Good thinking, i have a plate on the bottom that connects via the tripod screw it has a hand support attached to it, perhaps i could do something with this - trap it somehow?
P.
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AFMA Auto Focus Micro Adjustment
- Thread starter Paganman2
- Start date
Good thinking, i have a plate on the bottom that connects via the tripod screw it has a hand support attached to it, perhaps i could do something with this - trap it somehow?
P.
Don Kuykendall_RIP
RIP :(
If you get two sets of settings for Infin and say 200 feet away say infin showed it needed +10 and 200 feet needed +6 would you split the difference and set +8, as i shoot at both extremes.
P.
You need to read up on setting the Fine Tune. You would never set focus at infinity or even 200 feet. Read on on how it is done and at what distance. I think the standard distance is 50 times the focal distance. So your 300 mm should be at approximately 50 feet. the extremes they are talking about is not distance away but at what zoom you are using. I would always do it at the long end since it is the most critical (most shallow DOF)
You can't just make it up as you go or you will never get it as sharp as it can be.. 2 or 3 numbers off makes a huge difference.
Google it and follow the directions. You don't know more than the experts on this.
If you get two sets of settings for Infin and say 200 feet away say infin showed it needed +10 and 200 feet needed +6 would you split the difference and set +8, as i shoot at both extremes.
P.
What Don said.
There are several methods to fine-tune but you need to use one of them correctly else your result might make things worse than without fine-tuning. You can only use one fine-tuning value for one lens and the cam will apply that correction automatically whether you afterwards shoot the lens at the shortest or longest focal length or at the shortest or longest focal distance. Even when it would be fantastic, it is currently impossible to set more values for one lens.
The only reason why I check the shortest focal distance and infinity is to see if the correction does not affect the lens in such a manner I can no longer focus at one of both.
You need to pick one distance to fine-tune at (which usually is prescribed as 50 times the focal length you tune) and go through the process at that distance only. After that you're done. I find 50 times the focal length highly impractical for long lenses (and don't see the logic in that multiplier) so I pick a distance that suits me best but that should never be too close or at infinity.
If you're unsure any other distance will lead to correct tuning results, pick the 50*focal length as prescribed.
One distance to focus during tuning and one focal length only. Anything else won't work.
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Right then - I have had a go today with this i set the camera up on a cupboard by my open window, i set the lens to the zoom length i use 250mm then with manual focus selected and single point AF-S, i then selected LV and zoomed to max, i chose a Cell Mast on a hill about 2 miles away as it was very clear and had lots of contrast, i manually focused by eye till it was very clear and i could see the individual wires supporting the mast, then i selected the viewfinder view and without moving anything i looked through and pressed the shutter release halfway, i got the focus dot flickering with the front focus bracket, so i oped the micro focus adjustment and moved it one step in the positive direction, i did this in steps till i got a solid focus dot without brackets illuminating, i found that i had this solid dot over 3 steps + 9 + 10 and +11 so i selected +10.
I did the same test but on a house about half a mile away same set up till i could see a window sharp and defined in LV, and with the same settings i got the same clear sharp dot with no brackets.
I took a couple of pictures at the same time and they are nice and sharp and very clearly show all the details of the Cell Mast i chose for the test.
Have i done this correct?
P.
I did the same test but on a house about half a mile away same set up till i could see a window sharp and defined in LV, and with the same settings i got the same clear sharp dot with no brackets.
I took a couple of pictures at the same time and they are nice and sharp and very clearly show all the details of the Cell Mast i chose for the test.
Have i done this correct?
P.
Right then - I have had a go today with this i set the camera up on a cupboard by my open window, i set the lens to the zoom length i use 250mm then with manual focus selected and single point AF-S, i then selected LV and zoomed to max, i chose a Cell Mast on a hill about 2 miles away as it was very clear and had lots of contrast, i manually focused by eye till it was very clear and i could see the individual wires supporting the mast, then i selected the viewfinder view and without moving anything i looked through and pressed the shutter release halfway, i got the focus dot flickering with the front focus bracket, so i oped the micro focus adjustment and moved it one step in the positive direction, i did this in steps till i got a solid focus dot without brackets illuminating, i found that i had this solid dot over 3 steps + 9 + 10 and +11 so i selected +10.
I did the same test but on a house about half a mile away same set up till i could see a window sharp and defined in LV, and with the same settings i got the same clear sharp dot with no brackets.
I took a couple of pictures at the same time and they are nice and sharp and very clearly show all the details of the Cell Mast i chose for the test.
Have i done this correct?
P.
You can not pick a cell mast at 2 miles and fine-tune focus to that. The advised distance for a 300mm is 50*300mm = 15 meters = 50 feet. You can go shorter or even a bit longer but 0.5 miles or 2 miles is surreal.
If you shoot at infinity, how can you add +5 and check if it now focuses further. There's no infinity +.
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You can not pick a cell mast at 2 miles and fine-tune focus to that. The advised distance for a 300mm is 50*300mm = 15 meters = 50 feet. You can go shorter or even a bit longer but 0.5 miles or 2 miles is surreal.
If you shoot at infinity, how can you add +5 and check if it now focuses further. There's no infinity +.
I assumed my lens was still front focusing as it was when i first put my lens to the camera, i did my first test when i first had the camera on a set of batteries from a distance of about 25 feet this showed me quite a large front focus issue so i adjusted
the micro focus till i had the right range of focus i.e center battery and just behind.
