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Old Mar 3, 2006, 9:32 AM   #1
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I've been looking at a lot of the bird photos in the wildlife forum. In a couple of instances, there are shots of small birds filling the _entire_ frame, with for example, a Nikon D50 w/ 80-400mm VR lens from ~45 feet, with very minimal cropping, & no teleconverter.
This is where I get confused. I have an FZ30 w/ the Raynox 2020 teleconverter. This, on paper, gives me >900mm 35mm equivalent. If I shoot a small bird at 45 feet, the bird will be _maybe_ 10-15% of the frame, but no where near the composition that I'm seeing in the dslr shots with shorter "35mm equivalent" lenses.
Could someone with any knowledge of this clue me in on the whole picture, because I'm obvioulsy missing something really important in the these numbers?
If, for example, a beerbottle at 45' fills the frame of a camera with a 420mm 35mm equiv, shouldn't that beerbottle at that distance fill the frame of any camera w/ a 420mm 35mm equiv? If not, then what is the basis of comparison?

Feeling a bit disillusioned...

--==Neil==--
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Old Mar 3, 2006, 11:52 AM   #2
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Well I can not imagine it would be as far off as you are saying.....But 400mm on a Oly4/3 camera is 800mm and on a Nikon its 600mm because of the crop factor...

But here is a photo taken at about 25 ft with a Raynox 2020.....And I am not bragging th photo quality because the photo was taken thru a foggy window





And here is a minor crop of the same image.




The crop factor of a Canon 20D is 1.6

a nikon D70is 1.5

and with the 4/3 camerasits 2
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Old Mar 3, 2006, 12:00 PM   #3
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I have looked at the post in the Wildlife forum you are refereing to.

http://www.stevesforums.com/forums/v...;highlight=d50

The post does not say anywhere that he did not crop the images. If you look at theEXIF data for his pictures it is quite apparent that he has probably cropped asone of the images was captured at 280mm.
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Old Mar 3, 2006, 2:30 PM   #4
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I'm curious how you know the images aren't crops. Did they show both the original and cropped versions?

Some of the images are probably significant crops. They start on a tripod with a perfectly focused image with low noise – both easier to get with a DSLR. Displayed at 600 X 800 a 15% crop from a DSLR can look quite good, especially with good post processing.

Some others probably result from having a birdfeeder nearby.

I trust you are using a tripod for anything in the shade. Even with stabilization your setup requires 1/125 second, and that is hard to generate unless the bird is in bright light. Turn the stabilization off with a tripod.

This is a crop of about 15% of a frame taken with my 4Mp FZ10 on an overcast day. Just a handheld grab shot. Ospreys don't let me get too close. With 8Mp and an extender the shot would have been spectacular with four times the pixel density. Even with my limited setup I would have done better at ISO50 rather than the ISO 100 I used.



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Old Mar 3, 2006, 3:23 PM   #5
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The thread is actually here:

http://www.stevesforums.com/forums/v...mp;forum_id=11


I only know about the crop vs. no crop, cause I asked, & you can see the answer
You can see my questions re: crop, etc some ways down the thread. You'll see some posts after I posted this question here, it appears, at minimum, that there was a 15 yards vs 15 feet discrepency. In addition, some others are saying even at 15 feet, it can't be done, so I dunno. You will have to admit, that regardless, the Downy shot in question shows a level of detail that so far seems unattainable with my FZ30 at that zoom, optical or "digital".

Gene,
Could you explain "crop factor", I'm not familiar w/ it. Thanks. Here is a downy at exactly 15 yards from the camera, an FZ30, Raynox 2020 at full telephoto. All I am really trying to determine is:
1. Is this par for the course for ~900mm 35mm equiv?
2. If I took this same shot with a D50 with a 400mm + 2.2 converter, will the subject be approx the same size in the uncropped picture?
If you follow the thread above, you can see why I asked this.

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Old Mar 3, 2006, 7:05 PM   #6
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The crop factor is just the amount you multiply by to get 35mm equivalents for lenses on cameras of different sensors sizes. I have the panasonic FZ20 for which the crop factor is around 6 (I think theFZ30 is around 4.7?). This factor then converts actual lens focal length into '35mm film' equivalents (allowing for the much larger 'sensor size' of a 35mm frame over the small digital sensors in most consumer cameras) - with the FZ30's 7.4 to 88.8mm actual focal length becoming, relative to a 35mm camera, roughly equivalent to the Field of View (FOV) of a 35-420mm lens. (Note that crop factors assume you are comparing lenses of the same overall design, ie projection mapping for the image - as in rectilinear vs rectilinear, equiangle fisheye vs equiangle fisheye etc).

The other thing the crop factor gives is the conversion into equivalent Depth of Field (DOF) on a 35mm camera. ie the FZ30's F2.8-3.7/F11 aperature should give a DOF equivalent to something like F13.2-17.5/F52 on a 35mm full frame sensor.

The Nikon D50, though having a much larger sensor than the FZ30, is still not a full frame camera (the full frame DSLRs like the Canon 5D are much more expensive), so a 400mm lens on it will still not be '35mm equivalent'. As Gene says above, the 1.5 crop factor means a 400mm focal length lens on a D50 is equiv. to approx 600mm FOV on 35mm.

It is extremely unlikely that those posted bird shots are full frame shots if they were taken at significant distances - with many likely to be cropped a fair bit...
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Old Mar 4, 2006, 9:57 AM   #7
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Excellent description. It more or less confirms my original understanding, which is that "35mm equiv." is simply actual focal length corrected for sensor size (crop factor).
But I have to say it again. The level of detail, sharpness & clarity of the downy pic in question is something that I suspect might lie beyond the technical limitations of my FZ30. But I'm still trying, every combination of setings, etc.
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Old Mar 4, 2006, 11:37 AM   #8
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It has been explained fine I just wanted to include a photo from the FZ30 at 3 EZ and thru a window ..I am sure others can do bett but this is about par for me.

This was taken at about 20 ft and cropped a bit but I think its a satisfactory photo for a 500 dollar camera.


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Old Mar 4, 2006, 11:47 AM   #9
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One other thing that may help explain.. the New Canon 5D is a Full Frame DSLR which means a 400 lens on it is exactly the same as 400 mm on your FZ30.....The only difference is about $6000.00

The Canon 20 D has a 1.6 crop factor which factors in to both ends of the range...you need a 22mm lens on a 20D to equal the 35mm on your camera and 250mm on the long end equals about 400mm or near the 420 of the FZ30



And just to show if I get the exposure correct the FZ30 can capture lots of detail.

This was shot at about 15 ft with a tcon 17 and 12X

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Old Mar 4, 2006, 12:37 PM   #10
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Wow genece

That is one hell of a pic. Fantastic. I just wanna say i'm glad i'm not the only one that tries to take pics through foggy windows.

Here is a pic i took today of a Chaffinch (apparently) dont know much about birds I took it with a FZ20 and a tcon 14b through a quite mucky window. The pic was a bit hazy and we decided it looked better after applying Auto Levels in Photoshop.

Also Genece I was quite impressed with the pic you took with the Raynox 2020.

I've been struggling with this lens of late but the weather hasn't helped but i haven't given up yet

mark
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