 |
| |
| This site requires new users to accept that a small amount of member data is captured and held in an attempt to reduce spammers and to manage users. This site also uses cookies to ensure ease of use. In order to comply with new DPR regulations you are required to agree/disagree with this process. If you do not agree then please email the Admins using info@nikondslr.uk after requesting a new account. Thank you. |
| Moderated by: chrisbet, | ||
| Author | Post | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Robert
|
Last month I missed a chance to capture some amazing moon lit scenes of Ulswater at Glenridding. The silhouettes and reflections in the water were amazing and I am still kicking myself for not going back the next night to try to make some photographs of the scene. I think we are approaching full moon again and I have to go that way on Tuesday night, so I have the opportunity if the weather is favourable. My question is how do I make exposures which will give nice clean dark greys and capture the subtle blacks against a very dark sky without either creating excessive noise or other artefacts in the image, recognising that the Nikon D200 sensor isn't the greatest in poor light. I intend to use my Nikkor 50-f1.4 and probably the Nikkor 20 - f2.8. I remember Eric mentioning some technique which he has used in Photoshop of layering several identical exposures then combining them rather than trying to do it with one exposure. I can't remember any more about the technique. I will of course be using a heavy tripod and delayed shutter to reduce vibration due to mirror slap. This is an awful attempt with my iPhone to capture the scene. It does give some idea but fails dismally to capture the magic of the night. Attachment: Ulswater at Night.jpg (Downloaded 55 times) |
|||||||||
jk
|
What Eric was discussing was a technique of image layering so that noise is reduced. This works by each image having different noise characteristics so the result is a reduction in noise but no loss of detail. It might be interesting for you to do some HDR images 5-7 stopsas this will render an image closer to your 'sight'. |
|||||||||
jk
|
Here is a link I found to the technique. http://petapixel.com/2013/05/29/a-look-at-reducing-noise-in-photographs-using-median-blending/ |
|||||||||
Robert
|
That's very clever JK, thank you for the link, I will add Median Stacking to my techniques. All I need now is the weather to smile on me. In fact If I had realised, that image I took with the iPhone might have been almost acceptable if I had taken multiple exposures. |
|||||||||
Eric
|
My technique was a manual method I brought from the stoneage.....tripod mount and take 4 shots at same settings. Place each shot on a separate PS layer in turn. Drop opacity of top layer to 25%, 2nd layer to 50%...3rd layer to 75%...leave bottom layer at 100%. You can play with these % to modulate the effect. The reasoning is that noise varies its position and pattern in each shot. By superimposing several photos and dropping opacity you are ghosting the noise content of each image while keeping the static subject intensity. Wasn't aware that PS had median stacking as an option now...we live and learn. |
|||||||||
Robert
|
Thanks Eric, I will have a play around. It may be a miss tomorrow, the forecast isn't that good but I may get lucky with a break in the clouds. It seems I may be making this journey through the Lakes regularly from now on, my daughter has set up home in Carlisle and I prefer going through the lakes rather than 60 odd miles of motorway. |
|||||||||
jk
|
This is a nice video tutorial of the technique. http://www.lonelyspeck.com/stacking-noise-reduction/ |
|||||||||
jk
|
Did you manage to get your photo Robert? |
|||||||||
amazing50
|
jk, thanks for the link in post 3. Been looking for a way to remove people from shots. |
|||||||||
Robert
|
I keep losing my posts! This is the third attempt to reply to JK!!! Twice I have forgotten to press the 'Post Reply' button. Silly old fool...  I have taken lots of pix this afternoon just before and after Sunset. Nothing spectacular but I took lots of batches of exposures so I can experiment with some median blends in Ps. While I was by Ulswater I spotted several other vantage points to get more, different and interesting angles of much the same scene. I am looking forward to exploring these over the coming months. Having followed the link JK posted, I also found this link: https://www.youtube.com/watch?v=HSyxB9Zd3LU Which is quite a long video but I found it very interesting technique wise. Mike, I purposely took several sequences with cars driving past the scene just to try exactly that! These techniques are fascinating and I find them very stimulating. |
|||||||||
amazing50
|
Good luck on the car removal. |
|||||||||
jk
|
