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Sigma 18-200mm f/3.5-6.3 DC Macro OS HSM Lens - Nikon Fit


HollyDuff New Member
6
6 Dec 2018 7:34PM
Hello All

I'm new on here and quite a newbie where DSLR and lens are concerned.

I have a Nikon D3200 and started with the 18-55mm kit lens that came with the camera. Whilst this is a very limited lens in my opinion: I still managed to get some very nice, and importantly, sharp shots.
However the limitations of the lens caused me to buy the above lens: I know my limitations and I will not be carrying round various lens in a bag so I wanted an 'all rounder'.
I really thought I had done enough homework looking at reviews and estimated that the above would meet my needs more than adequately.

Well I'm very disappointed indeed: I have taken all kinds of shots and not one of them is sharp!

I have to rely on auto focusing quite a lot because of my lack of 20-20 vision: so ordinarily I'd auto focus on my subject and then compose my photo and none of them are sharp - not one. In comparison to my kit lens shots: the Sigma lens ones are extremely mediocre.
The reviews do mention 'it's a good lens but you get what you pay for' but I am hugely disappointed with what I am producing.

I've actually been back to Jessops in case there was something wrong with the lens or my camera had suddenly developed a fault but the very experienced sales person felt the lens was operating properly: I even asked her to take some shots in the shop so I could see if she managed a pin-sharp photo and no; she didn't (this was taking a photo of my bag on the counter...).

Does anyone have any thoughts?

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franken Plus
16 4.8k 4 United Kingdom
6 Dec 2018 7:57PM
It's difficult to know what the problem is here. If you were shooting at say the 200mm end, what shutter speed was used.
Do you have a tripod? If you do then take a few shots from the 18 mm.end and the 200 mm. Turn off any inbuilt anti shake on the camera first. If the images are coming out as sharp then it's possible that you are using too slow shutter speeds. If they are still unsharp then it may be a problem with the lens. Because the lens operates on the camera does not mean that there's not a focus fault with it.

Stickleman 8 83 3 England
7 Dec 2018 1:15PM
I had the Tamron version a few years ago, it was terrible, especially on the left side. I returned it and got the Sigma version and it was decent for what it was, an all rounder, you should have been a bit firmer with Jessops imo and asked for another copy to compare.
hi, maybe you can try this, one of the written (or unwritten rules) about focal length is to aim to have the shutter speed to be the reciprocal of the focal length, eg when at 200mm, aim for a shutter speed of 1/200s / or 1/250s in the case of the settings on your d3200. The reason being is that camera shake is amplified massively at longer focal lengths. with OS turned on, you will be able to push it to 1/160s or even 1/100s with a steady hand

another possibility is that you are using a tripod with the optical stabilisation turned on or vice versa. can you be more specific about its use, perhaps upload one of the pictures with settings on this forum post?

hope this helps



HollyDuff New Member
6
7 Dec 2018 7:17PM
Hello Folks

Thank you for taking the time to try and work out why my new lens is so disappointing: or perhaps how I'm just a complete goonda! (New word from a very good book I'm currently reading).
I do appreciate you trying to help me. 322278_1544209229.jpg



I'm going to try to attach one of some photos I took of a nearby lighthouse: this also highlights another issue I have now with my camera. When I use auto focusing: not all the red lights come on. On the day I took the attached photo: only one light on the right hand side came on irrespective of what I was focusing on or where I was pointing the camera...

It was getting on for dark: so I used this one red light as my focus - placed it on the lighthouse - every time for every shot! And not one shot came out sharp: in fact the lighthouse in all the photos was out of focus.
File info for lighthouse shot: ISO 6400 1/50sec f/14 18mm

Next shot is the one I asked the assistant in Jessops to take for me: I asked her to take a pin-sharp close up so I could be convinced that the lens would produce that. 322278_1544209857.jpg


File info: ISO 100 1/30sec f/3.5 18mm

right, thats an easy(ish) one, f14 when nearly dark is quite high when handheld, aim for f8 then the shutter speed will be reduced, also it looks like it in the mode where the camera selects the focus point as the rocks are more in focus. on the screen settings can you put it into single point mode (so that you can move the red square round with the dial on the back and not have it jumping around the scene

see how that goes......
Jestertheclown 10 7.9k 252 England
8 Dec 2018 9:59AM
Which mode are you using?
If you're using 'aperture' then the settings for your lighthouse shot are nowhere near ideal.
F14 in poor light is too tight. Opening the lens right up would have given you a much shorter exposure time and/or allowed you to use a lower ISO.
Likewise, the shot of your bag. At 1/30th. you can almost guarantee that you won't get a sharp image.
By your own admission; you're struggling to master the focusing modes. Have a look online for some tutorials; it doesn't matter which camera they're aimed at as the theory will always be the same.
Understanding how they all work will help you greatly.
That's not to say, of course, that your lens isn't performing badly; that could well be the case but I suspect a large part of your problem lies with your technique.
HollyDuff New Member
6
8 Dec 2018 12:00PM
Hello Darren

Which mode do you mean when you say that the 'camera selected the focus point'? I had it set on matrix...

