Lens soup

C

Chris Watson

Well-known member
I'm just about to purchase a GH1 or two and I'm searching for cheap fd primes, zoom lenses, etc. The samples on here are a big help in finding the lenses I'd like to have but I'm still a little lost. I feel like I'm learning to read again. Here's what I think I know.

Aperture:

The lower the number, the shallower the DOF and light sensitivity is? For example, an F 1.2 is going to be better for portrait type shots than a 4.7. Do I have that right?

Size of lens:

If I want to get a prime lens for wide angle shooting (or any fd lens) the lower the number is (say 20mm) the more coverage area there is. Is that right? The crop factor is another issue but I've heard it's 2x whatever lens you have so that's no problem figuring out.

Zoom Lens:

Basically you divide the lower number into the higher number and that number is your zoom range? For example, a 14-140 lens is going to be a 10x in terms of zoom range correct?

Sorry for the silly questions but I'd rather ask them and save money. Hope the info that comes out of this helps other people as well!

Chris W
Watson Videography
www.dallasweddingfilms.com
 
Size of Lens should read Focal Length, and "coverage area" is really "field of view," but I think overall it sounds like you have an understanding of the concepts. Once you start using some of the gear you'll figure it all out very quickly and you won't even have to think about it anymore.

With aperture, the smaller the number, the shallower the DOF and the more light the lens will let in, so lower number = higher sensitivity.

For what it's worth with camera lenses we usually didn't speak too much to the fact that a lens was a 10x or a 5x or a 2x zoom - that's really more of a video thing. The terminology still applies but you won't often see things like 5x or 10x listed on any still photography lenses. The minimum and maximum focal lengths are really what folks are interested in when talking about still photo lenses.
 
Chris Watson said:
I'm just about to purchase a GH1 or two and I'm searching for cheap fd primes, zoom lenses, etc. The samples on here are a big help in finding the lenses I'd like to have but I'm still a little lost. I feel like I'm learning to read again. Here's what I think I know.

Aperture:

The lower the number, the shallower the DOF and light sensitivity is? For example, an F 1.2 is going to be better for portrait type shots than a 4.7. Do I have that right?

Size of lens:

If I want to get a prime lens for wide angle shooting (or any fd lens) the lower the number is (say 20mm) the more coverage area there is. Is that right? The crop factor is another issue but I've heard it's 2x whatever lens you have so that's no problem figuring out.

Zoom Lens:

Basically you divide the lower number into the higher number and that number is your zoom range? For example, a 14-140 lens is going to be a 10x in terms of zoom range correct?

Sorry for the silly questions but I'd rather ask them and save money. Hope the info that comes out of this helps other people as well!

Chris W
Watson Videography
www.dallasweddingfilms.com
Click to expand...


To me a 'portrait lens' is twice the normal lens for a give camera. In the case of 35mm, a 50mm lens is 'normal', hence a 100mm lens is what I'd call a 'portrait lens'.

In the case of the GH-1, I just got reminded that a normal for the GH-1 is about 25mm. Hence, a 50mm is a 'portrait lens' using my criteria. (I'd personally rather think about 'what's normal' than the crop factor... which has to do with having used a variety of still formats ranging from 35mm, 6x6cm, 6x9cm, 4x5, 5x7, 8x10... in the digital world one needs to know sensor size, to determine the 'normal' lens for that sensor size.)

The 'f-stop' of the lens performs two functions... the primary function is how much light the lens passes. A lens with a lower initial f-stop will allow more light through than one with a higher f-stop.

Depth of Field is an attribute of f-stop and a quanity called 'circle of confusion'. The basic 'rule' is lower f-stop, shallower depth of field.

There's a DoF discussion in the cinematography section as I recall.
 
Hey Chris!

One way that might help to grasp the focal length of SLR lenses, is to look up the 35mm equivalents of the video cameras you're used to using...NOT the focal length written on the front of the video camera lens. For example, B&H usually list the 35mm equiv. in the specifications for a camera.

You'll notice that many video cameras are often the 35mm equiv of 28mm....which is considered a "wide angle" lens, like j1clark explains in detail above.

For example, I have a set of 35mm lenses for my Olympus OM 35mm SLR:

14mm would be a "super wide angle" (just an example....I don't have one)
28mm is my "wide angle".
50mm are my "standard" lenses...and often the "nifty fifty" that came as the kit lens with 35mm cameras back in the day....that's one reason why they're so plentiful and cheap on eBay. They're also usually very fast.
85mm is my "portrait" lens. Portrait lenses are usually in the 85-100mm range.
75-150mm is my "stays at home in the case" lens...because when I'm shooting 35mm photos for fun...I don't need something in that range. ;)

But since I'm not a professional film-maker, and only shoot wedding video as my full time job, most of MY 35mm lenses are pretty useless (and let me be sure to state that is my OPINION...as a few people have a hard time with that concept here) on the GH1 because of the 2X crop factor.

That's why lenses designed for micro-4/3 are typically TWICE as wide as lenses designed for 35mm/full frame cameras:

7mm is a "super wide angle" (e.g. the 7-14mm f4 lens)
14mm is wide angle (e.g. kit lens is 14-140mm)
20mm f1.7 is a "standard" lens (although wider than a 50mm on a 35mm camera...since it's a 40mm equivalent)
45mm f2.8 macro would be a nice portrait and macro lens...since it would be a 90mm equiv...although at f2.8 it's slow for m-4/3...not to mention it cost freaking $900.

If you're going to be shooting weddings or anything run-n-gun, you might consider picking up the 20mm f1.7, before buying a truckload of old Canon lenses off eBay and not being able to use any of the nice auto features that you paid for with the GH1. Modern technology is great...when you can afford it. ;) But if you're just going to be using it for making movies or corporate or commercial shoots...then I guess you could easier make use of cheap used manual lenses.

I've also got the 7-14mm, but it's more just for fun...I don't really use it for weddings.

I really want a second GH1 body AND the 45mm f2.8 macro...but at $900...it'll be hard to swallow.

Good luck!

RustyB
 
Chris Watson said:
Thanks for the indepth post Rusty. Good to see you over here. Getting the new Rebel when it comes out?
Click to expand...

:happy: Nah...I'm micro-4/3 all the way now...to me its what 4/3 SHOULD have been in the first place...so I sold all my 4/3 gear.

Video from the new Rebel...the 7D...and the 5D...just looks like home video on steroids....it just doesn't sit right with me. The look is catchy...but it's just not for me...looks too gimmicky for my videos. ;)

Now...if we could just get a "pro-ish" GH1 body with some bigger balls...Panny would have a mass murderer of a camera on their hands.....
 
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