Yes the blending technique works well. Also if there is a particular item to remove then you can select it and then put it on another layer and make the layer a Subtract layer type.  It then disappears as black!The wonders of Photoshop. |
|||||||||
Robert
|
OK, I have been playing on my MBP (13" mid 2010). Running Lightroom CC15.1.1 and Photoshop CC15.0.1. The camera was a D200 with Nikkor 20mm f2.8 1/8Sec @ f4.5, ISO 200. I roughly followed the tutorial in the astro photography video, with the exception of masking the foreground. I'm not confident there was NO movement between exposures, so I asked Ps to align the layers. Not sure that was a good idea but will try again without aligning layers when I get home. The first image was exposure 10 of 10, clearly showing cars and headlights in the scene, all bar one exposure had cars visible on the road.  The second image is after the median layer blend, all the cars removed and to my eyes it seems smoother, noise wise, although not really very sharp.  Finally a 100% crop in Ps which shows the lack of sharpness and chromatic aberrations at the junction of the road and wall. There is also a fringe on all of the images at the skyline. This may be mirror slap because I didn't take that much care with my exposures, this really only being a quick experiment.  I will post some more results when I have processed the other images at home. |
|||||||||
jk
|
Good start on the technique. Car removal has worked well.  I wonder if it is the technique or maybe some shake that is making the image less sharp? |
|||||||||
amazing50
|
Interesting to see if you lose any of the sheep. If they only move a bit you may have parts of sheep. |
|||||||||
Robert
|
Thanks JK, yes, very pleased especially given it was done on the MBP, it coughed a bit aligning the images in Ps but the rest of the process was quite quick. I am sure Eric would create an action and it would be a breeze. I think the lack of sharpness was a combination of wide aperture, lack of care on my part, the fact I just put the camera on high speed repeat shutter with my finger on the button and counted to ten. It needs much more care with the shutter, mirror up and use a remote. The individual images are not sharp either but I do wonder if the auto alignment in PS is averaging the alignment on moving parts of the image like the branches of the tree which were gently swaying in the breeze. This is why I tried it first on this image because most of my other images have moving water with wind created waves moving quite vigorously towards the camera. Mike, I think the two leftmost sheep are only partial, looking at the two complete images, will take a look at the full size image when I get home... I think masking may be needed or overlaying a complete layer for the water, but that's where I expect noise to occur, so will have to try other approaches and experiment a bit... |
|||||||||
Eric
|
Robert If you take the same images and use 4 in the variable opacity method I mentioned without aligning the layers, do you get the same degree of fringing and soft edges in the wall crop? My other question is why did you use 200ISO? Surely using a higher ISO and faster speed / smaller aperture would have reduced camera shake? After all, one of the benefits of stacking is to reduce high ISO noise. |
|||||||||
Robert
|
Hi Eric, I will try your method too. Currently in the midst of fairly major house alterations and upheaval so my photography input is a bit more disjointed than usual.  I am using ISO 200 to minimise the noise (the D200 does not like poor lighting, at any ISO), for the vast majority of my photography that does not matter but I have started to become interested in sunsets and post sunset photography. Until I get my D3 I need to resort to trickery! Its's bad enough at ISO 200, let alone ramping it up, although I do take your point, maybe ISO 400 might be a sweet spot, my current aim is to experiment with the software, which seems to work well enough, I processed another stack last night which included Ulswater with it's moving ripples. I intend posting some images from that stack later when I have beaten the kitchen sink unit and dish washer into submission!!! I am very impressed with the noise removal in the latest stack I have processed, the noise is clearly defined in the unprocessed images but after the median blend on only 4 images the image is nice and clean. |
|||||||||
Eric
|
Robert wrote:Hi Eric, I will try your method too. Currently in the midst of fairly major house alterations and upheaval so my photography input is a bit more disjointed than usual. Exactly my point...whichever method you use the noise will be reduced. You could probably go to 1600! |
|||||||||
Robert
|
ISO 1600??? with a D200... Oh my goodness, shock, horror! OK I will try it but it might blow a fuse. I suppose at this rate I might not need a D3. |
|||||||||
Robert
|
