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Messages - epsiloneri

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Lenses / Re: 100-400 Replacement
« on: November 22, 2010, 12:52:54 PM »
The only time that I've been in a rain forest, I can't recall having had need of a lens faster than 5.6.

Rain forests are often surprisingly dark, even at noon. Light conditions can also be difficult due to tree crown openings that let through spots of harsh sunlight, resulting in very contrasty conditions. Flash can actually be a good option, unless you're hunting easily disturbed animals.

Lenses / Re: EF 24-105 f/3.5-5.6 IS Patent
« on: November 22, 2010, 12:34:40 PM »
I wonder why it's not called 25-102mm, or even 25-100mm, since that seems to be the focal length range (for focus at infinity, I assume).

"Pojitiburidotaipu zoom" should be "Positive ride type zoom".

Ah yes, I wondered about that too. Not that "positive ride type zoom" is much more illuminating (to me).

EOS Bodies / Re: March, Lenses & Stuff
« on: November 20, 2010, 02:06:16 PM »
Thanks Kyle, for the nerdy summary of dSLR lifetimes. Posts like yours are a zillion times more interesting than the "why I prefer Canon/Nikon over Nikon/Canon" posts.

EOS Bodies / Re: No 1Ds IV? [CR1]
« on: November 10, 2010, 02:59:08 PM »
A long lens actually need a bigger mirror due to the narrower object angle. You can try to  draw it out yourself. or you can try to read some of the manual of film SLR in the 60's, they do mention the above effect.

Hmmm.... I'm not convinced. Wouldn't you get limb darkening unless the mirror reflected the full beam? Unfortunately I don't have any camera manuals from the 60's lying around  :) Perhaps you can direct me to a more accessible source for information?

Of course, Pros have a way to recover their equipment cost, whereas the amateurs, don't. What could be used as a business write-off for Pros, amateurs don't. Even more, since Pros can get their equipments' cost from jobs, amateurs don't.

I agree, but the point was that the equipment often are more than tools for the amateur. If the impact of scratches or dust is insignificant for its function, it is of no consequence for a pro; but for an amateur, they can be a major issue.

EOS Bodies / Re: No 1Ds IV? [CR1]
« on: November 10, 2010, 02:20:22 AM »
say Canon makes 500$ profit on every 1DsMk IV body and just 200$ profit ona each 5d Mk III.

Now, number of 5d MkIII buyers = 50x(1DsMk IV buyers).

So effectively canon makes 10000$ profit for every 500$ profit it makes on 1Ds Mk IV.
So it is logical for Canon to listen to a 5dMKIII demand.

But what if Canon makes a $3000 profit on each sold 1DsMk IV body and only $30 on each 5d Mk III? How do you know?

EOS Bodies / Re: No 1Ds IV? [CR1]
« on: November 10, 2010, 02:15:08 AM »
A Pelical mirror set up may work, at least for shorter focal length. For super-telephoto, It will lost some view at the top.
Why would a pelical mirror need to be smaller, and why would the focal length matter?

EOS Bodies / Re: No 1Ds IV? [CR1]
« on: November 09, 2010, 05:19:15 PM »
Is there any chance that Canon is thinking about a square sensor that is 31.5mm on each side? This format will use ALL the existing EF lens and take the bulk out of the medium format. Just like the  Rollieflex 127 in the OLD film days.

This topic has been covered before, and the conclusion was that it doesn't work for an EF dSLR because there is insufficient room for a mirror (to cover that field) between the lens and the detector. Canon would have to go EVIL to make an EF camera with a square super-FF detector. Then there is the issues with possible internal baffles on lenses (and the minor issue with tulip-shaped hoods).

Haha, I can see that we come from completely different cultures  :D That's fine, we have a common interest that brought us here. As for the OP, he (she?) will have to decide for himself the likelihood that he will benefit from having the same camera brand as his friends.

EOS Bodies / Re: 5D Mark III Specs [CR1]
« on: November 03, 2010, 04:34:03 AM »
That it is non-100% should be of no surprise to anyone. If it were 100%, then that would be a surprise.

