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bizarre experience with 3 copies of Nikon D5100

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Hi ,thank you all for all the input. My friend and I did extensive testing with his D3100 using the same setup, all wide open shots. The keeper rate for two copies of 35 1.8 and 105 VR is above 95%. For sigma 50 1.4 it is like 80% to 90%; for sigma 85 1.4 it is like 70 to 80%. I guess I am done testing. Either send the D5100 for repair or return for D7000.
 
sif20047 said:
Hi ,thank you all for all the input. My friend and I did extensive testing with his D3100 using the same setup, all wide open shots. The keeper rate for two copies of 35 1.8 and 105 VR is above 95%. For sigma 50 1.4 it is like 80% to 90%; for sigma 85 1.4 it is like 70 to 80%. I guess I am done testing. Either send the D5100 for repair or return for D7000.
Click to expand...
No disrespect, but if your tests were handheld or different subjects (not all exactly the same target with tripod) Then a 95% keeper rate is very good...same for the other lens. I would be happy. If the test were all using the same lighting and target with very steady and heavy tripod...then maybe seek calibration. Are you saying you didn't bring your D5100 along and test the same way? Sorry if I misunderstood.
 
It is side by side comparison between D3100 and D5100 in my house. The same target, same lighting with tripod. D3100 keeper rate is between 80 to 90% when counting all lens together. D5100 keeper rate is 0 with all other lens except with 50 1.8g. Still weird though because 50 1.8g is perfect with D5100. I may send my 35 1.8g, 105VR and D5100 to Nikon for recalibration. Hopefully after recalibration, it will work well with sigma 85 1.4. D7000 price went up today and may stay there for a while. With money spent on all the lens I have, I really don't want to buy the D7000.
Mako2011 said:
sif20047 said:
Hi ,thank you all for all the input. My friend and I did extensive testing with his D3100 using the same setup, all wide open shots. The keeper rate for two copies of 35 1.8 and 105 VR is above 95%. For sigma 50 1.4 it is like 80% to 90%; for sigma 85 1.4 it is like 70 to 80%. I guess I am done testing. Either send the D5100 for repair or return for D7000.
Click to expand...
No disrespect, but if your tests were handheld or different subjects (not all exactly the same target with tripod) Then a 95% keeper rate is very good...same for the other lens. I would be happy. If the test were all using the same lighting and target with very steady and heavy tripod...then maybe seek calibration. Are you saying you didn't bring your D5100 along and test the same way? Sorry if I misunderstood.
Click to expand...
 
sif20047 said:
It is side by side comparison between D3100 and D5100 in my house. The same target, same lighting with tripod. D3100 keeper rate is between 80 to 90% when counting all lens together. D5100 keeper rate is 0 with all other lens except with 50 1.8g. Still weird though because 50 1.8g is perfect with D5100. I may send my 35 1.8g, 105VR and D5100 to Nikon for recalibration. Hopefully after recalibration, it will work well with sigma 85 1.4. D7000 price went up today and may stay there for a while. With money spent on all the lens I have, I really don't want to buy the D7000.
Mako2011 said:
sif20047 said:
Hi ,thank you all for all the input. My friend and I did extensive testing with his D3100 using the same setup, all wide open shots. The keeper rate for two copies of 35 1.8 and 105 VR is above 95%. For sigma 50 1.4 it is like 80% to 90%; for sigma 85 1.4 it is like 70 to 80%. I guess I am done testing. Either send the D5100 for repair or return for D7000.
Click to expand...
No disrespect, but if your tests were handheld or different subjects (not all exactly the same target with tripod) Then a 95% keeper rate is very good...same for the other lens. I would be happy. If the test were all using the same lighting and target with very steady and heavy tripod...then maybe seek calibration. Are you saying you didn't bring your D5100 along and test the same way? Sorry if I misunderstood.
Click to expand...
Click to expand...
I see now, sorry it worked out that way. If you could post one OOC JPEG (with no crop or PP) were the D5100 missed with the 105 VR and the D3100 was good, I appreciate it. I'm still looking for the problem. Thanks
 
