Optomax 200/4.5

TedHarris · Joined: 10 Sep 2014 Posts: 23 Location: Manchester UK

Picked up a T2 mount version this week and have been giving it a tryout on the 5D3. I'm noticing the image is brighter and soft in the centre at f22, the effect diminishes as the aperture is opened. Not seen this before in a lens, any suggestions?

[img] http://i3.photobucket.com/albums/y94/TH-Photos/7L2A0494a_zpsthol2nel.jpg [/img]

Lloydy · Expire: 2022-01-01

I suspect you're pushing your luck with this lens Ted, have you got a deep hood on it? and it's probably at it's best mid range to maybe one stop away from wide open.

Oldhand · Posted: Sun Jan 25, 2015 11:04 am Post subject:

I had an early Komura that did this.
It was better wide open than at any other aperture as far as the hot spot in the centre was concerned.
A large and deep lens hood helped a little but did not cure it.
It most likely was the result of internal reflections and the uncoated glass.
I tried everything that I could think of to cure it but eventually gave up and sold it.
OH

TedHarris · Joined: 10 Sep 2014 Posts: 23 Location: Manchester UK

Thanks for the replies I'll have ago at making a hood and see if that improves the images. I photographed a black post against the sky looking for fringing only to find none, was impressed by that.

TedHarris · Joined: 10 Sep 2014 Posts: 23 Location: Manchester UK

I've tried using a deep hood and photographing a bland subject with no highlights. The brighter centre spot remains at all apertures other than wide open, so as Oldhand says it is probably down to uncoated lens elements and reflections. I thought about fixing a 40.5 coated sky or UV filter in the T2 mount to see if that would absorb reflections from the sensor, but there was no quick way of doing this that wouldn't foul the mirror so that experiment is on hold until I can find a way of holding the filter glass in place.