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Lens Adapters: There Is No Free Lunch
  
 
Bifurcator
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p.3 #1 · Lens Adapters: There Is No Free Lunch


alwang wrote:
I wonder if there is also a difference between heavier, longer SLR lenses (where the weight may cause a cheap adapter to warp out of alignment) and lighter rangefinder lenses. I definitely feel like SLR adapters are prone to a little more play.

No adapter would warp but the camera bodies do - and it's measurable too. Even quite visible in many combinations! You can actually see the front face of the camera bow out and twist. On M4/3, the two sony Nex's I looked at, three Canon and one Nikon DSLR (all mid-range or cheaper DSLR models) it's pretty bad. And if the lens is heavier than the camera and it's mounted via a lens collar then the camera actually has enough weight on it's own (500 to 700 grams) to also warp it's face. But the adaptors themselves you would need a truck to warp them.


Bifurcator wrote:
I have used a micrometer on the thicknesses of my Chinese cheap-0 $20 adapters and 14 of 16 were right on (within the tolerances of the micrometer itself). One was just not seated right (fixed), and the other is a tilt-adapter which doesn't zero properly.

sebboh wrote:
it takes a very shoddy machining job to make an adapter that is uneven thickness. i feel sure 95% (or more) of the $20 adapters you buy will show no measurable deviation in thickness with a standard micrometer. the much more difficult part is machining the mount and insuring that it holds both the camera and the lens perfectly flush against the adapter surfaces. this is the source of most of the issues and even if the adapter is made by the OEM vender to the same tolerances as their camera and lens mounts (say a canon EF mount to
...Show more

Yeah, that's a point. I had some that were a little loose till I figured out there's a tension adjustment - thanks to the folks here! (-_-)/ Now the only one I have that doesn't hold everything super tight and flush is that Tilt-adapter and really, that's because it uses a hinging pin design designed by someone's pet chimpanzee - I'm sure of it!

I would have to guess based on my own experiences, that the inner surface and the area inside the camera around the sensor is more critical to IQ than anything else. In my case I've flocked the inside area of my adapters which helped with a few lenses actually. This is probably what Rusty experienced as that surface shape and texture (coating) can be pretty critical for internal reflections and stuff - which can cause soft corners, and low contrast edges, reduced detectable resolution (due to lower contrast), and so on - especially with WA/UWA lenses I would think.

For m4/3 and APS-C users (which I guess is the majority of folks adapting) I'm going to say that besides the inner surface of the ring there's no difference between a cheap and expensive adapter when it comes to accuracy. Certainly for those formats centering and 4 or 5 microns of tilt isn't going to make any noticeable difference in 99.999999% of shots - again, the camera bodies themselves warp more than that. The worst one I measured had a 1.93mm outward warp at the top of the mount and a 1.12mm inward warp at the bottom of the ring. This was a Cannon 300/4L lens attached to the GH1. GH2 seems a little better tho I haven't tried to measure it yet. etc. etc. The others were less but I noticed with careful study and measurements that at about 450g (either from the camera or the lens) the face of Nex, GH1, and one of the Canon bodies distort slightly - enough to measure.

With that kind of distortion happening already, what are we talking about with adapters? Meh...





Oct 01, 2013 at 07:08 PM
naturephoto1
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p.3 #2 · Lens Adapters: There Is No Free Lunch


Bifurcator wrote:
No adapter would warp but the camera bodies do - and it's measurable too. Even quite visible in many combinations! You can actually see the front face of the camera bow out and twist. On M4/3, the two sony Nex's I looked at, three Canon and one Nikon DSLR (all mid-range or cheaper DSLR models) it's pretty bad. And if the lens is heavier than the camera and it's mounted via a lens collar then the camera actually has enough weight on it's own (500 to 700 grams) to also warp it's face. But the adaptors themselves you would need
...Show more

But it does speak to using heavier and larger lenses lacking lens collars adapted to lighter and smaller cameras when tripod mounting them. The best scenario in those instances is to use a rotating collar when available to support the adapter/lens combination and to hope that the camera body itself does not warp under its own weight. This is why with my larger and heavier Leica R lenses on my smaller Fujifilm, often with my M4/3, and soon to be hopefully FF Sony NEX I use Novoflex adapters with the appropriate Novaflex rotating collars. But, this should also hold true even for larger and heavier native lenses. When I use smaller and lighter Leica R or M mount lenses on a tripod I am relying on L brackets that will hopefully also limit the warping of the tripod screw sockets and camera bottom of the smaller lighter cameras and hope that the bodies/mounts are not warping due to the weight of these lenses and the camera bodies themselves.

