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Thread: WHY NO - TRAP Focus option with manual lenses?!

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    WHY NO - TRAP Focus option with manual lenses?!

    Hi!

    I have 5D + gf1....
    I like this combo because I can use the same manual focus lenses on both cameras... but

    sometimes it is pretty hard to use onscreen enlargement focus point preview because of shaky hands if I use longer than 80 mm lens .... + sometimes miss composition while focusing...

    SO - one thing what I wish for is - focus trap option via firmware for gf1!!!!!!!

    WHY OLY and PANA don't include this option?

    WHY?



    Martins

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    Member kwalsh's Avatar
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    Re: WHY NO - TRAP Focus option with manual lenses?!

    By trap you mean a focus confirmation beep while using manual focus?

    I think the reason it isn't implemented is that it is actually very tricky to do with a contrast detect AF system. All measurements are relative in such a system and the AF system actually works typically by moving past sharp focus and then moving back. It has no way to determine the absolute position of best focus without hunting for it. Hence, unless the AF system is "driving" it can't really tell you when you are at best focus.

    On a phase detect AF system (like in DSLRs) they can actually measure the position of best focus in one go, so a MF confirmation beep is easy to implement.

    Ken

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    Re: WHY NO - TRAP Focus option with manual lenses?!

    Quote Originally Posted by Reproster View Post

    sometimes it is pretty hard to use onscreen enlargement focus point preview because of shaky hands if I use longer than 80 mm lens .... + sometimes miss composition while focusing...

    Buy and use an EVF with your GF1. If you use a long FL length manual focus lens on a camera that can only be used like a P/S cam (fixed LCD screen) then what better can you expect?

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    Re: WHY NO - TRAP Focus option with manual lenses?!

    Focus trap is the ability of the camera to trip the shutter automatically once something comes into focus at the chosen point. For instance, a child running towards you--once he hits the focus zone, snap!

    The aforementioned problem implementing focus confirm with contrast detect would seem to be the sticking point...

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    Re: WHY NO - TRAP Focus option with manual lenses?!

    The other problem I can see is that the camera is in the 'shoot w/o lens' mode and is not involved at all with the focus--only the exposure as I understand it so wouldn't have any input to focus on MF lenses--right??? I'm far from a techie on this, but I don't see any way at all to implement this--or even a 'beep' at focus.

    I wouldn't think shooting a 300mm lens on the GF1 handheld would be easy to nail focus because we're talking about 600mm FOV (35mm FF) on a small lightish body--so increase shutter speed. use MF assist with the one button push of the dial and right back to the shutter to shoot---and using the EVF at least you can stabilize a bit against your forehead.

    Diane

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    Re: WHY NO - TRAP Focus option with manual lenses?!

    I don't know. When face detect is on with my EP-1 and a Contax G lens, it still detects faces reliably (as long as focus is close to correct). This "trap" option would seem like a reasonable idea. I mean, it's detecting a FACE, how hard could it be to get focus confirmation?

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    Re: WHY NO - TRAP Focus option with manual lenses?!

    Both my Pentax bodies and my Canon 10D body had trap focus. I experimented with it many times. Never once got a sharp photo with it, at anything other than about f/8 or smaller lens openings where DoF would cover the focusing error.

    I find it much more sensible to learn how to focus properly. ]'-)

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    Re: WHY NO - TRAP Focus option with manual lenses?!

    I just wish it...as option!
    because even my old E1 have it!!!!!!!!!!!! and it's works!!!!!!!

    sad for us.
    Because I don't believe in impossibility........
    I think it is just a marketing thing.....


    of course there is dumb solution take pictures in burst mode.....
    and for situations with moving subject just prefocus on area you wish to be in focus and wait for...subject move in....but.......this is not for bird shooting...

    I tried to nail focus with 200 mm F2.8 sonar handheld...... it is hard...for hand held more harder than my old bird combo canon 40D, 5d + 500 mm F4 IS......

    and I still dreaming about EOS -> 4/3 adaptor with F-stop and IS turned on option...I can live without AF..........

    imagine 1000 mm F4 with IS!!!!!

    and 2 x another things what i miss in GF1.....and sometimes it's slow down picture taking process.....

