Potpourri starting Dec 14, 2009

[JPG]

Re: 'Digital cameras and 35mm similarities.

Most Digital camersa today do not have the same focal length as their 35mm cousins. Most sensors are smaller than the size of the 35mm focal plane. As such, the 'Effective' focal length for the digital cameras is 'smaller'.

Since the light 'path' internal to the lense does not need to be as 'wide' as for the 'full frame' size 35mm(and 'full frame' digital cameras) there are now lens 'systems' designed for smaller frame digital cameras. They are less expensive due to the less stringent optic requirements.

Digital 'zoom' ?x decreases the area exposed on the sensor and therefore reduces the pixel count(Resolution decrease). Only good to sell cameras to the unsuspecting!

[mickyd]

I was taught with (35mm cameras) that as a general rule divide by half and that will give you your distance in feet.

200mm lens, 200/2 =100 feet.

There are some issues with digital cameras because the image sensor size(Charge Coupled Device or CCD). You cannot know whether a focal length is "normal", wide angle or telephoto without knowing the exact size of the CCD array. Unfortunately, even knowing the exact size of the CCD array may not help because sometimes the imaging area doesn't even cover the entire array.

But as suggested below, if you set your camera to capture the best image available this will allow you to enlarge the image with minimal pixilation.
And again, do NOT use digital zoom ONLY use optical zoom. Optical zoom moves the lens to make the target larger. Digital zoom makes the pixles larger to make the target larger. But by making the pixles larger then you degrade the image quality.

The formula above is what I recall also for 35mm world and is still good with a digital camera BUT the focal length needs to be adjusted since it is generally ~1.6x greater on a digital as compared to an equivalent 35mm film camera. For example, a 100mm digital lens will magnify the equivalent of a 160mm 35 mm film camera so the formula would have to be adjusted accordingly based on the zoom correction.

Assuming cocacola1012's 38-380mm lens is on a digital camera, that works out to the equivalent of about 600mm for a 35mm film camera. Awesome zoom!! The hand held rule of thumb means you've have to shoot at 1/600th of a second (1 over the lens magnification) to not get camera shake. That shutter speed would be impossible to to attain unless the lens is big $$$$ (low f-stop) and the ISO "film" speed is set high (high = grainy). Concert shooting at the high end of the zoom would most likely need camera support (i.e. monopod, tripod, head from person in front of you etc.) I have a monopod that I use all the time when using the big lens.

[JPG]

The formula above is what I recall also for 35mm world and is still good with a digital camera BUT the focal length needs to be adjusted since it is generally ~1.6x greater on a digital as compared to an equivalent 35mm film camera. For example, a 100mm digital lens will magnify the equivalent of a 160mm 35 mm film camera so the formula would have to be adjusted accordingly based on the zoom correction.

Assuming cocacola1012's 38-380mm lens is on a digital camera, that works out to the equivalent of about 600mm for a 35mm film camera. Awesome zoom!! The hand held rule of thumb means you've have to shoot at 1/600th of a second (1 over the lens magnification) to not get camera shake. That shutter speed would be impossible to to attain unless the lens is big $$$$ (low f-stop) and the ISO "film" speed is set high (high = grainy). Concert shooting at the high end of the zoom would most likely need camera support (i.e. monopod, tripod, head from person in front of you etc.) I have a monopod that I use all the time when using the big lens.

Although the "~1.6" factor above is common, not All digital cameras use a sensor of that reduced size.

[mickyd]

Re: 'Digital cameras and 35mm similarities.

Most Digital camersa today do not have the same focal length as their 35mm cousins. Most sensors are smaller than the size of the 35mm focal plane. As such, the 'Effective' focal length for the digital cameras is 'smaller'.
.....

You want to reword your last sentence? (It's ok if you edit it to make it correct also .)

Although the "~1.6" factor above is common, not All digital cameras use a sensor of that reduced size.

That's why I used the "generally ~" prefix.

[joedw00]

Boy who would have thought you could learn all this stuff on a woodworking forum. This is great.

[colday]

Boy who would have thought you could learn all this stuff on a woodworking forum. This is great.

That is one of the things I LOVE about this forum.

I ran into some real busy pre-Christmas days, so I'll let y'all handle the photo stuff, you're doing great!

But, one comment on the deleting files...

I'm not talking about accidental deletions, I'm referring to deleting an image then DTR (down the road) wishing you had that picture of Aunt Martha. At that point any hopes of recovering it are gone, the data has most likely been overwritten many times.

[JPG]

Boy who would have thought you could learn all this stuff on a woodworking forum. This is great.

Don't tell anyone from Montana!:D

[JPG]

You want to reword your last sentence? (It's ok if you edit it to make it correct also .)


That's why I used the "generally ~" prefix.

~ means approximate, not 'may vary'!:rolleyes:

How about I 'explain' my meaning instead. Since the sensor is smaller, it is located closer to the 'focal point' of the lense. I am referring to the inside of the lens/camera. To me that is shorter. I may be inconsistent with the rest of humanity in referring to it that way! Shorter inside/longer outside????

[mickyd]

Point and shoot vs. photography......For you point and shooters, there actually IS a correct answer to this question based on these facts.

Details needed to answer the poll question....

Bright sunny cloudless day, August 21, 2010, high noon, your in the middle of a field of lawn turf in Flagstaff, Arizona. You want to photograph the field and sky with a wide angle landscape shot with the blue sky horizon in the vertical center of the view finder. You want to under expose your photograph by 2 f-stops. Your film speed is ISO 400, your lens is a 28mm wide angle. Your shutter speed is 1/500th of a second. Your wearing size 10 red sneakers and a medium baseball cap.

Your cameras exposure meter isn't working and you don't have a light meter either. What will you set the cameras aperture at to under expose your photo by 2 f-stops? (I'm at lunch with too much time on my hands, bored stiff!!)

P.S. I tried to make the question non-googleable!! I will now go out and see if I can google the answer

[mickyd]

~ means approximate, not 'may vary'!:rolleyes:

And that changes the clarity of my explanation example....how??

How about I 'explain' my meaning instead. Since the sensor is smaller, it is located closer to the 'focal point' of the lense.

I'll give you time to correct (or in your case attempt to 'clarify') this one too.

I may be inconsistent with the rest of humanity in referring to it that way!

That"s ok.....your JPG and we all understand