This evening I stopped at Glenridding on the shore of Ulswater at about 9pm, the sun has set at about 4pm. There was an almost a full moon high in the sky, almost overhead but lots of fast moving cloud. I set the D200 fitted with Nikkor 20mm f2.8 lens to my heavy tripod and chose manual, 8 seconds at f2.8, ISO400, I set the White Balance to manual, cloudy.  I have played with it in Lightroom a bit but I am a bit limited using the MBP (laptop). Once I get home I can choose the best image more easily and process it. I had intended to stack median process to minimise the noise but the fast moving clouds and reflections pretty well rule that out. Last month, when the moon was at it's maximum, the 'blood moon', was the first time I had spotted this scene, there was no wind or clouds, the brightness was amazing and the reflections in the water were magical. I doubt if I will ever see it so spectacular again but I will try! |
|||||||||
jk
|
Now you know where to look I am sure that the opportunity will reoccur. Re the stacking you can in Photoshop select an area with your best clouds and put it onto a different layer then make it top of stack. You can then play with the blending options to get the best effect. |
|||||||||
Robert
|
Well yes, but the water mirrors the clouds, so that's ~80%? of the image which is different in each exposure in the stack, the water and clouds suffer just as much from noise as the land mass. A lot of the effect is lost because of the long (8 second) exposure, even ramping the ISO up to an acceptable level would still mean something like 1 second, while that would be better, the movement in 1 second will still kill the sharp reflections which are visible to the human eye. What is needed is less wind! Like it was a month ago... Zero wind and zero clouds. I have been narrowing the candidates down from 54 to half a dozen or so, this morning and I think I missed the best one by far. will have a go at it this evening if I get time. I have noticed a fringe or band on the junction between the sky and the left hand mountain, not sure if it's camera movement or some sort of an 'artefact effect' a form of CA? This is a 1:1 pixel zoom screen grab from Lr.  By way of some sort of control, this is another grab from the same image.  The second grab seems to discount camera shake, the houses and shore line are clearly defined with no secondary edge. |
|||||||||
jk
|
What lens are you using?. The fringing is possibly/probably CA that you should be able to reduce/remove in LR or Photoshop. However it could be induced by pre-sharpening done by LR in the default import process. Have you zeroed the default import process? |
|||||||||
Robert
|
Nikkor 20mm f2.8 D. The image I took the grabs from had not been processed by me, although as you say it will have had the preliminary Lightroom initial import process. I haven't turned it off, it's not usually a problem. If it's CA then I haven't seen black or dark grey CA before. |
|||||||||
Eric
|
Robert wrote:Nikkor 20mm f2.8 D. The image I took the grabs from had not been processed by me, although as you say it will have had the preliminary Lightroom initial import process. I don't think that is CA. That would show up more around the branches to the right of the frame. It's more like a sharpening or compression artefact or a sort of edge confusion. I don't suppose it's high ISO noise reduction ? |
|||||||||
Robert
|
The fringing wasn't present on all images, only some batches, mainly those with a full moon, the initial batches, which I dumped due to lack of contrast and interest, were taken with the moon partially obscured. At some point I turned on the shutter delay which delays the shutter releasing after the mirror has lifted. I don't think that has any bearing on this phenomenon, with an 8 second exposure any vibes from the mirror clanking up would be irrelevant. The in camera high ISO noise reduction was set to normal. The screen grabs were from an image which hadn't had any processing in Lr except the import process. I will take a couple of screen grabs of the processed image... |
|||||||||
Robert
|
First the mountain skyline, the fringe seems to be parallel? Southern shore and lower bush:  Southern shore and upper bush:  I can't be sure but it seems to me there is fringing in the branches of the bush but it's ill defined. If it were coloured it would be much easier to be sure. Given it's grey, will the 'CA de-fringe' command work? |
|||||||||
Eric
|
CA means Chromatic Aberration....nothing chromatic about that sky line. Also CA doesn't follow contours as faithfully as that..imho. That's got to be an in camera processing issue??? |
|||||||||
jk
|
I have seen similar effects with oversharpening but that halo effect at the edge of light and dark areas I have seen before. I know you here is a solution. I will need to do some searches! |
|||||||||
Eric
|
jk wrote:I have seen similar effects with oversharpening but that halo effect at the edge of light and dark areas I have seen before. I know you here is a solution. I will need to do some searches! Over sharpening tends to give high contrast halos. That's more like a noise reduction over cook. |
