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Archive 2013 · Sigma USB Dock in Stock for $59!
  
 
mcd0nald
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p.4 #1 · Sigma USB Dock in Stock for $59!


Hi All,

I am one of the users who experience problem with Sigma 35mm 1.4 focus in different focal distance. My body is 5d Mk III

Below 0.6m, i do not have to do AF adjustment but, I have problem with 2m focal distance that I need +6 AF to get it sharp...but if I do +6 AF from camera body, it will ruin my AF below 0.6m
Therefore, USB dock is the only fix I assume as SIgma breaks down 4 parts of focal distance (my USB dock is on the way today ....with driver for delivery)

Note: no problem whatsoever with live view manual focus, so it's just as a matter of AF tweaking



Jun 07, 2013 at 01:36 AM
austin.grant
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p.4 #2 · Sigma USB Dock in Stock for $59!


Photonic wrote:
My basic premise is as follows. Sigma has given users a mechanism to adjust MF at 4 different focus distances. I would find it very odd if they did not do their very best to put good numbers in as a starting point and call that the default.


Of course they don't do their "very best" because the market won't support the costs associated with it. Same for every other lens manufacturer. I'm sure they get it within tolerances and just zero out the numbers from there. Also, things happen after that lens leaves the factory. The ride from Japan to your camera bag is likely a bumpy one. Once you use the lens and parts wear in, things can also just naturally get slightly off from that initial calibration. The USB dock seems like a great solution over sending the thing in.

Take your example of the new 120-300 costing much more than the last version, despite it having the same optics. The last version had significant quality control issues. They likely upped the quality control, and the cost followed. Basic economics, they can't do more work and add more precision for free. Your response was to gripe about the cost increase. They are damned either way, it seems.

Here's a screenshot with my lens attached, and as we all assumed, the numbers are zeroed out. Why wouldn't they be? Ever buy a new camera with the global MFA setting to, say +7, straight from the factory? That'd be silly.








Jun 07, 2013 at 02:22 AM
Photonic
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p.4 #3 · Sigma USB Dock in Stock for $59!


Austin,

I can guarantee (because I have built complex things in both Japanese and Chinese factories) that each lens receives final calibration on an automated jig. A worker places it in the fixture and pushes a button, the rest is automatic. The fact that the default user settings are all zeros confirms my prediction that there is a shadow set of register used to hold the factory calibration numbers. I hope we can now agree on this point.

Sigma's "very best" therefore is simply a well designed calibration fixture whose only job is to dump four numbers into the shadow registers. My only expectation, and I don't think it is unreasonable, is that they are at least as competent as their users when selecting the base numbers.

I get the impression that you think I am opposed to the dock. Please go back and read my initial post:

I get the benefit of supporting software updates but I am still trying to wrap my head around doing focus adjustments on the lens. First, it seems far more logical to MFA the body to the lens allowing you to seamlessly use the lens on different bodies. Each body remembers the MFA settings rather than having to download new setting via USB with every body change. Second, unless there is something very clever in the supplied software it seems it is going to be a very tedious process to narrow in on the right values needed for the focus adjustment switching between mounting the lens on the camera and the dock on the lens. Would love to hear how this works when someone gets a copy.

I only expressed two concerns:

(1) The need to download new MFA settings with a body change.
(2) The MFA adjustment process is going to be tedious.

Earlier you claimed it would take you an hour to make the adjustments using Dot Tune or Focal. I have challenged the underlying assumption that lens MFA steps will be equal to body MFA steps. I think I am right and hope I am wrong. You are in the perfect position to answer this question and many of us would appreciate if you could take a moment to do the experiment. If the Dot Tune or Focal numbers transfer I will be doing back flips. If the numbers don't transfer then please explain your strategy for obtaining the numbers.



Jun 07, 2013 at 03:25 AM
austin.grant
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p.4 #4 · Sigma USB Dock in Stock for $59!


Photonic,

We agree on most points, and I don't think you are against the dock. Rather, I think you are obsessing over minutiae that Sigma has likely already taken care of. I don't think either of us have had any revelations during this thread that Sigma hasn't already considered. If so, I'm surprised they do as well as they do!