105 VR with D5100




Mako2011 said:
sif20047 said:
It is side by side comparison between D3100 and D5100 in my house. The same target, same lighting with tripod. D3100 keeper rate is between 80 to 90% when counting all lens together. D5100 keeper rate is 0 with all other lens except with 50 1.8g. Still weird though because 50 1.8g is perfect with D5100. I may send my 35 1.8g, 105VR and D5100 to Nikon for recalibration. Hopefully after recalibration, it will work well with sigma 85 1.4. D7000 price went up today and may stay there for a while. With money spent on all the lens I have, I really don't want to buy the D7000.
Mako2011 said:
sif20047 said:
Hi ,thank you all for all the input. My friend and I did extensive testing with his D3100 using the same setup, all wide open shots. The keeper rate for two copies of 35 1.8 and 105 VR is above 95%. For sigma 50 1.4 it is like 80% to 90%; for sigma 85 1.4 it is like 70 to 80%. I guess I am done testing. Either send the D5100 for repair or return for D7000.
Click to expand...
No disrespect, but if your tests were handheld or different subjects (not all exactly the same target with tripod) Then a 95% keeper rate is very good...same for the other lens. I would be happy. If the test were all using the same lighting and target with very steady and heavy tripod...then maybe seek calibration. Are you saying you didn't bring your D5100 along and test the same way? Sorry if I misunderstood.
Click to expand...
Click to expand...
I see now, sorry it worked out that way. If you could post one OOC JPEG (with no crop or PP) were the D5100 missed with the 105 VR and the D3100 was good, I appreciate it. I'm still looking for the problem. Thanks
Click to expand...
 
I deleted all photos on D3100, so had to retake one. The distance may not be exactly similar, but you can still see no backfocusing.



 
sif20047 said:

Mako2011 said:
sif20047 said:
It is side by side comparison between D3100 and D5100 in my house. The same target, same lighting with tripod. D3100 keeper rate is between 80 to 90% when counting all lens together. D5100 keeper rate is 0 with all other lens except with 50 1.8g. Still weird though because 50 1.8g is perfect with D5100. I may send my 35 1.8g, 105VR and D5100 to Nikon for recalibration. Hopefully after recalibration, it will work well with sigma 85 1.4. D7000 price went up today and may stay there for a while. With money spent on all the lens I have, I really don't want to buy the D7000.
Mako2011 said:
sif20047 said:
Hi ,thank you all for all the input. My friend and I did extensive testing with his D3100 using the same setup, all wide open shots. The keeper rate for two copies of 35 1.8 and 105 VR is above 95%. For sigma 50 1.4 it is like 80% to 90%; for sigma 85 1.4 it is like 70 to 80%. I guess I am done testing. Either send the D5100 for repair or return for D7000.
Click to expand...
No disrespect, but if your tests were handheld or different subjects (not all exactly the same target with tripod) Then a 95% keeper rate is very good...same for the other lens. I would be happy. If the test were all using the same lighting and target with very steady and heavy tripod...then maybe seek calibration. Are you saying you didn't bring your D5100 along and test the same way? Sorry if I misunderstood.
Click to expand...
Click to expand...
I see now, sorry it worked out that way. If you could post one OOC JPEG (with no crop or PP) were the D5100 missed with the 105 VR and the D3100 was good, I appreciate it. I'm still looking for the problem. Thanks
Click to expand...
Click to expand...
Yep, looks just a bit back focused....the D3100 pic doesn't look to sharp either. Might be mirror slap or light tripod. I could see getting the 105mm VR calibrated/checked. But not sure it's the body as the 50mm is so good you say. Did you compare LV on the D5100 with the 105mm? The D5100's extra resolve over the D3100 is really showing here IMO.
 
my first 5100 was defective--major color issues from shot-to-shot.

my second one has been perfect.

looks like your luck is worse than mine. :)
sif20047 said:
I have a very bizarre experience with 3 copies of Nikon D5100, hope to get some suggestions here.

I bought my first D5100 a couple of weeks ago. At that time I only dad some zooms. I tested some focus chart and found that it had backfocusing problem, so I returned it for another one.

The second was perfect with focus chart. Later on I acquired a couple of primes, 50 1.8g, 35 1.8g, sigma 50 1.4, sigma 85 1.4 and 105 VR, after a few days shooting in real world situations I feel like many images with these primes are soft. So I did another focusing test. I set up several rectangular boxes on a table, they were 5 inches apart away from me. The boxes have identical lettering on the outside, so it was easy to compare the sharpness between them. The front surface of the boxes were parallel to my camera sensor. I used tripod, remote control, ISO 400 so that the shutter speed never went below 1/200. I also setup the camera so that the distances between the camera and subject were similar to real world situations. With 35mm, it's 1.8m; 50mm, it is 2.5m; 85 and 105mm, it is 3.5m. All shots were taken wide open. I took 10 shots per lens, always waited a second after focus lock. I also borrowed my friend's 35 1.8g and sigma 85 1.4 for this test. You know what? All lens except 50 1.8g backfocus with this D5100. The degree of backfocus varies with lens, but I could easily tell by comparing the sharpness of the lettering on the boxes. If I moved 1 m closer in all situations, all lens were perfect. Liveview focus was also perfect.

