Quality of new lens

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stuarthamilton

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Stuart
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Hi,

Recently I upgraded my camera to the D850. At the time I still was using the kit lens that came with my previous camera so I felt I should invest decent lens for general purpose.

I decided to go for the Sigma 24-105mm F4 DG OS HSM 'A' Lens after reading impressive reviews on it. However after I started using it I noticed some issues with the images. There was heavy chromatic aberration in some shots where I wouldn't have expected any and there was blur as you got to the edges of frame.

So I decided to do a test comparison between the kit lens and the sigma. I took photos of my DVD collection at various focal lengths and F stops on both. I was pretty shocked at the results. All the photos taken on the kit lens were sharper and had better contrast than the sigma photos at the same F stops and focal lengths.

I don't understand how this is. I always understood kit lenses to be inferior quality and you need to invest in good lens. Is it possible there is something wrong with the sigma?
 
Just a thought... are you using it on a tripod? If so have you turned the IS off? I once had the canon version and tripod plus IS wasn't a great mix :)
 
Last edited:
Hi thanks for the advise.

Yes I did use a tripod, the IS was turned on, on both the Nikon and Sigma lens, I could test it again without.

For the lens update I checked their website and there are updates for the Canon and Sigma versions of the lens but not for the Nikon. But If there was I'd have to buy an extra bit of kit to update it which I'd rather not do.

I'll try another few tests on it. The shutter speed I had set was quite slow at 1/5 sec. This might have introduced some extra shake when the shutter opened on the Sigma as its a heavier lens, but maybe not.

If this fails I think I'll just have to return it!
 
If you are shooting Jpegs the camera might apply corrections to the Nikon lens but not with the sigma hence the chromatic aberations.
 
Which ‘kit’ lens are you using? Some so called ‘kit’ lenses are actually pretty darn good.
 
Did you manually focus or use live view?

don’t forget the D850 is very demanding even on ££££ primes so I wouldn’t expect a sigma ‘super’ zoom to be even remotely good enough to show off a 46mp sensor.
 
To answer a few questions:

Mintchocs: I shoot in RAW

snerkler: It's Nikon AF-S DX Nikkor Af 18 -105mm f/3.5-5.6G ED VR

Brazo: I used auto focus, I wouldn't expect to be as good as a prime but in comparison to a similar spec kit lens I would have thought it would be better.

So I did a few more comparison tests, this time I used a sturdier tripod, turned the IS off on both lens and used a faster shutter speed (1/200) this time the results were much closer, very little difference between the two. But I'm still disappointed, I expected the Sigma to have better results, the only advantage at moment I see is crop factor, the nikkor is a DX, the Sigma is a DG so it issues the full frame of the D850.

Also I'd like to try and do some comparison tests for chromatic aberration, what would be the best way to test this?
 
send lens back and buy the nikon 24-120 f4 great lens or even the nikon 28-300mm another good lens on the d850
 
stuarthamilton said:
To answer a few questions:

Mintchocs: I shoot in RAW

snerkler: It's Nikon AF-S DX Nikkor Af 18 -105mm f/3.5-5.6G ED VR

Brazo: I used auto focus, I wouldn't expect to be as good as a prime but in comparison to a similar spec kit lens I would have thought it would be better.

So I did a few more comparison tests, this time I used a sturdier tripod, turned the IS off on both lens and used a faster shutter speed (1/200) this time the results were much closer, very little difference between the two. But I'm still disappointed, I expected the Sigma to have better results, the only advantage at moment I see is crop factor, the nikkor is a DX, the Sigma is a DG so it issues the full frame of the D850.

Also I'd like to try and do some comparison tests for chromatic aberration, what would be the best way to test this?
Click to expand...
The 18-105mm is actually a pretty good lens I believe, although tbh I’d expect a full size image from the 24-105mm to look better than a cropped (DX mode) 18-105mm image. Sigma have been renowned for QC issues in the past so maybe you have a ‘duff’ lens.
 
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