I did claim that I would do the testing, and I also mentioned that I wouldn't be able to get to said testing until Sunday. Don't let the fact that I've plugged the dang thing into my computer lead you to believe that I'm in the same location as all my lighting gear, tripods, targets and space to do any testing. Everything is either in my office or in my car for an out-of-town wedding.

I assure you, I'll test it as thoroughly as possible. In fact, I hope to get some input from you and the forum on my methods, just to be sure all our bases are covered. I don't want my hope for the thing to work well to be perceived as any experimental bias, so I'll certainly lay it all out there.

No, I don't think you are against this concept at all. I just think you are jumping to a bunch of conclusions and that many of them, if true, would mean Sigma is composed of a bunch of idiots. I choose not to believe that.

I will tell you this much: If I put that lens on my cameras and Focal or Dot Tune suggests the same MFA for all focus distances, I won't be tuning anything. I'm very much in the "if it ain't broke" camp, and won't risk a perfect lens in the name of science!



Jun 07, 2013 at 03:46 AM
Photonic
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p.4 #5 · Sigma USB Dock in Stock for $59!


I did not mean to rush you and truly appreciate that you are blazing the trail for the rest of us. I hope everything goes well and look forward to learning what you have discovered when you are reunited with your gear and have the time to give things a try.

I hope to spend the weekend getting acquainted with my new 35mm.



Jun 07, 2013 at 04:07 AM
Sven Jeppesen
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p.4 #6 · Sigma USB Dock in Stock for $59!


Photonic wrote:
I get the benefit of supporting software updates but I am still trying to wrap my head around doing focus adjustments on the lens. First, it seems far more logical to MFA the body to the lens allowing you to seamlessly use the lens on different bodies. Each body remembers the MFA settings rather than having to download new setting via USB with every body change. Second, unless there is something very clever in the supplied software it seems it is going to be a very tedious process to narrow in on the right values needed for the focus adjustment

I only expressed two concerns:

(1) The need to download new MFA settings with a body change.
(2) The MFA adjustment process is going to be tedious.

...Show more

When Sigma don't make the bodies, it's rather obvious that they can't do what you ask for here. If it's better or not I don't know. And you can still use FoCal or any other method if you like those better.
But there is a huge advantage with doing it with a dock. The millions of users that have a body without MA can now do some MA on their lenses. And the price is also good on the dock. I get both hardware and software for a lower price than I paid for my FoCal



Jun 07, 2013 at 06:38 AM
svassh
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p.4 #7 · Sigma USB Dock in Stock for $59!


So I received my dock today to try with my 35mm lens. Focal has a recommendation for the lens of +13 on my 5D III and it looks pretty sharp at 1.4 with that setting. I put the lens on the dock and it updated the firmware then showed me the lens settings were 0 for all 4 distances. I set them to +13 on the lens for all 4 distances and retested with Focal. Here is a chart of what it took to get to 0 MFA on the body.

Body Lens Focal
+13 0 +13
0 +13 -5
0 +8 -1
0 +7 0

So it appears any changes to the lens settings are about 2x what a MFA adjustment on the body is. So a good starting point to set the lens to would be one half what the body MFA setting currently is.

Just my non scientific trial, YMMV



Jun 07, 2013 at 04:38 PM
Photonic
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p.4 #8 · Sigma USB Dock in Stock for $59!


svassh,

This is very important information and answers one of the two critical questions I posed earlier.

Given that lens MFA steps do not equal body MFA steps the quest now must be to figure out what the exact ratio is so we can continue to use tools like Dot Tune and Focal to speed up the process (otherwise I see a short life for the few hairs that remain on my head).

With any luck MFA steps between different camera models from the same company will be identical. Let's be prepared, however, that they may vary from model to model.

As folks start reporting the conversion ratios it will be helpful if they mention which body they tested on.

If it is not too much to ask and if you have access to a second body with MFA capability could you test to see if your optimal lens MFA settings produce similar results on a second body. This will answer the remaining critical question.

Thanks



Jun 07, 2013 at 05:05 PM
Lars Johnsson
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p.4 #9 · Sigma USB Dock in Stock for $59!


Photonic wrote:
svassh,

This is very important information and answers one of the two critical questions I posed earlier.

