Author Topic: Need advice on new Sigma 2.8 zoom 24-70...  (Read 5632 times)

Offline leroy

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Need advice on new Sigma 2.8 zoom 24-70...
« on: August 06, 2014, 09:10:38 PM »
Dear folks... I full well know there are some great photographers who participate in this forum, and i need some real adult advice on the overall sharpness of this photo...Please take a look at the picture below and give me your opinion as to overall sharpness... I've never been a fan of zoom lenses; but i broke down and bought this one used... Take a look and give my your collective opinions...

Say what ya think, I'm old enough to take the truth; and most anyone's version of it, so don't worry about offending me...  This picture was shot with the light on the right of the locomotive right at sundown... Check the notes below the picture to get the full story on the settings and processing in LightRoom...
Here it is:

https://www.flickr.com/photos/125458538@N04/14661521598/

PS--- I'm tryin to decide if i need to go ahead and get an 85mm prime... I used to use one all the time in the film camera days...


Thanks a bunch...
leroy
« Last Edit: August 06, 2014, 09:12:09 PM by leroy »


leroy

Offline Michael Knight

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Re: Need advice on new Sigma 2.8 zoom 24-70...
« Reply #1 on: August 07, 2014, 12:33:14 AM »
Really it's hard to say by just one photo. Nothing screams sharp, but it may not be the lens. Noise reduction blurrs pixels to eliminate noise. Try taking test shots with jpeg files in good light (to where lowest ISO setting is possible) and without any editing. An analysis can't be determined with noise reduction taking place. Hope this helps

Offline leroy

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Re: Need advice on new Sigma 2.8 zoom 24-70...
« Reply #2 on: August 07, 2014, 08:14:10 AM »
.... Nothing screams sharp, but it may not be the lens. Noise reduction blurrs pixels to eliminate noise. Try taking test shots with jpeg files in good light (to where lowest ISO setting is possible) and without any editing. An analysis can't be determined with noise reduction taking place. Hope this helps...

Michael... Your first impression wuz the same as mine with regard to the "sharp" thing...  The camera body is my beloved D80; which ain't much of a nite camera (...iso set at 800...)...  I didn't know how the "noise elimination thing worked; so that's a help...  I'll try to shoot some good light shots at 100 ISO as the opportunity arises... I'll did up the original RAW shot and JPEG it and take a look...

Thanks again,
leroy
leroy

Offline JCagle

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Re:
« Reply #3 on: August 07, 2014, 10:33:15 AM »
With I so set at 800 there will be some noise in the picture. I agree with Michael in a daylight test with a low iso is the best way to test. I also found that one of my teles was not shooting as sharp as I would have liked. After some troubleshooting I found out my eyepiece adjustment needed to be tweaked a little. It wasn't a problem on other lensesbecause of the greater magnification of the tele.
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Offline leroy

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Re: Need advice on new Sigma 2.8 zoom 24-70...
« Reply #4 on: August 07, 2014, 10:52:04 AM »
Guys... Here is the original shot from the camera without any processing...

https://www.flickr.com/photos/125458538@N04/14665601417/

Ya can see the noise which is (...i think, at least...) from the old D80...

leroy
leroy

Offline Ed Fury

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Re: Need advice on new Sigma 2.8 zoom 24-70...
« Reply #5 on: August 08, 2014, 02:25:09 AM »
If you shot at a faster shutter speed and a lower f-stop could you reduce the iso? How does it shoot in low light at f2.8 versus a f6.7 as listed in the exif data? I've heard the sigma lenses are sharp even in the corners but I'm not sure if they're super sharp at f2.8 or wide open as they say. I think a couple stops above that should yield maximum sharpness. I assume you are full frame so my advice might be off as I shoot asp-c.

Offline leroy

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Re: Need advice on new Sigma 2.8 zoom 24-70...
« Reply #6 on: August 09, 2014, 05:33:35 PM »
All... New stuff to look at... It looks like (...to me, at least...) everything will be ok in good light and low ISO...
Pictures here...
https://www.flickr.com/photos/125458538@N04/14683850209/
https://www.flickr.com/photos/125458538@N04/14870481035/
https://www.flickr.com/photos/125458538@N04/14867415471/

Will do some more low light tests later...
leroy
leroy

Offline Ed Fury

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Re: Need advice on new Sigma 2.8 zoom 24-70...
« Reply #7 on: August 10, 2014, 05:27:10 AM »
7630 leading, is that 23G?

1/180 is way to slow to shoot a moving train. The 1/750 look better. But that train looks parked.

Offline leroy

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Re: Need advice on new Sigma 2.8 zoom 24-70...
« Reply #8 on: August 10, 2014, 08:48:49 AM »
Ed... As to the 23G question... I didn't have my radio on and the train came on me pretty fast; so i dont know...
I do know it was a long train with DPU power on the end; so it must be pretty special... He did roll by about 3:40 pm...

As to the shutter speed thing; you've got me thinking a bit about it... I'll do some math and see what i can come up with as to shutter speeds... The relatively low shutter speeds work ok if the train is movin toward ya; but it may be a problem for trains movin away....

I'm bad to want to get all the depth of field i can on shots; so i tend to do the f 8 and above thing if i have the time (...and the light...)... I suspect you are exactly right that I'm getting some motion blur that is confusin me; especially on broadside shots and goin away shots... The blury lens thing may not be the lens at all...

Thanks again,
leroy
leroy

Offline Michael Knight

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Re: Need advice on new Sigma 2.8 zoom 24-70...
« Reply #9 on: August 12, 2014, 01:36:51 PM »
I think your lens is performing well based on those shots taken in better light. Any shutter speed below 1/2x focal length is generally too slow for moving action. Faster shutter speeds are better for moving subjects and also to combat any camera shake. Setting up at irregular spots trackside with poor footing, loose ballast, etc. doesn't always provide a firm foundation to support camera stability, so shutter speed is important, particularly at telephoto focal lengths.

Offline leroy

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Re: Need advice on new Sigma 2.8 zoom 24-70...
« Reply #10 on: August 12, 2014, 02:18:05 PM »
Thanks Michael... I appreciate it... My  problem is one of continually comparing stuff and reading too much (...too much time on my hands...)... I did a bit of investigating and i think that you and some other posters are dead right on the shutter speed thing... I'm uppin them now... I guess im just a geezer who is used to doin things the "old way"... I always try to shoot with a monopod to fix the "steadiness" stuff... I wuz never good at free style handholding of cameras anyway... I do like the way this newfangled zoom allows ya to "frame" shots, rather than shoot them with a prime and do the croppin later...

Thanks again to all...
leroy
leroy