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04-10-2012, 01:37 AM   #1
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Pentax F 35-135

Hello to all,

I've bought this Pentax F 35-135 f/3.5-4.5 recently and I am a bit disappointed. Photos have poor quality, they're very soft and blured. As I am begginer in photography, could someone look at samples and tell me, if this is 'feature' of this lens or something's wrong with this one of mine? Maybe it's dirty inside or sth...
I tried to step it down, but the result was not much better.
You can find few samples in the file linked below.
Download 35-135.zip from Sendspace.com - send big files the easy way

04-10-2012, 04:11 AM   #2
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Hello baster
As I'm in the market for a lens like this, this is quite interresting.

I've been looking at your shots. Yes, they are not crispy nor very sharp. Many things may have caused this:
Bad lens? Perhaps.
Rather high ISO (400-500). Yes
Too long shutters peeds (1/500 or 1/1600 sec.) not very likely.
Subject not in focus? Most likely.
No tripod used? May have some negative effect
Glas dirty, or missing filter or shade (flare)? Lens doesn't stop down properly? Perhaps - the shots are slightly overexposed.

Flare and subject out of focus seems to me to be the main problem!

My suggestions for further tests:

1. Make sure the lens is clean (rear lens too) and protected (filter and shade).
2. Make sure it stops fully down when released.
3. Please make tests using a tripod (ruling out other problems than lens flaws)
3. Make test on a not moving subjects (a brick wall is good, or a money note on a wall, or whatever very detailed subject) in order to make sure subject is in focus.
4. Make test af ISO 100 and for several apertures. Use self timer or Shake Reduction in order to rule out camera shaking.
5. Try to compare to lens tests concerning this lens (photodo or similar), I'm sure it's not as bad as you think

I hope you find this usefull?

Regards
Jens from Denmark

Last edited by Photodana; 04-10-2012 at 04:17 AM. Reason: errors
04-10-2012, 04:54 AM   #3
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Thanks for the response.
As I use K-x, this ISO level should not be the problem (at least it's not with other lenses ). IMO lack of tripod should not be the problem as well, considering fast shutter speeds. Shake reduction was on obviously. I will try to catch few photos testing FF/BF or generally focus quality.
Could you describe point no. 2, how to perform it?
04-10-2012, 07:05 AM   #4
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A few months back I purchased an F 35-105. The same day I got it, I took it out to take some pictures. I have never been so disappointed in a lens. The next day, I took it out again (bad day maybe?) and the same thing happened. I was just completely disappointed with the lens. The pictures were a lot like you described. I put the lens away (again) and didn't touch it for two months.

One day, I was pretty bored and decided to clean my lenses. After I was done, I remembered that I owned the F 35-105. I ended up cleaning that lens as well (had completely forgotten I owned it). The next day, I decided to take the lens out and give it one more try. To my surprise, the lens was performing so much better. It wasn't the lens to end all other lenses. But I was really happy with the results I was getting.

I would try cleaning the lens (as was previously recommended). You'd be surprised how much of a difference that can make, even when the lens doesn't appear dirty.

04-10-2012, 07:34 AM   #5
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Actually, I have cleaned both front and rear lenses. But as it has many years already, maybe it got dirty inside. I'll contact some service and let them take a look.
04-10-2012, 03:52 PM   #6
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Hello baster
Point number two:
The Aperture stop down mecanism is activated when the camera pushes a tiny arm (a flat metal pin) in the lens. If you take off the lens, shut it down to the smallest aperture and then pres the mentioned pin with your finger - repetedly and very fast. The aperture should still close down to the minimum size EVERY TIME. If it doesn't - it needs a lot of exercizing (do not add oil, please) before further use. Pentax lenses' aperture mechanism will get tired, if left on a camera for a long time. Pentax usually have this advice: Don't leave your Pentax lens on the camera, when not in use - take it off, stop it down and store it standing up / vertically.
Most Pentax lovers know this or have experienced this the unpleasant way :-)
But some people (sellers, not familiar with Pentax gear ?) disregard this and will naturally get lenses with a "tired aperture", which most likely will cause overexposed images later on. Somtimes a lot of exercize (as described above) will fix this. Sometimes it won't. I myself have experienced this problem at one time or two over the last 30 years. But of cource, the over exposure may have other reasons, I don't know :-)

Regards
Jens

Last edited by Photodana; 04-11-2012 at 12:06 AM. Reason: spelling errors
04-14-2012, 07:03 AM   #7
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Re 35-135, I just sold my copy, needed to be stopped down a couple of stops to get acceptable sharpness, and had bad halo effects wide open. I picked up an unboxed 18-135 WR and this is far better (mind you 5x cost!_
04-14-2012, 01:38 PM   #8
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Sounds like a good investment, Stephen :-)
Regards
Jens

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