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Digital SLR / DSLR Camera Question / DSLR Thread 2

VeloceMoto said:
Ok, so now I understand focal lengths, but that article didn't mention the word aperture once! :laughing

I guess by having a wider aperture, you are effectively increasing your focal length? :confused
Click to expand...

No. Aperture allows in light. Think of it like the way you see. Or rather, how your pupils react to light. When it's too bright, you squint your eyes (and your pupils get tiny (i.e., stop down)); when it's not light enough, you open up your eyes as wide as possible (and your pupils get bigger too (i.e., wider aperture)).
 
huh? (subscribe... I gotta figure this out sometime. Then it will change...)
 
masameet said:
No. Aperture allows in light. Think of it like the way you see. Or rather, how your pupils react to light. When it's too bright, you squint your eyes (and your pupils get tiny (i.e., stop down)); when it's not light enough, you open up your eyes as wide as possible (and your pupils get bigger too (i.e., wider aperture)).
Click to expand...

No, I get that... but what I don't get is why both aperture AND focal length affect depth-of-field (ie. you can use them both to blur out the out of focus areas)

Case in point, these images I found on Flickr below.

Both images have similar out of focus areas, but they have wildly different aperture and focal lengths. There must be a mathematical relationship between focal length/aperture/depth-of-field, at least that's what I am guessing.

50mm @ f/1.8:
http://flickr.com/photos/varun2911/3049186153/
vgtzxe.jpg


170mm @ f/7.1
http://flickr.com/photos/carpeicthus/2382343851/
15yaq0o.jpg
 
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VeloceMoto said:
Ok, so now I understand focal lengths, but that article didn't mention the word aperture once! :laughing

I guess by having a wider aperture, you are effectively increasing your focal length? :confused
Click to expand...

Bzzzt. No.

Depth of field is kind of a fuzzy concept, and it relates to the range of distance at which something will be in focus. Smaller apertures = more "depth" will be adequately in focus. Conversely, going to a wider aperture will cause your foreground and background to be more out of focus, therefore softer and smoother.

ALSO....

A lens with a longer focal length (ie 200mm instead of 50mm) will tend to have a "shallower" depth of field. There's a lot of math and physics behind it, but the basic premise is easy enough to understand.

So, if you want a soft background, you need either a long lens, a wide aperture, or a combination of both. They're two very different things, but can achieve similar effects as you're describing.

I personally love the look of a wide-angle lens with a shallow depth of field. Some of the Skip's pictures with the 5d and the 35mm f/1.4 are just stunning to me. I so wish Nikon would make a 35/1.4 or a 24/1.4, but they don't. :mad

Edit: found it. Not my picture.

_MG_6900.jpg
 
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Well, I don't know what the mathematical formula is. I think it has to do with the glass inside the lens. A long lens will blur the background of an image, whether it's shot wide open (f/1.8) or stopped down (f/8), because the lens glass is made to focus on the subject (forefront). In a sense a telephoto lens (and a 50 mm becomes an 80 mm on a non-full frame DSLR) is like a macro lens -- but it takes close up pictures from far away instead of near.
 
So how does one control depth of field with a 50 mm f/1.8 lens? It seems as though depth of field is often merely an inch or less, particularly in portraits.
 
Depth of field is affected by four different "variables" in the process of taking a photo. They are:

- Aperture: Wider aperture yields shallower depth of field.
- Focal length: Longer focal length yields shallower depth of field
- Distance to subject: Closer subject will have a shallower depth of field
- Size of imaging plane, or sensor size: Larger sensors yeild shallower depth of field.

These variables are all unrelated, but all affect the depth of field in your image in the same way. One direction gives you a broader depth of field, the other direction gives you a narrower one. Like with so many other aspects of photography, its all a matter of managing a number of different variables that will give you a similar, if slightly different result. If you want to know the science behind it, go read this wikipedia entry: http://en.wikipedia.org/wiki/Circle_of_confusion and good luck. :laughing there are various charts and calculators (even in iPhone ap!) to refer to, but I've always found it quicker to just take a shot at a few different aperture settings, and review the results.

