Cell Phone & Christmas Lights

[aakash_vakil]

Hello All !!

Wishing you all a very happy new year :-)

This is more of a 'tell me why' post.

I wanted to test the effect of out of focus diwali / christmas lights using the 50mm 1.8 @ 1.8.

I expected a clear 5 blade display for these out of focus lights, but got almost circular effect. The distance was around 4 feet from the lights.

Please help me understand why it came out to be circular when I had read that this kind of effect will be possible with the more expensive 50mm 1.4 or 1.2.

C&C too appreciated :-)

Regards,
Aakash

[tomw]

Wow that is wierd. I've never experienced that with my 50

[wulf]

Short answer: I don't know.

Longer answer (which involves you doing some work): you need to do some more investigation. What happens to the bokeh (patterns formed by very out of focus lights) as you step up through the apertures? As long as the lights are a fair distance from the point of focus you should be make several steps before the depth of field becomes too great. Also, what difference do you get as the lights move further away from the point of focus at a given aperture?

It won't necessarily answer why but performing such experiments will certainly help you learn what to expect from your equipment.

Wulf

[aakash_vakil]

Wulf, Thank You for the suggestion. I will try that and publish my findings.

[kunaldaswani]

Might not answer your question, but a interesting read.

http://photoscape.co.in/blog/posts/7

[aakash_vakil]

Hi Kunal -

Nicely written entry in there. I picked up the same technique from DIYP and here is the result.



As Wulf suggested, I am going to do some research on the blur shape without any cutout and see the effect.

Regards,
Aakash

[aakash_vakil]

I believe this is answering my question...very nicely explained the difference between 3 50mm lenses - f/1.0L, f/1.4 and f/1.8 along with pictures to explain the visual difference.

http://www.wlcastleman.com/equip/rev...okeh/bokeh.htm

Regards,
Aakash

[wulf]

A good find - looks like he has done your homework for you

However, it is worth taking time to do your own experiments as well. It is much easier to learn by doing than by glancing over the results of someone elses work.

Wulf

[aakash_vakil]

You bet. In this, he has kept the camera-subject distance static and played around with the f/stops. I will try and see the results when I keep the f/stop constant but change the distance of subject to camera.

Regards,
Aakash

[albert.cantaloupe]

The nifty fifty has really good bokeh alright.

Here is picture i did yesterday:


Well I hope you solve your dilemma.

Happy New Years!!!