Rich


Edited on Oct 01, 2013 at 07:34 PM · View previous versions



Oct 01, 2013 at 07:21 PM
JohnJ
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p.3 #3 · Lens Adapters: There Is No Free Lunch


RCicala wrote:
...John, I don't disagree. This wasn't meant to be an exhaustive report, it was basically a report of me going 'I thought out of 20 adapters I'd find one that didn't make significant changes to measurements on an optical bench and I didn't". It's interesting enough that I'll repeat it on Imatest since that gives us a full 2-D image of the lens, rather an series of liniear cuts across the lens like an optical bench does. That will also give a different distance result since the bench is working at infinity focus and Imatest will be in the 8
...Show more

Roger, I definitely think it's worth investigating further so I hope you do get a chance to do that. But, I'd suggest finding an adapter that DOES work as it should and finding out why it does and the others don't. Essentially an adapter is a very simple thing, so I don't see why all of them should be bad (even with the addition of 2 surfaces and tolerances). Have you considered that maybe the brands of adapters that you use are simply not as good as their reputations may suggest, hence most/all of them giving you the errors that you've found? Just spitballin, but there has to be a reason.



Oct 01, 2013 at 07:33 PM
U.C.
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p.3 #4 · Lens Adapters: There Is No Free Lunch


RustyBug wrote:
Which adapter?

I don't know what adapter is being used at photozone. Probably a quite normal Nikon->EOS adapter.



Oct 01, 2013 at 07:34 PM
jhinkey
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p.3 #5 · Lens Adapters: There Is No Free Lunch


RCicala wrote:
Ah, assumptions. I love assumptions.

Actually lensrentals does a fairly huge business in adapted lenses. They probably have 100 adapters of various kinds and in general an adapter goes out with 2 or 3 very expensive lenses (Leicas, Zeiss, wide-aperture primes) making a big rental. The majority of it is for video shooters but a fair amount goes to m4/3 and NEX photographers.

Most people here know I sold Lensrentals (I kept a minority interest, for full disclosure) 2 years ago. I still run their QA and repair department and write my blog. Part of the agreement is that they
...Show more

Your blog is what prompted me to do business with Lensrentals, so they should think twice about getting rid of it. Your data has done a lot to add credibility to their business . . . . at least in my mind anyways.



Oct 01, 2013 at 07:40 PM
Bifurcator
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p.3 #6 · Lens Adapters: There Is No Free Lunch


naturephoto1 wrote:
This is why with my larger and heavier Leica R lenses on my smaller Fujifilm, often with my M4/3, and soon to be hopefully FF Sony NEX I use Novoflex adapters with the appropriate Novaflex rotating collars.


Yeah! Adapters with a tripod mount are useful! Just to mention however, now there are cheap-o Chinese ones with the same rigging. So again, it doesn't really need to be any particular brand or anything. But absolutely, supporting it from the much more sturdy adapters where the only distortion will be from the camera weight is probably the best solution.

Also to mention is that when hand-holding there is also probably more than 450 or 500g of torque pressure on the camera mount collar for many combinations - so just because it feels balanced in one's hands doesn't necessarily mean this won't occur.

It's my contention however, that this kind of warping (when not too extreme) doesn't matter enough to normally even mention - outside of high precision professional lens testing benches.





Oct 01, 2013 at 07:54 PM
uscmatt99
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p.3 #7 · Lens Adapters: There Is No Free Lunch


sebboh wrote:
it takes a very shoddy machining job to make an adapter that is uneven thickness. i feel sure 95% (or more) of the $20 adapters you buy will show no measurable deviation in thickness with a standard micrometer. the much more difficult part is machining the mount and insuring that it holds both the camera and the lens perfectly flush against the adapter surfaces. this is the source of most of the issues and even if the adapter is made by the OEM vender to the same tolerances as their camera and lens mounts (say a canon EF mount to
...Show more

This is a good point. Speaking from experience, it took me a few tries to find an adapter for my M-mount lenses to NEX that allowed infinity focus and maintained proper alignment of the focal plane to the sensor. At first I thought the NEX mount was off as I got 2 adapters with soft upper left corners using lenses that were bang on with a Ricoh GXR (native M-mount). On further inspection, those corners never got to infinity, while the rest of the image focused past infinity. These were the $20-30 adapters off Amazon. Then I got a Fotodiox Pro adapter that worked well with all of my lenses, and kept it even though there is an annoying tab gouging my middle finger. Keep in mind that Roger tested high-quality adapters, I'd love to see how the cheap ones without spring tensioned mounts would do.



Oct 01, 2013 at 08:42 PM
RCicala
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p.3 #8 · Lens Adapters: There Is No Free Lunch


JohnJ wrote:
Roger, I definitely think it's worth investigating further so I hope you do get a chance to do that. But, I'd suggest finding an adapter that DOES work as it should and finding out why it does and the others don't. Essentially an adapter is a very simple thing, so I don't see why all of them should be bad (even with the addition of 2 surfaces and tolerances). Have you considered that maybe the brands of adapters that you use are simply not as good as their reputations may suggest, hence most/all of them giving you the errors that
...Show more

The brands are good (Photodiox and Novoflex) but they were physically large adapters, mostly (Leica and Nikon to m4/3 and NEX). They are also used. I'm not thinking of doing an adapter comparison, but some other things I'm considering looking at:

1) focal length. These were fairly moderate (35mm and 50mm). I want to see if it's different at other FL (I suspect longer is less impressive).
2) Doing some thinner adapters.
3) Comparing Imatest and it's close shooting distances to the bench, with infinity focus.
4) Running the bench at 6 angles to nail down and mark direction of tilt (I only did 2 here).

