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Focus Trap - fernando (3 Viewers)

Musoman

PETE - Nikon/Sony Shooter
United Kingdom
Fernando, i see you mentioned using ' Focus Trap ' somewhere here in the Digi Forums.

Is this something only a Pentax DSLR owner can use ?

I believe Focus Trap is where you can keep your finger fully pressed on the shutter, and you focus at the same time, and the camera will only take the shot once focus has been achieved, is that correct ?

I had a Pentax K10D sometime ago, but i didnt fully get to grips with this method. Basically, i didnt know how to set it in the menu
 
I think any brand can do it, I'm using Nikon in my case.

That's exactly that, the shutter only releases if the camera is focused. I'm still working in the same way I was for static birds, I focus and press the shutter at the moment I want, the improvement is that now that camera only fires if the image is focused, I never failed focus much but now I don't fail at all for static subjects.
For birds in flight I usually keep the focus pressed, and do my best to keep them in focus, the cameras fires every time I get the bird in focus.

There's still the chance for OOF images, I had to rethink my technique for this system, I have to slow down a bit at the focus point now, if I keep turning the focus knob after the camera fires the focus will still fail as by the time the camera releases the focus is off again.

The problem is using this with an ED80, the F/7.5 doesn't help at all here. I'm trying and ED70 F/6 for this, at F/6 the camera's AF sensors works extremelly well, any of them. With the ED80, only the central works fine, but even then it struggles in low light. Of course a better body would help here.
 
So if you have your finger on the shutter button, fully pressed down while focusing, what is stopping the shutter from firing ?

When i tried this, the shutter just fired immediatley when i fully pressed it. Even though i wasnt focused properly, it still fired.

Thats the bit i do not understand. What setting inside the menu of the camera is telling the shutter not to release until focus is achieved ?
 
Essentially you'll need the camera in AF mode, of course for that you'll need a chip that allows the camera to be in AF mode even without AF, dandelions do that perfectly.
With Nikon if you set it to AF-S, the camera won't fire unless the image is focused. In AF-C (continuous focusing) some bodies fire others don't, so for this is better to use it in single shot mode (AF-S). In other brand bodies I have no idea.
 
OK, i see what you mean fernando.

I would only be able to use Focus Trap with the Focus Confirm chipped adapter fitted ( i have one already ) but since this only works with the scope at 600mm, ( no barlow ) then i'll try this.

I'm not sure which setting in the menu of my Canon 40D to use, so i'll have to experiment
 
Essentially you'll need the camera in AF mode, of course for that you'll need a chip that allows the camera to be in AF mode even without AF, dandelions do that perfectly.
With Nikon if you set it to AF-S, the camera won't fire unless the image is focused. In AF-C (continuous focusing) some bodies fire others don't, so for this is better to use it in single shot mode (AF-S). In other brand bodies I have no idea.

Sorry guys for barging in.

Fernando, I am using a Nikon D300s and would like to know how you did the AF thing. I have checked through the dandelion product and good thing its a company in my country. I have attached a pic showing a pink circle on the selector lever, is this the one you're saying to set at AF-S or should the setting be done in the menu section? What about other camera settings? Where should the dandelion be glue on to since I sometimes attach the camera direct to the scope and sometimes to the 1.4X TC? (See attach adapter) I am currently using.

I have been getting 1 in a 100 keeper rate after so many tries, but still I am very unwilling to give up. Hope you can provide some insight. Thanks

tbc
 

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Hi TBC,

The easiest way is put that switch on S (AF-S). On the D300 you also have the choice to put it in C, and set on the menu for focusing priority... but just put it in S and it will work perfectly.

On that body you'll have also the advantage to use more than the central AF point, since it has several cross points, and also any of them work better than the central of my D90's, so that's a plus for you.

You should glue the chip on the adaptor on the scope, then it will work both with the TC or without the TC. But don't get your hopes high with working with the TC, at F/10.5 the camera will have an hard time focusing on anything.

1 on 100 is way too low...why are you getting a so bad rate? bad eyesight? missaligned mirror?
 