    THE MOST IMPORTANT NR 1.!
    1. Option via menu to change 1/30 minimum shutter speed to use it in Aperture priority mode !!!!!!!!!!!!!!!!!!!!!
    please, please!


    Because then we can get almost fully automatic perfect picture taking machine!!!!
    Just give it to Your girlfriend and You will know what I talking about!

    Am I missing something?


    2. why there are no option: when I set manual focus preview on screen to some interest area and then take a picture there are no option to see immediately that focus crop area in picture viewing playback mode...........I always need to zoom and move left,right,bottom, up from center to that area....

    again, Am I missing something?

    Thank You!

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    Re: WHY NO - TRAP Focus option with manual lenses?!

    Whatever is in the center of your MF lens composition will be what you see first in the center of the magnified view.

    Personally, I think what you want would be very very low on what others want for changes or options--so I don't expect that the camera developers are looking at that particular option. Certainly not for a firmware upgrade IMO.

    Lattiboy---I'm wondering about the face detection option on the OLy. I have face detection on the GF1 and G1 but not available when MF lenses are mounted as its an AF option--and there is no AF--but wonder how you see it being implemented??? Is it 'snapping' to focus on the face? I'm curious about this since there's no interaction between the MF lenses and the cameras--and my GF1 (assume G1 also) doesn't offer the option of face detection with an MF lens mounted as I said.

    Diane

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    Re: WHY NO - TRAP Focus option with manual lenses?!

    Quote Originally Posted by Reproster View Post
    I just wish it...as option!
    because even my old E1 have it!!!!!!!!!!!! and it's works!!!!!!!
    Because your old E1 has a phase detect AF system.

    Because I don't believe in impossibility........
    Actually, I believe in any practical sense it is in fact an impossibility with a live view based contrast detect AF system.

    I think it is just a marketing thing.....
    I believe this is a rare case in which it is in fact an engineering thing.

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    Senior Member Tullio's Avatar
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    Re: WHY NO - TRAP Focus option with manual lenses?!

    That's where in body IS comes to play. I find it easier to shoot with the G1 and MF lenses because of the EVF. However, as the FL increases, so does camera shake and obtain sharp focus w/o some sort of monopod/tripod is hard. On the other hand, shooting with the EP1 and MF lenses is not as easy due to the lack of EVF but the IS system helps a lot and I get more sharp images with it at long FL hand held than the G1 thanks to the IS.
    Tullio

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    Re: WHY NO - TRAP Focus option with manual lenses?!

    The EVF on the G! is golden when it comes to
    manual lens focus....
    http://hodad66.com Sony A7r,A7II, Sony 70-300G, Rokinon 14/2.8, Leitz Wetzler 35/3.5, Leica R Summicron 50/2 & Elmarit 90mm/2.8, Contax N 24-85 & 70--200mm AND Canon FD 20/2.8, 135/2, 500mm 4.5, Minolta 35/1.8, 45mm/2, Nikon 28-50/3.5, 105/1.8, 180/2.8

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    Re: WHY NO - TRAP Focus option with manual lenses?!

    Quote Originally Posted by Reproster View Post
    I just wish it...as option!
    because even my old E1 have it!!!!!!!!!!!! and it's works!!!!!!!

    sad for us.
    Because I don't believe in impossibility........
    I think it is just a marketing thing.....
    (...)
    You have to understand the technical difference between phase and contrast AF systems. It's not a conspiracy.

    And yes, there are several minor fixes that could be implemented via firmware.

    /Jonas

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    Senior Member Tullio's Avatar
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    Re: WHY NO - TRAP Focus option with manual lenses?!

    Quote Originally Posted by hodad66 View Post
    The EVF on the G! is golden when it comes to
    manual lens focus....
    Couldn't agree more!!!
    Tullio

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