my sigma 24-70 seems dim at f2.8 - Page 3

Chai · 15th Apr 2008, 07:49 AM

I think it's normal. Most third party lens are not good wide open, except maybe Tamron 17-50.

Adrian Wong · 26th May 2008, 02:10 PM

Goldfries,

I just did a few quick tests on my own Nikon mount Sigma 24-70 f/2.8. Everything was shot on the Nikon D300 with exposure set to 0 and ISO 200. Take a look.

This one is a shot of the condo opposite my unit. AFAICS, the lens is brighter at f/2.8 (shutter speed about 1/5000) and both f/4.0 and f/5.6 had the same level of brightness.

Adrian Wong · 26th May 2008, 02:12 PM

Here's another 3 shots of my plants.

Same thing. f/2.8 is brighter than f/4.0 or f/5.6. Both f/4.0 and f/5.6 were equally bright.

Chai · 26th May 2008, 06:53 PM

What is the shutter speed for every shot?

Adrian Wong · 26th May 2008, 07:42 PM

Quote:

Originally Posted by Chai

What is the shutter speed for every shot?

I set it to Aperture priority. But if I remember correctly, the f/2.8 shot was at 1/5000 while the second f/4.0 shot was at 1/2800. The last f/5.6 shot should be somewhere around f/1600. If I remember correctly!!!

Chai · 26th May 2008, 07:59 PM

Quote:

Originally Posted by Adrian Wong

I set it to Aperture priority. But if I remember correctly, the f/2.8 shot was at 1/5000 while the second f/4.0 shot was at 1/2800. The last f/5.6 shot should be somewhere around f/1600. If I remember correctly!!!

I need the accurate shutter speed to determine whether the camera exposed correctly or not.

And judging by your rought estimation, that explains why f2.8 is brighter.

Adrian Wong · 26th May 2008, 08:21 PM

Quote:

Originally Posted by Chai

I need the accurate shutter speed to determine whether the camera exposed correctly or not.

And judging by your rought estimation, that explains why f2.8 is brighter.

Hmm.. The thing is metering is done automatically by the D300. Don't tell me the D300's metering is a bit off with this lens?

Chai · 26th May 2008, 08:29 PM

Quote:

Originally Posted by Adrian Wong

Hmm.. The thing is metering is done automatically by the D300. Don't tell me the D300's metering is a bit off with this lens?

LOL. You can't rely 100% on the camera. After all, they still can't get the WB right after so many years.

Adrian Wong · 26th May 2008, 09:30 PM

Quote:

Originally Posted by Chai

LOL. You can't rely 100% on the camera. After all, they still can't get the WB right after so many years.

Hehe.. That (WB) is so true.

Never mind. Tomorrow, I will fix the exposure and retake the photos.

goldfries · 26th May 2008, 11:02 PM

Adrian, I had a friend who was using the Nikon mount 24-70 f2.8 as well and his output was as yours. brightness same. no contrast issue.

I sent mine to APD (Sigma disti) and after a week they came back saying the lens is fine. nothing else I can do.

15th Apr 2008, 07:49 AM	#21 (permalink)
Chai Administrator Join Date: 6 Oct 2002 Location: Maranello Posts: 26,041 Reputation: 3845 Rep Power: 70	I think it's normal. Most third party lens are not good wide open, except maybe Tamron 17-50. __________________ Chai (Contributor & Forum Admin) http://www.techarp.com/ Intel E8400 @ 4GHz \| Abit IP35 Pro \| Corsair TWIN2X4096-6400C5DHX \| Asus EN8800GTS 512MB \| WD Raptor WD740 \| WD 5000AAKS x2 \| Antec TPII-480 \| EMU 0404 PCI \| Dtek FuZion CPU \| Swiftech MCW60 \| Swiftech MCR320QP \| Swiftech MCP350 \| Dell 2001FP \| BenQ G2400W \| Logitech G5 \| Logitech G25 \| Microsoft Natural Ergonomic Keyboard 4000

26th May 2008, 06:53 PM	#24 (permalink)
Chai Administrator Join Date: 6 Oct 2002 Location: Maranello Posts: 26,041 Reputation: 3845 Rep Power: 70	What is the shutter speed for every shot? __________________ Chai (Contributor & Forum Admin) http://www.techarp.com/ Intel E8400 @ 4GHz \| Abit IP35 Pro \| Corsair TWIN2X4096-6400C5DHX \| Asus EN8800GTS 512MB \| WD Raptor WD740 \| WD 5000AAKS x2 \| Antec TPII-480 \| EMU 0404 PCI \| Dtek FuZion CPU \| Swiftech MCW60 \| Swiftech MCR320QP \| Swiftech MCP350 \| Dell 2001FP \| BenQ G2400W \| Logitech G5 \| Logitech G25 \| Microsoft Natural Ergonomic Keyboard 4000

26th May 2008, 11:02 PM	#30 (permalink)
goldfries More Than Meets The Eye Join Date: 22 Jan 2003 Location: KL/PJ Malaysia Posts: 7,836 Reputation: 398 Rep Power: 16	Adrian, I had a friend who was using the Nikon mount 24-70 f2.8 as well and his output was as yours. brightness same. no contrast issue. I sent mine to APD (Sigma disti) and after a week they came back saying the lens is fine. nothing else I can do. __________________ no computer specs \| no photography gear list \| no userbars \| no quotes

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