Howdy
Once again I did some 50mm lens work, sitting the uv/ir and UHCS filters in front of my 50mm lens.
2x5 mins ISO 800, 50mm F4, in camera N/R on, RAW converted to Tiff, then stacked and processed in Phtooshop. Gee the filters make the nebulae stand out
Scott
It needs some flats....can really notice the vingetting...but otherwise not to bad...but I'm only saying this now because your standards and expectaitions are so high now Scott.
thanks all
getting a flat field over a wide area is tough, as the bottom of the frame is in brighter light pollution than the top. I think also the filter is sensite to angle of incidence, so light coming in from the sides is altered differently than light in the middle which hits the filter at right angles.
Scott
thanks all
getting a flat field over a wide area is tough, as the bottom of the frame is in brighter light pollution than the top. I think also the filter is sensite to angle of incidence, so light coming in from the sides is altered differently than light in the middle which hits the filter at right angles.
Scott
Hi Scott,
Although I agree that much of the gradient in your shot is from LP, there also appears to be a degree of vignetting. How I deal with this is to make up a master flat by placing a white tissue over the lens and taking about a dozen shots in "P" mode. Applying these flats does make a difference to widefields. Of course there is still the LP gradient to deal with.
I put your jpeg through a little program called ABE. It did a reasonable job of removing the gradients. After that I readjusted the levels. I had to make a slight adjustment to the colour balance in the top left and this is the result:
