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04-08-2011, 02:46 PM   #1
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Help! SMC Pentax-F 35-70mm F3.5-4.5

Hello everyone,

I just bought SMC Pentax-F 35-70mm F3.5-4.5 from a Pentax store that sell film Pentax cameras only. It is mounted on an MZ so I thought it was ok, beside testing it on film camera shows that AF is working. However when I mounted it on my K200D at my home, I can't get sharp pictures, no matter what opening I chose. I am not good on shopping second hand lens. I bought it at around US$ 53 with free Hoya filter.

Is there anyone here who can tell me what's possibly causing the blurry pictures? I am planning to disassemble the lens, I just need to buy some precision tools.

TIA,
Lyzan

04-08-2011, 03:09 PM   #2
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I have the same lens - one of the best F series zooms Pentax made! Check to see if it is in the macro setting. In macro mode the lens will not focus at far distances. These zooms have a stiff point that separates the macro mode from the standard mode. Just twist the zoom ring past the 70 mm mark toward the 50 mm mark.
04-08-2011, 08:03 PM   #3
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Follow Mike's advice first. If you're not in macro mode, have you tried focusing manually? This lens - a very good one, BTW - has a thin focus ring on the front, which is easy to miss. Have a fiddle and see if you can get sharp pictures manually.
04-09-2011, 10:57 AM   #4
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I am not in macro mode, and I also tried manual focus. So far no luck. Here is sample pix.

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04-09-2011, 05:14 PM   #5
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lyzan, I cannot see the exif information, I'm wondering if the shutter speed is way too slow. That would be my first thought.
Also check your dipoter settings above your eyepiece sometimes they get bumped. If you point your camera to a blank wall the guide lines in the VF should be crisp and clear. If the diopter is out it will affect the manual focus stuff but not the AF.
If you can post the shots with the exif intact we can see what's going on much better.

NaCl(hope this helps)H2O
04-09-2011, 11:05 PM   #6
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Hi NaCl,

The shutter speed is fast enough. Anyway, I checked the lens more today and I noticed that it is kinda foggy and looks like there are some scratches inside which makes me feel that this lens is busted, and goodbye to my US$ 50. I am thinking to disassemble it and clean it. This is gonna be the first time that I will disassemble a lens, I am going to run to the hardware today and find some precision tools.

thanks everyone.
04-09-2011, 11:06 PM   #7
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Does this happen only with the lens at infinity or is it right through the range? something looks seriously out of alignment or maybe even the filter is smeared with something. Living where you do, have you also checked the lens for fungus?
I'd agree with our saltwater amigo - exif data would be very helpful.
04-10-2011, 02:49 AM   #8
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Those look pretty blurry and with the scratches inside it would make me think somebody had it apart and didn't put all the lenses back correctly. I would see if you can trade it back in maybe.

04-10-2011, 09:47 AM   #9
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It is right thru the range up to macro. I have no idea why there are no exif data on the pix above, maybe something I didn't knew happened when I upload it. Here is another one straight from the card.
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04-10-2011, 11:51 AM   #10
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QuoteOriginally posted by lyzan Quote
It is right thru the range up to macro. I have no idea why there are no exif data on the pix above, maybe something I didn't knew happened when I upload it. Here is another one straight from the card.
That is why. Images over 1024 on the longest side are automatically compressed, with exifs being stripped.

It doesn't really matter what the exif is. Even if it were low shutter speed camera shake one should still be able to tell there was something sharp. I tend to agree with the others, this lens has been taken apart and not properly put back together. It May be something as simple as the rear element set being unscrewed (easy check and fix). An element misaligned in its seat. I've taken photos with hazed, scratched, heavily fungused. and all other manner of damage. Contrast and colors suffer some but the pictures are always sharp. You don't by any chance have Contrast dialed way down do you?

04-10-2011, 12:05 PM   #11
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It might be the haze and scratches inside the lens - the pictures look pretty hazy... Try the "flashlight test" - shine a flashlight through one side of the lens and take a look from another, you may be surprised.
04-10-2011, 12:53 PM   #12
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@JeffJS and pbo,

Thanks. I examined the lens more closely using pbo idea but with a light bulb. Yes, I was surprised that there are a plenty of dirts inside the lens, I was hoping that those are not scratches. Keeping Jeffs thought in mind, it is either I returned the lens to the store whom I called and promise that his technician will clean the lens (with additional cost, he is asking for 50 riyals) or I'll do it by myself. If I do it by myself, are there anyone here who can guide me with diagram? I hope I'm not asking too much.

Again, thanks.
04-10-2011, 01:06 PM   #13
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QuoteQuote:
Thanks. I examined the lens more closely using pbo idea but with a light bulb. Yes, I was surprised that there are a plenty of dirts inside the lens, I was hoping that those are not scratches. Keeping Jeffs thought in mind, it is either I returned the lens to the store whom I called and promise that his technician will clean the lens (with additional cost, he is asking for 50 riyals) or I'll do it by myself. If I do it by myself, are there anyone here who can guide me with diagram? I hope I'm not asking too much.
Don't recommend cleaning yourself unless you're good at it - the autofocus zoom lenses are probably the hardest to disassemble. If the technician is good and 50 riyals isn't much, go with that option.
04-10-2011, 02:26 PM   #14
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Let the pros clean it! Manual focus primes are tough enough, but an AF zoom - your chances of getting it back together are slim.

Something is definitely wrong with that lens, though. Mine gives much nicer results.
04-10-2011, 10:38 PM   #15
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Definitely wouldn't recommend doing it yourself. Lens coatings are only a few microns thick and easy to damage with the wrong cleaning materials or a heavy hand. When you go to collect the lens, take someone with you who is an experienced photographer and get him/her to check the technician's work before you hand over the money.

If it were me I'd be asking for a refund and looking elsewhere. There's no shortage of decent lenses around.
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