Tagged: Rich

8th June 2017 – Macro to Astro

Our speaker this week was Richard Price talking on the very small and the infinite (at least the bit of it we can see) – Macro to Astro. As ever a hugely informative and accessible evening given to a packed hall.

 

When talking Macro (on a ratio of reproduction to actual size of the subject of 1:1 or greater) we will be including what is close up photography too as there is a technical difference but not, as far as next meetings practical is concerned, no difference worth the time.

 

These are both areas of photography that appear complicated but, whilst demanding, they can be easily accessed. And they are both absorbing aspects of photography and being both accessible and demanding  they teach us a lot about our equipment and how light works with it. It also tells us a lot about our kit and can involve finding work arounds. For instance my manufacturers own 50mm lens will not work on anything but manual and with the depth of field preview button held down with my extension rings. My third party lenses work just fine. Took a while to work out how to get the nifty to work, but it was worth the effort. With a mirrorless camera like mine the DOF preview button is usually redundant -what you see in the view finder is exactly what you get as an image. Only it isn’t redundant at all and I am rather glad it’s there.

 

Of course, how near/far you want to go is a matter of budget but only really at the extremes. You can get some perfectly acceptable macro shots with a kit lens and a reversing ring (about £7 for a 52mm filter – size it’s written on the front of your lens, in the case of our 52mm example as Ø52).  You can also use a coupling ring to reverse one and add another lens to it to make a longer focal length and a greater degree of magnification. In both case it might be advisable to take any UV filters you have off the end of the lens.

 

The next option Rich gave us was using screw in filters (lenses) of varying dioptres. These are available for around £15 (and upwards depending on filter size), but as with everything else you get what you pay for. Essentially these are like reading glasses for your lens, they are lenses that fit on the end of  lenses. If you buy them for the largest filter size you have in your range of lenses you can buy a set of step down rings to fit them to your smaller filter sizes (usually for around £5).

 

Extension tubes, moving the lens away from the focal plane foreshortening its focusing capacity, use no intermediary glass at all, so there is no risk of flare or softening enhanced by putting more barriers between subject and sensor.  By shortening that distance  a degree of magnification results by getting closer to the subject. This is generally a more expensive route than the two previously discussed. this is because a certain amount of electronic communication has to be allowed for in the design of the tubes and this complicates the manufacturing process making it more expensive. It isn’t always effective either (see example given above) and work rounds result. However, the more you pay, generally, the more you get in terms of functionality and performance, though this is not an absolute guide.

 

Finally there is the most expensive option, the dedicated macro lens. Without a doubt this is the higher performer when it comes to producing quality of images in terms of sharpness and contrast, and without a doubt. But all that comes at a cost and even the cheapest all manual lenses cost several hundred pounds. Whichever route we go, macro/close up photography can be done anywhere and relatively easily and cheaply. One extra technique that might help is Focus Stacking. It can be done in Photoshop, as per the link, but failing that you might want to try CombineZP which is free and simple to use.

 

Now focus stacking as a technique makes a good link to the second half of our evening, Astro-photography. The reason being that photo stacking is an often used technique when taking photographs of the stars. It’s not an absolute requirement, though, and the basics are relatively straightforward. Rich recommended using StarStax, which is freeware, as you were wondering and developed with astro-photography in mind. But we get a little ahead of ourselves.

 

Dark areas in the UK are few and far between. Light pollution is a serious problem, not just for photographers but for wild life too, in our rather crowded island. Even in designated Dark Areas there are problems at the extremities where towns and villages emit a glow low on the horizon. So it takes some work.

 

The pollution part is best thought of as the light you would eliminate if you could. The night sky isn’t black, the horizon is always discernible.  The sky itself is also quite bright. If we are trying to record as much detail as possible (known as Deep Sky astrophotography) we are going to be fighting the noise generated by the sensor of the camera, especially at higher ISO’s but even at the lowest setting because where there is a signal there will be noise. If we treat the sky as black either by exposing or reducing it to black in post production then the fainter details are going to get lost. The point is the sky isn’t really black, it’s closer to a dirty orange colour. Because of the light pollution and the reflective nature of Earth’s atmosphere.

 

We can get round this in post by adjusting levels, picking the darkest part of our image as a start point with the eye dropper and adjusting the levels. It’s a matter of trial and error really. As is white balance. Regardless, this will all be a matter of trial and mostly error at the beginning and that is actually part of the fun. Learning new techniques like this means we learn more about the competencies and capabilities of our equipment and allows us to do more things with it.

 

Our thanks again to Richard and good luck as he takes this and his other presentations on the road.

