DPNow Picture of the day, Thursday, August 23rd 2007

[DPNow]

Charles Annen, who goes by the user name of changeling on the DPNow discusssion forum and galleries, excels in photographing the wildlife on the west coast of the USA. Earlier in the year we featured his shot of northern elephant seals on Picture of the Day (POTD). This time it's the turn of the Western Brown Pelican (Pelecanus occidentalis californicus), mischievously re-named 'Pterodactyl' in his gallery. Would you like to show your photos on DPNow's free gallery space and get a chance of being featured on the Picture of the Day feature? Just register on the forum and your gallery space will be instantly available.

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[Pops]

Re: DPNow Picture of the day, Thursday, August 23rd 2007

That pelican looks like it is flying out of the screen. A superb capture indeed

[Pol]

Re: DPNow Picture of the day, Thursday, August 23rd 2007

A truly outstanding capture! Excellent stuff - I love everything about this wonderful shot.

Pol

[Ian]

Re: DPNow Picture of the day, Thursday, August 23rd 2007

A truly outstanding capture! Excellent stuff - I love everything about this wonderful shot.

Pol

Consider also that the lens is operating at f/4 - its maximum aperture considering it's down a stop from f/2.8 because of the use of the EC-14 1.4x converter. This like using a 840mm f/4 tele... It's pin-sharp, but the depth of field would have been absolutely paper thin, so Charles did a fantastic job of getting the shot right. And the bokeh of the defocussed background is pretty good too.

Ian

[Pol]

Re: DPNow Picture of the day, Thursday, August 23rd 2007

Consider also that the lens is operating at f/4 - its maximum aperture considering it's down a stop from f/2.8 because of the use of the EC-14 1.4x converter. This like using a 840mm f/4 tele... It's pin-sharp, but the depth of field would have been absolutely paper thin, so Charles did a fantastic job of getting the shot right. And the bokeh of the defocussed background is pretty good too.

Ian

Oh I did, I did consider all that ...... and I went green with envy and stayed green.

Pol

[lumix]

Re: DPNow Picture of the day, Thursday, August 23rd 2007

Consider also that the lens is operating at f/4 - its maximum aperture considering it's down a stop from f/2.8 because of the use of the EC-14 1.4x converter. This like using a 840mm f/4 tele... It's pin-sharp, but the depth of field would have been absolutely paper thin, so Charles did a fantastic job of getting the shot right. And the bokeh of the defocussed background is pretty good too.

Ian

Not being too clever with all this technology. Does a teleconverter really alter the DOF of a lens. I can't see that it does. My thoughts are that the converter only magnifies the image that has passed through the lens. So could someone explain how it works.

[Jocelyn Walker]

Re: DPNow Picture of the day, Thursday, August 23rd 2007

I wouldn't know how a converter works, or know what bokeh means...but a marvellous job of capturing the peli in flight has been attained! I tried to get pics of pelis in flight & the couple I managed were pitifull! Did you pan the camera, whilst using a tripod or was it handheld shot?

[Ian]

Re: DPNow Picture of the day, Thursday, August 23rd 2007

Not being too clever with all this technology. Does a teleconverter really alter the DOF of a lens. I can't see that it does. My thoughts are that the converter only magnifies the image that has passed through the lens. So could someone explain how it works.

In this sense I was emphasising the point that the lens was wide open and so the DOF for such a long lens would be just a few inches.

DOF is also determined by focal length, so the converter would have some effect but the maximun aperture is reduced, so that may have canceled it out.

Quite by coincidence, I'm getting a 1.4x converter to try out so I will try to remember to answer your question from a practical experiment!

Ian

[Ian]

Re: DPNow Picture of the day, Thursday, August 23rd 2007

Hi Joecelyn, a tele converter is a lens unit that fits inbetween another lens and the camera body (we're talking SLR cameras here ). It has the effect of increasing the focal length of the original lens while maintaining its ability to focus to infinity. The cost is in the brightness of the image projected by the lens through the converter and a 1.4x converter reduces the brightness by one stop (-1 EV).

Bokeh is the quality of out of focus region of an image, usually referring to the background blur in telephoto shots. It especially refers to blurred points of brightness. Poor bokeh results in geometric shapes that are formed by the edges of the iris blades inside the lens. Better bokeh sees these points being near or actually circular. More blades in the iris of the lens leads to better bokeh.

Ian

[Patrick]

Re: DPNow Picture of the day, Thursday, August 23rd 2007

Lenses of smaller aperture can loose auto focus as the light reduction can be too great

For example f2.8 with a 1x4 converter the aperture becomes f4 and with the 2x f5.6.
So if the lens is f4 to start with 2x converter becomes f8

Getting past f5.6 is the point auto focus can struggle.

I own both a Sigma 1x4 and a 2x with my Sigma 70-200 f2.8.

The 70-400 I used to own wouldn't auto focus with the 2x converter, but my 70-200 f2.8 will retain auto focus be it more slowly even with the two converters attached at the same time despite the lens becoming f8.
That did surprise me.

Patrick