marmar42643
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Thank You for the internet !!
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why f2.8 on the D5?
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Ken Huckeba
Leading Member
Er, you would have to thank Albert Gore for that I thinkThank You for the internet !!
B
Bryan Biggers
Guest
No, there are several. Probably the best example is the E-10 which is f/2.0 at wide angle and 2.8 at zoom. The E-10 lens is supposed to be pretty good too, but not as much zoom as the D7 and more chromatic aberration, and the entire camera costs more than the D7 is projected to cost. The Oly 3040 has an f/1.8 lens! but is considered to have pretty apparent chromatic aberration at wide angle and less zoom. Those are the only two I can think of off the top of my head, there may be more.
Bryan
Homer40784
Senior Member
for supplying the rest of the world with food, technology, protection,
entertainment, and medical advancements
Well Ken if you had just stopped there, you would have been alright.
I'm in complete agreement with you, but downing others, in an offhand kind of way, is not the way to go.
But on this Memorial Day 2001, I have to ask why the "stupud" post isn't the one under fire?
Is thisoriginal "stupid" post OK by you Marmar?
I find it in poor taste and totally inappropriate for a camera forum.
Hang in there Ken.
Homer
entertainment, and medical advancements
Well Ken if you had just stopped there, you would have been alright.
I'm in complete agreement with you, but downing others, in an offhand kind of way, is not the way to go.
But on this Memorial Day 2001, I have to ask why the "stupud" post isn't the one under fire?
Is thisoriginal "stupid" post OK by you Marmar?
I find it in poor taste and totally inappropriate for a camera forum.
Hang in there Ken.
Homer
lawprofkk43598
Forum Enthusiast
Bryan:
You are pretty close, but not precisely correct.
The definition of f:stop is as follows:
F-number
The f-number series is a geometric progression based on changes in the size of the lens aperture, as it is opened and closed. As the scale rises. each number is multiplied by a factor of 1.4. The standard numbers for Calibration are 1.0,1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, etc., and each change results in a doubling or halving of the amount of light transmitted by the lens to the film plane. Basically, calculated from the focal length of the lens divided by the diameter of the bundle of light rays entering the lens and passing through the aperture in the iris diaphragm.
Given that the only aspect of the physical dimensions of the D5/D7 lenses appears to be the change in the focal length (for this discussion, only the WA focal length is relevant), and the WA focal length of the D5 is longer than that of the D7, the diameter of the bundle divided into the larger focal length of the D5 yields a higher number, eg the D5 lens has a higher (therefore slower) maximum f:stop than the D7.
It would not take a doubling of the surface area, but it would involve an increse in the diameter of the ojective element of hte lens system in order to have made the D5 the same f:max as the D7. I'm certain that a desire for standardization in lens housings, glass element sizes and the like account for the different max f: numbers for what are essentially the same lens structure (min focal langth excepted).
lawprofkk (just another dummy)
You are pretty close, but not precisely correct.
The definition of f:stop is as follows:
F-number
The f-number series is a geometric progression based on changes in the size of the lens aperture, as it is opened and closed. As the scale rises. each number is multiplied by a factor of 1.4. The standard numbers for Calibration are 1.0,1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, etc., and each change results in a doubling or halving of the amount of light transmitted by the lens to the film plane. Basically, calculated from the focal length of the lens divided by the diameter of the bundle of light rays entering the lens and passing through the aperture in the iris diaphragm.
Given that the only aspect of the physical dimensions of the D5/D7 lenses appears to be the change in the focal length (for this discussion, only the WA focal length is relevant), and the WA focal length of the D5 is longer than that of the D7, the diameter of the bundle divided into the larger focal length of the D5 yields a higher number, eg the D5 lens has a higher (therefore slower) maximum f:stop than the D7.
It would not take a doubling of the surface area, but it would involve an increse in the diameter of the ojective element of hte lens system in order to have made the D5 the same f:max as the D7. I'm certain that a desire for standardization in lens housings, glass element sizes and the like account for the different max f: numbers for what are essentially the same lens structure (min focal langth excepted).
lawprofkk (just another dummy)
Ken Huckeba
Leading Member
I was being sarcastic. As an owner of the "junky instamatic" E-10, I know it has an f2.0. The other thread about how much more the f2.0 lens would cost is my point. I've shot pics at all ranges of the lens and don't see the chromatic aberration. I imagine that if you had some objects such as straight lumber or tall buildings, you would make out a very small amount on the corners. In 99% of my shots, none detectable. The E-10 has very very excellent low light capability. I'd love to have a carry around like the Dimage 7 for the glove box or for my son but I'm certainly going to wait until more ambitious people have wrung it out for awhile.
Ken
marmar42643
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Actually it wasn't ok.. not because i want to defend Americans , but like you said i don't agree with downing any nation, however big or small...
The reason i did not reply was because i might have easily been among those he considers "stupid" had i not learned only recently through this forum what f2.8 or f2 means & implicates
The other thing i learned in this & other forums i looked into was that a lot of times one writes something & doesn't realy mean it the way everyone reading understood it.. and he later finds himself "the villain".
