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New test coming

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MyReality said:
Sorry about your fall. I fell last year and had some neural damage, but my leg function was greatly improved with therapy.

" One nice thing about getting the gear from LensRentals is that they test everything before they ship it, so the odds of getting a bad copy are low."

Should not you be testing a random sample from them, or are you just trying to verify their tests blindly. The temptation for confirmation bias will always be there.
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Hi,

They used to test the lenses using large slanted edge charts with Imatest. That gives them numerical data. All lenses coming back from rentals are individually tracked and there are individual records for each lens.

They also have a fast evaluation method using the MTF bench, but I doubt they would MTF test all lenses coming in,

Best regards

Erik
 
If the camera was not damaged, I admire your sacrifice.
 
Testing the best of the best (a subsample of the total population) may be of interest to very particular renters who ask for those lenses and for discussion on this forum. The average renter will just receive a lens from the total population.

Jim's tests will have more meaning only if he does technically more than Lensrentals does.
 
MyReality said:
Testing the best of the best (a subsample of the total population) may be of interest to very particular renters who ask for those lenses and for discussion on this forum. The average renter will just receive a lens from the total population.

Jim's tests will have more meaning only if he does technically more than Lensrentals does.
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Lensrentals have never published any data on any MFD equipment, except about market share.

Best regards

Erik
 
MyReality said:
Testing the best of the best (a subsample of the total population) may be of interest to very particular renters who ask for those lenses and for discussion on this forum. The average renter will just receive a lens from the total population.

Jim's tests will have more meaning only if he does technically more than Lensrentals does.
Click to expand...
Lensrental’s MTF analyses are limited to a FF sensor diagonal. Jim’s are not.
 
Doppler9000 said:
MyReality said:
Testing the best of the best (a subsample of the total population) may be of interest to very particular renters who ask for those lenses and for discussion on this forum. The average renter will just receive a lens from the total population.

Jim's tests will have more meaning only if he does technically more than Lensrentals does.
Click to expand...
Lensrental’s MTF analyses are limited to a FF sensor diagonal. Jim’s are not.
Click to expand...
It's a bit worse than that, almost all data Lensrentals publishes is for full aperture, which is quite interesting but not so relevant if we typically shoot at smaller apertures.

Best regards

Erik
 
Erik Kaffehr said:
Doppler9000 said:
MyReality said:
Testing the best of the best (a subsample of the total population) may be of interest to very particular renters who ask for those lenses and for discussion on this forum. The average renter will just receive a lens from the total population.

Jim's tests will have more meaning only if he does technically more than Lensrentals does.
Click to expand...
Lensrental’s MTF analyses are limited to a FF sensor diagonal. Jim’s are not.
Click to expand...
It's a bit worse than that, almost all data Lensrentals publishes is for full aperture, which is quite interesting but not so relevant if we typically shoot at smaller apertures.

Best regards

Erik
Click to expand...
Excellent point - different goal/audience for the testing.
 
Doppler9000 said:
MyReality said:
Testing the best of the best (a subsample of the total population) may be of interest to very particular renters who ask for those lenses and for discussion on this forum. The average renter will just receive a lens from the total population.

Jim's tests will have more meaning only if he does technically more than Lensrentals does.
Click to expand...
Lensrental’s MTF analyses are limited to a FF sensor diagonal.
Click to expand...
Just a friendly minor correction, Lensrentals' MTF test station is limited to +/- 20 mm from center and can't cover the entire full-frame image diagonal. It comes close, but cannot measure all the way into the corners of the image.
 
TechTalk2 said:
Doppler9000 said:
MyReality said:
Testing the best of the best (a subsample of the total population) may be of interest to very particular renters who ask for those lenses and for discussion on this forum. The average renter will just receive a lens from the total population.

Jim's tests will have more meaning only if he does technically more than Lensrentals does.
Click to expand...
Lensrental’s MTF analyses are limited to a FF sensor diagonal.
Click to expand...
Just a friendly minor correction, Lensrentals' MTF test station is limited to +/- 20 mm from center and can't cover the entire full-frame image diagonal. It comes close, but cannot measure all the way into the corners of the image.
Click to expand...
It can get to within 1.6mm of the corners. I call that close enough.
 
TechTalk2 said:
Doppler9000 said:
MyReality said:
Testing the best of the best (a subsample of the total population) may be of interest to very particular renters who ask for those lenses and for discussion on this forum. The average renter will just receive a lens from the total population.

Jim's tests will have more meaning only if he does technically more than Lensrentals does.
Click to expand...
Lensrental’s MTF analyses are limited to a FF sensor diagonal.
Click to expand...
Just a friendly minor correction, Lensrentals' MTF test station is limited to +/- 20 mm from center and can't cover the entire full-frame image diagonal. It comes close, but cannot measure all the way into the corners of the image.
Click to expand...
👍🏽
 
Jim, one of the great mysteries of GFX gear has been the wide-ranging of opinions concerning the 100-200. I think we all agree that the lens is good, but many say that it is at the lower quality end of the GF spectrum. It is the only GF lens that has an actual IQ quality concern expressed by so many people.

But I have said for years that I love that lens and that the IQ is very tight.

But, for example, Kristian, has said for years that his two copies were weak, especially at 200 and in the corners.

