f- stop on manual mode locks to a minimum at DVinfo.net

Dan Farzad · August 8th, 2005, 12:28 PM

There are instances specially on darker area that i need to open up my shutter to 1.6 but I can not move it down lower than 2.6 (the num varies at times) why does it lock I am on full manual and it should allow me to open it as much as i want!!!!

Boyd Ostroff · August 8th, 2005, 12:36 PM

If you analyze the situation I think you'll see that the minimum f-stop varies with your zoom setting. This is the way pretty much all prosumer cameras behave. Look at the specs in your manual and note that it says "f1.6 to f2.8." So at the wide end of the zoom you have an f1.6 lens; at the telephoto end you have an f2.8 lens. In between the f number will be proportional to the focal length.

Augusto Manuel · August 8th, 2005, 12:58 PM

The lens on the Z1 is not really a top notch lens. There is no fixed f-stop with the lens you get with the Z1. Take some photography classes and you will understand why this happens.

But basically, the lens loses light gathering at the telephoto settings. It is normal. You are still in manual mode. The f-stop display is just an indicator how much the lens is opening or closing.

Quote:

Originally Posted by Dan Farzad

There are instances specially on darker area that i need to open up my shutter to 1.6 but I can not move it down lower than 2.6 (the num varies at times) why does it lock I am on full manual and it should allow me to open it as much as i want!!!!

Boyd Ostroff · August 8th, 2005, 01:12 PM

Quote:

Originally Posted by Augusto Manuel

The lens on the Z1 is not really a top notch lens. There is no fixed f-stop with the lens you get with the Z1.

I'm sure that $10,000+ removeable lenses on pro cameras are better than the Z1, but all the reviews I've seen have given high marks to the Z1 lens. There's a study by the BBC which has been quoted here and elsewhere where they discuss their plan to replace existing PD-150's with Z1's. One of the main reasons cited was the quality of the lens.

I think you'll find that the DVX-100a, XL2, PD-170 and just about every other prosumer camcorder behaves just like this. This topic comes up regularly in our different forums; Lamar wrote a good explanation in another thread:

http://www.dvinfo.net/conf/showpost....28&postcount=8

Jeremy Rochefort · August 8th, 2005, 03:03 PM

Quote:

Originally Posted by Boyd Ostroff

I'm sure that $10,000+ removeable lenses on pro cameras are better than the Z1, but all the reviews I've seen have given high marks to the Z1 lens.

Hear hear!

We shouldn't compare lenses of the Z1 and FX1 with those of the high end cameras - its not fair 'sob' :)

With the quality of the footage from Z1 being lossely compared to the likes of those shot with a F900 (Jody Eldred of JAG fame) I think we can safely say that the Z1 has a DARNED good lens.

Cheers

George Griswold · August 8th, 2005, 05:18 PM

Even 2/3" broadcast lenses lose some light at full zoom. It is the nature of the beast.
George

Bill Pryor · August 8th, 2005, 07:53 PM

A professional lens loses some light when zoomed in all the way, but it still opens up to the maximum f-stop. It's just that, if you're open all the way on the wide shot for a proper exposure, when you zoom in, you may find yourself slightly underexposed, usually no more than a quarter of a stop, often less, on most lenses today. If the wide open position is f1.4, you can set it at f1.4 no matter what your focal length.

August 8th, 2005, 12:28 PM	#1
Dan Farzad Regular Crew Join Date: May 2005 Posts: 107	f- stop on manual mode locks to a minimum There are instances specially on darker area that i need to open up my shutter to 1.6 but I can not move it down lower than 2.6 (the num varies at times) why does it lock I am on full manual and it should allow me to open it as much as i want!!!!

August 8th, 2005, 05:18 PM	#6
George Griswold Major Player Join Date: Apr 2005 Location: New Orleans, LA Posts: 218	Even 2/3" broadcast lenses lose some light at full zoom. It is the nature of the beast. George __________________ George T. Griswold, Jr. www.videonow.info New Orleans

August 8th, 2005, 12:36 PM	#2
Boyd Ostroff Wrangler Join Date: Dec 2002 Location: Mays Landing, NJ Posts: 11,802	If you analyze the situation I think you'll see that the minimum f-stop varies with your zoom setting. This is the way pretty much all prosumer cameras behave. Look at the specs in your manual and note that it says "f1.6 to f2.8." So at the wide end of the zoom you have an f1.6 lens; at the telephoto end you have an f2.8 lens. In between the f number will be proportional to the focal length.

August 8th, 2005, 07:53 PM	#7
Bill Pryor Contributor Join Date: Jan 2003 Location: Kansas City, MO Posts: 4,449	A professional lens loses some light when zoomed in all the way, but it still opens up to the maximum f-stop. It's just that, if you're open all the way on the wide shot for a proper exposure, when you zoom in, you may find yourself slightly underexposed, usually no more than a quarter of a stop, often less, on most lenses today. If the wide open position is f1.4, you can set it at f1.4 no matter what your focal length.