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Old May 31, 2005, 10:08 AM   #1
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Hi All,

My first post, so please be gentle. I decided to take the plunge into the digital slr world and have just purchased the *istds rather than either the d70 or EOS350D after much information gathering and actually holding and using the cameras. The Pentax impressed. BUT, I have a nagging question re the sharpness of the *istds jpg files at 6MP and highest quality (apologies for the following long post). Out of interest I ran some comparisons with my 4MP Nikon Coolpix 4100 with approx. the same field of view on various subjects. Always the 4100 jpg output was much sharper and have noticed from previous posts in this forum that this may be the case without some post-processing of the Pentax jpgs. However, I've just noticed that the Pentax jpgs are only 72 ppi as compared to 300 ppi for the Nikon files. I also took some RAW images of the same subjects and noticed in RawShooter that I'm only able to convert to 8bit jpgs - these jpgs are noticeably inferior to the Nikon images re detail at various magnifications. It's only when I convert these same RAW images to 16bit 300ppi TIF files that I can get similar or slightly improved detail to the supposedly 'inferior' 4MP jpgs of the Nikon. I understand that most monitors are only good for 72 ppi but why the difference and does anyone know why the Pentax only apparently stores jpgs at 8bit quality and at 72ppi? I've looked in the manual and on the Pentax web site, but have been unable to find any further info. I've enclosed a screenshot of the pentax (on the left) vs the nikon (on the right) - hopefully it comes out. To my eye there appears to be more detail in the mottling of the tree trunk in the Nikon photo. Any help, advice would be much appreciated.

Cheers
Alan
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Old May 31, 2005, 11:02 AM   #2
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Only 8 bit? That doesnt make sense, i thought jpegs were 24bit. Yeh, i found it wierd that they are only 72 dpi, i got some shots done with a canon 10d they were only 150dpi.

However, with only the 72dpi and 6mp i decided to get an A1 print done. Suprised myself, and the shop guys, came out better than expected - you can only really see flaws (like seeing pixels) if you look really close, from a short distance that you'd normally look you would notice anything wrong with it.
My 6x4 prints come out beautiful - i get them done at the minilab for 33c each (AUS) and anything larger i print on my uncles Canon i9950 printer - upto borderless A3, and i cant tell the difference from a lab print.

But as far as the jpg sharpness goes, i dont find any problem with mine in jpg. I cant be bothered shooting RAW because i have only a 256mb card and cant be assed converting each one all the time. Maybe one day ill start using raw.
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Old May 31, 2005, 11:03 AM   #3
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Consumer digicams such as your Nikon are set to apply much more in-camera processing, intentionally,than are dslr's. The consensus as far as the istDs goes is the following settings:

Tone: Natural. The Bright setting punches up the colors at the expense of sharpness.

Quality: 6MP ***jpg.

Contrast & Saturation: 0

Sharpness: 1 (perhaps 2).

Avoid the picture mode settings on the Mode dial as they all default to the Bright tone setting and cannot be changed. The Raw setting applies no processing no matter what the camera is set to, so the picture modes are OK when shooting RAW.

Read this for a whole lot of discussion on this topic:

http://forums.dpreview.com/forums/re...hread=13647345

Lou


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Old Jun 1, 2005, 10:16 AM   #4
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Lou/Errno,

Thanks for the feedback. Still puzzled by the in-camera jpg processing though. Guess i was a bit deflated that there appeared to be not much difference between P&S and dslr after having coughed up the dosh for the istds, but things like better colour saturation, lower noise levels and general 'pizzaz' more than make up - so on the sharpness issue I'll move on and start taking some piccies.

Cheers
Alan
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Old Jun 1, 2005, 12:16 PM   #5
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Also, you make no mention od which lens you're using, but the 18-55 mm kit lens is considered soft at any focal length above 18 mm. Try reshooting your test at that setting, moving toward the tree to get the same field of view and see if there is any improvement. There are many sharper lenses on ebay, cheap. Just last week I picked up a Pentax A 50 mm f/1.7 for $31. The backward compatability of the Pentax system is a very nice fringe benefit.

Lou
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Old Jun 1, 2005, 1:49 PM   #6
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albo wrote:
Quote:
Lou/Errno,

Thanks for the feedback. Still puzzled by the in-camera jpg processing though. Guess i was a bit deflated that there appeared to be not much difference between P&S and dslr after having coughed up the dosh for the istds, but things like better colour saturation, lower noise levels and general 'pizzaz' more than make up - so on the sharpness issue I'll move on and start taking some piccies.

Cheers
Alan
It's seems strange that when you pay a lot more for dSRL, you have to do more work to get similar results in terms of sharpness, saturation & contrast as from a P&S camera.

I poured over reviews of many cameras & rejected many, including dSRLs, because the review shots were dull lookingslightly 'blurred'. It was through these forums that I learnt that P&S cameras perform a lot more 'in camera' processing to produce a more immediately pleasing result; the downside to this is that the general algorithm applied is not necessarily correct for all situations & it becomes difficult - perhaps impossible - to correct for these results i.e. you can't remove sharpness once it's been added internally.

More upmarket Prosumer cameras (Minolta A200, A2) leave much of the internal processing just like dSRLs leaving the user to apply whatever level of correction is preferred - what's good for me, may not be for you.

I personally like the JPEG output. It doesn't take too much effort on my part to adjust the overall brightness using the histogram function to tweak both ends & the middle and applying a slight amount of UnSharpMask to sharpen up the picture.

Whilst RAW does produce better results & it's pretty near impossible to mess up the image during image capture, I find it difficult to get the correct amount of 'everything' even using PS2 & RAW ACR3.1

Not necessarily the best subject to view this comparison, but it does show what I mean:

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Old Jun 1, 2005, 9:42 PM   #7
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Also, try using a tripod. Maybe you are getting a little bit of camera shake
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Old Jun 1, 2005, 10:07 PM   #8
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This photo is shot in jpg and seems quite sharp to me and is much nicer than my 4 Mega Pixel Nikon point and shoot will put out.



Tom
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