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03-24-2009, 10:53 PM   #1
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lens advice

New to photography i do know how to use photoshop very well but i would like to learn how to photograph an object that is in focus but the background is somewhat out of focus or softer i can do it with photoshop but i was wondering how to do it with the camera is it a special lens, mode, or what ?


thank you for any advice

03-25-2009, 12:55 AM   #2
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You don't need to know how to use Photoshop to get into photography. People have been taking pictures for way longer than they have had computers on their desks. What you do need to know is got to take the pictures you see in your head. Poke around the web to get the basics and take a look at some photography books at your local library or bookstore. As for equipment you don't need anything fancy to start out with.

For the type of picture you specified here are some things to get you started. You can use any number of lens to get the effect you desire. But to start get yourself a good fast 50mm prime lens and play around. They are readily available and pretty well priced. A lot of people like the FA 50mm/1.4 and the FA 50mm/1.7 ($150-$200). The trick is to control the depth of field, hint: wide aperture = low aperture number = shallow depth of field. Keep the camera in Av (aperture priority), change the setting and see how it affects the photo. Set the aperture to give the depth of field that will include the object of focus and have the background out of focus. Play around and see what you get. You could get this effect in Photoshop with a mark and a blur, but it would take longer and I don't think the effect would be as pleasant.

Hope that gets you started.
03-25-2009, 02:43 AM   #3
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Depth of field.

For the most control you will have to shoot in Av mode (Aperture priority). Not as scary as it sounds. The camera will take care of shutter speed, ISO etc. No need to go down the fully Manual set-up at this stage. Basic Av facts: Smaller the f number the wider the lens is open. Eg, F3.5 (Kit lens widest?) is fairly wide open and gives a limited DOF (soft in front and behind subject). f16 very small and sharp, DOF greater, that is most of the pic will be sharp (in focus).
A great online calculator for you to play with to see the effect of changing aperture values, distance from subject and DOF effects can be found here: Depth of field calculator
Just play about with the settings to get a good idea of where will be sharp or not etc. Hope it helps, Ray
03-25-2009, 02:58 AM   #4
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QuoteOriginally posted by bsod Quote
New to photography i do know how to use photoshop very well but i would like to learn how to photograph an object that is in focus but the background is somewhat out of focus or softer i can do it with photoshop but i was wondering how to do it with the camera is it a special lens, mode, or what ?


thank you for any advice
its called bokeh or intentional blur...believe it or not, there is a science to it as well as lens specially designed for such work.

03-25-2009, 01:59 PM   #5
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The short answer: you need a lens capable of a large maximum aperture (meaning, smaller f-number). f/2.8 is starting to get there, f/2 better, f/1.something better still. The cheapest most widely avaiable option are the various 50mm lenses that go f/1.7 or f/1/.4. They can be used at smaller f-stops too (eg, larger f-numbers), but it's using them at or near their maximum that they'll give you the effect you want. If you don't mind doign the focus manually - which s often necessary anyhow to control focus accurate with a shallow "depth of field" like this - you can get an M50/1.7 for around $20-$40 used at just about any pawn shop, or here on the Marketplace forum, or on Ebay, etc.
03-25-2009, 11:35 PM   #6
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thank you for all of the help everyone i plan to read the forum a lot i have an 18 55 lens that came with the camera my budget i limited so what lens would you suggest i start with ? i really don't know yet what i will take photos of yet i guess that's the lack of an attention span but i will for sure find something i like im sure. how do you folks feel about used lenses ? i mean do they wear out ? thanks again for the help with my noob questions. BTW if you have any computer questions i can help with me let me know
03-26-2009, 04:31 AM   #7
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I dont think lenses wear out easily, especially old lenses, they were made much better and with metal instead of plastic like modern lens. So, there's nothing wrong with buying old used lens. Only thing you need to keep in mind when buying used lens is the glass, see if it's foggy (not clear), scratched or has fungus inside. And especially with Pentax, you'll find a lot of old and compatible lens for sale, with very cheap price and competitive quality. The only drawback is they're manual focus lens of course, not auto focus.