Given that lens MFA steps do not equal body MFA steps the quest now must be to figure out what the exact ratio is so we can continue to use tools like Dot Tune and Focal to speed up the process (otherwise I see a short life for the few hairs that remain on my head).

With any luck MFA steps between different camera models from the same company will be identical. Let's be prepared, however, that they may vary from model to model.

As folks start
...Show more

Why would you use FoCal & Dot Tune together with the Sigma dock if they don't work together and have the same MA ?
Also remember that he upgraded his firmware. The +13 from before upgrading the firmware could be different after the upgrade in FoCal also



Jun 07, 2013 at 05:47 PM
Photonic
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p.4 #10 · Sigma USB Dock in Stock for $59!


Lars,

Clearly the better outcome would have been if the two worked together as many assumed they would. Given that they don't, then what are the alternatives?

(a) Manual approach: This is the extremely "tedious" option that I have been warning about. It would involve mounting and unmounting of the lens to and from the body and dock. I can imagine it would take hours and hours to complete.

(b) "Ratio" Approach: Through experimentation we determine the scaling of body MFA steps to Sigma MFA steps. You perform body MFA adjustments in the way you normally do it and then apply the ratio to those numbers before entering into the lens. WARNING: We are still trying to figure out if the ratio is camera model specific or if one ratio will work for all models by a given camera maker. Not ideal for sure, but infinitely better than option (a).

(c) Sigma owners everywhere unite and request that Sigma modify their firmware (which we can update with the dock) to scale their steps to the step size of the camera body (this will only be viable if the step sizes of all Canon's are the same and all Nikon's are the same, etc. which is still TBD)

(d) Snapsy has another stroke of genius and gives us a simple Sigma Dot Tune procedure.



Jun 07, 2013 at 06:22 PM
 

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svassh
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p.4 #11 · Sigma USB Dock in Stock for $59!


Photonic wrote:
svassh,

If it is not too much to ask and if you have access to a second body with MFA capability could you test to see if your optimal lens MFA settings produce similar results on a second body. This will answer the remaining critical question.

Thanks


Sorry, only have the one body currently.

Personally I am not surprised the adjustment doesn't match between lens and body as it would be unlikely Sigma would want to create multiple firmware versions for each manufacturer's body. That would likely mean some changes to the lens design also even more problematic. My guess is between Canon and Nikon this was the closest they could get to a ratio. Hoping others will post to validate my ratio assumption is correct.



Jun 07, 2013 at 07:07 PM
austin.grant
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p.4 #12 · Sigma USB Dock in Stock for $59!


While the dock is nice for allowing non-MFA owners to adjust a lens/body combo, that's really not what I think it's for. I think Sigma wanted a way to normalize focus behavior across a range of focus distances and, if applicable, zoom positions.

If you are just going to go with a single offset, such as +7 for each lens focus position, why not just use the traditional in-body MFA? Changing the lens numbers to a new, matching set serves no purpose.



Jun 07, 2013 at 07:22 PM
badlydrawnboy
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p.4 #13 · Sigma USB Dock in Stock for $59!


austin.grant wrote:
While the dock is nice for allowing non-MFA owners to adjust a lens/body combo, that's really not what I think it's for. I think Sigma wanted a way to normalize focus behavior across a range of focus distances and, if applicable, zoom positions.

If you are just going to go with a single offset, such as +7 for each lens focus position, why not just use the traditional in-body MFA? Changing the lens numbers to a new, matching set serves no purpose.


I think his point was that a lens offset value isn't the same as an MFA value. So if you use FoCal to MFA the lens at the 4 different shooting distances, inputting that value into the lens software wouldn't produce the desired result. You'd have to reduce the MFA value by 50%, if other people have the same results (not at all clear yet). That becomes difficult with odd numbers and 0 values, of course.



Jun 07, 2013 at 07:27 PM
Lars Johnsson
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p.4 #14 · Sigma USB Dock in Stock for $59!


Photonic wrote:
Lars,

Clearly the better outcome would have been if the two worked together as many assumed they would. Given that they don't, then what are the alternatives?

(a) Manual approach: This is the extremely "tedious" option that I have been warning about. It would involve mounting and unmounting of the lens to and from the body and dock. I can imagine it would take hours and hours to complete.

