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Old 3rd November 2009, 16:57   #1891
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LOL Jaggu, I guess you need to go to P&S thread .

@it_inspector, no issues, it is indeed confusing!

Continuing my previous post, lets compare actual aperture area of LX3 at wide end with the canon 24-70L lens.
For Panasonic LX3, the Focal length at wide angle is 5.1
So when the lens is open at lets say F2.8 the Area is
pi*((5.1/(2*2.8))^2) = 2.61
When the Canon 24-70 is open at F2.8, the area is 57.7

But the histogram will be identical, provided the ISO speed is same!

This also answers a question. Why do we not have a 500mm F1.8 lens, and why is the 500mm 2.8 like a bazooka?
F2.8 at 500mm requires -> 25044mm2 area
F1.8 at 500mm requires -> 60000+,

Due to their small sensors P&S cams have lenses like 5.1-51mm(10x lens) etc.,
So even having an aperture like F2.8 at telephoto end will not increase the size of the lens drastically.

Last edited by tsk1979 : 3rd November 2009 at 17:05.
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Old 3rd November 2009, 17:05   #1892
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1000D is a good choice but if you can stretch a bit go for 450D, without B&W but genuine ones are good VFM
Gurus !!

Couple of quick questions
1) What does 18 and 55 means in a 18-55 lens? I have also seen 2nd value stretched to 105 or even 250. Is it good?
2) Confused between cannon 1000 (27K); Nikon 3000(33 K) and Nikon 5000 (47K). Please help me in selecting good camera. FYI this would be my first DSLR.

Apologizes for my ignorance
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Old 3rd November 2009, 17:32   #1893
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Originally Posted by tsk1979 View Post

This also answers a question. Why do we not have a 500mm F1.8 lens, and why is the 500mm 2.8 like a bazooka?
F2.8 at 500mm requires -> 25044mm2 area
F1.8 at 500mm requires -> 60000+,

Due to their small sensors P&S cams have lenses like 5.1-51mm(10x lens) etc.,
So even having an aperture like F2.8 at telephoto end will not increase the size of the lens drastically.
These issues are the reason why defractive optical design was introduced in the first place and is one of the many ways to reduce lens size.

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40D+17-55/2.8 IS (around $1600-1800)

You are a bold man to have washed the lens & body. On second thoughts I might have done the same becuase any damage due to liquid was probably already done and beer if left unwashed would get sticky and gum up the mechanicals....snip....
D3+70-200mm are both weather sealed.
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Old 3rd November 2009, 18:20   #1894
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CA and distortion in a lens is not just dependent on the size of the lens alone. A lot is also contributed by the lens design, arrangement and grouping of various elements and the glass composition. All other things being equal, if you scale down the design of a particular lens of a dSLR to the smaller sensor size of a P&S, both the lenses will exhibit similar CA and distortion characteristics. However, since you cannot fully follow the design principles of a dSLR lens in P&S due to design constraints of a compact form factor, a few compromises have to be made.

Quote:
For Panasonic LX3, the Focal length at wide angle is 5.1
So when the lens is open at lets say F2.8 the Area is
pi*((5.1/(2*2.8))^2) = 2.61
When the Canon 24-70 is open at F2.8, the area is 57.7
The size of the aperture in case of the canon lens is more than 20 times compared to the LX3 at 2.8. Surely the amount of light entering (or rather exiting) should be more in case of the canon lens (larger pupil). But the exposure remains the same for the two. Do we mean that, all other things remaining same, the light density falling on the sensor is the same in both cases at same aperture and equivalent focal lengths??
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Old 3rd November 2009, 19:31   #1895
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Yes, what I mean to say is that if you take camera A, shoot a scene at 1/X shutter speed 1/Y aperture and Z ISO, and then do the same with a different camera with the same settings, you will get a similar histogram.
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Old 3rd November 2009, 20:18   #1896
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Originally Posted by it_inspector View Post
Point of weather sealing is not only for rain but for the fact DUST/MOISTURE etc. Its not uncommon to see people doing rally shots falling in pit of mud and body/lens combo getting a good wash in mud, no rain cover protects you there. This is one of the main reasons Pentax is still in market since almost all of upper pentax segment is Weather Sealed and those DA and Ltd`s just make me go drooling, but i can`t use any on my nikons

Personally i had beer spilled on my D3+70-200mm, i just washed it under tap and its all fine.
Righto, I didn't thought about those scenarios, but there will be hundred other scenarios where the lens or the camera will have to bear the burnt of the calamities. I think I'll keep off from Rally's

Samurai san, point of discussion was not the availability of the NEW ones but the availability of used cheap ones. I would bet that it won't be easy for you to find a used one and that's what you also expressed. I do know that Olympus make some good stuff.

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My lenses weren't cheap, but I already own it. So, why change?
Don't change it, my post was just to pull your leg. Sorry.

