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Old 17th May 2011, 18:21   #7456
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Default Re: The DSLR Thread

Well, after 1.5 years of usage, I am selling off my Olympus 590UZ and joining DSLR club. I am in a tight budget though - 25K (+-3K). I went through last 30 pages but I am all confused now . All I could gather is, I can buy 1000D, 1100D (Stretching budget), D3000 and D3100 (Again stretching budget).

I am a SLR beginner and wont be able to justify advance features right now. Also, my interest is in capturing birds and portraits with little landscape exposure. So eventually, I would like to put money into lenses rather than spending all my money on body. Please guide me on buying the camera.
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Old 17th May 2011, 18:57   #7457
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Originally Posted by neoonwheels View Post
I am a SLR beginner and wont be able to justify advance features right now. Also, my interest is in capturing birds and portraits with little landscape exposure. So eventually, I would like to put money into lenses rather than spending all my money on body. Please guide me on buying the camera.
For birds you need a fast body with good AF and long telephoto lenses. I suggest you do a literature survey on the net, of the type of equipment used by experts, for bird shots. Then decide on the lenses that are needed for your type of shots (not necessarily what you can afford today). That would give you an idea of what you are getting into.

After that decide on what brand of lenses you want. The body is quite cheap compared to the lenses. The lenses would last you a long time in which span you will be going through at least three or more bodies.

Do not ignore the second hand market. You can get excellent pre-owned Super Telephoto lenses at a reasonable price.
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Old 17th May 2011, 19:17   #7458
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Default Re: The DSLR Thread

Sorry missed out the discussion on sensors.

Sensors heat up as there is always current flowing in it during exposure. The noise also increases with heat. From what I have read heat is a major problem for digital sensors and that limits long exposures. As said previously for really long noise free exposures, astronomers use cooling - water, refrigerants and at times liquid nitrogen.

Here are some articles on DSLR sensor heating

DSLR sensor heating study - Stargazers Lounge
Nikon D300S Digital Camera Video - Full Review - The Imaging Resource!

Will come back after finding more articles.
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Old 17th May 2011, 20:24   #7459
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Originally Posted by tsk1979 View Post
So when does the CMOS/CCD sensor show activity?
Just before the shutter opens (to reverse bias each diode in pixels) and after the shutter closes (to read out the remaining voltage on each pixel and get a measure of light intensity on each pixel).

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Originally Posted by tsk1979 View Post
When you open the shutter, the sensor cavities start collecting "photons". I am sure this process will require power consumption. I
Normally I wouldn't write what follow on team-bhp, but since you are into semiconductors:

while the shutter is open, each diode (one diode per pixel) is absorbing the photon falling on it. When a photon is absorbed in the depletion region of the diode it generates an electron-hole pair. Due to the in-built electric field in the depletion region electrons are swept one way and the holes the other way - the depletion charge and voltage is reduced every time a photon is absorbed (this is roughly the physics, actual mechanism is slightly more complex and one photon does not generate one electron-hole pair).

In a way, power is being consumed - but that power is coming from the light being absorbed by the sensor. In low light scenarios it will be very small, in high light scenario you'll keep the shutter open for short duration.

Either way your sensor can not become hot from this.

Quote:
Originally Posted by tsk1979 View Post
Hot pixels are colored pixels which come on the picture. As you increase exposure time, their number increases. Amp glow is a purple/green tinge corners of some older sensors get. Google for images, you will find many
Dark frame simple takes and exposure with shutter closed. Its like shooting with lens cap on.
So you take a picture, lets say 30 seconds long. Then you close shutter and again take a picture for 30 seconds. Hot pixles from 2 are subtracted from 1 leading to a cleaner image.
thanks

I searched and found both - simple phenomenon I didn't know much about because in scientific sensors these pixels are determined in testing and eliminated by software (also, it seems commercial photography grade sensors have a lot more of them than scientific sensors do). The senosrs I'm familiar with were either very high speed or very low noise (back illuminated with nitrogen cooling and buried diodes - away from the silicon wafer surface)

The pixels that get "hot" by long exposure are probably the statistical outliers that had high leakage currents anyway, but for short exposures were fine.