My first manual lens is Pentax A 50mm 1.4. Same as you, I upgraded to DSLR because I was interested in bokeh / narrow DOF, but I could not get it easily with the kit lens. But with the A50mm 1.4 it's easy, just use wide aperture (i.e smaller f-number like 1.4). So, I recommend you to get a 50mm 1.4 or 1.7 lens first, cheaper manual focus ones (Pentax M or Pentax A) or auto focus ones (Pentax F or Pentax FA)
03-26-2009, 04:42 AM   #8
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It really depends on what the object is and how far away it is as to which lens you will want. I find the fast 50 to be a good portrait lens, but truthfully, the first lens I would get would be the FA 35. It is also has a wide aperature of 2.0 and it is a more normal view on a DSLR. I just find the 50 to be a little long for a lot of what I shoot.


Last edited by Rondec; 06-08-2009 at 07:22 PM.
03-26-2009, 08:28 AM   #9
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As I said, the easy obvious cheap choice is a manual focus 50mm lens with a maximum aperture of f/2 or better, found at at any pawn shop in the USA for under $50, also readily available on Ebay, the Marketplace forum on this site, or a used lens dealer like KEH.com. The "A" series lenses are easiest to use, so I'd look for an "A" 50mm lens. The f/1.4 version is usually a lot more expensive, but the f/1.7 version is only a little more expensive than the f/2 version and is quite a bit better, so that's my recommendation - an A50/1.7 that you should be able to find for $50 or less.
03-26-2009, 01:59 PM   #10
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Fast glass isn't the only answer...

Even with your existing lens you can do this to some extent. Shoot in Av mode at the lowest f-number you can for your focal length, and shoot with the subject close to the camera but with a background that's further away. Even with relatively slow glass you can isolate the subject from the background.

This was taken at f/10:


K10D + A35-70/4 @f/10

This was taken at f/8:


K20D + F35-70/3.5-4.5 @f/8
03-26-2009, 02:27 PM   #11
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Great examples! Yes, if you are much closer to the subject than to the background, you can get that effect even with the basic 18-55. Also you get that effect shooting with longer telephoto lenses even if they don't have a large maximum aperture. I geuss I'd point out that while while the 18-55 or longer telephoto lenses let you get it in *some* shots, a large maximum aperture can give it to you in just about *any* shot.

Last edited by Marc Sabatella; 03-26-2009 at 06:58 PM.
03-26-2009, 03:29 PM   #12
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Thanks, Marc.

Conversely if you want the another extreme, there are also special-effects lenses like lensbabies.

I know these forums are gear-heavy so people like to find solutions they can buy...I'm certainly not immune, but wanted to mention other factors.
03-26-2009, 11:24 PM   #13
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used lenses

great example i looked around but i seem to still be a bit confused i will read a little more on these lenses i don't know what brands to look for or to stay away from a few i found on here
[URL="https://www.pentaxforums.com/forums/photographers-marketplace/55329-cosina-50mm-f1-9-a.html"] seems to be the only one in that range. this is great i thought there was less then this looking in from the outside, i have worked with alot of photographers and they make it look so easy but now i can really appreciate their skill, i am really looking forward to this challenge. i did get a lens from a pawn shop today it was $20 brand new still in the box 70-210mm f4.0-5.6 quantaray brand looking on craigs list and ebay right now for the suggested lenses what would i use the one i just bought be good for ?

thanks again for the help
03-27-2009, 11:14 AM   #14
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While there are lots available, to make things simle, I'd sugest looking for the Pentax-A 50mm 1:1.7, aka A50/1.7. It's probably the best combination of price, quality, and functionality (manual focus, but at least auto exposure) out there.

There might not be one on the marketplace today, but if not, there probably will be one next week, and I guarantee there are a dozen on Ebay, and it's also always available from KEH.com, price usually around $50 depending in condition. It's an extremely common and very versatile lens (it's very good for portraits, for example).
03-28-2009, 04:47 AM   #15
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Depth of Field controlled by F-stop is only one aspect of visually isolating a subject when composing a scene. Perspective is another important aspect.

Perspective is determined by the len's focal length*; a long focal length lens makes background items large and paradoxically often less distracting than if they are small. Here's a good example:

With a long lens it is also easy to adjust your position to effectively remove items from the background. In the top photos above (long lens) it would have been easy for the photographer to shift his/her position a little to the right & remove the car from the scene, and not so easy with the shorter lens.

Dave

* there is a one-to-one relationship between focal length and distance to the subject for the same subject size in the viewfinder.
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