Quote:
Originally Posted by JA
Hi Alex,
Good on you for getting out there with a nice result 
There are a few ways to get rid of the vignetting: - Flat frames
- Adjust the exposure in specific areas of the image in Photoshop
- Dodge/Burn in Photoshop(your mehod)
- Vignetting correction in Photoshop
- Lens correction in Photoshop
- Lens correction in Camera either for specific Nikon recognised lenses or general correction other lenses from Min to max
Of course flat frames are the most complete method as they handle your specific lens's characteristics in terms of vignetting and dust spots, BUT if you want a simpler / easier ride that corrects for the vignetting and other lens distortions then you should consider using Lens corrections in Photoshop. Photoshop recognises many lenses and can correct for their distortion, vignetting and somewhat correct for some chromatic abberation using Lens profiles for most lenses. I checked and your Nikon 18-55mm AF-P VR lens profile is listed in Photoshop CC2017. To employ lens profiles, open Photoshop, select and drag in your images to the Photoshop work space, whereupon an Adobe Raw Panel will open with the multiple images shown. You then select the Lens Icon (the 6th icon in the list in the TOP RIGHT) and CHECK "Remove Chromatic Abberation" and CHECK "Enable profile Corrections". Your lens may come up automatically or your can select it manually from a Maker's lens list. This change is made for the selected image you can then apply it to all your image set using the synchronise function. Try it - A Lazy No Flats method that does more than flats do, except for removing handling dust spots.
I will link to a great video by Tony Hallas which shows the method as well as other astro techniques and equipment.
It's an OLD video from 2014 and Adobe Raw is now a part of Photoshop so it looks different and lens corrections by maker and lens model are now included for most lenses, rather than the simple "vignetting correction" control shown in the video.
Watch the whole thing or go from the 12:40 minute mark for processing in Adobe Raw. https://youtu.be/PZoCJBLAYEs
Best
JA |
Thanks you so much for taking your time to help me. I do appreciate it and believe me I do not take it for granted.
I tried to use the lens we were discussing and although I could manually focus when I took the photo it was really way out of focus..I can't explain what happened and admittedly I did not even try to work out what was going wrong as I changed immediately to my little 50 mm lens which is another cheapie..because I knew I had a window of clear sky that would not last...the lens we discussed is the one I would like to use as the shorter the focal length the better for this static tripod thing obviously but I just love getting in as much Milky Way as possible.
I suspect that even having manually focused with the lens we talked about ( and things looked good on screen blown up nice and sharp) the camera at some point tries to refocus...I suspect..unless I bumped it which I will look to next time I try...and it may be crude but if I get another chance I will blue tack the focuser ring once focused..now the camera may not work until it has its way with focus but its behaviour will identify that issue...
Thanks again I am looking forward to watching the video.
Alex