(b) "Ratio" Approach: Through experimentation we determine the scaling of body MFA steps to Sigma MFA steps. You perform body MFA adjustments in the way you normally do it and then apply the ratio
...Show more

How many negative posts about the dock can you make without having used it

A manual approach will not take hours and hours. If you think the Sigma Dot Tune procedure is genius, why would you even think about using the dock that you complain about in every post



Jun 07, 2013 at 07:30 PM
austin.grant
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p.4 #15 · Sigma USB Dock in Stock for $59!


badlydrawnboy wrote:
I think his point was that a lens offset value isn't the same as an MFA value. So if you use FoCal to MFA the lens at the 4 different shooting distances, inputting that value into the lens software wouldn't produce the desired result. You'd have to reduce the MFA value by 50%, if other people have the same results (not at all clear yet). That becomes difficult with odd numbers and 0 values, of course.



I perfectly understand what he said, especially since he keeps saying it. I agree with him, it would be ideal if the lens and body MFA were aligned. The fact that they aren't in no way devalues this system, in my opinion. Like I said originally, if you want simple just buy and use a lens as it is.

It's just absurd for us to sit here and complain about more options to possibly make our gear work more efficiently. I don't know about you guys, but I like options...



Jun 07, 2013 at 07:37 PM
badlydrawnboy
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p.4 #16 · Sigma USB Dock in Stock for $59!


I'm not complaining, but I think it's useful to know if the lens and body MFA values are equivalent or not. I am planning to buy the dock; knowing in advance a little about what to expect will help me use it more effectively.

Edited on Jun 07, 2013 at 07:46 PM · View previous versions



Jun 07, 2013 at 07:38 PM
Lasse Eriksson
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p.4 #17 · Sigma USB Dock in Stock for $59!


Photonic wrote:
svassh,

This is very important information and answers one of the two critical questions I posed earlier.

Given that lens MFA steps do not equal body MFA steps the quest now must be to figure out what the exact ratio is so we can continue to use tools like Dot Tune and Focal to speed up the process (otherwise I see a short life for the few hairs that remain on my head).

With any luck MFA steps between different camera models from the same company will be identical. Let's be prepared, however, that they may vary from model to model.

As folks start
...Show more

It's obvious that you have something against the dock or Sigma. Do another MFA method that you like instead of the dock.



Jun 07, 2013 at 07:41 PM
Lasse Eriksson
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p.4 #18 · Sigma USB Dock in Stock for $59!


austin.grant wrote:
I perfectly understand what he said, especially since he keeps saying it. I agree with him, it would be ideal if the lens and body MFA were aligned. The fact that they aren't in no way devalues this system, in my opinion. Like I said originally, if you want simple just buy and use a lens as it is.

It's just absurd for us to sit here and complain about more options to possibly make our gear work more efficiently. I don't know about you guys, but I like options...


+1
I also like a few options. And many people don't have MFA in their camera's either



Jun 07, 2013 at 07:42 PM
Photonic
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p.4 #19 · Sigma USB Dock in Stock for $59!


Sigma has given us some powerful knobs to turn. Absent a straight forward method for turning them to the right position this feature has little practical value (even to the person with a non-MFA lens).

Until a relatively straight forward method for making the adjustments is discovered I don't think anyone will be able to use this feature on any camera.

The ratio method offers a glimmer of hope in that you can use current methods to determine body MFA numbers and "translate" them into Sigma lens MFA numbers. If this works, it will allow you to set MFAs for multiple focus distances. It is a kludge but better than the alternative.

Personally, I am happy to continue brainstorming other possible work-arounds to help those who are determined to use this "feature" but I don't see myself using the dock and software as currently designed to make lens MF adjustments. I think it still has utility for firmware updates and some may find value in the other parameters than can be tuned.

Regrettably, I think Sigma is going to get hammered for marketing a feature which in practice cannot be used.



Jun 07, 2013 at 07:52 PM
Photonic
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p.4 #20 · Sigma USB Dock in Stock for $59!


I have done my best to share what I think have proven to be valid concerns about the dock with those who have interest in this feature. I am growing weary of being constantly placed on the defensive and will politely exit this thread. To those who purchase the dock with hopes of fine tuning focus, I hope you find it a rewarding use of your time.


Jun 07, 2013 at 07:59 PM
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