Getting sharp focus

  • peter sharland
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10 years 1 month ago #5925 by peter sharland
peter sharland created the topic: Getting sharp focus
Hi guys

Being new to digital photography, I am still trying to master the technique of achieving sharp focus with my Pentax 75-300 zoom, particularly when on maximum zoom. Can I get get better results by only zooming to 200 mm when taking the shot, and then using the zoom facility on the post-processor?

Any advice will be much appreciated.

Regards
Peter Sharland

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10 years 1 month ago #5927 by gordon
gordon replied the topic:
Hi Peter,

Sharp focus depends on several factors, environmental, equipment and your settings.
Our lenses are very good for the price but we need to use perfect settings on our camera's to get anywhere near what a 300mm F2.8 prime lens would achieve.

I am not sure which camera body you are using? (presumably either the K100D or the K10D?)

For the K10D users, I normally use aperture priority with the camera set to F8.0 sometimes going down to F7.1 or lower in low light conditions. Sometimes if the subject is very close and there is a lot of bright glary light I will set the camera on F9.0 to expand my depth of field and try to bring out more colour. Recently I have learnt how to use the white balance. In fact I would go as far to say that this seems to be the most critical setting on the K10D. So far I have managed to get some fairly decent shots using the bright sunlight setting as opposed to using the auto function. If you look at the my pictures of the plover on her nest at Marievale, this was prior to me discovering the white balance feature. Note that the images are all washed out with a blue/white "haze". This extra noise affects the sharpness of the picture as well.

Depending on the shot I also use post processing to sharpen the images. Particularly if the picture was shot in very bright light. Our lenses tend to get a very soft image on maximum zoom in harsh light. You will soon learn when to take a shot, for example the golden hour after sun up, or taking all your shots with the light source behind you, cloudy weather is also good.

I am sure Doug can respond on how he uses he K100D.

Hope this helps.

Cheers,
Gordon

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10 years 1 month ago #5928 by Doug
Doug replied the topic:
Hi Peter.

I have also found that when you use an entry level zoom lense like the 75-300 pentax, it is generally noy much use over 200mm. The firt and most important thing is to get as close as you possibly can to the subject. In fact my best ever shot, the Cape Rockjumper, was shot less than 3 meters from the bird on 90mm.

Secondly, even with the top end lenses, they all say that they get a little soft when the apperture is wide open. For that reason most photographers will stop down a bit. That means on an F2.8, shoot at F4 or higher and on a an F4, shhot at F5.6 or higher. The end result is that lenses like the 75-300, shooting at anything lower than F8.0 will almost never work well at all. You are pretty much restricted to F8.0 up to 200mm for good results.

Also as Gordon said, light is crucial. I was at Rooiwal and shooting in bright harsh midday light. Even on pictures at low focal lengths (150mm or less) the flaring etc is bad.

You need to concentrate on early mornings and overcats days are also good as they soften the light.

I know when you go to Marievale and watch the guys from Outdoor photo, they often have 500mm ED canon lenses and EOS 1D cameras - top end stuff and come 9/10 am when the light starts getting harsh they don't even bother to photograph after that and they pack up an go home.

Finally when it comes to post processing, this is just as important. Even the top photographers with top end gear also apply post processing including sharpening the image afterwards.

In short you need to:
1) Work within the limitations of the lens
2) Shoot in the right light conditions
3) Post processing is the modern equivalent of a darkroom.

good luck and welcome to the marriage-ending past time of digital photography! <!-- s:lol: --><img src="{SMILIES_PATH}/icon_lol.gif" alt=":lol:" title="Laughing" /><!-- s:lol: -->

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  • peter sharland
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10 years 1 month ago #5933 by peter sharland
peter sharland replied the topic:
Thanks, guys. for all the tips from the experts! :)

I already have tried many marriage-breaking pastimes, but my better half is still very much my better half......

I'm certainly looking forward to trying out the tips.

Best regards
Peter

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