Amp glow is probably coming from packaging issues - higher stress on chip corners and edges is well known and causes higher leakages in some devices.



Quote:
Originally Posted by tsk1979 View Post

When you downscale a image, your "apparent" sharpness increases.
Take a P&S, and view the picture on a 15" laptop screen. It will look wonderful.
Now view it on a 60" TV, you will find it soft because its downsampled much less!
I got your point earlier too
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Old 17th May 2011, 20:46   #7460
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Exclamation Re: The DSLR Thread

Quote:
Originally Posted by siddutta View Post
Is 18-55 mm lens ( that comes standard with entry level DSLR ) good for
1) Portrait type photos.
2) Family pics (mostly inside home )
3) Landscape photos ( a hill , river, forest, or sky background)
Same query, except that I intend to buy a 18-105mm VR. Camera body would be Nikon D-90.

In addition to the 3 points,

4) Family at outdoors.
5) Very very occasionally animal photos.

Any additional lens required?Which brand mem card (and what capacity) to buy?Camera usage would be sparse to moderate.

PS: I am noob, using Canon PowerShot mostly on auto mood.

Last edited by sachinj12 : 17th May 2011 at 21:09.
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Old 17th May 2011, 20:54   #7461
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Originally Posted by neoonwheels View Post
... I am in a tight budget though - 25K (+-3K). ...
On that budget, i would buy a sparingly used Nikon D80 and still be left with plenty to grab a prime. D80's an excellent cam that will autofocus just about any AF and will meter all AI and later Nikkor lenses. If you can stretch to 30k, you may even stumble on a used D90 body. But not really necessary unless you are mainly into low-light work.

If you are like me, you would ignore gimmicks liked MP value, video, flip screen, kitchen sink, blah blah blah and concentrate solely on learning and taking photographs.

All the best.

Last edited by WindRide : 17th May 2011 at 21:11.
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Old 17th May 2011, 23:50   #7462
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Originally Posted by rajb3125 View Post
With all this talk or 50mm being too long for portraits(indoor) and landscapes. I must be doing something wrong, shooting portraits indoor at 200mm and shooting landscapes at 200mm.
Do I see a bit of sarcasm in that, gentlemen???
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Old 18th May 2011, 02:56   #7463
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Do I see a bit of sarcasm in that, gentlemen???
Yes and No. More of a mix of sarcasm and truth
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Old 18th May 2011, 09:48   #7464
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Originally Posted by WindRide View Post
On that budget, i would buy a sparingly used Nikon D80 and still be left with plenty to grab a prime. D80's an excellent cam that will autofocus just about any AF and will meter all AI and later Nikkor lenses. If you can stretch to 30k, you may even stumble on a used D90 body. But not really necessary unless you are mainly into low-light work.

If you are like me, you would ignore gimmicks liked MP value, video, flip screen, kitchen sink, blah blah blah and concentrate solely on learning and taking photographs.

All the best.
Quote:
Originally Posted by Aroy View Post
For birds you need a fast body with good AF and long telephoto lenses. I suggest you do a literature survey on the net, of the type of equipment used by experts, for bird shots. Then decide on the lenses that are needed for your type of shots (not necessarily what you can afford today). That would give you an idea of what you are getting into.

After that decide on what brand of lenses you want. The body is quite cheap compared to the lenses. The lenses would last you a long time in which span you will be going through at least three or more bodies.

