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04-17-2013, 11:53 AM   #1
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pentax k5 wr Shutter-Aperture-Iso

hi, i just bought my first dslr, and thank you for your great advices folks, this is a true dslr, never had one like this in the past, in fact i never had something better then a compact, a lumix from panasonic, so i a am a noob, i don't understand how to choose shutter speed, aperture and iso, i know that this 3 elements are basic for photograpy, so please help me understand the principle.
can you offer me some values for shutter speed, aperture when i shoot portraits and landscape for the kit lens? i am planning to buy a sigma 8-16 for landscape in the future and a da 70 mm, or maybe fa 77mm, if i have money, but i don't understand why 77 is superior to 70, and the price is double for it, does this difference justify the higher price?

please help me understand this triangle Shutter-Aperture-Iso and maybe you can explain me later what is with compensation and bracketing?

thank you so much for you advices in the past guys, and i still wait for them in the future

04-17-2013, 12:18 PM   #2
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QuoteOriginally posted by pitagora Quote
please help me understand this triangle Shutter-Aperture-Iso
You can see the sensor in your camera as a bucket that you need to fill with water; the water represents the light. A big bucket represents a low ISO and a small bucket a high ISO.

You put the bucket under the tap and open the tap. The tap represents the aperture and it's clear that the wider you open the tap (lower aperture number), the shorter the time required to fill the bucket; this time represents the shutter speed.

If you close the tap too early, the bucket will not be full and this can be seen as underexposure. Keep the tap open too long and the bucket will overflow; this can be seen as overexposure.

The sensor is actually a whole number of buckets; one for each pixel. The fuller each bucket is, the lighter it shows in the image.

So assume you get correct exposure with ISO200, 1/250s and f/8. You can also achieve the same correct exposure with ISO200, 1/125s and f/11 or with ISO200, 1/500s and f/5.6.
If 1/500s is not fast enough and you can not open your aperture more, you need to increase the ISO. So you can use ISO400, 1/1000s and f/5.6.

QuoteOriginally posted by pitagora Quote
can you offer me some values for shutter speed, aperture when i shoot portraits and landscape for the kit lens?
In general, you want to keep the ISO as low as possible; higher ISO results in noise. The current Pentax cameras are very good with regards to noise so you don't have to worry too much till ISO3200.

To freeze motion, you need fast shutterspeeds like 1/1000 or 1/2000; this selected shutter speed depends on the speed of the moving subject. For correct exposure, you want to fill the bucket, so if you have a shorter time, you either need to open the tap wider (lower f number) or use a smaller bucket (higher ISO).

For landscapes you often want both nearby and far away in focus; this can be achieved by closing the aperture to e.g. f/11 (read up on depth of field in your camera manual and on the web). As a result (to fill the bucket) you need to keep the tap open longer (use a longer shutter time e.g. 1/50s) or a smaller bucket (higher ISO).

For portraits, one usually only wants the subject in focus (again read up on depth of field); for this you will use a wide aperture (e.g. f/2). To prevent the bucket from overflowing, you will use faster shutter speeds or use bigger buckets.

Note on depth of field: wider apertures and longer focal lengths give a narrower depth of field for a given subject distance.

PS
I'm aware that the kit lens can't do f/2

Last edited by sterretje; 04-17-2013 at 12:50 PM.
04-17-2013, 01:46 PM   #3
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i saw that in M mode, i can increase/decrease the EV, when is recommended to decrease, or increase it, and with wich values?this is compensation?but bracketing at what is good?i also want to know if the pentax k 5 does have any senzor to turn off the senzor when i aproach my eye to the viewfinder, like nikon? i saw that the display turn off just if i place half the shutter button.
regarding lens which i mention early, does it deserve the investment?

regards
04-17-2013, 10:59 PM   #4
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Your camera tries to achieve correct exposure for, what is called, 18% gray. The K5 has three measuring 'modes'; they define which are of the image is used to determine correct exposure for 18% gray. Spot, center weight and and multi segment.

So lets assume you have set the camera up for multisegment and you have a bright subject in front of a dark wall where the subject only covers e.g. 20% of the image. Because there is such a large dark area, the camera (in its attempt to expose the whole image for 18% gray) will overexpose the subject; in that case you will set a compensation of e.g. -1 eV. If you have the reverse situation (dark subject and white wall), the subject will be underexposed and you want to set a positive compensation. Only experience can teach you how much you need to compensate. If in doubt, you can always use bracketing and pick the best one

You can also set the camera to spot metering for the above situations. In that case it will only take the center of the image into account and you might achieve correct exposure of the subject without compensation.

I don't think that the K5 has an eye detector to switch the LCD off; I haven't found it on mine and it does not worry me.

Regarding the lenses
Start with what you have and determine the limitations and prioritize your needs. You might find that 18mm of the kitlens is wide enough for your landscapes (for me it is) in which case you don't need the 8-16. You might find that you always have a (relative) problem in low light; in that case you can consider a faster lens (widest aperture f/2.8 or better) and / or a flash. Or that you're lacking reach in which case a telezoom might be the first lens to add.
I have one very very expensive lens and I think it was worth the investment. But only you can determine if it's worth it or not. I don't have either the FA77Ltd nor the DA70Ltd so can not judge those; buy the DA70Ltd if the need for that focal length arises; if you don't like it, you can sell it and get the FA77Ltd

04-18-2013, 12:07 AM   #5
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now i understand when increasing/decreasing exposure, thanks a lot, but like you said if i change the mettering mode into spot the camera will concentrate just on the subject that i shoot. so i guess, spot is very useful on portraits with one person, on macro, and multispot for landscape, right?but i still don't understand what is bracketing?
04-18-2013, 06:46 AM   #6
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Bracketing is taking multiple shots of the same subject with different exposures. Usually one shot under-exposed and one over-exposed. It can be useful when the lighting is complex and you aren't sure which exact settings will give a good exposure.
04-18-2013, 11:41 AM   #7
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when i selected in the camera raw dng and shoot photos in camera they appear like raw files if i press the "info" button it says is raw, but when i export in lightroom, aperture they appear like jpg, why is happening this?i have to mention that the file version is to small to be RAW, but i selected in the camera menu to shoot raw, i don't get it, can you help?
04-18-2013, 11:42 AM   #8
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And I'll jump in with the other topic ... not all lenses are of equal optical quality. Focal length is only one factor. Want an extreme example? Pick up a pair of binoculars from the children's toy section some time. Then wander over to sporting goods and look through a pair of coated field glasses with the same power ('X') factor.

