A Few Newbie Questions


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Zhiliang

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Dec 20, 2006
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#1
Hi, sorry got some amateur problems that i do not understand. Really need some help.

1. F number usually refers to aperture due to my very limited knowledge. There is always a F number range on lens. What does that stands for? Is it the maximum size the aperture can open till?

2. Does image quality and sharpness depends more on the sensor, or the lens, or the camera body/model?

3. Related to question 2, does it means using a older DSLR model but using it with a very good lens, will still give you brilliant results or not?

4. Is there any difference between say bigger lens 72mm and say smaller ones like 58mm lens?

5. Does it mean that a poor sensor with a very high megapixel number will still yield very poor results?

6. Is it a must to get a dry box or dry cab for a prosumer camera?

Thanks
 

Michael

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Apr 5, 2005
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#2
1. F number usually refers to aperture due to my very limited knowledge. There is always a F number range on lens. What does that stands for? Is it the maximum size the aperture can open till?
for prime lenses the largest aperture is constant, for zoom lenses it tends to change with the focal length (not on all tough), the range indicates this change. The smallest aperture is usually not indicated in the lense name, only on the aperture adjustment ring.

2. Does image quality and sharpness depends more on the sensor, or the lens, or the camera body/model?
lens and mathematic algorithms used for the interpretation of the data.

3. Related to question 2, does it means using a older DSLR model but using it with a very good lens, will still give you brilliant results or not?
yes also an older DSLR will still produce good results, however older sensor may be more sensible to noise....

4. Is there any difference between say bigger lens 72mm and say smaller ones like 58mm lens?
bigger as in focal length or bigger as in diameter of lense?

5. Does it mean that a poor sensor with a very high megapixel number will still yield very poor results?
yes

6. Is it a must to get a dry box or dry cab for a prosumer camera?
if you dont keep it in aircon conditions and you prefer to have no mould on your lens, yes
 

Zhiliang

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Dec 20, 2006
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#3
Thank you Michael for helping me make sense on those things.

For question 4, i was referring to the diameter of the lens. Thanks once more.

Zhiliang
 

Artosoft

Senior Member
Aug 31, 2005
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#4
Thank you Michael for helping me make sense on those things.

For question 4, i was referring to the diameter of the lens. Thanks once more.

Zhiliang
Diameter of the lens? Do you mean filter thread size?

Usually (not always), the bigger the filter thread, the faster the lens. Faster lens usually come with quality (not always too) and price (this one always :bsmilie: ).

Regards,
Arto.
 

Andy Ang

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Jan 10, 2006
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#5
The diameter of the lens, normally if larger, will means more light can enter. Thus, normally they can allow a smaller f-number, what we normally called fast lens.

However, because it is more difficult to make a large piece of glass, thus they are more expensive.
 

ExplorerZ

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Jan 9, 2006
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#7
Diameter of the lens? Do you mean filter thread size?

Usually (not always), the bigger the filter thread, the faster the lens. Faster lens usually come with quality (not always too) and price (this one always :bsmilie: ).

Regards,
Arto.
the larger diameter is your lens, the larger the hole in your pocket. ;)
 

Nov 21, 2006
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#8
the larger diameter is your lens, the larger the hole in your pocket. ;)
Agree...:)

To TS, as said before, I only would like to add a little bit information

f number is refer to the lens capability of open or close. Normally must write f/2.8 but people are lazy and only type f2.8.

If a lens focal lens is 50mm f/1.8 mean the maximum diameter the aperture could open is equal f/1.8=50/1.8=27.77mm

For longer lenses, it is hard to achieve large f number (means open wider) because let compare 200 f/4 and 200 f/2.8

The maximum aperture for f/2.8=200/2.8=71mm
The maximum aperture for f/4=200/4=50mm

So you can see the difference..That's why the longer lense often requires larger barrel (results in all glasses inside lens are required to be larger in size, thus,harder to fabricate and in quality control, increased in weight...), so the the price for long lens increase in exponential function...


Just go compare the 70-200 f/4 and 700-200f/2.8..He he..You will see the prices are much much different...
 

Artosoft

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Aug 31, 2005
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#9
...Just go compare the 70-200 f/4 and 700-200f/2.8..He he..You will see the prices are much much different...
Can also compare 50/1.4 and 50/1.8 price :sweat: . It is less than 1 stop difference. Same made in China.

Regards,
Arto.
 

yanyewkay

Senior Member
Sep 22, 2004
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#10
wow.. so many pros give input already.. don't mind me amatuer give some also.

