Sigma 10-20 focussing ????

R

Rodintee

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Name
Russ
Edit My Images
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I recently purchased a Sigma 10-20 from Photogaz on here, no complaints whatsoever but I can't quite understand whats happening with the focus control....

Usually I shoot in aperture priority, control DOF as required and vary ISO within reasonable bounds to get acceptable shutter speeds. Again, usually set centre point as focus point. Now using the 10-20 at 10mm, f8-f11 with shutter speeds of 250 and upwards the images were quite soft. Before anyone jumps in I've been reading up about hyperfocal distance so have been focussing on quite close items then recomposing, same soft image.

The lens seems to use the hyperfocal principle especially at wide settings, even distant objects result in a focus distance according to the scale of 1m or so. At 10mm virtually everything should be in focus.

I then tried setting all the focus points active to let them camera have a bit more control.... no change.

Now, if I set the control dial to the helpful mountain icon, the setup ends up pretty much identical to the Av based setup in every sense but the resulting images are sharp as you like......

What on earth is going on ????? :thinking:

Anyone shed any light....... please

Its doing my nut in !!! :bonk:

Like I said not unhappy with the lens in anyway, it is capable of taking sharp photos, I think its me that needs to learn some aspect of it.

Russ
 
Yeah I'll try to put some up later but I'm at work ATM just taking a breather.

Wondered if anyone has had similar.

Like I said though I was comparing the exif and they were to all intents and purposes identical.

It's like the body sets the focus actually different in the "mountain mode"
 
Is the auto landscape mode applying heavier processing to the jpeg output? It usually applies a larger amount of sharpening and contrast.
 
When you are shooting in AV mode are you shooting raw or jpeg? Just thinking along the same lines as A1ex, could just be a sharpening issue.
 
Thats a possibility I hadn't considered, I do shoot raw in Av. I'll have to have another try tonight and revisit the images see if sharpening picks them up cause its completely unadjusted from the camera.

Just downloaded a hyperfocal calculator for my phone. I'll have a go setting manually too.

Thanks

Russ
 
In that case the next question is, did you do any sharpening to the processed raw image? if not then I recon that could very well be the problem as I find I always need to sharpen when coming from raw to get the best out of the image. Hope you get it sorted :)
 
Yeah, to be honest the in camera processing didn't cross my mind but the difference is startling.

Thanks for the replies.

Must say, great lens though, offers great creative options, just need to get a handle on clean operation.

Thanks again

Russ
 
Hi Rodintee,

I hope you're enjoying the lens. That's quit odd. Did you try to run sharpening on the files as thats the only thing I can think of. Does it do it in other modes such as shutter priority?

--
Gareth
 
Morning

Played again last night with Av set to use fine jpg, same as "mountain mode".

Same ISO, same exposure and after taking a shot in the auto setting switched the lens to MF so no refocussing would happen.

Result, still visibly different images. I couldn't get them on the PC to PP in any way (kids were in bed) so it could still be heavy in camera sharpening being applied in the simple mode. The gap is clearly narrowing though.

At the end of the day, it is clearly capable of very sharp images, the principles of operation are quite different to longer lenses with having such great DOF, and I need to extend my knowledge to get the best from it.

Gareth, very pleased with the lens, the field of view is immense, thanks for a smooth transaction. When you get a mo, can you do the itrader thingy for me.

Cheers all

Russ
 
Wide angles have a very strange focus I find. I had a 10-20mm and I'd do a close-up car shot, and then a scenery shot and the focus didn't change what-so-ever yet they were very sharp at f/4. I couldn't figure it out.
 
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