Nikon D300

[shabab]

راننده : یعنی میخوای بگی تو دی ۳۰۰ داری ؟ یعنی میتونی اونو توی مد 3D قرار بدی ؟
من : بعله .حالا گاز بده .......
این عکس رو روی دست گرفتم البته مد کانتینیوس .۵۱ نقطه و 3D .

http://www.digitalnegar.com/index.php?showimage=231

آقاي خليلي جسارتا" ميتونيد راجب اين مد 3d كمي برام توضيح بدي

[rezakh]

آقاي خليلي جسارتا" ميتونيد راجب اين مد 3d كمي برام توضيح بدي

51 point 3D tracking

حداکثر دقت فکاس در دی ۳۰۰ است که سوژه در حال حرکت رو دنبال میکند وبارزترین رنگ و کانتراست رو دنبال میکند که در ۹۰ درصد مواقع درست است

[shabab]

آقاي خليلي ممنون شما يا ساير دوستان آيا كسي از مكانيزم اوون اطلاعي هرچند جزئي داره ؟
فكر كنم بار اوله كه در دوربينها از چنين سيستمي استفاده ميشه .

[rezakh]

آقاي خليلي ممنون شما يا ساير دوستان آيا كسي از مكانيزم اوون اطلاعي هرچند جزئي داره ؟
فكر كنم بار اوله كه در دوربينها از چنين سيستمي استفاده ميشه .

بنده بیشتر مصرف کننده محصولات هستم .زیاد از مسائل فنی سردرنمیآورم
اینو تونستم براتون پیدا کنم

There are several concepts and controls at work here, and without an understanding of what each one really entails, it will be hard to accomplish the task at hand - to consistently get photographs with the intended subject in focus. OK class, let's begin. Just to make it simple, please place the focus area mode selector found under the Multi Selector on the back of the camera in the middle position - dynamic area AF. We'll talk about this in a minute.
Let's first consider the focus mode selector located on the front of the camera. It has 3 positions - C, S, and M. "C" stands for continuous - the lens will continue to focus as long as the shutter button is held down halfway (or one of the AF buttons are utilized, but let's not confuse the issue further). The only mode in which focus tracking will occur is the "C" or continuous mode. Here's an easy test: with the mode selector in the "C" position, focus on something close by depressing the shutter button half way. The green focus light in the viewfinder should come on, and the object will appear to be in focus. Now mash the button all the way down - you have taken a picure and it should be in focus - yahoo!!! Now press the button halfway down again and focus on your subject. Holding the shutter button halfway down, walk backwards 4 feet. You'll hear your lens AF working, and when you press the button all the way down and take another picture, it will also be in focus. Yahoo again! Now try this same test in the "S" mode. "S" stands for single - once the camera acquires focus, it will remain focused at that distance. We'll repeat the test. Of course the first picture will be in focus - hooray! But when you try the second half of the test, as you walk backwards you'll notice the green focus light stays on, but the autofocus will be silent, and when you snap the picture, your object will not be in focus. Don't despair, your camera isn't defective - that's the way single servo autofocus works. In "M" or manual - there is no autofocus, you have to manually twist the focus ring on the lens to get it to focus.

OK this was all about tracking. Now that we've decided that continuous ("C") is the only Focus Mode tracking can occur in, we'll look at the Autofocus Area Modes. These are selected by the Autofocus Area Mode Selector. Again, there are 3 positions. The lowest position is Single Point Mode. In this mode, autofocus is based on the information gathered by the single selected focus sensor. As the manual states, this is used for relatively static compositions. Strangely enough, if we repeat the test, as you move backwards, as long as the subject remains in the selected autofocus sensor the lens will continue to autofocus. So to some extent it will do AF tracking, as long as the subject remains in the selected focus sensor. The second mode (center position) is Dynamic Area Autofocus. Here you find more of what we really are looking for in autotracking because if the subject moves out of the selected sensor, the camera will use information from the surrounding sensors to attempt to keep the subject in focus. We have a choice of how many of the surrounding sensors we want to use: 9, 21, or 51. I've worked with this a little, and have found 21 works fairly well in my photography. However there are several factors to consider in making the choice - how far and fast the subject is moving out of the initial focus area, the amount of contrast, the nature of the subject, etc, etc, etc. Remember also we are dealing with 15 cross sensors in the central area, and only unidirectional sensors on the periphery. This gets into the Multicam 3500DX autofocus internals, and I haven't found any discussion of how it really works. Who cares - just mess with it and find what works for you. RTFM, page 269-270 for Nikon's recommendations on where to use which number of sensors. Remember also that using the Multi selector you can choose the group of sensors to use in 9 and 21 point settings. In Dynamic Area Autofocus there is one other option, called 51 point 3D tracking. Like standard 51 Point tracking, this will use the selected sensor, and all of the surrounding 50 sensors as the subject moves off the selected sensor. I haven't found any detailed description, but it seems that 51 point 3D uses the colors in the selected sensor area to assist in the focus tracking over the surrounding 50 sensors. It is said to work best with subjects moving horizontally across the frame. I haven't used this much; my results were not as good as with the other dynamic area AF settings. I keep thinking that if I understood it better, I'd get better results. In Dynamic Area Autofocus, you will always see the selected sensor (otherwise it would be unusable). You should always start with your intended subject in the selected sensor area. You can illuminate the selected sensor always with the setting in a6. The third mode is called Auto Area Autofocus. Here the camera chooses what is the subject, and focuses on it for you. It seems to work well for point and shoot applications, but if there are multiple subjects in an area, it may choose the wrong one. This mode is where the active focus points are highlighted for one second after focus, but only in the Single Servo AF mode ("S"). In the "C" mode you will never see a selected focus sensor because you have no control over it. There is no auto tracking in this mode as far as I can determine.

