So, the difference is 9.80mm -- and I would expect that to be the width of an M-to-E adapter, right?
But according to the DPreveiew post cited above, he kept measuring adapters at 9.72mm.
So, I emailed Novoflex to ask them what their width is, and they replied: "Our NEX/LEM-adapter has an exact width of 9,74mm."
Can anybody make sense of this? Is this .08mm or .06mm intentionally short? Or is there something wrong with the calculation that resulted in 9.80mm?
Thanks!
Dec 05, 2013 at 08:22 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
p.1 #2 · Should M-to-E adapters be 9.80mm or 9.74mm?
Many people like to make adapters slightly thin, because this ensures even with slight variations in sensor placement and lens construction the lens will be able to reach infinity focus. For most cameras and lenses it will focus a bit beyond infinity, but for those at the far end of tolerances it will still work. I think metabones takes a different approach and makes theirs exactly 9.8mm, but this means with some lens/camera combinations it won't quite reach infinity. My own take is that for a lens that one plans to use mostly at infinity and that doesn't have a floating element I would choose a thinner adapter like Novoflex. For a lens with a floating element I would choose the metabones approach.
p.1 #3 · Should M-to-E adapters be 9.80mm or 9.74mm?
Plot thickens!
Look what Novoflex just told me: "We took our own measurements when we received one of the first E-Mount cameras back in 2010. Therefore we use a flange focal length of 18,05mm for Sony's E-Mount."
I've heard the suggestion that adapters are often intentionally short to accommodate lenses -- but that never seemed to make sense to me (I can explain way) -- and according to this comment from Novoflex, their *intention* is to build it to the correct width, but they think the correct width is different from Sony's spec.
p.1 #4 · Should M-to-E adapters be 9.80mm or 9.74mm?
Is there some reference that lists what the various adapter widths (Metabones, Fotodiox Pro, Novoflex, Voigtlander, etc.) are expected to be machined to?
Steve Spencer Offline • • • • • • • Upload & Sell: On
p.1 #6 · Should M-to-E adapters be 9.80mm or 9.74mm?
Well it looks like Novoflex does try for a thicker adapter. That is good to know, but unless I missed something they still try for an adapter that is .01mm thinner than their measurements. I sure don't know of any database on adapter thicknesses. Maybe you would like to start one turnstile
p.1 #7 · Should M-to-E adapters be 9.80mm or 9.74mm?
fwiw, I can actually understand intentionally designing an adapter to be .01mm short -- for those who suggest it should compensate slight potential machining variations in the lens or body, without becoming too wide -- but .06mm seems too much just for that.
I wonder if E mount is really 18.05mm, or if Novoflex is just machining to the wrong width.
Just curious -- you believe Metabones is machines to 9.80mm and the others to someting shorter? Do you happen to remember where you saw that?
p.1 #10 · Should M-to-E adapters be 9.80mm or 9.74mm?
Wouldn't the measured mechanical flange distance be off anyway because of the unknown thickness and refractive properties of the filter stack altering the length of the optical path? Just taking a camera and measuring the distance from the mount to the sensor seems to be a bit of a too simplistic approach for digital cameras.
Dec 05, 2013 at 09:47 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
p.1 #11 · Should M-to-E adapters be 9.80mm or 9.74mm?
turnstyle wrote:
fwiw, I can actually understand intentionally designing an adapter to be .01mm short -- for those who suggest it should compensate slight potential machining variations in the lens or body, without becoming too wide -- but .06mm seems too much just for that.
I wonder if E mount is really 18.05mm, or if Novoflex is just machining to the wrong width.
Just curious -- you believe Metabones is machines to 9.80mm and the others to someting shorter? Do you happen to remember where you saw that?
I don't have a link, but in the discussion of adapters on this forum Bo Minh (i think his screen name is conurus as he is behing the company by that name that does the Contax N to EOS conversions) who is involved in making the NEX EOS adapter for metabones said that metabones tries to make the adapters the exact width and do not try to make them a little thinner. This statement is also consistent with some people claiming they don't quite reach infinity focus with the metabones adapter. Like I said above I like this approach for lenses with floating elements as a too thin adapter can have bigger effects on this type of lens and a too thick adapter simply works like an extension tube and typically does not reduce image quality. For some shots at infinity, however, it might make a difference.
p.1 #13 · Should M-to-E adapters be 9.80mm or 9.74mm?
turnstyle wrote:
I actually included that in the OP.
It seems that Novoflex believes E mount is 18.05mm rather than 18.00mm.
So you did.
Post deleted
Dec 05, 2013 at 10:01 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
p.1 #14 · Should M-to-E adapters be 9.80mm or 9.74mm?
turnstyle wrote:
Right -- and so, for example, the Lux 50 ASPH should perform better on a Metabones than a Novoflex?
If I were to get the Lux 50 ASPH, I would get the Metabones based on the reasoning I laid out. I would love to see the reasoning tested, however. There is more to adapters than just thickness. I think the most important feature is symmetry (i.e., is the exact thickness the same all the way around the adapter). There is also the issue of how much play there is in the adapter. For tight tolerance you need a tight fit of the lens to the adapter and the adapter to the camera. From all I can tell the Metabones adapters are very well made and they are trying to make them to the thickness I would prefer for some lenses, but Novoflex adapters are very well made and I think would have excellent symmetry and a tight fit. Both seem to be very good choice, but like I said I would pick the metabones for a lens with a floating element unless testing were to show otherwise.
p.1 #15 · Should M-to-E adapters be 9.80mm or 9.74mm?
I have two LM-to-E adapters here, one new Novoflex and one older and very less expensive auction site no-name. The no-name measures 9.72-9.73mm thickness around its perimeter, the Novo at 9.72mm all-round. However, both mount equally and tightly on my NEX bodies with the Novo slightly tighter as it reaches lock position (no A7R to use/test yet).
Both adapters have 4 expansion slots to even out their thickness, and both show uneven opening slot adjustments where that process may have been done after assembly. I haven't checked for the effect of that .01mm measured variation in images made with the NEX, and no EXIF doesn't help with looking back. I expect it would be easier to see if tightly controlled on a FF body.
p.1 #17 · Should M-to-E adapters be 9.80mm or 9.74mm?
Novoflex will tell you - directly in writing - as they did me, that all of their adapters allow for pass infinity focus.
Straight from Novoflex -
"All our camera to lens adapters are calculated such as to allow a minimum focusing beyond infinity.
This will ensure that a focusing to infinity is guaranteed with each camera body and each lens of the proper combination. Even with maladjusted older lenses."
p.1 #18 · Should M-to-E adapters be 9.80mm or 9.74mm?
MaxBerlin wrote:
Novoflex will tell you - directly in writing - as they did me, that all of their adapters allow for pass infinity focus.
Straight from Novoflex -
"All our camera to lens adapters are calculated such as to allow a minimum focusing beyond infinity.
This will ensure that a focusing to infinity is guaranteed with each camera body and each lens of the proper combination. Even with maladjusted older lenses."
This will certainly be true if they believe that E mount is 18.05mm rather than 18.00mm.
Per comments above, an adapter intentionally designed to focus past infinity can be disadvantageous (eg, for lenses with floating elements).
p.1 #19 · Should M-to-E adapters be 9.80mm or 9.74mm?
My original design had the smaller tolerance at 9.7mm and could at times come out to 9.78. This was mainly due to the 4 component stack up (2 mounts, one separator and one circuit board.
The newly designed e-mount adds adjustment screws (no shims required!) to allow for fine tuning. All the new adapters I send out will be set to a nominal 9.80 mm.
