Hi all

[dvp]

Hi everyone
I just joined this forum and wanted to say hello to everyone reading this. This is a much better site than many others that I have looked into on the web in terms of explanations of the physics behind imaging with light (I use the term "imaging with visible light" to be more precise definition of photography, as opposed to imaging with other electromagnetic spectra). I am familiar with imaging with non-visible spectra but only just starting to learn the nuances of imaging with visible spectrum. I found good articles on many topics on this site that have perplexed me. One topic I am still searching is rendering of colour. I understand "MTF" but there is more to "MTF" than just spatial resolution and edge sharpness (what is referred to broadly as "quality" of MTF in the article on this web site. So, more specifically, I am attaching a picture here that shows lack of accurate capture of the colour yellow and also blue. The picture was taken early AM (6-30 AM). For a better analysis of the picture, it was shot with a Nikon D70, using 200 ISO, 17-55 f2.8 lens using 55mm focal length with f10 f-stop. I find that the f10 should be reasonably close to the "sweet spot" of the lens, and should and does render good depth of field for this particular composition. However, I am very unhappy with the colour rendition in this picture. There needs to be more yellow and more blue in the picture that is missing. Any explanations how to improve the colour MTF of this picture? BTW the picture is untouched and in JPEG.
I am trying to find explanations for shortcomings in my pictures and hopefully some of you will explain what went to wrong with a particular picture and what could be done to improve my photographic technique.
In my earlier life, I have lived in New Zealand and find it a a very pretty country, probably one the most beautiful parts of the world bar none. I have not visited Nelson, but have seen most of New Zealand.
Any comments and suggestions are most appreciated. Colin, your pictures are gorgeous. Are you shooting film?



Thanks in advance.

[dvp]

Just as a comment, I have reduced the size of the picture (the website will not accept higher than around 150 k picture) and hence there is loss of detail. The full size picture is much sharper; but pay attention to colour rendition (or lack of it).

[Shadowman]

Welcome dvp,

Three areas to research would be lens performance, colorspace, and prospective output. Along with the correct white balance and exposure settings, you should be able to render color comparable to what is seen by the human eye. What you actually see on the monitor or a print is another thing entirely. I assume the yellow you are referring to is the color of the sun. What white balance were you using and did you tone down the exposure to eliminate overexposed areas?

[arith]

Hi, the picture looks great, I've had a quick look and note some abstractness in your view. I would just like to say welcome and hope you enjoy your time here. cheers

[dvp]

Welcome dvp,

Three areas to research would be lens performance, colorspace, and prospective output. Along with the correct white balance and exposure settings, you should be able to render color comparable to what is seen by the human eye. What you actually see on the monitor or a print is another thing entirely. I assume the yellow you are referring to is the color of the sun. What white balance were you using and did you tone down the exposure to eliminate overexposed areas?

Thanks.
WB used was direct sunlight. No, exposure compensation (had I used this, would the human subjects be completely dark (sillouettes)?). Time of exposure 1/1000s. Matrix metering with if I remember correctly exposure lock used with sand as object for exposure value (may have created some overexposure; could have bracketed I suppose). What really bothers me is completely flat color contrast (for lack of a better term); there is no blue in here, no yellow either.
The lens I am using is a 17-55 f2.8 nikkor, pretty sharp copy. The yellow i am referring to is the color of the sky.

[Shadowman]

dvp,

That is a very short exposure for the lens setting (55mm) you were using. You were only able to get a fraction of the light to reach the sensor, which would render an underexposed image. With a 55mm lens you should be able to use a 1/50" shutter speed.
Also, the f/10 aperture setting will also only allow so much light to reach the sensor. Try a combination of wide aperture (f2/8) and 1/1000" and (f2.8) and 1/50" next time and see what differences you capture.

Thanks.
WB used was direct sunlight. No, exposure compensation (had I used this, would the human subjects be completely dark (sillouettes)?). Time of exposure 1/1000s. Matrix metering with if I remember correctly exposure lock used with sand as object for exposure value (may have created some overexposure; could have bracketed I suppose). What really bothers me is completely flat color contrast (for lack of a better term); there is no blue in here, no yellow either.
The lens I am using is a 17-55 f2.8 nikkor, pretty sharp copy. The yellow i am referring to is the color of the sky.

[arith]

Auto white balance doesn't work very well into sun and it is best to shoot RAW. But also the exposure value range might be too high for a single shot and because people are in it a GND filter could be used. I thought the silhouettes were deliberate and they are very dark so it may be too bright for normal photography and HDR would have to be used.

But I don't think it would work here.

[dvp]

dvp,

That is a very short exposure for the lens setting (55mm) you were using. You were only able to get a fraction of the light to reach the sensor, which would render an underexposed image. With a 55mm lens you should be able to use a 1/50" shutter speed.
Also, the f/10 aperture setting will also only allow so much light to reach the sensor. Try a combination of wide aperture (f2/8) and 1/1000" and (f2.8) and 1/50" next time and see what differences you capture.