Do not ignore the second hand market. You can get excellent pre-owned Super Telephoto lenses at a reasonable price.
I am not sure of any used market, at least in Pune. Secondly, if I would like to buy a first hand body, which would be good to start? 1100D or 550D or something from Nikon?
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Old 18th May 2011, 10:49   #7465
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Originally Posted by rajb3125 View Post
Yes and No. More of a mix of sarcasm and truth
I first got to know about using higher focal length lenses for landscape pics while reading about 70-200 f2.8 in ken rockwell's website but really made sense when shooting the hills at Horsley Hills with a prosumer digicam!!
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Old 18th May 2011, 11:09   #7466
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I am not sure of any used market, at least in Pune. Secondly, if I would like to buy a first hand body, which would be good to start? 1100D or 550D or something from Nikon?
Let me explain in more detail.

If you re going to acquire Super Telephoto Lense (400, 500 or 600 prime), the lense is your major investment. So you must find what you want from the lense

- F stop, construction quality, optical quality etc.
- Teleconverters available and their optical performance when coupled to the super telephoto lense. Some lenses are designed along with a matching teleconvertor, others use a generic one. The best performance comes with a specially designed matching one, but then they cost a lot.
- Auto focus and Vibration Reduction. Most of the modern lenses have these options, but if on a budget a manual focus non VR lense can do the work if you have steady hands and can anticipate the object location (that is how it was done before AF and VR), but be prepared for low keeper rate initially.
- Backward and forward compatibility of the lenses with bodies. Some lenses can be mounted on any SLR/DSLR of a manufacturer, some are not supported on older bodies, hence may not be supported on newer bodies also.

Once you have decided which manufacturer's lense suit you best in the long term, then you can choose an appropriate body. Initially a simple body with less frills will get you started. Later on as you progress you will home down on feature you must have and features desirable, and that is the time to change your body.

Remember DSLR technology changes very fast, while the lense technology changes slowly, especially Super Telephotos.

For second hand lenses, your best bet is the US firms like KEH, B&H, Adorama etc, whose have large stock and large transaction volume, else you have to find some one in India who is upgrading.
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Old 18th May 2011, 11:20   #7467
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Originally Posted by neoonwheels View Post
I am not sure of any used market, at least in Pune. ...
Try desi online classifieds. There are plenty around and the genuine offers are very tempting. Sellers also ship to your address for a marginal extra.

To repeat, there is almost no value in going for a new body especially for a beginner. Always better to buy used and grow "into" the system.

Just my opinion - take it for what it's worth

Last edited by WindRide : 18th May 2011 at 11:23.
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Old 18th May 2011, 19:20   #7468
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Probably an inconsequential doubt but here goes ..

If one has a 12MP camera but chooses to shoot pics at say 8MP, then how is the scaling achieved ?

I was wondering if less of the sensor is used or is the image resized via software. I'm keen to know if a 8MP photo would have higher saturation than a 12MP photo taken in the same camera.
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Old 18th May 2011, 20:21   #7469
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Originally Posted by absynthguzzler View Post
Probably an inconsequential doubt but here goes ..

If one has a 12MP camera but chooses to shoot pics at say 8MP, then how is the scaling achieved ?

I was wondering if less of the sensor is used or is the image resized via software. I'm keen to know if a 8MP photo would have higher saturation than a 12MP photo taken in the same camera.
Nice question, even I would like to see some discussion on this subject!!

But I think the saturation wont be effected!!


PS: I guess, Absynth is talking about his D90 here just in case if anyone is wondering!!!
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Old 19th May 2011, 11:20   #7470
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Originally Posted by absynthguzzler View Post
Probably an inconsequential doubt but here goes ..

If one has a 12MP camera but chooses to shoot pics at say 8MP, then how is the scaling achieved ?

I was wondering if less of the sensor is used or is the image resized via software. I'm keen to know if a 8MP photo would have higher saturation than a 12MP photo taken in the same camera.
Most cameras do not do pixel binning. So if you take a picture at lower MP, the camera software simply resizes the image. ITs always better to shoot at full MP, and later resize in computer, as desktop software can do a much better job of resizing, esp if you use the advanced scaling algorithms.
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