Bap: with the 50mm f/1.8, when taking portraits, you really only have one variable you can change to alter your depth of field: change the aperture, which in your case will mean sacrificing shutter speed (get a steadier hand) or bumping your ISO (and perhaps investing in some noise reduction software). One technique to work on in portraiture: Make sure the eyes are in focus. You can achieve this by setting your autofocus system from using all AF points to just the center. Place the center AF point over your subject's eye, focus in on that, and recompose your image.

I do suppose in your case that you do have two options in varying your depth of field - wife and baby. The wife will have a bigger head, so you'll be further away. Further subject distance = broader depth of field. Science!
 
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okay the bigger the aperture (f1.4 or f1.8) you get more DOF...which tends the photo to be soft...
the smaller the aperture (f16 foe example) will give you less DOF and a sharper image...
 
zypher said:
okay the bigger the aperture (f1.4 or f1.8) you get more DOF...which tends the photo to be soft...
the smaller the aperture (f16 foe example) will give you less DOF and a sharper image...
Click to expand...

yes, but your terminology is wrong.

Less DOF means that a narrower slice of your image will be in focus, resulting in a blurry background.

More DOF means more of your image will be in focus.

this is why I prefer a broad vs. shallow terminology rather than less vs. more.
 
TylerW said:
yes, but your terminology is wrong.

Less DOF means that a narrower slice of your image will be in focus, resulting in a blurry background.

More DOF means more of your image will be in focus.

this is why I prefer a broad vs. shallow terminology rather than less vs. more.
Click to expand...

okay
 
This is a great thread, I've been seriously considering stepping up to a dSLR but I didn't know much about them.

I have a proposal for anyone interested. I am the rep for Suomy helmets here in the US, I'd be willing to trade a brand new 2009 Spec1R Extreme of your choice (valued at $719.95) for a Nikon or Canon dSLR camera and lenses. Used is ok with me as long as it's in good shape. It seems like a fair trade to me, and if I can avoid paying retail for the camera I'm down with that! PM me if you are interested.

Donny
 
This thread is awesome! I've been kicking around the idea of getting back into photography for a while now. I did a lot of film work way, way back in the day (like 81-85ish), but ultimately I found that my skills didn't match the sort of shooting I liked to do. In particular, I had f'd up eyesight, and couldn't focus moving subjects well at all. I always thought I was focusing well, but the images would come out improperly focused. I've always felt that I have a decent eye for composition, but ultimately couldn't do what I enjoyed to shoot very well.

In the last year or so, I've borrowed friends' dSLRs (a D90, a 30D, and a 40D) on a few occasions, and I with the modern auto focus systems, I can produce much better, more consistent results. So now I am shopping.

I've gone to a local store and checked out the D90, D300, and 40D. I like them all, though the handling and controls of the D300 seemed the nicest. The focusing system on the D300 seems wicked awesome, but it's a little more than I was hoping to spend on a body. I plan on shooting some sports (~35%), so a faster body is a nice to have. The remaining 65% would be a combination of random people, city, and landscape shots. I'd probably rent lenses for the sports shooting, at least in the near term.

So, if you were getting back into the game, and wanted good burst speed, but also decent low light performance, would you get:

- the D90 + kit lens at around $1100+ tax ($1282)
- a 40D body new for $850+ sales tax
- a 40D body, low mileage used, for about $700
- a D300 + 18-200 lens new, for $1950 + sales tax ($2119)
- something else altoghether?

* The video on the D90 wouldn't be of great use to me as I admittedly suck at manually focusing dynamic subjects.

I guess, at the end of the day, the D300 feels the sweetest to me, but it is in the neighborhood of 700-800 more. I can afford it, I'm just not sure I want to afford it.
 
Also, while I am on the subject, I'm doing me best to learn about post-processing tools. I have photoshop CS3 (I needed InDesign and Acrobat for work, so I just bought the suite). The suite also comes with Adobe Bridge and Adobe Camera raw.

