D7100 and Tam 150-600 problem

[J-see]

Before it went back i decided it didnt need any

Mine did well in the past without AF tuning. I never had a problem there so I was surprised when dot-tuning the range was that different. It could explain why I have such issues on the D3300 with it. If it requires about as much, since the D3300 can't fine-tune, she hits it wrong plenty.

Then again, I now tuned her purely to the 420mm stop.

 

[nikonpup]

any news yet?

i got an email that they received my lens, hope to learn more by tuesday.

 

[nikonpup]

i saw info on the dot-tune after i sent my lens in, something to try when i get it back.

 

[mikew_RIP]

Got some thinking to do,been to the dealers and he will sort things out to suit me,i could try another Tamron but as Tamron will not admit to a problem the dealer would rather i didnt as if i return it he would be left with two lenses to sell secondhand,understandable that.The other choice is a different lens,the Sigma sport would be too heavy for me,the contemporary is an unknown factor,his first delivery of the contemporary is early April,so at the moment while i think about it my name is down for the first Sigma he gets.

 

[Ironwood]

Mine wouldn't AF at one stage today. I turned the camera off and back on, it worked normally after that.
I hope its not the start of a problem.

 

[mikew_RIP]

Sometimes you dont need to do any thing just give it a few seconds and its ok.

 

[Ironwood]

Sometimes you dont need to do any thing just give it a few seconds and its ok.

If it does it again I will try the wait test.

 

[mikew_RIP]

J-see ime interested in the exposure difference and wondering if VR reduces the light so in certain circumstances could cause focus problems,although i would still expect the focus to hunt not freeze.

 

[J-see]

J-see ime interested in the exposure difference and wondering if VR reduces the light so in certain circumstances could cause focus problems,although i would still expect the focus to hunt not freeze.

I'll repost the comparison:



I assume that difference is created by Adobe in their software or by their cam profile when reading the RAW which still leaves the question what exactly caused it.

Normally VR can not have an effect on exposure since it only corrects the lens and is independent of what happens on your sensor. At least in regards to the length of exposure.


Another difference between both is when you check the EXIF you get at a part called Sub Sec Time which is 40 for the one and 70 for the other but I have to look that up to know what it exactly applies too.

For the rest both shots are highly identical 'value wise' but those two differences jump out.

Strike that last, I checked the tag and it's just the sub seconds in the DateTime.

 

[mikew_RIP]

Could VR cause a light loss which could then explain those differences,its possible that no difference in exposure would be noticed unless some fool took two pictures of the same sign

 

[J-see]

Could VR cause a light loss which could then explain those differences,its possible that no difference in exposure would be noticed unless some fool took two pictures of the same sign

It's simple to check if it is the shot or the editor. Load both RAW in Nikon soft and export them there. If both match, it's Adobe creating a difference, if both differ, it is the shot.

All the XMP shows is values being applied in either ACR or Elements but it doesn't give any indication why. Still -0.60 exposure can be 2/3th stop if it follows the LR logic.



Btw, I didn't check that part but did you shoot both in manual?

 

[mikew_RIP]

Good question, no auto ISO you could have solved the different readings

 

[J-see]

Good question, no auto ISO you could have solved the different readings

I was just thinking about lens profiles being applied or not. I know if I apply the Tam, it leads to a visible difference not only in regards to distortion correction.

 

[mikew_RIP]

Right i think i have picked my toys up and got them back in the pram,this means i am considering giving Tamron another chance to cure the freeze problem when my dealer has a suitable second hand lens to lend me,this is the cover note i am going to send with it,any thing you think i should add.



Info note


This will be the second time this lens has been returned to you with the same fault,i am now finding this a frustrating situation. The first time I was without the lens for four weeks during which time I believe you sent it to your facility in Germany for testing and repair.
On its return during the first few hundred shots the problem did not show itself, this could have been due to your service work or as happens with intermittent faults just not showing itself,we are now over 1000 shots past the service work and the fault can happen as much as 3 or 4 times per 100 shots,or not at all in that period.
With wildlife photography which this lens is billed as excellent for its a none acceptable situation,i may get only a few seconds to capture a bird in the perfect pose and needing to turn the camera off and on or remove and refit the lens before I take often makes me lose the picture.


My camera is a Nikon D7100 and I use centre point focus,this being the most sensitive good down to F8.the Nikon forum I belong has other members experiencing the same problem to various degrees,cameras include other D7100,D600,D750 and D4.


The problem itself to avoid confusion,the focus will freeze and stay there for several seconds,or until I take one of the above actions, it does this in all lighting conditions at all focal lengths,i really do believe at the price I paid for this lens I am not being unreasonable to expect 100% correct function.

 

[J-see]

I think it says all that is required.

I myself would have added a lot of #@!! but I don't think such would improve the situation.


What I wonder about is why there's no reaction at all from their side on the Nikon problem. It's not just us here, the focus freeze problem starts to surface everywhere which implies there is something fundamentally wrong with the lens and it only gets worse as time goes by. Some months ago this was a freak occurrence and look at us now.

 

[mikew_RIP]

I was just thinking about lens profiles being applied or not. I know if I apply the Tam, it leads to a visible difference not only in regards to distortion correction.

I think i may redo the test on a tripod using spot metering,i know this may not suit the VR but it should keep the focus and exposure reading spots the same and use manual ISO for one set and auto for the other.

 

[mikew_RIP]

I think it says all that is required.

I myself would have added a lot of #@!! but I don't think such would improve the situation.


What I wonder about is why there's no reaction at all from their side on the Nikon problem. It's not just us here, the focus freeze problem starts to surface everywhere which implies there is something fundamentally wrong with the lens and it only gets worse as time goes by. Some months ago this was a freak occurrence and look at us now.

Thats why ime better doing it on paper than face to face

 

[J-see]

I think i may redo the test on a tripod using spot metering,i know this may not suit the VR but it should keep the focus and exposure reading spots the same and use manual ISO for one set and auto for the other.

If you shoot manual without auto-ISO and a fixed WB, the results should be identical in all cases. There might be a difference created by the change in light itself but all values being applied should match perfectly in the EXIF and XMP.

It's no shooting weather so I'm roughly calculating when VR applies during a focal shutter travel at different shutter speeds and what effect it has. It's interesting that after 1/500s even when VR corrects, it no longer does to the complete image and the faster you shoot, the smaller that area will become. It should also correct around 4 times during a 1/1000s exposure and two when the exposure is already finished.

But even that should not lead to your exposure differences.

 

[J-see]

Mike, if you're still in test mode, can you check something for me if you have interest or time.

I was testing if VR on or off had an effect on my continuous rate so I set JPEG small lowest quality and fired away at different shutter speeds, VR on and off.

VR doesn't affect the speed of series. At high shutters like 1/4000s each shot takes about 0.15s between and it is very regular. Once in a while there is a strange duck that took longer or less. But the lower I go in shutter speed, the more those irregularities pop up and I get very different durations.

I'm curious what the reason is and if it is a common phenomena for all of us or related to my cam.

 

[nikonpup]

i got my lens back today, all looks good. @600mm locks on target, no hunting. The service report does not say much "check and adjust focus and image quality". I called for further info but all customer service would say was on the s.o.. She did say they have a machine they put it on for testing.