Paul, what would you set in the menu ?

I'm thinking the 450D + 40D might not be too far apart in the menus ? Maybe i could try this Focus trap thingymajig
 
I've copied and pasted below what I read on the DP Review forum. It involves going into the 450D custom function menu so I don't know if this is similar to the 40D.

Set up the camera with C.Fn-10 to 0 (focussing is triggered by the shutter), One-Shot AF mode, single focus point, and the lens set to AF.


Paul.
 
What exactly is Custom Function 10 on your camera ? I only have 9 but it maybe that its in a different position, but i need to know what it is.

1 shot + single point focus is no trouble, but setting a MF lens to AF.. How do you do that
 
but setting a MF lens to AF.. How do you do that

That's what the dandelion does, dandelion comes with default programing as an AF lens, it can be change to MF if needed but AF is the default.
In "nikon language" it works like any G lens, it fools the camera into thinking there's a G type lens with a built in motor, but not having a motor on the lens obviously it doesn't move. Yet the camera thinks the lens it's doing it job and releases the shutter only when focused.
I don't how canon works but it should be more or less the same.
 
There's no custom function on the 40D for ' AF/AE lock ' :C

Does the adapter have to be a ' Dandelion Chip ' ? I've never heard of Dandelions, just regular Focus Confirm adapters like i already have.

Mind you, this is all academic now, as this crucial custom function is missing on my cam
 
Oh, I know nuts about Canon or Nikon. On my old Sony A350, I can set my shutter release priority to release or focus. Meaning if set to release, the shutter will release regardless of focus. But if set to focus, it will not release until the focus is spot on. But I can't find that on my A550 now??????

I belief that function works on AF lenses (while in MF mode) as well as MF lenses with the Dandelion Chip.
 
Hi TBC,

The easiest way is put that switch on S (AF-S). On the D300 you also have the choice to put it in C, and set on the menu for focusing priority... but just put it in S and it will work perfectly.

On that body you'll have also the advantage to use more than the central AF point, since it has several cross points, and also any of them work better than the central of my D90's, so that's a plus for you.

You should glue the chip on the adaptor on the scope, then it will work both with the TC or without the TC. But don't get your hopes high with working with the TC, at F/10.5 the camera will have an hard time focusing on anything.

1 on 100 is way too low...why are you getting a so bad rate? bad eyesight? missaligned mirror?


Hi Musoman, Sorry for asking question in your thread. Let me know if it does bother you, I'll open a new one.

Hi Fernando, thanks for the reply. I'll order the chip ASAP. I am not sure of the low keeper rate as well because I am new to DSLR, don't know if the techniques are wrong / wrong settings / bad eyesight or a combination of all.

Mind to elaborate more on misaligned mirror? How do I know and how to check? Mirror in the DSLR? I thought they are just there to reflect to images to the viewfinder?



tbc
 
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I don't think there's any technique involved except having decent eyesight. With time the eye gets "educated" to see the needed details to distinguish what is or not focused, but still even in the beginning anyone with a good eyesight should have a better keepers rate than that.

The mirror you see when you take the lens of your camera is the mirror that reflects the image to the viewfinder and that's the mirror that can be misaligned.
So, behind that mirror there's a eccentric bolt (two actually, but the other is for the AF sensors, forget the other, you only need the first for this), that bolt aligns the mirror so the image it reflects is aligned at the same plane of the sensor.
The easiest way to check it is to get the fastest lens you have, preferably one that focus very close, a macro lens is about perfect. Put your camera on a solid tripod, get a ruler, focus manually on any number, keep the lens wide open, put the line referring to the number at the exact centre of DOF on the viewfinder, if the mirror is misaligned the resulting image will have that dof decentered from the line you focused on. If that's the case you'll need to either send the camera to nikon, or mess with that bolt until it's right. I'm a DIY guy so you know my choice ;)

Here's a link that explains all this better:
http://www.leongoodman.com/d70focus.html

The article refers more to the AF part, but the process is nearly the same.
 
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