Sigma Dock

[SCraig]

Last fall I got a Sigma 18-300 and have been quite pleased with it. Not quite as sharp as my 17-70 but close enough that the extra flexibility made it worthwhile. It's far more convenient than carrying two lenses around when I know I'm going to need a wide range of focal lengths.

I had a gift credit with B&H I needed to use so a few weeks ago I ordered the Sigma lens dock (for those that don't know what it is, Click Here). When it came in I hooked it up to my lens, opened the software, and did nothing. I didn't change any of the focus settings, it already had the latest firmware, so it was pretty much a ho-hum experiment. Again, I changed NOTHING.

I used it yesterday for the first time since I hooked the dock up, and it is significantly, noticeably sharper than it was. I think. I know the photos are sharper, but both the last time I used it prior to hooking up the dock and on Saturday I was shooting fast-moving subjects. So, I freely admit that it could simply have been the circumstances and I just plain shot a little better Saturday than a few weeks ago. I was using a 2/3 stop smaller aperture Saturday (F/18 vs. F/14) which could have been part of it. I'm just not sure.

My question is, has anyone else noticed this? Even though I KNOW I didn't change anything on the lens it is possible that the dock "Tweaked" something without my knowledge. I don't particularly want to do a reset on the lens since I really like it the way it is. But I'm just curious if anyone else has noticed anything similar after using the dock.

 

[pixmedic]

placebo effect?

 

[SCraig]

Quite possibly. I don't think so, but I can't discount it either. That's why I thought I'd ask if anyone else had noticed anything similar.

 

[Overread]

I think it must be placebo effect.

The dock only really allows for things like AF and control adjustments so that the lens can continue communicating with the camera without Sigma having to rechip the lens.

Calibration for AF can be done through it; but calibration for overall sharpness is totally an element for the optics alone and far as I know we don't have any DSLR lenses that allow a user to perform that calibration task at home. Elements are held firm in place so the only way to adjust them is to have them adjusted by a service centre or the disassemble and adjust the lens yourself.

At best the dock could adjust AF performance, but that wouldn't affect overall sharpness just where the focus plane is set

Remember not just a different subject but even just shifts in the weather (eg sun) can affect the quality of your shots. We've all had those days where our best lens delivers rubbish and others when we took out the weaker lens and it performed really well.

 

[SCraig]

I think it must be placebo effect.

The dock only really allows for things like AF and control adjustments so that the lens can continue communicating with the camera without Sigma having to rechip the lens.

Calibration for AF can be done through it; but calibration for overall sharpness is totally an element for the optics alone and far as I know we don't have any DSLR lenses that allow a user to perform that calibration task at home. Elements are held firm in place so the only way to adjust them is to have them adjusted by a service centre or the disassemble and adjust the lens yourself.

At best the dock could adjust AF performance, but that wouldn't affect overall sharpness just where the focus plane is set

Remember not just a different subject but even just shifts in the weather (eg sun) can affect the quality of your shots. We've all had those days where our best lens delivers rubbish and others when we took out the weaker lens and it performed really well.

Yeah, I understand that. Different conditions, different light (partly cloudy one day, perfectly clear the second), moving subjects, etc. But at the same time, think about this: The software doesn't say what it's doing at all, no notifications other than whether an update is available. So perhaps it's running quick diagnostics on the lens when it's attached, and if it finds things out of spec it adjusts them when it can. Since the focus can be adjusted with the dock "Focus Tweaking" is something that it would be capable of. I'm not saying that it does or doesn't, I just don't know.

 

[Overread]

Focus adjustment is only adjusting how the AF sensors affect the AF motors in the lens; the lens can adjust how much the motors move the mobile elements inside in order to adjust how it responds to the cameras AF commands. However there are, far as I know, no lenses that have mobile elements inside that can be adjusted for overall sharpness.

It might well come in time, heck it would cut down a huge amount of warranty repairs if users could perform their own sharpness calibrations at home and some lenses like the superzooms (50-500mm etc....) would get a lot more popularity if their oft problematic calibrations were fixable through a dock at home.

 

[SCraig]

You're probably right. I suspect the whole thing is just my imagination or simply having a better day.

Thanks everyone for the help, it's much appreciated.

 

[DarkShadow]

Any firmware updates or adjustments have to be written to the firmware to be saved otherwise it stays default.I had two firmware updates on the 150-600 C and no changes to sharpness but I did gain AF speed.So far from what I can tell,any micro adjustment don't seem to be needed as mine seems dead on and razor sharp even at 600mm

 

[SCraig]

Thanks, David. I intentionally didn't change anything since there wasn't anything to change. Firmware was up to date and I didn't mess with the focusing. It just seemed that afterwards everything was slightly sharper so I was curious.