Wed 28-Nov-12 12:24 AM | edited Wed 28-Nov-12 12:33 AM by tincam7
I am stuck with my D5000 for now, although I want to upgrade to a D600 , but in the meantime I am trying to be productive in getting better equipment (I cannot afford a better lens currently) to help me make better images of birds, and at the same time be able to use the equipment to its full potential when I eventually get the D600. I just started using an old Rokunar 2x teleconverter (that I forgot I had) with my AF 300 f/4, so effectively 900mm. But I noticed that I am getting an increased amount of chromatic aberration on the images. Is this simply due to the poor quality of the teleconverter? I soon will have a Kenko 1.4x DGX teleconverter, but is there anything I can do in the meantime to increase IQ? Any suggestions for this lens and camera combo would be helpful.
I am posting a shot I took today, just trying out the combo for the first time. I tend to shoot wide open, but when I noticed the aberrations I switched to f/5.6 and I think once or twice f/8 (It was a cloudy day today).
I normally do not see as much chromatic aberration as I was seeing today.
I'm surprised it's even that good. Count your "blessings." Most old 2x TCs are quite a bit worse than this. You can try using post processing software, but I wouldn't hold out that much hope as this is rather more CA than I usually am able to get rid of, at least with LR4.2.
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!
You have a couple things going against you in this photo. First the very high contrast coupled with the out of focus twigs are taxing for most lenses. That's worse case for lateral CA's. Your attempt to stop down will certainly help. The problem is not the TC but more the prime lens. I've tested the AF 300mm/f4 versus the AFS 300mm/f4 and the newer lens is much better than the older lens but CA's are still visible. I see you shoot raw. The built in camera CA distortion control is very good and will remove most of it if you use CNX2. I don't have Light Room so I don't know how that handles imbedded controls but CS5 won't when in raw.
Actually I think your photo is pretty good. I've seen much worse under those conditions. It's just one of the problems you run into when birding. And against a bright background.