I'll admit that Photoshop is a bit intimidating. I have to find an online tutorial to do just about anything, but in defense of that, there are a bazillion good online help resources. ACR seems simpler, though the disadvantage is that I can't make changes in layers. Simple adjustments seem quicker and easier in ACR, but photoshop allows for much more in terms of effects, etc.

How do tools like Lightroom and Aperture compare to photoshop or ACR? What are they good and not good at compared to photoshop, ACR, or iPhoto? I tried aperture before version 2.0, and didn't like that I had to put my photos in an Aperture library, I think that's no longer the case though.
 
get the D700...i think its gonna be 8 fps with the additional battery grip...my brother has one and sure thing is its really nice...and its full frame...

radvas said:
This thread is awesome! I've been kicking around the idea of getting back into photography for a while now. I did a lot of film work way, way back in the day (like 81-85ish), but ultimately I found that my skills didn't match the sort of shooting I liked to do. In particular, I had f'd up eyesight, and couldn't focus moving subjects well at all. I always thought I was focusing well, but the images would come out improperly focused. I've always felt that I have a decent eye for composition, but ultimately couldn't do what I enjoyed to shoot very well.

In the last year or so, I've borrowed friends' dSLRs (a D90, a 30D, and a 40D) on a few occasions, and I with the modern auto focus systems, I can produce much better, more consistent results. So now I am shopping.

I've gone to a local store and checked out the D90, D300, and 40D. I like them all, though the handling and controls of the D300 seemed the nicest. The focusing system on the D300 seems wicked awesome, but it's a little more than I was hoping to spend on a body. I plan on shooting some sports (~35%), so a faster body is a nice to have. The remaining 65% would be a combination of random people, city, and landscape shots. I'd probably rent lenses for the sports shooting, at least in the near term.

So, if you were getting back into the game, and wanted good burst speed, but also decent low light performance, would you get:

- the D90 + kit lens at around $1100+ tax ($1282)
- a 40D body new for $850+ sales tax
- a 40D body, low mileage used, for about $700
- a D300 + 18-200 lens new, for $1950 + sales tax ($2119)
- something else altoghether?

* The video on the D90 wouldn't be of great use to me as I admittedly suck at manually focusing dynamic subjects.

I guess, at the end of the day, the D300 feels the sweetest to me, but it is in the neighborhood of 700-800 more. I can afford it, I'm just not sure I want to afford it.
Click to expand...
 
radvas said:
This thread is awesome! I've been kicking around the idea of getting back into photography for a while now. I did a lot of film work way, way back in the day (like 81-85ish),<snip>

- the D90 + kit lens at around $1100+ tax ($1282)
- a 40D body new for $850+ sales tax
- a 40D body, low mileage used, for about $700
- a D300 + 18-200 lens new, for $1950 + sales tax ($2119)
- something else altoghether?

I guess, at the end of the day, the D300 feels the sweetest to me, but it is in the neighborhood of 700-800 more. I can afford it, I'm just not sure I want to afford it.
Click to expand...

Well, even though it sounds as though you have your heart already set on a price range, I will offer you my $0.02. Wanting to get into the whole digital SLR thing, and being wholly unsatisfied with the quality of point-and-shoot cameras, I bought a used D70 on Craigslist 3 weeks ago; it does EVERYTHING I could possibly want or need. It cost me $460 and came with the well regarded 18-70mm lens. I bought a 50mm f/1.8 prime and with the exception of perhaps a flash unit down the road, I am completely satisfied. Like riding a new 1098, I'm really the only limitation in the equation. More money spent would have been, well, ...more money spent.

A four-year old, 6.3MP camera can take really great pictures, check out the D70 pool on Flickr. I am amazed every time I browse there.

http://www.flickr.com/groups/d70/pool/

I guess over the last few weeks, I really have come to appreciate the "it's the glass, not the body" mantra I have read many times on other forums. If your budget is $2,000+, I bet you could make a pretty compelling case for buying a cheap/used body and buying a few excellent lenses that match your shooting style. I'm curious what the pros on this thread have to say about this.

Just being in the SLR class has been a huge step up for me, a noob, an amateur. YMMV.

In any event, have fun and let us know what you decide!!
 
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