I did say that only one red light came on (on the right hand side of the photo): so had to use that for the auto focus. I put the spot on the lighthouse: it wasn't on the rocks; so I don't get that.

HollyDuff New Member
6
8 Dec 2018 12:12PM
Hello Jestertheclown

Thanks for trying to help. I would have chosen aperture mode for the lighthouse photo: so take your point.

The shot of my camera bag was taken by the assistant in Jessops: I asked her to take it on auto so we could both see whether she could achieve a pin-sharp photo. So if 1/30 sec wasn't ideal for that shot: what does that say about the lens because with my camera the focusing is done in the lens...
Jestertheclown 10 7.9k 252 England
8 Dec 2018 5:02PM
The auto setting is always going to be a compromise.
The camera's software will attempt to put together a setting that will produce what it hopes is the best result that can be achieved but as in this case, it doesn't necessarily work.
Your camera's used the widest aperture that's available and selected ISO 100; in fact, I'm not sure that the camera selects the ISO, even in auto mode. That may have been set earlier.
Anyway, all of that has left it with no choice but to expose for 1\30th. of a second. That's a long, long time to hand hold a DSLR with a long lens attached, even if you're propped against something, without there being some movement. I'd even go so far as to say that it's almost an impossibility.
As for the focusing taking place within the lens; as far as I'm aware, that's how they all work.
There are ways to check a lens' ability to focus; personally, I've never done it but I've seen explanations re. how it's done.
Could be worth looking up?
dark_lord Plus
14 2.2k 556 England
9 Dec 2018 9:31AM
It's important that you included the camera settings as that's where the problem is. They can be easily sorted and that cause eliminated - if the problem persists then it#s tme tp look at the lens.

Your lighthouse shot. f/14 isn't going to be the best performance for the lens. f/8 to f/11 is best, and given the 18 mm focal lenght used f/8 would be fine. ISO 6400, far rtoo hich an ISO for clear and sharp images. ISO 400 is much better. Shutter speed is borderline at best for safe handholding to reduce the effects of camera movement.
Given a lower ISO for improved image quality may mean a slower shutter speed than that, which really means some form of camear support.

The camera bag image. If that was taken ny a camera store assistant then you have to despair, greatly dispair. Lenses don't perform so well at full aperture, but should be adequate. But shooting handheld (I guess) at 1/30 isn't going to cut the mustard. Why not shoot a scene from the shop doorway (assuming it is a shop and not a unit in a shopping mallwhich aren't brightly lit.

Technique needs to be sorted, and understood first. Matrix is just the light metering system, nothing to do with focus. Set a single focus point and use that for your tests. Make sure the camera is firmly supported and/or use a fast shutter speed, say 1/250 or even 1/500, for your test conditions.
HollyDuff New Member
6
9 Dec 2018 12:39PM
Hi dark-lord

Thank you for trying to help me with the efficacy of my new lens.

The camera bag photo was most certainly taken by the assistant in the camera shop (why would I say otherwise?). It was however a unit in a shopping mall so perhaps that's why she simply took the photo of my bag. Having said that: I reasoned that if the bag was that close (relatively speaking); then we would be able to clearly see whether she could achieve a pin-sharp photo with my lens.

I'm clearly inexperienced and don't mind having to put in the time to get the hang of my new lens but my BIG worry was and is322278_1544359067.jpg

: that I might spend too long doing so and then find that actually my hunch was right all along and the lens is not performing as it should. It might then be too late to take the lens back: they may say I have done something to it...

I did say in my initial post: that I managed to achieve some more than decent shots with my Nikon 18-55mm kit lens (see photo attached) - ISO 800 1/6 sec f5/3 48mm - hand held)
Not perhaps pin sharp but nothing like as mediocre as I'm 'achieving' now. And that was with the same lack of experience and dearth of knowledge...

Would it be fair to say that this is probably because the focal length of that lens was much shorter and therefore I could get away with hand held shots?
Your thoughts on that will help me to at least feel comfortable if I end up keeping the lens.

I will however do as you suggest and perform a test - once I work out the best way to do that!

Jestertheclown 10 7.9k 252 England
9 Dec 2018 1:44PM

Quote:
Would it be fair to say that this is probably because the focal length of that lens was much shorter and therefore I could get away with hand held.


You'll certainly get away with using longer exposure times with a shorter lens but you still need to be careful.
It's hard to tell from your upload here, just how sharp it actually is, particularly as it was taken in the dark.
1/6th. hand held is achievable but you're pushing your luck.
You say that you're going to carry out some tests; as I posted earlier, I've never done so but there's plenty of info. available.
It would be a good idea to post one of your not--sharp-enough images in the critique gallery, explaining your reason for doing so.
You'll get honest answers and opinions re.whether the issue lies with the lens or its user and more importantly, how those issues could be best addressed.
Jestertheclown 10 7.9k 252 England
9 Dec 2018 1:57PM
Just a thought . . .

Have you tried taking a shot with that lens, using a flash?

when you are on matrix mode, it will focus on the main area of contrast in your shot, switch to single point mode and then adjust the red square to what you want to focus on. then I guarantee your shots like the lighthouse will be better focussed


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