Tack sharp/ or my never ending search for tips

digicammad (e2 Member)

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29 Sep 2011 - 10:28 AM

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There is no reason you shouldn't be able to get it pin sharp. Things to look for are:

- is your lens image stabilised? If so make sure it is turned off when on a tripod

- what aperture are you using? The bigger the number the bigger the depth of field (area of sharpness). Another rule of thumb is that the closer you are to your subject the smaller the depth of field, so for your bowl of fruit you would need a larger depth of field to get it all in focus than say a car 20 feet away.

- where are you focussing? It may be that the shot is in focus, just not where you expect it to be

- aperture again. Unless you have spent megabucks on your lens it will have a sweet spot a couple of stops from either end. So if you are using it on f22 you will probably see soft'ish results.

- how sturdy is your tripod?

- are you shooting raw or jpeg? If raw then the photo will need sharpening and if jpeg what settings do you have on the camera?

Hope some of this helps.

Ian

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cameracat (e2 Member)

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29 Sep 2011 - 11:21 AM

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Quote: Interesting. I always use 100% when sharpening for screen and 50% for print. After all people will be seeing it at 100% on screen.

That is and has been debated a number of times, Some swear you need to view at 100% some half that much.

Cole has it spot on, If your viewing an EPZ sized image at 100% no problem, But when your viewing a full size image at 100% Things change, 50% to 60% max for evaluating print sharpness, No more than 80% for screen sharpening as this is generally a much lower sharpen level, Try sharpening something for print, Then you'll see its way oversharpened for screen use, A very common mistake by many, Always worse when its something " Hairy " or " Furry " or " Feathered " .....LOL.... Clouds don't look that good sharp either....!!!

But I diverse, Because most of the previous suggestions are all good and at least some options to look into.....

Here are a couple of extra items, First the " Aperture " be very very carefull with regard to using small apertures for greater depth of field....? ? ?

Why.. All lens types no matter what brand or cost ( Yes even the mega bucks versions ) Will suffer from something called " Refraction " at some point in their aperture range....!

Very small apertures like f/22 will give you DOF, But the price you are paying is " Lack Of Sharpness " due to refraction, Hence aperture choice is a balancing act between subject and your intentions, This is one of the reasons many " Macro " ( especially those superb images we see on EPZ ) are done using the " Focus Stacking " technique.

Next not all lens are equal, But they all suffer from refraction softness, What you need to do is find the aperture that your lens is best at, As a rule of thumb it will be around the middle of their range, That often winds up at somewhere between f/8 & f/16, Once you know the sweet spot for your particular lens, You can use it to best advantage....After that its all the other rules & tips as mentioned already......

The last little thing that " Often " gets overlooked is your " Monitor/Display " some are lots better than others for evaluating image quality, A higher native resolution will give you a better view of detail as well as colour, For the really keen I would say a minimum in 4/3 format would be 1600 X 1200, For the widescreen toys at least HD, Though higher is better.....

Whatever, Some older screens are absolutely awful, The newer items are better, But look at the options in the monitor settings, Some have a sharpness option, That might need adjusting to taste, Go carefull though to much and its worse than non at all, By monitor settings I mean the OSD not the computers own display options, Thats something completely different.

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mikehit (e2 Member)

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29 Sep 2011 - 11:45 AM

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It may help to manually focus instead of using AF.
Choose a nice contrasty subject such as printed page (magazine, not newspaper because when seen really close up the edges of letters on newsppers is not all that distinct). Use a solid tripod (not gorillapod), good sturdy tripod head and shoot RAW/JPEG. See how sharp you can get it when processing the RAW image and compare this to your JPEG.
All this will show you what your camera is capable of doing (including whether sharpness is constant over the whole frame) and giev you confidence later on when judging your shots.
As has been said, looking at an image at 100% on screen is like looking at a 4-foot print from 12" - it will never be sharp.

You can use an on-line calculator ( http://www.dofmaster.com/dofjs.html ) to predict not only DOF but also where you need to focus to get both front and back acceptably sharp.

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adrian_w

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29 Sep 2011 - 11:50 AM

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Looking at your image, it is sharp in the foreground and the front of the bowl. It starts to fall away a little at the red apple, and the banana at the back is out of focus. I think your main problem is you have focussed to near the front and used a shallow depth of field at f4. Had you focussed on the red apple I think the bowl & fruit would have all been sharp at the expense of the cloth in the foreground.

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Coleslaw (e2 Member)

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29 Sep 2011 - 11:51 AM

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That photo looks sharp to me, but probably not at the area you wanted, as the table cloth looks sharper and the DOF falls off half way through.
How do you do your focusing?

Oops too late, Adrian was faster.

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davey_griffo (e2 Member)

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29 Sep 2011 - 1:15 PM

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Another thing to consider when doing close-up work (rather than macro), is the minimum focus distance of your lens. If you are inside of it, then no amount of focusing/f-stop/software sharpening jiggery-pokery is going to work. If you do a lot of close up/macro, you may wish to consider a macro lens, as it'll let you get much closer to your subject.

For the shot posted, if you used a macro lens or adaptor, you are ok, & it probably is a focus problem. But if it was your standard kit lens, it may only focus down to 40 or 50 cms, in which case you may be closer, & that'll be your problem. I doubt that though, since as Cole says, your tablecloth looks sharp.

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