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04-22-2007, 04:20 PM   #1
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portraits and depth of field

Hi
First, I'm new tot the (d)srl world so please excuse me if I say stupid things

I really like the K100D and want to buy one because it has such great features and image quality. Also the kit lenses I heard they are extremely decent , both the Da 18-55 and DA 50-200 and the whole kit is very cheap compared to other dslrs.

But now the main problem that I see: I want to get the camera mostly for portrait photography , and sometimes normal photography (group photos, maybe landscapes, etc).

So my questions are:
1)how great the "blur" in the background the kit lenses offer for portrait photography ? Let's say if the background is not very far away ? From my understanding they will not offer shallow depth of field ?


2)can you please recommend me an autofocus lens that can be similar to the Canon EF 50mm f/1.8 II that produce a lot of blur and also is decent and very cheap ? So the result is something like this ? EF 50mm f/1.0L, f/1.4 and f/1.8 Bokeh
My budget is limited and I'm thinking in dropping the 50-200 in favor of a prime that can deliver very nice "blurred" backgrounds but also decent in quality ? But as I said..something that is not very expensive ?

Thank you

04-22-2007, 04:58 PM   #2
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The kit lens offers decent bokeh, it's a good performer overal.

The lens you are looking for is the Fa 50mm f1.4. Cheap and awesome bokeh, much nicer bokeh than what i see in those Canon samples.
04-22-2007, 04:58 PM   #3
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Hi Raz and welcome to the forums!

As you mentioned, kit lens is indeed very impressive, and since you have looked at the Canon gear (based on the link) - its beyond than "much better" than stock kit EF-S 17-55 Canon supplies, I think I've used that EF-S for about a week, that's how disappointing it was.

Pentax DA 18-55mm on the other hand is fairly sharp, versatile and beautiful colors, imo - best kit lens period! I actually ordered my camera in "body only", but after seeing so many fantastic captures with that lens, I had to get it just to see for myself!

Blurring background - well, you are right, DA 18-55mm is not as fast, but there are always a way around. Generally speaking, these things will attribute to the narrow depth of field:

-Closer you are to the subject
-Longer focal length

To achieve even more blur on the background, subject has be be as far away from the background as possible. So it is very well possible with the kit lens, but - only in a good light condition (unless you are using flash)

Otherwise, the alternative to EF lenses you will have is Pentax FA 50mm f/1.4. Wonderful lens, much better built than EF f/1.8 or f/1.8 II, sharp, solid, just a pleasure!

If you want to start on extreme budget, do not overlook Pentax SMC A 50mm f/2, sure, it is a manual focus lens, but in fair condition, it can be purchased for about $20-25, like new for under $50, now thats budget

Regards,
D
04-22-2007, 05:01 PM   #4
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Depth of Field

Raz,

The depth of field is the acceptable area of sharpness in a photo.

Depth of field depends on several factors.

1. The focal length of the lens. The longer the focal length the less the depth of field.
2. The aperture. The smaller the aperture the greater the depth of field.
3. The distance of the subject focused upon. The farther away the object the greater will be the depth of field.
The converse is true for all of the above. All three factors can be utilised to maximise or minimise your depth of field.

You must open the aperture to lessen the depth of field and stop it down to increase depth of field.
Or you must get closer to decrease D of F or get further away to increase D of F.
Or change to a different focal length. A consideration here is if you get too close you may distort to your subject's features.

One caveat however. The given focal length of lenses when used on the K100D must be multiplied by a factor of 1.5. See your manual.

I think a 90 mm lens on a 35 mm camera is generally considered an ideal focal length for portraiture so your 18 mm to 55 mm kit lens is the equivalent of a 27 mm to 82.5 mm lens on a 35 mm camera. Close enough to 90 mm.

I hope I haven't confused matters.

Mickey

04-22-2007, 05:28 PM   #5
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I've found the kit lens difficult for portraiture because of the small maximum aperture (f/3.5 @ 18mm). It's true that you can just get closer to the subject, but this has its limits, especially if the background is close to your subject.

An example: This photo was taken at 18mm and f/3.5, at just about the minimum focusing distance. This offers the shortest depth of field possible, yet the background is only starting to blur. Granted, the background is only about six feet (2 m) behind the subject, but for indoor shots this is not an unusual situation. If you have the cash, go for an FA 50/1.4 -- otherwise, pick up a (manual focus) M or A 50/1.4 or 50/1.7.

04-22-2007, 05:28 PM   #6
raz
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Thank you all for the quick replys, this is a very friendly forum

Yes you are right, I looked first over Canon dslr-s (since I own now a ps canon s45 which has full manual control as its big brother G3), but after seeing the reviews on the K100D it felt just right and i cannot wait to buy it
So you are saying even with the 18-55 from the kit, while I shoot at 55 with the widest aperture, I should get some decent blurring if the background is not very close to the subject ? (maybe outdoors).