I wish you could get 5 copies and run a few bench tests and star charts, and maybe shoot all five at a busy outdoor scene too.

I will ship you my lens if we can find 3 or 4 other volunteers to ship you the 100-200.

It would be very interesting. My copy is from the first batch, and I have had it repaired three times in NJ! You might remember it had a bad drop 4 years ago.

What do you think?
 
Greg7579 said:
Jim, one of the great mysteries of GFX gear has been the wide-ranging of opinions concerning the 100-200. I think we all agree that the lens is good, but many say that it is at the lower quality end of the GF spectrum. It is the only GF lens that has an actual IQ quality concern expressed by so many people.

But I have said for years that I love that lens and that the IQ is very tight.

But, for example, Kristian, has said for years that his two copies were weak, especially at 200 and in the corners.

I wish you could get 5 copies and run a few bench tests and star charts, and maybe shoot all five at a busy outdoor scene too.

I will ship you my lens if we can find 3 or 4 other volunteers to ship you the 100-200.

It would be very interesting. My copy is from the first batch, and I have had it repaired three times in NJ! You might remember it had a bad drop 4 years ago.

What do you think?
Click to expand...
Hi,

You can just do Jim's screening test. Takes half an hour, or so. The test yields 9 crops for each focal length.

Large sample variation is fairly typical for zooms, at least according to Roger Ciala of Lensrentals fame.

Best regards

Erik
 
Erik Kaffehr said:
Greg7579 said:
Jim, one of the great mysteries of GFX gear has been the wide-ranging of opinions concerning the 100-200. I think we all agree that the lens is good, but many say that it is at the lower quality end of the GF spectrum. It is the only GF lens that has an actual IQ quality concern expressed by so many people.

But I have said for years that I love that lens and that the IQ is very tight.

But, for example, Kristian, has said for years that his two copies were weak, especially at 200 and in the corners.

I wish you could get 5 copies and run a few bench tests and star charts, and maybe shoot all five at a busy outdoor scene too.

I will ship you my lens if we can find 3 or 4 other volunteers to ship you the 100-200.

It would be very interesting. My copy is from the first batch, and I have had it repaired three times in NJ! You might remember it had a bad drop 4 years ago.

What do you think?
Click to expand...
Hi,

You can just do Jim's screening test. Takes half an hour, or so. The test yields 9 crops for each focal length.

Large sample variation is fairly typical for zooms, at least according to Roger Ciala of Lensrentals fame.

Best regards

Erik
Click to expand...
 
According to the posts above, Jim is going to be receiving the best of the best (subsample of a sample) from lens rentals. The sample variation should be vary small, therefore, the tech test results should be close together.

If he just does a lens screening like Lensrentals, it may not prove much.
 
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Actually, the question I've been wondering about for the past couple of pages is this:

Just how wide and deep are the variations for a given lens across samples of that lens?

I can certainly believe one would run into greater variation across samples of a given zoom lens, more so than for primes, given all the crazy ways glass is moving inside some zooms.

But it would be interesting to hear how severe, or how common, these sample variations turn out to be.

I've never returned a lens for obvious optical flaws, but I've also not exposed them to the technical scrutiny that accompanies rigorous testing. I just take pictures with them. I print, sometimes at a not-insignificant size, and I check out those prints closely.

When a flaw shows up in my output (not unheard of), it typically turns out to involve operator error: wrong aperture for the depth of field I wanted, wrong shutter speed for handholding the focal length, goofed-up framing... the list goes on and on. (An aside: you want to discover new ways to screw up? Try Large Format. It'll straighten you right out....)

Are modern lenses produced typically to a higher standard of consistency than older ones? Have tolerances tightened? I would guess so, though the medium format lenses I've used over time, older Hasselblad Zeiss optics for example, have seemed glorious in their optical and mechanical consistency (I'd certainly take one to the Moon...).

Does the variability follow the brand?

A particular star-crossed design?

Primes n' Zooms?

Plastic components in the innards?

Or is it just the general cussedness of things?

What are the contributors to this sample variation?
 
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MyReality said:
Testing the best of the best (a subsample of the total population) may be of interest to very particular renters who ask for those lenses and for discussion on this forum. The average renter will just receive a lens from the total population.
Click to expand...
I've never seen any indication that Lensrentals will cherry-pick a lens from their inventory. To the best of my knowledge, everyone "will just receive a lens from the total population".

Inspection and testing of lenses during return check-in and rental check-out is done to check for any damage or defects which may have occurred with time, use, and constant shipping and handling before supplying it to a customer.
 
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TechTalk2 said:
MyReality said:
Testing the best of the best (a subsample of the total population) may be of interest to very particular renters who ask for those lenses and for discussion on this forum. The average renter will just receive a lens from the total population.
Click to expand...
I've never seen any indication that Lensrentals will cherry-pick a lens from their inventory. To the best of my knowledge, everyone "will just receive a lens from the total population".
Click to expand...
That's what I expect.
TechTalk2 said:
Inspection and testing of lenses during return check-in and rental check-out is done to check for any damage or defects which may have occurred with time, use, and constant shipping and handling before supplying it to a customer.
Click to expand...
And also to make sure the lens was assembled correctly in the first place.
 
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