Camera lenses likewise exhibit a range of optical characteristics and mechanical build quality. A great place to discover more about a lens before purchase is to visit the lens reviews in this forum.

04-18-2013, 04:03 PM   #9
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QuoteOriginally posted by pitagora Quote
now i understand when increasing/decreasing exposure, thanks a lot, but like you said if i change the mettering mode into spot the camera will concentrate just on the subject that i shoot. so i guess, spot is very useful on portraits with one person, on macro, and multispot for landscape, right?but i still don't understand what is bracketing?
You have to remember two things about spot metering:

1. Spot metering completely ignores the rest of the scene, 99% of your shot.
2. The readings it gives you will expose the spot for that middle 18% gray.

It seems fairly simple but in practice can be hard. The first rule means you should pay attention to the rest of the frame. Experienced photographers can just look and have a good idea of how the other elements in the shot will be exposed. You will probably have to point the spot at other places in the frame and make sure they will not be totally white or black, or if they are, it's OK. The second rule means knowing the subject's light properties pretty well. Is it OK for a face to be a middle tone? What about a white dress or black tux or red rose?

Spot metering works better with a graphic metering display or actual analog needle. When you are trying to figure out how many stops there are between 1/15 and 1/500, it's harder.
04-19-2013, 12:36 PM   #10
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can you please explain me why in User Mode i can't increase/decrease ISO from 50, or 100 to 512.000. I can go just from 200-400-800-1600 etc. i want to have full control for iso, what should i do?

i always shoot in user mode, and i selected M in the menu for my user mode, can you explain me when is best to use other modes?do you use it guys? or you spend almost 90% in Manual, or User mode?

regards
04-19-2013, 01:12 PM   #11
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anybody?
04-19-2013, 10:33 PM   #12
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QuoteOriginally posted by pitagora Quote
can you please explain me why in User Mode i can't increase/decrease ISO from 50, or 100 to 512.000. I can go just from 200-400-800-1600 etc. i want to have full control for iso, what should i do?

i always shoot in user mode, and i selected M in the menu for my user mode, can you explain me when is best to use other modes?do you use it guys? or you spend almost 90% in Manual, or User mode?

regards
I can't help you with the user mode.

I use Av mostly (probably 98% of my shots) for general shooting and keep an eye on the shutterspeed; this allows me easier control over DOF (depth of field; deep DOF for landscape so e.g. f/8 or f/11, shallower DOF for portraits or special effects so e.g. f/2 or f/2.8). If the light changes, the aperture does not change, only the shutter speed. You can use Tv as well for this and check the aperture, but if the light changes a bit, the aperture changes as well effecting the DOF.

I occasionally use Tv; this is when I want to have control over the shutter speed mostly, e.g. to freeze the movement of a fast moving subject.

And for indoors sports I would use TAv as light conditions can vary significantly depending on scene (which includes the background); set a shutter speed that allows to freeze movement, an aperture that gives a reasonable DOF and let the camera decide on ISO.

QuoteOriginally posted by pitagora Quote
anybody?
Relax and don't kick your post too quickly; we understand that you're eager to learn and get the perfect shots But some people are sleeping, others are working and again others are out shooting photos. And sometimes nobody knows the answer A general rule of thumb is to wait 24 hours (a long time, I know). No hard feelings.
04-19-2013, 11:37 PM   #13
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But, I don't understand why the k 5 doesn't allow me to change the gradation of iso, like I said I want a full control over iso, not increasing/decreasing by 200, 400, 800 this is to much, so, mostly the k 5 limits my iso preferences because I only have to choose from 200-400-800-1600-3200-6400(but this one I don't quit use). Is there any setting I can change, or if User manual doesn't allow me to change iso, which mode allow, but is hard for me to believe that User not allow to change iso, cause in User you have full control over the camera.

Cheers
04-20-2013, 01:07 AM   #14
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QuoteOriginally posted by pitagora Quote
but when i export in lightroom
Right this is going to sound a bit weird but here goes. When you import into the Lightroom, the catalog is not actually made up of images, it's just data of those images, any changes you make in Lightroom are then also added to that data.

When you export, the changes are applied to whatever file type you have selected in the output dialogue box, jpeg, tiff etc, you can't actually make changes to the raw file.

Does that help at all or has it made it worse.
04-20-2013, 12:58 PM   #15
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QuoteOriginally posted by pitagora Quote
can you please explain me why in User Mode i can't increase/decrease ISO from 50, or 100 to 512.000. I can go just from 200-400-800-1600 etc. i want to have full control for iso, what should i do?
Just looked it up; one possible option that limits the iso to 200 is given in point 6 in the manual on page 215:
QuoteQuote:
When [Highlight Correction] is set to [On], the minimum sensitivity is set to ISO
200. When [3. Expanded Sensitivity] is set to [On] in the [A Custom Setting 1]
menu (p.91), the minimum sensitivity is set to ISO 160.
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