Many people are realy not what they write.. some very mean ones can seem so sweet & vice versa... so lets not judge each other based on one post...
B
Bryan Biggers
Guest
Hmmm, I think that I am correct. F2.0 to F2.8 is one "f-stop" or doubling of light. Here is a great web site about it...
http://www.cliffshade.com/dpfwiw/exposure.htm
In order to double the light, you need twice the surface area of lens, all other things being equal.
I think that the same lens is used for the D5/D7, but because the CCDs are different size, you get a different multiplication factor with the two cameras when you calculate the "50mm equivalent" . The factor is larger with the D5 because the CCD is a little smaller, the lens actually has the same physical focal length in both cameras, but the 50mm equivalent is different.
Bryan
http://www.cliffshade.com/dpfwiw/exposure.htm
In order to double the light, you need twice the surface area of lens, all other things being equal.
I think that the same lens is used for the D5/D7, but because the CCDs are different size, you get a different multiplication factor with the two cameras when you calculate the "50mm equivalent" . The factor is larger with the D5 because the CCD is a little smaller, the lens actually has the same physical focal length in both cameras, but the 50mm equivalent is different.
Bryan
F
Flavio Atas
Guest
Hi. I'm no expert but isn't the D7 lens 2.8 - 3.5?
Meaning 2.8 at full wide and 3.5 at full zoom? I think when you use the 7x at the maximum the max aperture size is 3.5 and not 2.8.
Flávio
Meaning 2.8 at full wide and 3.5 at full zoom? I think when you use the 7x at the maximum the max aperture size is 3.5 and not 2.8.
Flávio
Ken Huckeba
Leading Member
You're right, I went overboard. I'm tired of paying so much taxes and of having served my country in protection of non-Americans only to be called stupid. I gave FIVE years of my life in service. Was I protecting my country? NO! We were serving other countries. I've got this to say, provide your own national defense. Well, we couldn't allow that now, could we? Wouldn't be very effective without stupid Americans. I agree, why was I singled out for flame when a whole country was called stupid. Yes, it made me mad...
Ken
marmar42643
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Are you sure the aim was protecting & serving other countries or is it protecting U.S. interests in these countries
I don't think many of these countries actually own the right to make their own dicisions in the first place!! They are independant by name only!!
Politics is a dirty game & it is regular people like you or me who pay the price of their dicisions....
lawprofkk43598
Forum Enthusiast
Bryan:
Whatever the relative merits of our respective positions, I want to thank you for the link to the "FWIW" site - the amount and quality of information there is astounding!!! I'll be spending significant time there, that's for sure.
Thanks again.
lawprofkk
Whatever the relative merits of our respective positions, I want to thank you for the link to the "FWIW" site - the amount and quality of information there is astounding!!! I'll be spending significant time there, that's for sure.
Thanks again.
lawprofkk
B
Bryan Biggers
Guest
Don't worry, I'm not entirely sure what if anything we are arguing about ha. That is a great site, I just wish that I could say that it was mine but it isn't. Bryan
Mike S40844
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OHH stop!! People choose a longer zoom range over a fast lens because it fills their needs NOT because they are stupid There is no need to resort to name calling just because YOU have different needs and wants.
The reason the 4X and 10 X ( and many 3 x ) zooms have f2.8 aperatures is because it is much more difficult to produce a fasy zoom plus the size of the lens would be larger
The reason the 4X and 10 X ( and many 3 x ) zooms have f2.8 aperatures is because it is much more difficult to produce a fasy zoom plus the size of the lens would be larger
Mike S40844
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Have you noticed that they guy who said Minolta used f2.8 because Americans were stupid hasn't been heard from since?
In addition to bigger zoom making the aperture smaller, adding more elements and complexities to the lens results in an inferior image finally being transferred to film or CCD. Ironically, people pay MORE for a zoom lens that produces a POORER picture.
And a REALLY big zoom is going to make camera shake a much bigger problem.
Mike S40844
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you really should consider peoples NEEDS not your OPINIONS people opt for a long lens because it fills their NEEDS
and i will tell you what i will put up MY Olympus C-2100 LONG ZOOM pictures up against anything you can produce. I'll bet it can produce pictures at 1600 X 1200 as sharp if not sharper than any camera with an f2.o lens
and i will tell you what i will put up MY Olympus C-2100 LONG ZOOM pictures up against anything you can produce. I'll bet it can produce pictures at 1600 X 1200 as sharp if not sharper than any camera with an f2.o lens
Jack40001
Leading Member
It's right, the 7x zoom is an excellent lens on the dimage 7, which is maybe the best available in consumer digital cams as well. And it didn't push up the d7's price too much. Having such a lens will result in less missed shots. If you have a heavy bag full of lenses you may happen too shoot a slightly better quality as far as we talk about the technical aspect of digital shooting. But you may loose on the fact you simply will miss your shot completely. Also the dust which can come in during the changes of the lenses all of the time may not really help you keeping up the benefits of technically high quality pictures.
Jake.
Jake.
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