|||||||||
Robert
|
It seems to be at the (distinct) boundary between dark and light areas. I opened the original NEF in ACR and zoomed in to 400%. There appears to be a light fringe at the light side of the grey fringe. Screen Shot of ACR:  |
|||||||||
jk
|
Robert wrote:Nikkor 20mm f2.8 D. The image I took the grabs from had not been processed by me, although as you say it will have had the preliminary Lightroom initial import process. If you go into the Develop module all value should be zero. Sometime the defaults the LR applies are horribly wrong! Take a single image that looks to show the haloing effect and try processing it in Photoshop. Are the results the same as from LR? |
|||||||||
Eric
|
Robert wrote:It seems to be at the (distinct) boundary between dark and light areas. There is a small element of CA on that image enlargement in the blue red...but it's not causing that thick edge effect. You can try using the CA reduction filter in the ACR interface. Move the red blue slider...but I bet it won't get rid of that edge effect. I hate to say it, but do you think it's a limitation of the D200 sensor? The D200 did suffer from Line Noise at high ISOs. I wonder if this is some sort of manifestation of that sensor issue? I guess the only way to check this is repeating the shots under test control conditions using different lenses and different camera settings. There is such a thing as blooming ....the spill of over exposed pixels into adjacent darker pixels. This obviously happens along contrast edges. I have always assumed the pixels neeed to be over exposed to create this spill over but maybe to some degree it happens along any light/dark interface??? Groping in the dark a bit here. |
|||||||||
jk
|
I think that Eric is correct. The limitation may indeed be in the D200 sensor. I know I have seen this effect before and the reason for its occurrence but I cant remember what it was. Robert, has this camera been Full Spectrum converted? It may be that the conversion has induced a limitation in the camera. |
|||||||||
Eric
|
jk wrote:I think that Eric is correct. The limitation may indeed be in the D200 sensor. I know I have seen this effect before and the reason for its occurrence but I cant remember what it was. I thought this was Roberts colour D200 not the one converted to IR? |
|||||||||
Robert
|
Thank you gentlemen! It's hard to replicate the conditions at will, I intend to keep trying in this challenging aspect of photography. Had it not been for the moon it would have been very dark, indeed it was pretty dark as it was, I am amazed the D200 sensor picked up the amount of detail revealed in the full image in post 21, I feel it's truly remarkable. I definitely couldn't see any of the colours with my naked eye which are clearly visible in the photograph above, all I saw was a black mountain side. I can, and as an experiment I probably will remove the fringe from the mountain skyline, if only manually. I will also try various stacking median blend experiments when I get home from visiting my Daughter. I am actually quite impressed how little noise is in the image, OK not technically excellent but not disastrous either. I will have a closer look at all the images I took that session once I get home, there may be some room for recovery once I have a bit more screen 'elbow room'. I will try importing two batches one for Lightroom and a second separate import solely for Photoshop, that may help clear up whether Lr is messing with the import process by over processing the image. Eric is right, it's my normal, un-mollested D200! I suspect the full spectrum D200 would possibly not have suffered this issue. Again perhaps room for experiments. |
|||||||||
Eric
|
Robert wrote:Thank you gentlemen! I knew it was Robert. I took all the fringing settings off the IR body.  But ...you could next time try shooting the same shot with the IR body as well...to see if the fringe is there with that sensor. |
|||||||||
Robert
|
Eric wrote:But ...you could next time try shooting the same shot with the IR body as well...to see if the fringe is there with that sensor. I am convinced the D200-IR body produces far crisper images than my D200. The standard LPF filter has a slight blurring effect to combat moire. |
|||||||||
jk
|
Robert wrote:Eric wrote: That makes sense and is why Nikon now seem to be removing the use of the LPF in their cameras. |
|||||||||
Robert
|