So are you saying that to get the correct focus that takes into account going up to infinity, doing this test at close to 15 meters is the only accurate way of doing this? its no problem i will have to look for a subject from my vantage point(Table at window) and do this again.
Its an easy pleasant exercise and dead easy to put back and just do over and over again till i nail it perfect for my use.
P.
I assumed my lens was still front focusing as it was when i first put my lens to the camera, i did my first test when i first had the camera on a set of batteries from a distance of about 25 feet this showed me quite a large front focus issue so i adjusted
the micro focus till i had the right range of focus i.e center battery and just behind.
So are you saying that to get the correct focus that takes into account going up to infinity, doing this test at close to 15 meters is the only accurate way of doing this? its no problem i will have to look for a subject from my vantage point(Table at window) and do this again.
Its an easy pleasant exercise and dead easy to put back and just do over and over again till i nail it perfect for my use.
P.
You can only tune focus at a certain distance if you dot-tune and that's it. Too close to the minimal focal distance won't work and too close to infinity won't work either. I pick a distance that is practical and doesn't require me to call a taxi to set up my focus target. Like I said, advised is 50*focal length but it's up to you if you prefer shorter or not or a bit further.
At a too long distance you simply won't know if you set the lens at its sharpest since there is too much elbow room. Your DoF is gigantic at 2 miles. At a close distance when you see every detail of your focus target, it is much easier since your DOF is also much smaller and even the tiniest bit focus is off, shows at max magnification on the live-view.
If you focus on some distant object, how can you know if it is at a 90° angle to your camera and if the surface you set focus on is perfectly flat?
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My problem where i live is room(lack of it) the distance from my front room, strait to my back wall and visible in a strait line is only about 8 meters 25 feet, this was the maximum distance i had when i did my batt test, its a built up area with houses behind me then mountains after that, the best way for me to get support is a desk type unit i can put against my back window, this then gives me views of the above, the houses with windows are about 50 feet away but i would have no way of knowing if these houses are square to my camera etc.
This is the best i can do without going to a public place and setting a test chart up, but i am not going to do that, i used to have a much lager garden were i could have done this test real easy, i used to have tripods and art easels etc but not now.
P.
This is the best i can do without going to a public place and setting a test chart up, but i am not going to do that, i used to have a much lager garden were i could have done this test real easy, i used to have tripods and art easels etc but not now.
P.
My problem where i live is room(lack of it) the distance from my front room, strait to my back wall and visible in a strait line is only about 8 meters 25 feet, this was the maximum distance i had when i did my batt test, its a built up area with houses behind me then mountains after that, the best way for me to get support is a desk type unit i can put against my back window, this then gives me views of the above, the houses with windows are about 50 feet away but i would have no way of knowing if these houses are square to my camera etc.
This is the best i can do without going to a public place and setting a test chart up, but i am not going to do that, i used to have a much lager garden were i could have done this test real easy, i used to have tripods and art easels etc but not now.
P.
I tuned my Tam at 400mm using a shorter distance than that and it worked fine.
You can better tune your lens inside at 8 meters and remain in control of all factors involved than try to do it at such distances where you lack that control. It is critical you focus at a perfect angle at your target and that the cam is in level.
It's important that whatever tuning method you use, you follow the required steps. You can make some changes to the procedure but you have to know what you are doing and why. If not, whatever the outcome of the tuning, I'd not dare to bet money on it being correct.
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I tuned my Tam at 400mm using a shorter distance than that and it worked fine.
You can better tune your lens inside at 8 meters and remain in control of all factors involved than try to do it at such distances where you lack that control. It is critical you focus at a perfect angle at your target and that the cam is in level.
It's important that whatever tuning method you use, you follow the required steps. You can make some changes to the procedure but you have to know what you are doing and why. If not, whatever the outcome of the tuning, I'd not dare to bet money on it being correct.
So would it work if i set up a good target indoors on my wall that is flat and well lit, then set up my camera steady as before and about 20 feet away at 250mm and dot tune from it?
P.
So would it work if i set up a good target indoors on my wall that is flat and well lit, then set up my camera steady as before and about 20 feet away at 250mm and dot tune from it?
P.
It worked for me. After you tuned it and set the middle of the range, all you need to do is test it and you'll directly find out if it is better or not.
It worked for me. After you tuned it and set the middle of the range, all you need to do is test it and you'll directly find out if it is better or not.
I have just done another test indoors as mentioned, i supported the camera on a table and supported the lens, i used a greetings card with some fines writing and did very fine subtle adjustments of the lens manual focus ring in LV, when i got the focus as sharp as i could see on the screen at max zoom, i then switched over to viewfinder and pressed the shutter, after setting the micro adjust up to a distant subject it was now showing back focus with the brackets flashing so i adjusted back down to 0 and worked my way through.
I eventually found that +5 was giving the most consistent solid dot focus, so with any luck this is done now??
P.
I have just done another test indoors as mentioned, i supported the camera on a table and supported the lens, i used a greetings card with some fines writing and did very fine subtle adjustments of the lens manual focus ring in LV, when i got the focus as sharp as i could see on the screen at max zoom, i then switched over to viewfinder and pressed the shutter, after setting the micro adjust up to a distant subject it was now showing back focus with the brackets flashing so i adjusted back down to 0 and worked my way through.
I eventually found that +5 was giving the most consistent solid dot focus, so with any luck this is done now??
P.
If you went through the whole range that gave a consistent dot and then set the AF-tuning to the middle of that range, you should be done.