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Adapter accuracy (or not)!
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PostPosted: Thu Feb 15, 2018 2:51 pm    Post subject: Adapter accuracy (or not)! Reply with quote
During lunchtime today I tested out one of my recent job lot of lenses on the adapter that arrived last night.
The Lenses' focus seemed a bit off at 70mm... & WAY off at 28mm.
On getting back to the office I checked the spacing provided by the adapter. As suspected it was more than a bit out!
Internet sources I've seen quote the flange distance of the Minolta SR/MD/MC mount as either 43.5mm or 43.72mm.
So the adapter to go to MFT should be 24.75mm or a bit more if the longer measurement is right.

My calipers make this adapter 23.4mm which is well over a millimeter out Exclamation
I've had other adapters that arrived slightly out on length, but never previously to this extreme.

What are the largest adapter errors you've seen?


PostPosted: Mon Feb 19, 2018 4:35 pm    Post subject: Reply with quote
The largest error will appear when you put the wrong adapter. Wink

P.S. knowing the one with the 'right' thickness is much more useful.


PostPosted: Mon Feb 19, 2018 8:44 pm    Post subject: Reply with quote
I've bought about a dozen adapters from various sources to convert manual focus lenses to my digitals. All of them are accurate at infinity. Most of them are the Chinese Fotga brand. One is Photodiox.


PostPosted: Mon Feb 19, 2018 10:49 pm    Post subject: Reply with quote
cooltouch wrote:
I've bought about a dozen adapters from various sources to convert manual focus lenses to my digitals. All of them are accurate at infinity. Most of them are the Chinese Fotga brand. One is Photodiox.


Strange the worst one I have is a Fotga.
When just using them the errors are not too noticeable with longer lenses, but with a 28mm mounted on this I can't focus as close as 5m.
I've been through my adapters checking the length with calipers/micrometer. Many of the longer ones are about ½mm shorter than they should be. Fortunately the flat type are generally very much closer (my EF-OM adapter is 1.98mm when internet registration measurements put the proper length as 2mm)

At least the inaccurate ones are all two part adapters where one plate can be unscrewed & some shims fitted behind. Perhaps this has already been done with some adapters & I've managed to pick up some that never made it to the end of the production line Shocked


PostPosted: Tue Feb 20, 2018 5:05 am    Post subject: Reply with quote
I've used even 17mm lenses -- two different ones, one with a Canon FD to NEX Fotga and the other with a Nikon F to NEX Fotga, and I was able to achieve infinity focus with both 17s. Knowing very well that Chinese quality control can be very hit or miss, perhaps you just got a bad one. Fortunately, I did not.


PostPosted: Tue Feb 20, 2018 7:43 am    Post subject: Reply with quote
cooltouch wrote:
I've used even 17mm lenses -- two different ones, one with a Canon FD to NEX Fotga and the other with a Nikon F to NEX Fotga, and I was able to achieve infinity focus with both 17s. Knowing very well that Chinese quality control can be very hit or miss, perhaps you just got a bad one. Fortunately, I did not.

There is no quality control on the cheapest adapter. Wink


PostPosted: Sat Feb 24, 2018 10:12 pm    Post subject: Re: Adapter accuracy (or not)! Reply with quote
DConvert wrote:

Internet sources I've seen quote the flange distance of the Minolta SR/MD/MC mount as either 43.5mm or 43.72mm.
So the adapter to go to MFT should be 24.75mm or a bit more if the longer measurement is right.


I believe the correct register for Minolta is 43.72mm. Micro-4/3 has a register of 19.25mm, so the correct adapter thickness is 24.47mm.

I have 26 m4/3 adapters in my database and the worst are easily the two FOTGA ones. They are so bad I would never buy FOTGA gain. One is a Konica AR adapter and it is 0.95mm too short and the other is M42 and that is 0.71mm too short.

My most consistently accurate adapters are by Fotodiox (2 samples) and Pixco (9 samples). These vary between 0.03mm too short (Fotodiox Pentax PK) and 0.26mm too short (Pixco PK). This last is a rogue since every other one of my Pixco adapters is within 0.15mm of the correct length. While the Fotodiox were very good, I found the Pixco to be nearly as good and a lot cheaper.

My other adapters are either BigIs or have no brand name. They vary between 0.57mm and 0.05mm too short. I have good and bad from BigIs.

It is interesting to observe that I also have a genuine Olympus OM to m4/3 adapter and that is 0.2mm too short. The adapters tend to be made deliberately too short to ensure that the lens will be able to focus at infinity given the inevitable tolerances on camera body, adapter and lens. The problem with ones that are very much too short (like FOTGA) is that the min focus distance with a wide angle lens is badly affected because a lot of the small focus throw on such a lens is wasted in going beyond infinity.