Not wishing to split hares... All normal cameras must have a low pass filter, even such as the D810, otherwise the images would be contaminated by infra red and ultra violet imagery. This would result in an extremely hazy and wooly image. My understanding is Nikon have stopped dipping the glass filter in front of the lens in acid which created a micro etch to diffuse the light rays in an attempt to reduce the ugly moire effect when fine parallel lines appear in photographs. I think this has in part been enabled by higher resolution in some of the high end bodies which reduces the tendency for the moire effect to occur, and possibly built in software to correct it although that is a guess on my part. A pass band filter to remove light below about 400nm (ultra violet) and above about 680nm (infra red) is pretty well essential for a clear image. I have often wondered what would happen if I used an ultra violet <400nm and an infra red filter >680nm in combination on my full spectrum D200, given that it has no low pass filter just a piece of extremely thin quartz glass in front of the sensor. The downside would of course be a lot of messing with filters and potential ghost images due to the two filters being in front of the lens in tricky lighting, instead of just in front of the sensor. It would be so much easier if Nikon had provided the facility for the user to easily change the sensor filter. [OK, I know it's splitting the wrong hair but I rather liked the typo, so being in a obtuse mood I left it!] |
|||||||||
jk
|
If you can catch the hare then you can split it. Even shooting them is very difficult much less running and catching them! Sometimes these typos intentional or otherwise bring humour into the internet world. |
|||||||||
Robert
|
Well I'm back home with the luxury of my 24" screen again! I have revisited the images I took last week at Glenridding of Ulswater in moonlight. I sifted through the 50 odd images I took and settled for one of the last which was taken with a full, unobscured moon. The details are as before, D200 (normal, not IR or UV), Nikkor 20mm f2.8, @ f2.8 with an 8 second exposure, Hi-ISO NR, normal; long exposure NR, ON. With my larger monitor and easier working I have been able to have a better look at the fringing. Here is my best effort at processing the image: I am still unsure about the tint towards sepia, but reducing the saturation seems to detract from the effect?  I am very pleased with it, If I had realised how good the D200 was going to handle the extremely difficult lighting I would have gone home for it at the previous full moon. The water was as flat as a mirror and the reflections were perfect, but that's life as they say. The fringing. It appears to come in three colours depending on the orientation of the contrast junction with which it is associated. Horizontal seems to be grey, vertical on the left seems to be magenta and to the right, cyan. These screen shots have been taken in Photoshop at 400% I have manually remove much of the fringing in the image above, I tried using the CA removal tool in Lightroom but it didn't do anything, I think there is one in Ps but I couldn't find it. The skyline of the large mountain:  The branches of the nearby tree:  The cyan and magenta fringing can be clearly seen in this screenshot. The fringing seems to change to grey on the horizontal branches. Very strange, I have removed most of the cyan and magenta fringing but the grey was much harder and where the branches were tightly packed I gave up! |
|||||||||
Eric
|
Robert wrote:Well I'm back home with the luxury of my 24" screen again! If you overlay magenta on top of cyan..what colour do you get? Maybe the grey is just the result of close interaction of tightly packed different color fringes? Have you examined the individual channels? |
|||||||||
jk
|
Like I said before I think there is a CA effect. It may be in the Adobe algorithm, or in the sensor capture process or even in the lens but if you havent noticed it in the lens before I would think it is a sensor or algorithm artifact as long exposures do not behave 'normally'. |
|||||||||
Robert
|
Eric wrote:If you overlay magenta on top of cyan..what colour do you get? I dud wonder about that... My new En-suit sink... Nothing do with the topic but I thought you might like to see it!!!   Back on topic! I have converted the image to CYMK and taken a screen shot of each channel: Fringing CMYK.  Fringing C.  Fringing M.  Fringing Y.  Fringing K.  Fringing CM.  Over to you Eric... Do those images tell you anything? They are taken from an un-adjusted NEF. |
|||||||||
jk
|
I'm lost. Nice bathroom. I know more about plumbing than CA and fringing problem resolution. |
|||||||||
Eric
|
Robert wrote:Eric wrote: Using the channels you get a clearer picture of where color problems lie....although you had already deduced there was a magenta/cyan issue. You can play a lot of games tweaking channels, like copying the black Chanel outline onto magenta and cyan channels to lose the difference. |
|||||||||
Robert
|
