Capturing the world with Photography, Painting and Drawing

Posts tagged “Foveon sensor

Sigma SD15

Sigma SD15 1
Sigma SD15 with 15-30mm f3.5 lens

Sigma’s SD15

If anyone has read my other camera reviews you will have noticed that I don’t review any of my Pro level slr cameras from Nikon or Canon , the reason I don’t do that here is simple.

Here is a good reason why, I was out walking our golden retriever, one Sunday about two weeks ago and passed two photographers with Canon SLR’s, Tripods, all top of the range equipment. On passing I overheard one talking to the other about the lens he had just purchased “It the best in the country , the only one so far”, I am mostly very good at passing on these types of comments and I didn’t know them . However on returning past them again about an hour later, they were still talking cameras, pointing in the same direction and taking pictures of very little if anything.

If this is what they enjoy doing then good luck to them, it did however remind me of just how some people can be, when it comes to camera equipment and the need to have the best. For what reason though, for image creation or talking to friends about.

So I don’t believe that the race to the top of the camera food chain has anything to do with good or great photography, photography is the skill of good and interesting image making, it goes back well over a hundred years and in all that time photographers have been making images that are both iconic and outstanding.

You don’t need the perception of owning the best and greatest equipment to create good images.

While being into image creation, you do need a camera that you both like to use and can trust. For me out in the field the choice of which camera I would take for any given function is selective. I don’t think I have a best camera body, they all do something differently good and bad, they can be used in different ways.

So down to this review

The Sigma SD15

Sigma SD15 2
Sigma Sd15 Slr.

Firstly I think this is one of the most interesting, challenging and creative cameras to be produced for a long time, it will never be seen as the king of the food chain nor will many photographers, with the need for the best to boost their self esteem, stop looking down on it and the even newer Sigma SD1.

Sigma cameras contain foveon, ccd imaging sensors

Foveon X3® direct image sensor

Foveon has combined the best of what both film and digital have to offer. This is accomplished by the innovative design of the three layer Foveon X3 direct image sensor. Similar to the layers of chemical emulsion used in color film, Foveon X3 image sensors have three layers of pixels. The layers of pixels are embedded in silicon to take advantage of the fact that red, green, and blue light penetrate silicon to different depths – forming the first and only image sensor that captures full color at every point in the captured image.

A Dramatically Different Design

The revolutionary design of Foveon X3 direct image sensors features three layers of pixels. The layers are embedded in silicon to take advantage of the fact that red, green, and blue light penetrate silicon to different depths — forming the world’s first direct image sensor.

From point-and-shoot digital cameras to high-end professional equipment, Foveon X3 technology offers multiple benefits to consumers and manufacturers alike. At the same time, it opens the door for other innovations, such as new kinds of cameras that record both video and still images without compromising the image quality of either.

Having read about this sensor technology and the camera for sometime, in May 2013, I exchanged an old Nikon D200 for a Sigma sd15 camera and a couple lenses, ( 15-30mm f3.5 and a 70-300mm f4-5.6).

I was no longer using the D200 so felt, why not take a chance and try the claims for the Foveon sensor and the SD15 out.

Sigma SD15 3
Sigma SD15

Something that is less important than you my think to the pro/semi-pro photographers alike is images size or pixel counts, a much more important aspect of a digital image is the amount of details captured at any defined pixel location and this is something that I have found the Sigma SD15 to be wonderful at.

There is little point in crushing huge amounts of pixels on to an image sensor if the detail capture is low or poor.

The simple facts with the Foveon x3 sensor is that all possible colours are captured at each pixel location, this fact alone increases the level of detail some three fold over a traditional sensor, that splits colour detection into groups of three pixels, each of which can only see one colour from (Red, Green or blue), the effect on an image using this method are the creation of unwanted artefacts in the final image. So the use of a filter over the sensor is needed to stop this effect. This filter blurs the detail level in the image by a factor of around a third at each pixel group locations.

In recent times traditional sensors have increased in pixel counts to a point where the effects of artefact creation are less than before, so some expensive camera models have removed the needed filter over the sensor. This is good and produces better image resolution, however you need a three times bigger image file size to produce the same level of true detail that you find from the Foveon sensor.

Large image sizes take up more disk space are slower to process and longer to upload or email.

My final question related to printed and end results, if you print an unprocessed file from the SD15 at the same size as one from say a Nikon D700, do you get the same detail in the final image, well I have found the answer to mostly be yes, in most cases, yes looking at large prints I can detect very little difference if any.

Don’t get me wrong, I still own and use other cameras , however I have been amazed at the results from this Camera and its Foveon sensor, the colour definition is also wonderful.

Sigma and Foveon claim that the SD15 has 14 million pixels, but this is in three layers and that the newer Sigma Sd1 has 48 million pixels again layered, this is a difficult and controversial claim as each image size is only the given amount divided by three.

However if you take into account that they are only saying this because the camera market has taken as a standard, mega-pixel counts, image detail and colour definition are a much harder subject to sell, to the general public. So what Sigma and Foveon are doing with this claim of high pixel count is to say our cameras produce the same detail yet better colour definition than other cameras with traditional sensors at the level of 14mp or 48mp.

Is this claim true, well side by side A3 or A2 prints appear to say yes. This along with the fact that I just love the colour and image brightness and the great exposure produced from these cameras.