The FA 50mm f/1.4 sounds good and is not very expensive, so it's fully autofocus and compatible with the K100D ? I was looking only at DA lenses - thought the others are not autofocus but I see I was wrong.
Duh_Vinci , yes I probably buy some manual focus ones, but here where I live probably they are hard to find second hand or even new.

Thanks again to all of you for the answers

later edit: Finn, thanks for the picture, I'm buying this camera also to photograph my 1 year old son Your photograph is nice, I expected indoors photo not to have shallow dof with the kit lens, but I think outdoor should have a lot nicer background. I will see what I can do to buy the 50/1.4.
04-22-2007, 05:38 PM   #7
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QuoteOriginally posted by raz Quote
Thank you all for the quick replys, this is a very friendly forum

Yes you are right, I looked first over Canon dslr-s (since I own now a ps canon s45 which has full manual control as its big brother G3), but after seeing the reviews on the K100D it felt just right and i cannot wait to buy it
So you are saying even with the 18-55 from the kit, while I shoot at 55 with the widest aperture, I should get some decent blurring if the background is not very close to the subject ? (maybe outdoors).

The FA 50mm f/1.4 sounds good and is not very expensive, so it's fully autofocus and compatible with the K100D ? I was looking only at DA lenses - thought the others are not autofocus but I see I was wrong.
Duh_Vinci , yes I probably buy some manual focus ones, but here where I live probably they are hard to find second hand or even new.

Thanks again to all of you for the answers

later edit: Finn, thanks for the picture, I'm buying this camera also to photograph my 1 year old son Your photograph is nice, I expected indoors photo not to have shallow dof with the kit lens, but I think outdoor should have a lot nicer background. I will see what I can do to buy the 50/1.4.
Yep, ALL Pentax lenses are compatible with the K100D (although screwmount lenses need an adapter). F, FA, FA J, D FA, and DA lenses are all autofocus, K, M, and A lenses are all manual focus. Other than the DA 40mm, all DA lenses are only compatible with DSLR's.
04-22-2007, 05:47 PM   #8
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Pictures with the K100d and FA 50mm f1.4





04-22-2007, 06:59 PM   #9
raz
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thank you

I was thinking..instead of buying the k100d with the kit (18-55 and 50-200), isn't it better to buy just the camera body then the FA 50/1.4 plus something else..like the FA 28-105mm f/4-5.6 IF Autofocus Lens ?

Or it would be ashame not to buy at least the 18-55 since it's so cheap in the kit ?
04-22-2007, 07:41 PM   #10
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As far as I'm concerned, the best reason to buy the kit lens is because it's just about your only inexpensive option for a wide angle lens. With the 1.5x crop factor, all those 28's on the used market are "normal" lenses, not wide angles.
04-22-2007, 07:42 PM   #11
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The kit lens also gives you a lot of range for very little money, and it's not half bad to boot.
04-22-2007, 07:47 PM   #12
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QuoteOriginally posted by Finn Quote
I've found the kit lens difficult for portraiture because of the small maximum aperture (f/3.5 @ 18mm). It's true that you can just get closer to the subject, but this has its limits, especially if the background is close to your subject.

An example: This photo was taken at 18mm and f/3.5, at just about the minimum focusing distance. This offers the shortest depth of field possible, yet the background is only starting to blur. Granted, the background is only about six feet (2 m) behind the subject, but for indoor shots this is not an unusual situation. If you have the cash, go for an FA 50/1.4 -- otherwise, pick up a (manual focus) M or A 50/1.4 or 50/1.7.

Finn:
I'm confused. I thought that the depth of field increased as the focal length of the lens got smaller and got less as the focal lenth increased. Your example above says that the shortest DOF with the 18-55mm kit lens is at 18mm and f/3.5. I thought it would be at 55mm and f/5.6. Looking through the viewfinder on my camera seems to confirm this. What am I overlooking? Thanks

Last edited by Clem Nichols; 04-22-2007 at 09:20 PM.
04-22-2007, 08:04 PM   #13
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Whoa there chuckie. The kit lens (like most zooms) slows down as you get towards the long end. So it's not f3.5 it's f5.6

In this case, the f3.5 @ 18mm results in a shallower DOF than 55mm and f5.6.

In you case, buy the twin kit 'cos it's insanely priced and to buy then on their own will cost hundreds more. Then save for a 50/1.4.
04-22-2007, 08:05 PM   #14
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QuoteOriginally posted by nystateofmind27 Quote
-snip-Cheap and awesome bokeh, much nicer bokeh than what i see in those Canon samples.
Much nicer? I say... well... it's very good having faith in the brand you use.
04-22-2007, 08:38 PM   #15
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QuoteOriginally posted by Jonas B Quote
Much nicer? I say... well... it's very good having faith in the brand you use.
I'm not saying that the fa 50 is better than a canon f1.2 or f1.8, etc. just that, judging by those pics in the his link, the fa 50's bokeh seems much creamier.
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