OK, there you have it. Let's recap. To have any real auto tracking, the focus mode should be in the "C" - continuous mode, and the Autofocus Area Mode Selector should be in the middle or Dynamic Area AF position. Choose the number of sensors you want to use, and go out and start shooting. Hold the shutter button halfway down with the subject in the selected focus area. Continue to hold it halfway to maintain focus as the subject moves. Once you release the shutter button, you will need to regain focus on the subject by pressing the shutter button halfway again with the subject in the selected focus area. If the subject leaves the sensor area you will also need to let go of the shutter button and recapture the focus on your subject. Mash the button down all the way anytime you want to take a photo. Take lots of photos. It's fun, and actually it's the only way to learn how autofocus and tracking really works.

Sorry this was so long, but I don't think any understanding of the process could be attained with anything less.

Tom

Oops - after re-reading the initial post, and reading my response, I came up with a few other points. In Dynamic Area AF with anything except 51 Points (3D Tracking) selected, you will not see the selected sensor move. It uses information from the surrounding sensors, but the selected sensor doesn't change. In 51 Point 3D, the camera actually moves the selected sensor based on the colors it has gleaned from the initial focus point, and you can watch the selected sensor move as you blast away. It's sort of kewl. In high contrast situations with good color differentiation it seems to work well - again, this is best for horizontal motion across the frame. Tracking is all about maintaining focus on a moving subject, rather than obtaining focus on different subjects as you move the camera. Also I may have made it sound like you need to refocus after each shutter activation. Not so my friend. As long as you don't completely release the shutter button, it should maintain focus on your subject and allow you to happily snap away at 8 frames/second (with the MB-D10).

http://www.nikonians.org/cgi-bin/dcforum/dcboard.cgi?az=read_count&om=27907&forum=DCForumID202&viewmode=all

[Arash]

برای اینکه اینجا از رونق نیفته!



F-stop f/4
Shutter speed 1/4000 sec
Category Nature
Lens 300mm f2.8
Camera Nikon D300

[Amin Zarif]

از معدود مقایسه های رودر روی D300 و 40D :

:Nikon D300 vs Canon EOS 40D: A Hands-On Workout



http://www.popphoto.com/cameras/5062...n-workout.html

[Persian]

از معدود مقایسه های رودر روی D300 و 40d :

امین خان ممنون گرچه چندان وارد جزییات نشده ولی مقایسه ایست كه به خواندنش می ارزد. در انتها من فكر كینم فرق خریداران دی300 و 40دی نسبت به خریداران 400 دی و دی60 این است كه خریداران دی300 و 40دی معمولا اولین دوربین اس ال ار انها نیست و احتمال اینكه سرمایه گذاری قبلی روی یك برند داشته باشند بیشتر است

[farhad44]

سلام

نمی دونم منظورمو بتونم درست بیان كنم یا نه

به نظرم اگر یك آدم بی طرف ( مثلا یك شیفته ی اولیمپس یا پنتكس نه طرفدار یا دارنده ی یكی از دو غول ) كل مطلبو با دقت بخونه اونو به طور كامل با نتیجه گیری انتهایی یكسو نمی بینه. نمی دونم شاید اشتباه می كنم. با این پس زمینه كه از اول دوستدار D300 بوده و هستم و نه به عنوان یك دارنده ی 40D با خوندن كامل متن فكر می كنم نتیجه گیری بیشتر برای همسو شدن با جایزه ی بهترین دوربین سال 2007 كه توسط همین نشریه داده شده كمی هول هولكی و بی جزئیات بود. همین جمله ی " بدون در نظر گرفتن قیمت " مقایسه دو رقیب رو كمی غیر منصفانه جلوه می ده و جمله ی آخر كه D300 رو برنده ی بدون در نظر گرفتن قیمت و 40D رو بهترین با توجه به قیمت می دونه اون جایزه ی كذایی رو زیر سوال برده و به عبارتی پارادوكس عجیبی ایجاد كرده.

البته از طرفی خوندن این ریویو رو به علاقمندان اولیمپس و پنتكس و .... شدیدا توصیه می كنم.:biggrin:

[Amin Zarif]

سلام

وقتی صحبت از مقایسه D300 و 40D میشه یاد حرف قشنگ مسعود خان قدیری در پست 357 میافتم:

 اگر برتری در دی 300 وجود داره ،نیکون داره پولشو میگیره.....

.

به قول جناب غفاری عزیز خریداران این دوربینها معمولا اولین خرید slr شون نیست،یعنی اینكه در این رنج،گزینشون از قبل مشخصه.....
به هر حال من نمیدونم چرا كانن از این سنسور جدید 450D برای 40D استفاده نكرد؟(میبخشید كه آف تاپیك شد)

[Arash]

به هر حال من نمیدونم چرا كانن از این سنسور جدید 450d برای 40d استفاده نكرد؟(میبخشید كه آف تاپیك شد)

والا قدیمترها همین سوال رو در مورد سنسور ۴۰۰ دی و ۳۰ دی می‌پرسیدند...
اول اینکه این سیاست کمپانی کانن بوده و هست...
دوم اینکه لزوما این سنسور قابلیت نصب روی ۴۰ دی رو نداشته و ندارد... چون مشخصات یک سنسور فقط مگاپیکسل اون نیست.