1. F number usually refers to aperture due to my very limited knowledge. There is always a F number range on lens. What does that stands for? Is it the maximum size the aperture can open till?
Yes.. single digit f-numbers means constant throughout zoom range.
eg:70-200/2.8 means from 70mm to 200mm max aperture is f2.8.
2 numbers means a range of max aperture depending on focal length.
70-300/3.5-4.6 means at 70mm max aperture is f3.5 at 300 is f4.6


2. Does image quality and sharpness depends more on the sensor, or the lens, or the camera body/model?
Both. But more on the lens. If you have a very sharp lens but only 2megapixels with lousy sensor the image will be sucky. vice-versa, a fantastic sensor with lousy lens will also give crappy picture.


3. Related to question 2, does it means using a older DSLR model but using it with a very good lens, will still give you brilliant results or not?
digital bodies these days up to 3years back can give quite impressive results.

4. Is there any difference between say bigger lens 72mm and say smaller ones like 58mm lens?
yes, as previously mentioned. bigger thread size bigger hole in wallet.

5. Does it mean that a poor sensor with a very high megapixel number will still yield very poor results?
My personal opinion yes. Unlike the days of film where you can change the film if you didn't like certain tones or colours, but with digital, the processing style is stuck and you can't do anything about it other than post process it afterwards to get the results you want. That said for an inferior sensor that is inherently noisy, you can't do much about it. It's better to get clean and good output from the start.


6. Is it a must to get a dry box or dry cab for a prosumer camera?
individual preference. I don't stay in an aircon room and my "hand-me-down" cams previously didn't have that luxury as well. They've been enjoying the same humid environment as me without fungus. Then I bought an air-tight box and use silica gel to pamper them. 2 years after that, I could afford a small dry cab and now it's storing my stuff neatly inside.


Thanks
 

Zhiliang

New Member
Dec 20, 2006
684
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Serangoon
#11
wow.. so many pros give input already.. don't mind me amatuer give some also.

1. F number usually refers to aperture due to my very limited knowledge. There is always a F number range on lens. What does that stands for? Is it the maximum size the aperture can open till?
Yes.. single digit f-numbers means constant throughout zoom range.
eg:70-200/2.8 means from 70mm to 200mm max aperture is f2.8.
2 numbers means a range of max aperture depending on focal length.
70-300/3.5-4.6 means at 70mm max aperture is f3.5 at 300 is f4.6


2. Does image quality and sharpness depends more on the sensor, or the lens, or the camera body/model?
Both. But more on the lens. If you have a very sharp lens but only 2megapixels with lousy sensor the image will be sucky. vice-versa, a fantastic sensor with lousy lens will also give crappy picture.


3. Related to question 2, does it means using a older DSLR model but using it with a very good lens, will still give you brilliant results or not?
digital bodies these days up to 3years back can give quite impressive results.

4. Is there any difference between say bigger lens 72mm and say smaller ones like 58mm lens?
yes, as previously mentioned. bigger thread size bigger hole in wallet.

5. Does it mean that a poor sensor with a very high megapixel number will still yield very poor results?
My personal opinion yes. Unlike the days of film where you can change the film if you didn't like certain tones or colours, but with digital, the processing style is stuck and you can't do anything about it other than post process it afterwards to get the results you want. That said for an inferior sensor that is inherently noisy, you can't do much about it. It's better to get clean and good output from the start.


6. Is it a must to get a dry box or dry cab for a prosumer camera?
individual preference. I don't stay in an aircon room and my "hand-me-down" cams previously didn't have that luxury as well. They've been enjoying the same humid environment as me without fungus. Then I bought an air-tight box and use silica gel to pamper them. 2 years after that, I could afford a small dry cab and now it's storing my stuff neatly inside.


Thanks

Thanks so much, they have been very very helpful. Does ALLl lens of DSLR have the real focal length as stated unlike a prosumer which might only have a equavalent?
 

kcuf2

Senior Member
Dec 29, 2005
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KFC
#12
Thanks so much, they have been very very helpful. Does ALLl lens of DSLR have the real focal length as stated unlike a prosumer which might only have a equavalent?
yes, all the lens of dslr state their exact focal length. to calculate the equivalent focal length for dslr, it depends on the camera brand and which camera already...

for nikon dslr, the whole lineup of dslr is 1.5x
for olympus dslr, the whole lineup of dslr is 2x
for canon dslr, there are 1.0x, 1.3x and 1.6x

1.5x means if the lens focal length is 70-200, the equivalent focal length is 105mm to 300mm
 

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