Because of marketing reasons or something more fundamental?

EOS Bodies / Re: Canon 5DmkIII
« on: November 03, 2010, 04:31:58 AM »
I understand your point, but you're talking about the artistic side.

No, I'm not talking about the artistic side, I just gave the bird as an example. I could just as well have said "the ability to image an intensity distribution of a given solid angle that just fits onto the FF sensor".

Of course you can test the sensors only, without an optical system. It's the statement "bigger sensors collect more light" that is misleading. I agree that photosite size is only of second-order importance for a well-sampled image.

Well, as I said, I guess it depends on your friends. I assume you wouldn't lend them your car either then, since a lens usually isn't more expensive than a car (or even the service costs to a repair a damaged car).

But I think I start to see your point: it's the loss of control that worries you. Even if you got the lens back in apparent perfect condition, how do you know it had been handled with perfect care?

Regarding a pro pool, I have a feeling amateurs are much more touchy about their gear than pros. A minute scratch on the front lens of no consequence for the IQ would in general not bother a pro while an amateur with a personal attachment to the lens would be devastated. In general, I say, but I'm sure there are plenty of exceptions on both sides.

EOS Bodies / Re: 5D Mark III Specs [CR1]
« on: November 02, 2010, 07:13:25 PM »
The specs seem like what I'd expect actually, though the non-100% viewfinder surprises me.  I guess it'll still be larger than the 7D's however.

Yes, I wonder about this as well, in general. Why aren't all view finders 100%? 98% seems so close to 100%, what makes the last 2% so hard? In contrast, I don't find the magnification factor as important. Sure, with a higher magnification you are probably able to discern more detail, but for composition it's a bit tiring on the eye to roll around too much to cover all corners of a magnified frame (for FF, for APS-C it's no issue).

You're right that the 5D viewfinder is much larger than the 7D.

but if most of your friends have Nikon, I'd still go for the D7000 (so you can trade lenses with them  :) ).
Ha, ha...worst suggestion ever.  Lenses lost, friends lost.  I wouldn't loan out any of my lenses, except maybe for the film-era EF 24-90mm III which I wouldn't care about losing.

Well... I guess it depends on your friends. I have no problems in trading lenses with my friends. Of course I would fully expect a lost lens to be replaced, that goes without saying, it's part of the deal. I'd do the same. I think lens-sharing is perfect for specialty lenses you don't use/need that often, like fish eye, macro, tip-tilt, super tele.

EOS Bodies / Re: Canon 5DmkIII
« on: November 02, 2010, 06:41:59 PM »
Consider a photo taken with a D3s and the same taken with a camera with a sensor with a size of 360 * 240 millimeters (with the same photosite size). There is no equivalence in directly comparing the two photos; the one taken with the camera with the larger sensor would have an absolutely stupefying technical quality. Why? Because the larger sensor gathers 100 times more light for the same exposure - almost 7 stops (6.64 to be exact), but the noise level doesn't increase proportionally with the sensor size.

I'm not very fond of this simplified argument, removing the optical system from the question, which you really can't: for your simile to work, you have to assume that both detectors use the same (10xFF) lens. Now what if you were imaging a bird that just fit onto the small FF frame. Would the image of the bird be better with the 10xFF detector? No. Sure, you would capture 100x more photons, but 99% of those photons would come from the boring forest, of no consequence for the image quality of the bird.

A detector doesn't produce an image by itself. It needs optics. The reason a FF camera has an IQ advantage over APS-C is that it is easier to produce suitable optics for FF than the equivalent for APS-C. In your example, if you put a 50/1.2 lens in front of the FF and a 500/12 lens in front of the 10xFF, they would produce equivalent images. They would collect the same number of photons. There would be no difference in IQ. But while a 500mm f/12 lens can be readily produced at home by an amateur astronomer (they actually do a bit better), you need Canon's expensive top-of-the-line L-optics to find a 50mm f/1.2 lens.

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