The above discussion makes me want to consider lens sag, too. I have some spring supports for large lenses on Imatest that might be adaptable to moderate size lenses on adapters.

Other suggestions are welcome. I've got an article to finish this weekend, but maybe can ramp this up next week.



Oct 01, 2013 at 09:16 PM
Mescalamba
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p.3 #9 · Lens Adapters: There Is No Free Lunch


I would be quite interested how would Leitaxed lens fare against regular adapters or native ones.


Oct 01, 2013 at 10:19 PM
 

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Krosavcheg
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p.3 #10 · Lens Adapters: There Is No Free Lunch


And I would wonder how replacing a mount oneself will guarantee a micron precision.
Considering all the concern, we shouldn't even bother replacing lens elements. Going even further, can we guarantee a vendor would replace a mount/element correctly enough if it's not done in original manufacturing facility's controlled environment?

Not a swipe at Richard - more or less question of mount replacement v adaptation.



Oct 02, 2013 at 01:25 AM
millsart
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p.3 #11 · Lens Adapters: There Is No Free Lunch


Nope, never a free lunch, Anyone who tells you otherwise is selling something (literally)


Oct 02, 2013 at 01:51 AM
sebboh
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p.3 #12 · Lens Adapters: There Is No Free Lunch


Krosavcheg wrote:
And I would wonder how replacing a mount oneself will guarantee a micron precision.
Considering all the concern, we shouldn't even bother replacing lens elements. Going even further, can we guarantee a vendor would replace a mount/element correctly enough if it's not done in original manufacturing facility's controlled environment?

Not a swipe at Richard - more or less question of mount replacement v adaptation.


mount replacement essentially removes one source of alignment error. as i mentioned earlier making a cylinder of uniform thickness is easy while making a perfectly fitting mount is not. as long as the screws are tight the connection between the mount and lens should easily have greater precision than any mount connection (even oem lens to camera mounts). this means that you only have one mount point to provide alignment error instead of two.

it isn't that alignment errors can't happen from simple cylinders (as demonstrated by the many examples we see of decentered lenses), it's that on average the magnitude of alignment errors due to mount to mount connection are much greater.




Oct 02, 2013 at 01:57 AM
philip_pj
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p.3 #13 · Lens Adapters: There Is No Free Lunch


'how replacing a mount oneself will guarantee a micron precision.'

It won't and no one said it would. What it will do is remove one 'quality loss point' in two surfaces, and duplicate what the makers themselves do. It's simple and well proven, every lens has a mount ;-) The aim is to close in on total precision, if engineering matters at all.

I'd like to see Sony make the adapters themselves, with close attention to tolerances and QA - start with Leica M please. Remove the middle man, who has no more interest in the quality outcome than their bottom line, whereas the maker has a huge investment in high IQ and can offer warranty support.



Oct 02, 2013 at 02:01 AM
Bifurcator
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p.3 #14 · Lens Adapters: There Is No Free Lunch


sebboh wrote:
making a perfectly fitting mount is not [easy].

...the magnitude of alignment errors due to mount to mount connection are much greater.


I think it's pretty easy. Maybe easier than making an apple pie. (I love pie!) The only difficulty would be in tensioning and they have a tension adjustment - even the $10 ones.

I also have never seen an alignment error occur - like, ever. So I guess that's rarer than hens teeth (which with all the radiation floating over to California may actually happen. Naaah probably not - and if it does then) just like a lens alignment error I'll never see it....



Oct 02, 2013 at 07:00 PM
sebboh
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p.3 #15 · Lens Adapters: There Is No Free Lunch


Bifurcator wrote:
I think it's pretty easy. Maybe easier than making an apple pie. (I love pie!) The only difficulty would be in tensioning and they have a tension adjustment - even the $10 ones.

I also have never seen an alignment error occur - like, ever. So I guess that's rarer than hens teeth (which with all the radiation floating over to California may actually happen. Naaah probably not - and if it does then) just like a lens alignment error I'll never see it....


you should note that alignment errors are much harder to see on 4/3 than on FF because of the shorter diagonal for the same alignment error angle the distance out of alignment will be much smaller on 4/3 than on FF. i have seen alignment errors and they produce measurable differences in lens performance on cameras, even OEM lenses on native cameras.

but i agree, i don't find them very troublesome in real use.




Oct 02, 2013 at 07:30 PM
Mescalamba
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p.3 #16 · Lens Adapters: There Is No Free Lunch


Another win for m4/3!

My Leitaxed lens seems fine. Tho I really doubt I could tell it isnt, unless it was seriously off.

But, my native KM lens is slightly decentered.. (which means probably not so slightly)

Funny is that I saw way more faulty lens with native mounts than those adapted or used with adapter.



Oct 02, 2013 at 09:34 PM
Jeff Kott
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p.3 #17 · Lens Adapters: There Is No Free Lunch


Mescalamba wrote:
Funny is that I saw way more faulty lens with native mounts than those adapted or used with adapter.


I was thinking the same thing - I'm probably more likely to get across the frame sharpness with an adapted leica, ZM or CV lens than with a native mount Sony lens.



Oct 02, 2013 at 09:43 PM
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