Weird colour distortions when using an old lens

Hello,

Recently I purchased a cheapy old Chinon 50mm 1.7 on ebay and have been playing around with it. It's a great lens and I wanted to learn more about manual photography before I invest in more expensive lenses, since I quite nooby at photography.
The photos i've been getting are great, but i've noticed some weird colour distortions when doing night photography where lighting is particularly harsh. This is best expressed in this photo (its been compressed a bit, but you can see whats wrong, the lights on the boat show up in a harsh blue tint):

[IMG]http://img535.imageshack.us/img535/2974/igp3203.jpg[/IMG]

I suppose an even better example would be this:

[IMG]http://img825.imageshack.us/img825/445/igp3209.jpg[/IMG]

Hi Amama. Have you tried taking a similar scene with your 18-55 at all? - to see if you get the same outcome? I think there may be a couple of contributing factors - the first is that a lot of the lights around there are in fact bluish - especially around the London Eye, and that gets reflected on all the water etc... My guess is that the blue tint on the left side of the boat in the foreground of pic 1 is caused by reflections of the blue lights on the London Eye on the opposite side of the river. The 'white' lights hanging along the edge of the embankment in the background look more or less white... Secondly the white balance setting in the camera can be adjusted either before shooting or (if you shoot RAW), after - it might be worth having a play with that to see if you end up with a result which you are happier with. Finally, if you are shooting JEG and have PSE or similar, there is a tool which enables the removal of a colour cast which you can also try and see what happens:

Hope that helps

I have a Chinon 50mm F1.9 and it is superb. It is very sharp, renders colours superbly and does not display any of the colour aberrations seen here. I suspect these may be caused by processing; do you save your jpegs at 100% quality, or does your software apply compression? The colour stepping on the first one looks typical of a compressed jpeg to me.

Regards
David