Knowing that I would return this D5100 for sure, I bought another D5100 for side by side comparison. The results were almost the same except that the third D5100 worked better with sigma 50 1.4 (5 out of 10 shots were spot on). Finally, I took my old D50 from the closet and did the same testing, Now every lens are spot on. For sigma primes, I actually took 20 shots just to make sure. This is so strange. Did I do anything wrong? How come three D5100 all have backfocusing problems but the D50 is perfect. I googled and did not find many complaints about D5100. What are the odds?
Click to expand...
--
Dave

Dee fifty one hundred

Honest debates welcome.
 
I can't read the fine print on the Bic boxes.

WHOA! why are u shooting at 1/40th? that's useless for determining lens focus. sigh.
--

Dave

Dee fifty one hundred

Honest debates welcome.
 
dave1812 said:
I can't read the fine print on the Bic boxes.

WHOA! why are u shooting at 1/40th? that's useless for determining lens focus. sigh.
Click to expand...
Why is 1/40s useless for determining lens focus?

--
Patco
A photograph is more than a bunch of pixels
 
Because its to slow, unless you use tripod
 
Patco said:
dave1812 said:
I can't read the fine print on the Bic boxes.

WHOA! why are u shooting at 1/40th? that's useless for determining lens focus. sigh.
Click to expand...
Why is 1/40s useless for determining lens focus?

--
Patco
A photograph is more than a bunch of pixels
Click to expand...
Makes it very hard to take mirror slap and light tripod affects out of the equation. You can still get a fair general ideal but hard to be precise if you're really trying to come up with an adjustment to the body or comparing bodies and lens.
 
It is very hard to eliminate a lot of things in the OP's testing.
Mako2011 said:
Patco said:
dave1812 said:
I can't read the fine print on the Bic boxes.

WHOA! why are u shooting at 1/40th? that's useless for determining lens focus. sigh.
Click to expand...
Why is 1/40s useless for determining lens focus?

--
Patco
A photograph is more than a bunch of pixels
Click to expand...
Makes it very hard to take mirror slap and light tripod affects out of the equation. You can still get a fair general ideal but hard to be precise if you're really trying to come up with an adjustment to the body or comparing bodies and lens.
Click to expand...
--
OK, not so purely a hobby.
 
yes, I will send camera along with 35 1.8 and 105 VR for service. The live view is always perfect with all the lens.
Mako2011 said:
Yep, looks just a bit back focused....the D3100 pic doesn't look to sharp either. Might be mirror slap or light tripod. I could see getting the 105mm VR calibrated/checked. But not sure it's the body as the 50mm is so good you say. Did you compare LV on the D5100 with the 105mm? The D5100's extra resolve over the D3100 is really showing here IMO.
Click to expand...
 
The key point is to compare the relative sharpness between the target box and the out of focus box. If the target box is sharper, then no backfocusing. Slight mirror slap and camera shake are not big deal as long as I can tell if one is sharper than the other.
dave1812 said:
I can't read the fine print on the Bic boxes.

WHOA! why are u shooting at 1/40th? that's useless for determining lens focus. sigh.
--

Dave

Dee fifty one hundred

Honest debates welcome.
Click to expand...
 
Another test I also did was with the handrails in my house at various distances and angles. No tripod so not very convincing, but the D3100 and D50 focused much better than D5100.
 
I owned a 3100 and two 5100's. All three focused identically. If yours doesn't it has a problem.
sif20047 said:
Another test I also did was with the handrails in my house at various distances and angles. No tripod so not very convincing, but the D3100 and D50 focused much better than D5100.
Click to expand...
--
Dave

Dee fifty one hundred

Honest debates welcome.
 
Here are two shots both taken on mu D5100 on a tripod using F1.8. Only difference is one was taken using viewfinder focus (the out of focus image) and the other using live view.

Certainly no problem with the lens.







 
Actually my D5100 35 1.8 does the same thing at f1.8, When I shoot buildings and signs outside, I could always get sharp results, but I think the reason is that with that distance between camera and subject the DOF is large, so the backfocusing did not affect the sharpness. Only my headshoulder shots are soft, which led me to all these tests.

Edit: I just did a DOF calculation, with D5100, 35 at 1.8, 15 feet, the DOF is 4 ft.
David195 said:
Here are two shots both taken on mu D5100 on a tripod using F1.8. Only difference is one was taken using viewfinder focus (the out of focus image) and the other using live view.

Certainly no problem with the lens.







Click to expand...
 
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