jk wrote:I'm lost. Same here! I can see some sort of effect but what the cause is I haven't a clue, the fringing is definitely cyan and magenta with the magenta one side and cyan the other, where there is no definite 'side' it becomes grey, a mixture of cyan and magenta overlay. It seems to happen at high contrast boundaries. Perhaps it's the lens? I only used the 20mm f2.8 so I don't have anything else to compare with. It was also evident in the low contrast images taken with the moon obscured by the heavy cloud cover. |
|||||||||
Robert
|
Eric wrote:Using the channels you get a clearer picture of where color problems lie....although you had already deduced there was a magenta/cyan issue. Thanks Eric. It's getting late now but can that be done in layers, then by increasing or reducing opacity of the layers adjust the effect, this is way beyond my experience... |
|||||||||
Eric
|
Robert wrote:Eric wrote: Well it's a long time since I did this sort of thing but I would suggest trying to create a selection mask on a channel, saving it, and applying it to the errant channel and deleting the inverse. Need to sit at the computer and think/work it through...but today I am tree pruning. |
|||||||||
Robert
|
No great rush Eric, this is really just an exercise for the future. I have fixed this image manually as good as I need it. Enjoy your pruning! My rose 'Louisa' is in dire need of savage pruning, it's almost filling my tiny garden. Last night I went back to Photoshop and renewed my search for the CA rectification/control panel. Eventually I found it! It's hiding in the filters menu under 'Lens Correction...' I had stupidly been searching in the 'Image' menu! Using the lens correction panel I experimented with the sliders and found the best combination. It hasn't removed the grey fringe but it has largely eliminated the very indistinct and annoying cyan and magenta fringes. There are some traces remaining but not worth bothering with. I took a look at Bj¸rn R¸rslet's lens database, he mentions that CA isn't a significant issue with this lens, so I can only surmise this instance is provoked by the extreme lighting conditions which exist at 9pm in the evening when the sun set at 4pm in a full moonlit sky? Pushing the limits! Before CA adjustments:  After CA adjustments:  Given the D200 is not recommended for low light photography I am really very impressed by the image I have obtained, I don't feel the noise is excessive, when compared with the iPhone image I put at the beginning of this thread it's wonderful. I have been trying to retain the sense of a moonlit scene, rather than a daylight scene. If I made the adjustments available I can actually make it look pretty much like a daytime scene. It shows the extremely sensitive nature of the sensors even an 'antiquated' one like the D200. What film would do this without golfball grain clumps? |
|||||||||
Eric
|
So ...using the CA option in Photoshop, does it remove the line along the hillside? |
|||||||||
jk
|
I am betting yes but I dont know! |
|||||||||
Robert
|
It takes the colour out of it but the line remains. You can just about see it at the right hand side in the CA control panel images above. On the skyline it's pretty easy to clone out but in the tangle of twigs and branches in the tree I gave up and areas of grey remain where the gaps are too tight and too numerous to spend that much time on. I feel the grey patches detract from the image somewhat. I am still a bit unsure about the image as a whole, I like the effect but not sure I have made the best use of the capture I made, I have got too hung up on the CA, or whatever it is and have rather lost the plot on the image itself. I think I am developing the skills I need, so that if I ever do see a full moon, a clear sky and little or no wind up there in Glenridding, or elsewhere, I might actually manage to capture something worthwhile... The site where I am taking the pix is a long way from here, ~35 miles or so, I suppose there will be comparable places much nearer home but not sure where! Perhaps any dark hillside skyline would do, after dark with a full moon and no clouds... Try other bodies and other lenses at various settings. Maybe wide open isn't best for CA? I need to learn more about it. |
|||||||||
jk
|
Have you used the Content Aware Brush for this? It works for these complex pieces. |
|||||||||
Robert
|
Not sure... I have been using the stamp tool, sampling from very close to the same place I am removing the grey line. Not clear about the content aware brush. |
|||||||||
jk
|
Just paint and it wil resolve. |
|||||||||
Robert
|
Well, this is about my best effort, I don't know if I have succeeded or not but there it is... |
|||||||||
jk
|
That looks much better. The haloing on the hillside is almost gone. |
|||||||||
Current theme is Blue
| A small amount of member data is captured and held in an attempt to reduce spammers and to manage users. This site also uses cookies to ensure ease of use. In order to comply with new DPR regulations you are required to agree/disagree with this process. If you do not agree then please email the Admins using info@nikondsl.uk Thank you. |