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-   -   K100 w/ MF 50mm 1.7 (focus trap) (

Tullio Jun 7, 2007 10:37 AM

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Last night I read some threads discussing the "focus trap" technique used with MF lenses. Since I happen to have a 50mm prime MF lens from my old SLR days, which I haven't used much with my K100 because I kept missing focus, I decided to give this technique a try. So, this morning on my way to work, I stopped at a nearby reservoir and took these shots (no PP of any kind, just some cropping). It worked! I am so darn impressedby the sharpness of the images (unless my monitor is playing tricks on me)that I think I'll keep this lens on the camera at all times. I find these images to be much better than anything I've obtained with the kit and two Tamron zoom lenses I have. It's unbelievable the amount of great, useful information one can get atSteve's forums!

Tullio Jun 7, 2007 10:39 AM

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Tullio Jun 7, 2007 10:40 AM

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Tullio Jun 7, 2007 10:40 AM

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Tullio Jun 7, 2007 10:41 AM

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bper Jun 7, 2007 12:09 PM

Isn't the M50-1.7 a wonderful lens? I also have been playing with this method that basically makes a manual lensinto an auto focus one, only better in my opinion. With the AF lens, there is often a slight delay in the time the focus is set and the shutter fires. If you are shooting a flower in the wind, it might be out of focus when you finally press the shutter. The focus trap method fires only when it reaches sharp focus. Food for thought - Bruce

Dal1970 Jun 7, 2007 1:04 PM

Love the last shot!

With regards the 50mm, I have this and use it in low light. Great lens.

Only one major downside with the prime lenses though, and that is you have to move position to take different shots. Too much exercise is not good!


mtngal Jun 7, 2007 2:10 PM

There is no such thing as too much exercise. I actually like primes because they make me look at what's there and how to use it to the best advantage of the lens you are using - it changes the way you look at something. Of course, I habitually carry two camera bodies and still am changing lenses all the time...

Corpsy Jun 7, 2007 3:49 PM

I posted about this 5 days ago when I tried it for the first time, and then a couple days later Bper posted about it and was told by Robar that this technique has been around for a while. Well, I'd like to know why nobody has ever mentioned it before! I've been reading plenty of posts in the Pentax forum since last winter and haven't come across any mention of this, though I can recall numerous instances of people complaining that the focus assist in MF mode isn't accurate enough.

Anyway, since discovering this technique I've also found that my 50mm 1.7 lens (A version, lucky me) has become a far more valuable lens. Good timing too, as I recently need it to shoot some model shots of my Mom as a birthday present for my Dad. The 50mm prime is noticeably sharper than the kit lens and performs quite well in dimmer light using f/2.8. It was always rather rare to shoot someone with a mf lens and have it so sharp I could blow up the photo 2x and have it still look sharp, but now that's how most shots look at lower ISOs.

Here's a topic I just posted using the technique to shoot birds in flight:;forum_id=80

Dal1970 Jun 7, 2007 4:01 PM

It has been mentioned in this forum several times to my certain knowledge.


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