Pixel Counting Definitions

Prior to the existence of the Foveon X3 direct image sensor, there has been a 1:1 relationship between the number of pixels (photodetectors) and the number of pixel locations for a traditional CCD and CMOS image sensor. Given this relationship, the generic term “pixel” has been commonly used to reference both the pixel (photodetector) and the pixel location. Foveon direct image sensors are a new type of image sensor that incorporates three pixels(photodetectors) at every pixel location on the image sensor. The definition of a pixel as indicated below is consistent with standard industry conventions as applied to CCD image sensors, CMOS image sensors, and the Foveon X3 direct image sensor.

A pixel on the image sensor of a digital camera is a light absorbing element (photodetector) that converts light (photons) into electrons. A pixel is also referred to as a pixel sensor when there is a need to distinguish the pixel from its location.

Pixel Location
A pixel location is the X,Y coordinate on the two-dimensional grid of an image sensor at which the pixel is located.

Below I have included some images from my first six months of personal photography while using this camera, I have grouped them into colour and black and white images.

I have also found the camera to be wonderful in the production of black and white photographs, the fact that it is naturally capturing colours in the way it is helps to produce a black and white result as a finish image.

One area that is possibly the only down side I have found is the fact that at higher than 800 iso, the images are noisy in low light, which is why you would need higher ISO, my reaction to finding this out is to say well so, every camera has its weak points. I guess what you could ask is , do the good sides of this camera out do the bad, in my own opinion yes they do, every single bit of camera equipment on the market today has good sides and bad sides.

This is what photography is about, learning what your camera is good at and bad at and working with these details in order to get the best results possible.

Can this sigma help you do that, yes it can and some !

Colour Gallery

Dragon fly on the Barrow 1

Golden Trees of Autumn 2

Grubb Monument the Vee county Tipperarys

When Rhododendron Bloom at the Vee 3

Kilkenny slate quaries 8s

Kilree Round Tower Kilkenny 1

Lismore castle 5


Sigma SD15 Golden fall 1

Sigma SD15 Kilkenny sunset 1

Sundays on the river bank 1

Sundays on the river bank 3

Black and white Gallery

The forgotten at rest 1

The forgotten at rest 4

Trees on the river bank

Images from the banks of the river suir 1

Kilcooley Abbey 3

Kilcooley Abbey 4

Sigma sd15 trees

Yellow Tutsan flowers

Yellow Tutsan flowwers 1
(hypericum), known as tutsan.
Irish nature and wildlife photography : Nigel Borrington


is a genus of about 400 species of flowering plants in the family Hypericaceae

Some species are used as ornamental plants and have large, showy flowers. Numerous hybrids and cultivars have been developed for use in horticulture, such as H. × moserianum (H. calycinum × H. patulum), H. ‘Hidcote’ and H. ‘Rowallane’. All of the above cultivars have gained the Royal Horticultural Society’s Award of Garden Merit.

St. John’s-worts can occur as nuisance weeds in farmland and gardens. On pastures, some can be more than a nuisance, causing debilitating photosensitivity and sometimes abortion in livestock. The beetles Chrysolina quadrigemina, Chrysolina hyperici and the St. John’s-wort Root Borer (Agrilus hyperici) like to feed on Common St. John’s-wort (H. perforatum) and have been used for biocontrol where the plant has become an invasive weed.

Hypericum species are the only known food plants of the caterpillar of the Treble-bar, a species of moth. Other Lepidoptera species whose larvae sometimes feed on Hypericum include Common Emerald, The Engrailed (recorded on Imperforate St. John’s-wort, H. maculatum), Grey Pug and Setaceous Hebrew Character.
Medical properties
Hypericum olympicum in Botanic garden Liberec

Yellow Tutsan flowwers 3

Common St. John’s-wort (H. perforatum) has long been used in herbalism. It was known to have medical properties in Classical Antiquity and was a standard component of theriacs, from the Mithridate of Aulus Cornelius Celsus’ De Medicina (ca. 30 CE) to the Venice treacle of d’Amsterdammer Apotheek in 1686. Folk usages included oily extract (“St. John’s oil”) and Hypericum snaps.

H. perforatum is the most potent species and it is today grown commercially for use in herbalism and medicine; other St. John’s-worts possess interesting properties and chemical compounds but are not well researched. As these secondary compounds appear to be related to deterring herbivores, they are present in varying and unpredictable quantities: still, a number of high-yield cultivars have been developed.

Two main compounds of interest have been studied in more detail: hyperforin and hypericin. However, the pharmacology of H. perforatum is not resolved, and at least its antidepressant properties are caused by a wide range of factors interacting. As psychiatric medication, it is usually taken as pills, or as tea. Standardised preparations are available, and research has mainly studied alcoholic extracts and isolated compounds. What research data exists supports a noticeable effect in many cases of light and medium depression, but no significant improvement of severe depression and OCD.

The red, oily extract of H. perforatum may help heal wounds. Both hypericin and hyperforin are reported to have antibiotic properties. Justifying this view with the then-current doctrine of signatures, herbalist William Coles (1626–1662) wrote in the 17th century that

“The little holes where of the leaves of Saint Johns wort are full, doe resemble all the pores of the skin and therefore it is profitable for all hurts and wounds that can happen thereunto.”

Hypericum perforatum may also be capable of reducing the physical signs of opiate withdrawal. Caution should be taken, as high-dosage H. perforatum interacts with a wide range of medications due to activation of the Pregnane X receptor detoxification pathway, and it also causes photosensitivity.

Hypericum extract, by inducing both the CYP3A4 and the P-glycoprotein (P-gp), can reduce the plasma concentrations of different antineoplastic agents such as imatinib, irinotecan and docetaxel, thus reducing the clinical efficacy of these drugs.

Yellow Tutsan flowwers 2