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03-05-2010, 05:27 PM   #1
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Sharpness, or not...

I searched and didn't find exactly what I was looking for, so I thought I would ask...

I have a K7, and have bought about a dozen lenses since I bought the camera back in November. Mostly old lenses heralded here, and some new and old from ebay, and even a couple at garage sales and Pawn Shops.

I have a really interesting lens I got for five bucks (with a camera) from a garage sale. It is a 55mm f1.9 Asahi lens. It has ten aperture blades, is very small, and in excellent shape. The filter size is 46mm, and it has a lever for opening the aperture before each shot (to focus I assume), and a 'paddle' in the camera pressed the post to release the aperture to it's appropriate setting when the shutter release is pressed.

The problem I'm having is sharpness. I have done some test shots, repeated the same shot with numerous lenses, and they all seem to be about the same. When I zoom in with the camera, or in picasa/photoshop, the edges seem fuzzy.

Am I asking too much from the technology? I have a few shots from my brother-in-law's Canon 50d, and they look about the same when zoomed in, maybe a bit sharper. I love the K7, and don't care that much about it's low iso/low light capability, but I don't want to compromise on the sharpness of my pictures.

If I'm getting what everyone else is getting, the best the camera will do, I'm happy. If I need better glass, fine. If it's me doing something wrong, I'll accept that and learn. I know that sharpness could be an issue, as Pentax added a 'Fine Sharpness' level 2 in a firmware update.

What do you guys do? The Think Tank here seems to be without equal. I've received a lot of great information in the short time I've been a member, and as always I'm grateful. The photo's here are amazing, and I would like to do what all of you seem to be able to do. What Sharpness level do you use? Do you use portrait, natural or bright? What ISO do you shoot for?

I researched MTF as best I could. That's the 'Program Line' setting I use with Auto Lenses. When using a Takumar or Manual lens, I try to set between f5.6 and f13, striving for f8 when possible.

I can upload some pictures so you can look at the sharpness yourselves if you wouldn't mind. I'm not exactly sure how to do that so that you will have an 'original' to work with, so please tell me how to do that if you're interested.

Thanks

03-05-2010, 05:48 PM   #2
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If I understand you right, you have what amount to what I call glowing edges. That is, everything seems in focus but the outer edges appear smeared.

First of all, I wouldn't rely on the camera screen to evaluate anything but basic information. Even as good as the K7 LCD is, it can lie to you.

Second, I would make sure that the camera isn't adding any processing (sat, contrast, etc), set them all to 0.

Third, Shoot RAW+ so you can really see what's going on. I don't know what if anything Picasa does to images but if you are evaluating camera / lens performance I think you should actually have the full unprocessed image.

Fourth, Aim for a little bit of Underexposure. What I Really think is going on, is that you're slightly over-exposing the photos. I once thought All of my lenses and cameras were bad because I kept getting blurry edges. Turns out, I was just washing things out with too much flash and over-exposure in general.

Yes, some photos would help. With a Takumar lens (M42?) you should be able to get tack sharp images.

03-05-2010, 06:06 PM   #3
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JeffJS,
I'll take a look at that...

I should've uploaded pics, so I will do that later tonight or tomorrow.

Thanks...
03-05-2010, 09:47 PM   #4
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It might be an uncoated lens. You might be asking too much of it. The K7 is not an easy camera for older lenses that may be past their prime, so to speak.

03-05-2010, 09:47 PM   #5
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pictures would really help here. Are you using the same lenses on the canon and the pentax? older uncoated lenses have some issues depending on lighting conditions.
03-06-2010, 07:49 AM   #6
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southy, I will upload several to show what I mean, but I don't want to overload anyone's computer with several raw files. How does everyone upload photo's here? Is there a special technique, or do you just attach a file from your hard drive? Do I resize them? CAN I upload a raw file?

Thanks
03-06-2010, 07:53 AM   #7
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QuoteOriginally posted by Snydly Quote
southy, I will upload several to show what I mean, but I don't want to overload anyone's computer with several raw files. How does everyone upload photo's here? Is there a special technique, or do you just attach a file from your hard drive? Do I resize them? CAN I upload a raw file?

Thanks
A lot of people use flickr to upload them then you can paste the image link here using [img] tags.
03-06-2010, 09:45 AM   #8
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Resize to decent filesize (max around 500k, lower like 100k is better). If necessary, make a crop of a specific area of interest to show what you mean. Oh ja, obviously not RAW.

I usually open an private album here or upload them to my own website and link them in the post (there is a little icon when creating a post (even in the quick reply) that allows you to link. It asks you for the URL of the image.

03-06-2010, 09:23 PM   #9
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If you're trying to demonstrate something abut sharpness, resized images won't be very useful. Instead, cro out a small section *without* resizing. Maybe also post a resized image. You can upload directly whileposting your image, or uplaod to Flickr or somewhere else first than post a link.

I'd also suggest osting images from the Canon that are allegdly just as sharp if not sharper whn zoomed in. That's impossible.
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