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Why compromise? I never worry of dust, water, humidity, moisture, fungus, etc. Never needed to clean the sensor either.
Money matters, can't spend too much money on buying all those high end stuffs. BTW, most of the time sensor gathers dust while changing lenses, and at that moment no weather sealing will help I guess.
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Old 3rd November 2009, 20:24   #1897
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BTW, most of the time sensor gathers dust while changing lenses, and at that moment no weather sealing will help I guess.
That hasn't happened in Olympus dSLR system ever. It had working dust protection system since 2003, when the the first Olympus dSLR E1 came out.
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Old 3rd November 2009, 20:40   #1898
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That hasn't happened in Olympus dSLR system ever. It had working dust protection system since 2003, when the the first Olympus dSLR E1 came out.
But SSWF is also a method of shaking off the dust from the sensor. So it's not preventing the dust to go inside the camera, right? In that sense many other Cameras have sensor cleaning system these days. If one is very careful while changing lenses than that itself is a good(probably the only) dust prevention mechanism.
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Old 3rd November 2009, 23:25   #1899
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Guys I have a noob question:

Keeping the ISO constant, a large aperture (small F value) with a fast shutter speed and a small aperture with a slow shutter speed produces similar results. I know it has changes bokeh, depth of view.

But my question is how does one decide what to use? (Small F, fast shutter speed OR large F slow shutter speed)
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Old 4th November 2009, 00:04   #1900
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Nikon D90 costs close to 80K in BLR with 18-55 lens (which has live view).
Reality check buddy! Its around 67 - 68K with 18 - 135 and that too with proper bill and warranty.
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Old 4th November 2009, 00:30   #1901
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Quote:
Originally Posted by navin View Post
Quote:
Originally Posted by Samurai View Post
What is the cheapest weather sealed (body+standard zoom) cost with Canon?
40D+17-55/2.8 IS (around $1600-1800)
Wrong, 40D is not fully weather sealed.

Quote:
Originally Posted by http://www.dcresource.com/reviews/canon/eos_40d-review
One of the new features on the 40D (in terms of design) is that certain parts of the camera are now weather-sealed. These parts include the battery and memory card compartments, and the I/O ports. The various doors and covers on the optional battery grip and wireless file transmitter are sealed as well. This doesn't mean that you can take a shower with the 40D -- it's really just extra protection against dust and moisture.
The Olympus E3 + 12-60mm is fully weather sealed, what is the Canon or Nikon equivalent?
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Old 4th November 2009, 04:09   #1902
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Originally Posted by kaushik_s View Post
But SSWF is also a method of shaking off the dust from the sensor. So it's not preventing the dust to go inside the camera, right? In that sense many other Cameras have sensor cleaning system these days. If one is very careful while changing lenses than that itself is a good(probably the only) dust prevention mechanism.
Not true. Sigma SD14 comes with removable IR cut off filter. Whole point of this filter is to give user more options, if you want/need IR capable camera on a shoot immidietaly, with in less than a minute you have it and you can change it back when required. Compared to this no other DSLR has this feature. In order to get an IR capable camera you need to disassemble the whole camera to reach the sensor and then remove IR cut off filter and make necessary adjustments in the focusing system(namely just to adjust the sensor itself), in some DSLR`s even the mirror needs to be replaced. Some newer digital film cameras are also going this route too. The biggest advantage is that it stops dust from entering the sensor/mirror box while changing lenses.

And if the dust does manage to creep onto IR cut off filter, well then first of all its out of focus till f8 and secondly its way easier and less risky to clean compared to a sensor. Its a shame such good design and such a beautiful sensor in one of the worst cameras ever produced.

Nikon implemented a new dust removal-collection system in D60(i might be wrong about the model no. as its been a time and i don`t spend much time with base models). Its basically small tunnels inside the sensor box, particularily at the bottom of the mirror assembly. When the mirror slaps, it pushes air in a way that all the dust goes through these tunnels and gets stuck to adhesive piece of tape. This was meant to remove dust off the sensor and get it stuck to the tape. How effective it is/was i am not too sure. Maybe someone with a D60 can check it out.

Also Dust is not only the problem, moisture is worse than dust. Fungus is the biggest nightmare you can think of (ofcourse other than shutter death). And fungus on a sensor is not an easy task to repair.
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Old 4th November 2009, 11:35   #1903
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What are the places around Chandigarh/Delhi where one can sell/buy secondhand Photography equipment for decent prices.

Thanks
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Old 4th November 2009, 11:48   #1904
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Quote:
But my question is how does one decide what to use? (Small F, fast shutter speed OR large F slow shutter speed)
A basic rule of thumb is that the minimum shutter speed should be equal or greater than 1/focal length of the lens you are using, for hand held photography.

Over this, you would use a higher shutter speed/ larger aperture combination if you want to catch motion photographs, or if you wish to keep the depth of field less. A lower shutter speed/ smaller aperture combination would be used if you want a larger depth of field.
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Old 4th November 2009, 14:22   #1905
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Originally Posted by chaudhrysan View Post
A basic rule of thumb is that the minimum shutter speed should be equal or greater than 1/focal length of the lens you are using, for hand held photography.

Over this, you would use a higher shutter speed/ larger aperture combination if you want to catch motion photographs, or if you wish to keep the depth of field less. A lower shutter speed/ smaller aperture combination would be used if you want a larger depth of field.
Actually that isn`t the best advice. What you use depends upon the situation and light. For example, if you are in snow and even if there are clouds, you will struggle to use f4 with anything below 1/2000, despite the lens range being 18-100mm, since there is huge amount of light.

I ran into a situation similar earlier this yr, for the required result I needed to have very slim DOF, so I was using f1.4 at 85mm but that meant some shots had blown highlights and pretty much everything was overexposed at 1/8000. Ended up using Nd400 filter with fill flash at 1/250 to rectify the situation.

Point here is, thumb size changes with each scenario
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