Shadowman
Thanks for the suggestion; I see what you are saying. My f10 was intentional to increase the depth of field; but yes, I do have some play room here with a 55mm focal length, I should be able to use a wider f stop (my feeling is that f2.8 may produce too shallow a depth of field, also increasing light flux, reducing time to 1/2000-1/4000th of a second. in either case light flux will remain the same with 1/1000s (and f10) or lower time (with f2.8). I shall have to try some more.

[dvp]

Auto white balance doesn't work very well into sun and it is best to shoot RAW. But also the exposure value range might be too high for a single shot and because people are in it a GND filter could be used. I thought the silhouettes were deliberate and they are very dark so it may be too bright for normal photography and HDR would have to be used.

But I don't think it would work here.

arith
Thanks. The silouhettes were unavoidable. Yes, the picture has a very high dynamic range by definition. Is there a way to capture such dynamic range (film should be the obvious answer, unless I am missing something here).
What is the dynamic range of the D70 sensor? How does it compare with dynamic range of film. I remember from my younger days that film always had very forgiving latitude (remember the old heel toe graphs, anyone??).
Yes I did think about a graduated neutral density filter. However, I do not have one. Any suggestions which one to buy? It would intutively cut down the total light flux passing through, forcing a longer exposure, but would it increase ability to capture such wide dynamic range (I have little experience in this field, but some more experienced shooters may be able to help here).
The image was captured using RAW (I do not like the concept of post processing). What is HDR?

[Shadowman]

dvp,

Would like to see what you come up with.

[arith]

HDR just stands for High Dynamic Range; measured in Exposure Value a range of 128:1 from the brightest definable thing to darkest definable thing is all that can be achieved by most printers and monitors or displays.
An increase in one EV (exposure value) represents a doubling in light so 128:1 represents 7 stops, however a dslr can typically manage 11 ev although most of the extra is used to avoid posturisation (too great a difference between adjacent colours).
Some camera's at the top end can manage 18 ev range.
A GND (Graduated Neutral Density) filter is graduated; grey one end and clear the other, various are available GND 2, GND 4, GND 8
representing (2 to the 1) to (2 to the power 3) or (1 stop or 1 ev) to (3 stop or 3 ev) difference between one side and the other.
They also come with hard gradient or softer gradient.

Using these can shade bright bits and brighten darker bits; I mean bring them closer together. They come in a range of prices.

More about HDR can be found herehttps://www.cambridgeincolour.com/tu...amic-range.htm

[Colin Southern]

HDR just stands for High Dynamic Range; measured in Exposure Value a range of 128:1 from the brightest definable thing to darkest definable thing is all that can be achieved by most printers and monitors or displays.

Hi Steve,

In reality the DR of most paper is close to 4 Stops, and monitors typically in the 5 to 6 stop region (despite the ridiculous claims some monitor manufacturers are making).

Herein lies some of the problems matching prints to screens - not only is one using active additive colour and the other reflective subtractive colour, they also have differing dynamic ranges

[Colin Southern]

Colin, your pictures are gorgeous. Are you shooting film?

Thanks DVP - no, all digital

[Colin Southern]

Yes I did think about a graduated neutral density filter. However, I do not have one. Any suggestions which one to buy? It would intutively cut down the total light flux passing through, forcing a longer exposure, but would it increase ability to capture such wide dynamic range (I have little experience in this field, but some more experienced shooters may be able to help here).
The image was captured using RAW (I do not like the concept of post processing).

I use Singh-Ray filters exclusively for my GND requirements. If you're interested, I've also written a few articles on using them for their blog. Using a GND doesn't necessarily mean a longer exposure; often it means the same exposure for the shadoes, but without blowing the highlights!

PS: ANY shot with naked sun showing is going to "challenge" something ... in this shot I had 6 stops of GND over the sun (note how quickly the shot transitions to black at the periphery of the frame) - and the bottom section is a living tribute to RAW captures and ACR's fill light!

[agaace]

Colin.. arrrrgh.. you owe me some $200 now! You just convinced me to buy a GND filter now, I'm losing money because of you man!
More seriously, I just have to decide how many stops I want for the start..

Hi dvp, nice to see you on the forum!

[Colin Southern]

Colin.. arrrrgh.. you owe me some $200 now! You just convinced me to buy a GND filter now, I'm losing money because of you man!
More seriously, I just have to decide how many stops I want for the start..

Hi dvp, nice to see you on the forum!

Hi Agata, you should form a condolences club with Ali - he's in the same boat!

Seriously though, you're probably going to need a 3-stop hard edge Normal or a 3-Stop hard edge reverse GND; 2 stops isn't enough and 4 stops is often too much. Here's a little test for you - open your favourite lens right up, and then stop down 3 stops - look through the viewfinder and then repeatedly press and release the DoF preview button to see what a 3-Stop change looks like to the human eye. It's noticeable, but it looks more like you've cut the light by around 20% than to a full 1/8th of what it was. In many scenes though what you require is around 13EV which you camera is capable of, but the shadows will be too noisy - so by using a filter you effectively just move the good stuff 3 stops away from the noise floor, but without it being particularly visibly obvious - so 3 stops works pretty well.

Just make sure you get the ones that are 4 inches (100mm) wide - not the 3 inch (75mm) versions. The Lee filter holder is also higher quality than the Cokin equivalent. I can give you more info is you need it.