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Rob Grauert
buying lenses
on Mar 12, 2009 at 7:06:46 pm

Soon (hopefully soon) I will be working with a team to create a documentary, and I think we will have a relatively large budget. All the excitement has got me looking at real cameras with real lenses, but I have a few questions about lenses that I haven't found answers for on the web:

1: What makes one lens more expensive than another. The only thing I've heard was chromatic aberration and the quality of the glass.

2. What are some things to look for. The HD lenses on B&H all seem to be very similar. I only see differences between prices and the sizes for the image plane.

3. What is a common price range many professionals are satisfied from. I realize you can't always buy cheap equipment. Certainly a $20K grand lens will be better than an $8k lens, but is a $70k lens necessary? How many pros actually use lenses from that price?

If it helps you answer more accurately, we will not be shooting our video in run-n-gun situations. It will be more controlled, like EFP.

Thanks for the tips.

Robert J. Grauert, Jr.


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Nick Griffin
Re: buying lenses
on Mar 14, 2009 at 6:42:38 pm

I have little doubt that there are any number of people in these forums far more qualified to address this than me... but let me give it a stab.

Lens price/value comes down to what you are asking the lens to do and therefore by extension what its manufacturer must put into it in order to accomplish that.

Huh?

Let's make it simple. A camera with a 1/3" CCD (lets say a Canon XL-H1 or JVC GY-HD250U) requires a lens which puts out a circular image larger than 1/3" in order to cover the whole CCD. If it just barely covers the CCD then there is fall-off at the very edges, in other words the image is brighter in the center than it is in the corners. Not having this happen requires more and better elements. This equals more expense.

A camera with a 1/2" CCD (lets say a Sony 355) obviously requires a bigger image circle at its back end in order to cover the bigger area of the bigger CCD. This means the lens elements themselves are larger. Hence (see where I'm going here?) more expense.

A camera with a 2/3" CCD (lets say a Sony 700, 900, Panasonic 1000 & up, etc.) needs still larger pieces of glass to create a still larger image area at its back end. A "High Definition" lens will be designed and manufactured to tighter specs to make it able to define a sharper image than one of the older generation of "Standard Definition" lenses. Hence lenses labeled as HD command a higher price than those which are not. SD lenses may still fit HD cameras, but probably won't look as good.

And here's where it gets interesting. Much to the chagrin of the purists, someone like me comes along and, with the help of an adapter ring puts a older (Standard Definition) 2/3" wide angle on a 1/2" camera and viola -- the CCD is well within the "sweet spot" of the lens and almost everybody who sees the output agrees that it is, in fact, High Definition. The downside for me in this scenario is that my wonderful 5.5mm wide angle which looked great on my old SD camera has now a fairly normal angle of view because the 1/2" CCD is only seeing part of the image circle the lens is putting out.

Then there are lenses which cover even larger areas like those used for cameras like Red, 35mm /70mm film and so on. (Wonder what iMax lenses must cost!)

Other factors that come into play, and again contribute to the amount of glass elements inside the lens and the size of these elements, are what you are asking the lens to do. That's why a specialized wide angle or extra long telephoto lenses cost more than a "normal" lens. And there's more to it. The higher cost lenses will, as you stated, have less chromatic aberration because they have better (ie.- more expensive) coatings which cuts down on the reflectivity between the elements inside the lens.

Anyway, that's what I think I know on the subject and, can state from experience, you get what you pay for, just be sure you don't pay for more or settle for less than you need.

(OK, boys. Tell me what I've missed or mis-construed.)


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Rob Grauert
Re: buying lenses
on Mar 15, 2009 at 6:24:10 am

Nick,

Thanks for that great explanation. I am certain this information will help us when choosing equipment for our production.

Thanks again.

Robert J. Grauert, Jr.


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