

Active member
Would you please be more specific ?

Helped with what ? Reduced what ?
Slight attenuation of some green magenta splotches and reducing drastically the lens noise.

Well, no need to go technical endless thread. An UV filter cost nothing and the differences are subjective and up to the users. Some may see some may not so better time to try. Speaking will not help ;)
 

Jim DE

New member
Thanks Hulyss for the first hand feedback. Your images are exceptional and if you found a UV filter to be beneficial to your results I will surely try one as well. It was just a filter type I abandoned very soon after going digital.

Kirk, I like you have yet to see any of the negatives discussed on the net like splotches, banding, etc.... But then again I have only had my Merrell for a very short time. This site has a exceptional group of highly talented and knowledgable photographers. Many are far more deeply involved with the technical aspects of digital photography than I would ever hope to achieve at my age. I respect the conclusions that these people have found. Basically, for the past decade or more I never considered going back to a UV filter on a digital camera due to its negative characteristics when used on Bayer sensors. This foveon Merrell sensor is entirely new to me. If these site members who are far more technically involved with this system state a UV filter has its merits or if they state the effects are identical to those when used on a Bayer sensor then I am better off than blindly putting one on and snapping away with it when I have yet to even see the defects it may or may not correct. What's the saying " an ounce of prevention is worth a pound of cure?" Right at this time I would not know if it helps or hurts IQ by first hand testing because as I said I have not shot my Merrell enough to see these irregularities. I am sure Huylss has as have many others here so I value the lessons and suggestions they may offer. There will be time later to venture on a different path to try and improve my images from this tool and I then can offer my experiences for others to try but I like starting off benefiting as much as I can from the lessons others have learned who were on this path longer than I.
 
I wish I knew what causes the magenta/green splotches, Jim. I can't seem to duplicate the effect... but it happens at the strangest and most unpredictable times. The attached image is a good example... and it's not under exposed. No uv filter was used on this shot... so I don't know if a uv filter would have helped.

A recent thread on the dpreview forum claims that this is a function of underexposure and that shooting at 200 iso and over exposing with the camera and underexposing in SPP will cure this... but it sounds counter intuitive to me. I shoot a lot of coastal scenes with white water, and over exposing this subject matter will quickly result in blown highlights that can't be recovered.

The Iridient Developer 2.0 update exacerbates the problem. Here is a shot developed in Raw Developer and the magenta hot spot in the middle of the frame is more than a little disturbing. The SPP software reduces this to an almost imperceptible degree... though it's still there:
 

kgelner

New member
A recent thread on the dpreview forum claims that this is a function of underexposure and that shooting at 200 iso and over exposing with the camera and underexposing in SPP will cure this... but it sounds counter intuitive to me. I shoot a lot of coastal scenes with white water, and over exposing this subject matter will quickly result in blown highlights that can't be recovered.
It doesn't cure it, but I think it reduces the issue - the main reason to shoot ISO 200 and over-expose is you get more dynamic range. You can recover nearly two stops of highlights at ISO 200, more than using ISO 100. By shooting ISO 200 at +0.7ev generally, you are taking advantage of the greater highlight headroom to bring more exposure into the shadows while still being able to recover most highlights (you do at times still have to adjust exposure compensation further of course depending on the scene).

The Iridient Developer 2.0 update exacerbates the problem. Here is a shot developed in Raw Developer and the magenta hot spot in the middle of the frame is more than a little disturbing. The SPP software reduces this to an almost imperceptible degree... though it's still there:
It would be nice if Irident could filter out that effect better.
 

Hulyss Bowman

Active member
The UV sensor just adjust a little the "symptoms" but do not cure the fact. The green and magenta splotches are due to the sensor recording. This is a disturbance between layers and the info is not correctly translated. It might be an erratic electrical problem. SPP get rid of this a little but the true champion is Lightroom.

Have a look on the DP3m jpeg (I just moved two cursors):
 

Jim DE

New member
Yeah I have seen examples by others on several sites and it does seem to be a random issue with little rhyme or reason. If I had one of those once in a lifetime shots and something like that popped up on it I surely would not be pleased.

So far I have not seen this happen yet on any of my images but the camera is very new to me and I am sort of old school in that when I shoot scenics I take few but precise images at each scene. I have know sports guys that shoot more images in a day than I do in several years ;). I also attribute my limited success in getting some very sound advice from other's who are currently using this camera and following their guidelines in setting up the camera and processing in SPP.
 

Jim DE

New member
Hulyss, Lightroom is about the only PP software I have not tried.... I have PS6 but the adobe tech when I could not get lightroom to work due to one of my other PP softwares using a path stated the ACR in PS6 is essentially the same as Lightroom uses.

Oddly, I have used Aperture and C1 on the Merrell 16bit tiffs and I am liking C1 results a bit better..... still need to try DXO and ACR on these files.

Hulyss what software are you using for your B&W conversions? They are about the best I have ever seen....
 

Jim DE

New member
Really!?!? I would of bet you were using NIK Silver effex pro .... your B&W images are truly exceptional.......

I am going to have to try Paint NET. Right now I have been using a Topaz B&W software.

Thanks for the info Hulyss
 

Hulyss Bowman

Active member
I do not like Nik. I tried but I absolutely don't want to be dependent of such software so I try my best to use the free ones. Then, all around the world, if someone ask me to produce the same, I can, for free.

The software of the camera and paint.net :)
 

biglouis

Well-known member
The first accessory I bought for my DP2M was the 49mm Sigma UV filter. I figured buying Simga's filter was probably best because (I assume) they have checked it to make sure there is no vignetting with use.

I mainly shoot landscapes and because invariably I will adjust WB in post processing I honestly can't say I've seen any ill-effects, or after-effects with the filter.

LouisB
 

Jim DE

New member
Thanks for the input biglouis and Quentin. That is valuable information to know.

biglouis, I am assuming you remove the UV filter before using polarizers or vari-ND's or sheet gradients?

I carry my filter case with me all the time when doing scenics and have a array of SinghRay circular and 4"x6" sheet filters. The reason I asked the above question is I wondered being as the UV filters seem to help on a merrell sensor IQ if I should just leave it on when I use my scenic filters so it can do it's thing while the other filters do theirs.

Since Hulyss post I found a Hoya Super HMC Pro 1 UV(01) 49mm filter and installed it and the hood (even found a neoprene slip over lens cap that covers the lens hood very well when moving from place to place .. one acquires a lot of crap over nearly 50 years with cameras) but I have yet to get out and use it. I had a step ring already that goes from 49mm to 77mm for when I use my scenic filters. My plan was to remove the lens hood and the UV filter and then install the step ring and use whatever filter I want. If the UV has a positive effect on merrell IQ I may want to keep it on and skew the step ring to it. I am kinda typing aloud right now (ie rambling) ;) but I thought it would explain my above question. The next day I can get out and try this on my own is Monday. Plus this subject may of be of value for those who have been there to share their results with those who may want to go there and just have not given this much thought before.
 
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Jim DE

New member
Hulyss, I just went looking for Paint net but looks like I am SOL as it seems to be a windows based software and I run all MAC's :(
 

biglouis

Well-known member
Thanks for the input biglouis and Quentin. That is valuable information to know.

biglouis, I am assuming you remove the UV filter before using polarizers or vari-ND's or sheet gradients?
Ummm. I hate to tell you this but the only filter I have used with my DP2M apart from the UV to protect the lens is the gradient feature of Lightroom and layers Photoshop.

I'm not 100% convinced there is a purpose for actual lens filters in the digital world with digital post-processing.

Does this make me a bad person?

LouisB
 
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