Given the tolerance on the genuine Olympus, I consider anything within 0.2mm to be 'accurate'.

Mark


PostPosted: Sun Feb 25, 2018 7:30 am    Post subject: Reply with quote
I have heard the adapter from K&F Concept has good tolerance. My PB to NEX is ok but not great in terms of thickness. Surprisingly, the thickness of the generic FD to NEX i bought are nearly perfect on my Canon 24/2.8 and Vivitar 135/2.3.


PostPosted: Wed Mar 21, 2018 9:06 am    Post subject: Reply with quote
I am currently in discussion with a foreign retailer about a supplied Pixco PK-NX adaptor, which was described as "retaining infinity focus" (but doesn't) and which appears to be too long by about 0.7mm.

I'm probably flogging a dead horse as he doesn't appear to understand what I'm complaining about (or doesn't want to) and the item in question seems to be out of production Sad


PostPosted: Wed Mar 21, 2018 10:08 am    Post subject: Reply with quote
kypfer wrote:
I'm probably flogging a dead horse as he doesn't appear to understand what I'm complaining about (or doesn't want to)
This is often my experience with ebay sellers, regardless of what the item is. In the ad, they present themselves as specialists in what they sell. But once you start to ask specific questions, especially after the sale, they suddenly (conveniently?) seem to suffer from amnesia.

In my cases, the items were either so cheap that it was a gamble anyway and I could happily forget about it, or with more valuable ones, persevering would eventually also result in proper answers/support.


PostPosted: Wed Mar 21, 2018 2:13 pm    Post subject: Re: Adapter accuracy (or not)! Reply with quote
SXR_Mark wrote:
DConvert wrote:

Internet sources I've seen quote the flange distance of the Minolta SR/MD/MC mount as either 43.5mm or 43.72mm.
So the adapter to go to MFT should be 24.75mm or a bit more if the longer measurement is right.


I believe the correct register for Minolta is 43.72mm. Micro-4/3 has a register of 19.25mm, so the correct adapter thickness is 24.47mm.

I have 26 m4/3 adapters in my database and the worst are easily the two FOTGA ones. They are so bad I would never buy FOTGA gain. One is a Konica AR adapter and it is 0.95mm too short and the other is M42 and that is 0.71mm too short.

My most consistently accurate adapters are by Fotodiox (2 samples) and Pixco (9 samples). These vary between 0.03mm too short (Fotodiox Pentax PK) and 0.26mm too short (Pixco PK). This last is a rogue since every other one of my Pixco adapters is within 0.15mm of the correct length. While the Fotodiox were very good, I found the Pixco to be nearly as good and a lot cheaper.

My other adapters are either BigIs or have no brand name. They vary between 0.57mm and 0.05mm too short. I have good and bad from BigIs.

It is interesting to observe that I also have a genuine Olympus OM to m4/3 adapter and that is 0.2mm too short. The adapters tend to be made deliberately too short to ensure that the lens will be able to focus at infinity given the inevitable tolerances on camera body, adapter and lens. The problem with ones that are very much too short (like FOTGA) is that the min focus distance with a wide angle lens is badly affected because a lot of the small focus throw on such a lens is wasted in going beyond infinity.

Given the tolerance on the genuine Olympus, I consider anything within 0.2mm to be 'accurate'.

Mark


Thanks for that, yes anything upto 0.2mm short is generally usable, but I've had a few lenses where I've definitely wanted it closer than that - shimming 2 part adapters it is generally fairly easy to get them to within 0.05mm.

As your experience of brands seems similar to mine I'll do my best to avoid FOTGA ones in future - I've never seen issues with the Pixco ones.

I'm surprised the genuine Olympus one is that far out, all my one piece 3rd party adapters are much closer than that and I've definitely had cheap 2 piece ones that are closer too.


PostPosted: Wed Mar 21, 2018 2:18 pm    Post subject: Reply with quote
Sjak wrote:
kypfer wrote:
I'm probably flogging a dead horse as he doesn't appear to understand what I'm complaining about (or doesn't want to)
This is often my experience with ebay sellers, regardless of what the item is. In the ad, they present themselves as specialists in what they sell. But once you start to ask specific questions, especially after the sale, they suddenly (conveniently?) seem to suffer from amnesia.

In my cases, the items were either so cheap that it was a gamble anyway and I could happily forget about it, or with more valuable ones, persevering would eventually also result in proper answers/support.


At least with e-bay you can raise a case get a refund without the supplier needing to understand the issue. E-bays policy is very heavily on the side of the buyer. I'm now reluctant to sell via e-bay as they are so biased towards buyers if any issues arise.
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