I have just begun to use lens filters on the Sony 70-350 telephoto lens. I currently have:
K&F Nano X Series CPL MRC 67 mm
K&F ND 1000 Nano X Series CPL MRC 67 mm
K&F ND 64 Nano X Series CPL MRC 67 mm
K&F ND 8 Nano X Series CPL MRC 67 mm
K&F ND 4 Nano X Series CPL MRC 67 mm
This is a probably all I will need.
I bought these filters a few months ago, and promptly forgot about them! I was prompted to use them on one of the AYWMC homework assignments.
A CPL filter is a Circular Polarizer/Linear filter attaches to the front of the lens and reduces glare from reflective surfaces. Reflections are everywhere- off glass, water such as a lake or a puddle, even moisture in the air. Polarized light is made of scattered rays and can reduce the quality of an image. The CPL filters these rays out, creating brighter colours, and a sharper image. It helps creating better contrast and reduce haze. It cannot make a bad composition or a poorly focussed shot a better one though!
How to use- You screw the filter onto the lens. There is an outer ring that you turn to change how light or dark the image is.
When not to use a CPL filter- when the sun is directly behind or in front of you. It is not good in low light, as obviously there is already less light hitting the sensor, and a filter will reduce that light even further.
I am grateful to https://www.youtube.com/watch?v=lOZeRIZfFzQ A.V. with Rodney for his helpful video.
An ND filter is a Neuro Density Filter. It works in the same way polarized sunglasses work on our eyes, managing the amount of light hitting the sensor. This enables slower shutter speeds to be used, which can help if you want to smooth out subjects such as water. They are good for moving subjects such as the sea and clouds. It helps you use a larger aperture in bright light conditions to get better Depth of Field. They are useful when used in bright light, such as mid day. They are useful for reducing the likelihood for overexposing an image.
If there is less light, use a ND filter with less stops, such as ND 8 (3 stops), then if it gets lighter, use a ND 64, or ND 1000 depending on how much the light increases.
To make the best use of an ND 10000 filter you need to use the tripod. I use a two second delay to prevent any camera shake. A low ISO of 100 or 200 is best. Shutter speed from 6 secs to 30 secs.
An ND64 filter reduces the amount of light entering the camera lens by 6 stops,
I decided to try to be systematic in understanding how the ND filters worked. With the Sony 70-350 telephoto lens I used each filter going through the following focal lengths: 70mm, 100mm, 135 mm, 200 mm and 350 mm. ISO was 100 for all images. I adjusted the aperture with each filter to try to maintain EC at 0
My objective was to see how each filter affected light, and the effect it had on water. I have chosen the following to make observations on these areas, and they are unedited. I also tried, with varying degrees of success to manually focus.
The first image is without any filter.
f.11 1/200sec, EC 0
I adjusted the aperture with each filter to try to maintain EC at 0
ND4 f.22 1/15 sec At 70mm
The water already looks quite smooth, at 200mm it looks overly smooth and blown out further into the frame, but less so at the front of the frame. At 350 mm the boats look as if they are on a hard surface!
ND8 f.13/1/15 sec at 70mm
The sea is much smoother than the ND4 filter at the same focal length. There was little variation in the sea until 200 and 350 mm, when it became smooth but uninteresting.
ND64, I preferred the light and the smoothing of the sea much more with this filter. There was also better contrast with the clouds. 70 mm -F.13 3/5 sec
350 mm f/11 4/5 sec
Finally, ND1000. I like this filter most of all. The light is richer, the sea not blown out. 70 mm f.11 4 secs
350 mm f11 6 secs.
This article from B&H is one of the most informative online and I recommend reading it.
I am glad to have started using filters, but equally happy that I spent my first year not using them. I think it has been helpful to figure out how to expose using manual mode and learning about aperture and shutter speed without filters. Now I have started to use them more I can start experimenting but would not want to use them all the time.
Now if I could just figure out why longer focal lengths give a shallower DOF! To be continued……….
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