 

 

N E X T  M E E T I NG

Macro and close up practical evening. Bring cameras tripods and that reversing ring you just ordered off Amazon.

 

 

 

 

22nd January 2015 – On Colour Space

Colour space and gamut. Sounds like a poor man’s crime fighting duo, but as Rich Price showed us it is a surprisingly powerful way to subtly (or not so) expand the presentation of colour in an image. Concentrating on derivatives of RGB, Red, Green, Blue, from which all other colours can be made and moving towards white, there are a number of different models – the basic physics of how we end up seeing the rendering – all existing to do the same job: Turn 1’s and 0’s into recognisable colours on screen or in print ( the model is the printer’s map, the image the contour lines). CMYK mixes cyan, magenta, yellow and black (the K stands for Key ), on the page and is popular with magazines and similar publications, and works by subtracting light from white as the start point. Then things start to get complicated with other models, such as CIELAB and CIE XYZ that approximate human vision in constructing colours and are used converting RGB images to CMYK. In itself all fascinating but not something that we need particularly concern ourselves with in depth.  It gets very technical but is interesting.

 

So much for the models but we were concentrating on the work spaces. There are a number of them: sRGB – the most common found in display screens and cameras, PhotoRGB, the aforementioned CIELAB and Adobe RGB are a few. Rich concentrated on sRGB, and Adobe with a  brief excursion through ProPhoto which Adobe use between LightroomTM and PhotoshopTM. Prophoto has a very large gamut, in fact 15% of it cannot be seen with the human eye. More is not always better, as with everything else, more is only useful when you have a need for it. If your image is looking muddy it is far, far more likely that you are viewing the narrower sRGB profile in an image that was modelled in the more defined Adobe RBG than the straight forward “fault” of the more limited spectrum. Most people cannot tell the difference most of the time. The gamut of any two profiles will have colours in common but when comparing sRGB and Adobe RBG the number of shades that can be represented between two points of saturation. What the smaller gamut will produce is an approximation of the colour defined in the larger one and necessarily, it will be different. The basis is in the degree of colour gradation that can be shown, that is the number of steps (shades) you can produce in the transition between two (complimentary) colours on the colour wheel. Just for the record the “small” sRGB colour space has 16,777,216 (256 for each of the RGB channels) colours in it.

 

The most likely time you will see the difference is when you print a digital image. Printer manufacturers have their own profiles and these are usually pretty easy to get hold of – unlike the Linux version of Adobe which seems to have disappeared from their website. These can then be loaded into your editor, the internet will show you how for your programme if you don’t know. Paper manufacturers also have different profiles for their papers and the respective manufacturers web sites are the best places to start with this. What this means is that if you are sending off your treasured image to be printed then you get a heads up on what the final thing will look like through your editing programme. It can change quite a bit, for example, an early morning mist shot I took yesterday, an almost golden light, when reviewed via a Fuji printer ICC profile downloaded from the print shop, showed some of the shadows moving from an almost dark chocolate to cyan – the valley opposite had oxidised! It also saves you time and money when printing at home, and quality inkjet ink is not cheap and cheap inkjet ink can quite often look it, especially on a quality photo paper.

 

Rich, when he started his presentation, stated that there is an important factor to be taken into consideration when we are talking about colour space, which can easily be overlooked and comes to us from the familiar colour wheel. Colour space is three dimensional, whereas the colour wheel as most of us remember it is two dimensional. The three dimensions are hue, saturation and lightness aka HSL aka HSV (v – value) and they form the backbone of all image editing software. What we are doing when we edit is navigating our way around this space, forwards, backwards, side to side and up and down and in a combination of these three. That gives us a clue that there are work flow questions to be answered here. Work flow in itself is a whole separate blog and we will return to that sometime in the future, but essentially it is all the production, administration and physical actions it takes to complete a process. There are many different forms of workflow, probably as many as there are photographers practising, but, when it comes to colour space there are some basics worth heeding – not least the effect your monitor is having on the images you are viewing and the accuracy and compatibility of colours when your image meets other devices. The club has a device for calibrating monitors which is available to borrow to club members. Ask about it at a meeting if you want to know more.

 

The second half of the meeting was a practical and members were busily engaged in the delights of LightroomTM and PhotoshopTM and there were more than a few “Aha!” moments. So, our thanks to Rich for his time and energy in putting this together. Next meeting is our own Adrian Cooke who will be talking us through a selection of his images.

 

Next meeting is also the deadline for Deadline for “Dear Reflex…” questions      “Dear Reflex…” is a question and answer session where club members can ask any photography-related questions of the club. These will later be presented to members who will have the opportunity to volunteer to answer them, and given time to present their answer.

 

See you Thursday!