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thighslapper

Infinity Calibration with Manual Lenses .....

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My T appears to be miscalibrated when using manual lenses at infinity .......

 

Could other users please do a quick check and see if this is a generic or a specific problem.... ???

 

I would expect for distance use just setting the lens to infinity would be fine ..... but on my T focus at infinity occurs significantly before the infinity stop on the lens (I have tried several).

 

This has only been apparent after a days walking with the 40/2 when I took mostly landscapes on a bright day at f8 .... and didn't bother focussing and just set the lens on infinity .....

 

I would have thought the sensor position would be adjusted manual lens use with the adapter in place ....... but as this is a mainly AF camera perhaps Leica have been a bit careless with this adjustment ......

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Well the deafening silence either means I am the only one using manual lenses, or I am the only one that has noticed trouble.

 

Looks like another homing pigeon heading for Wetzlar ......

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I would never trust the infinity mark when using an adapter – with any adapter on any camera.

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errr....... yes ...... but this is a Leica made expensive piece of engineering ..... and specifically designed to allow you to use manual Leica lenses on a T .... the least you can expect is that the manufacturing tolerances allow you to use it as if you are focussing manually.

 

I would hope that Leica are careful enough with the sensor alignment to factor in use with the adapter and manual lenses .......

 

The question is ...... is my camera poorly adjusted ..... or do Leica expect this degree of tolerance in usage with manual lenses and we have to focus for everything ..... even when taking photos at infinity when you would expect just setting the lens to be sufficient ?

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In a world where metals wear or can change dimensions with temperature and micron level tolerances are not always affordable, allowances are necessary. If you cannot focus on infinity at all you may have a problem.

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Mine also focuses past infinity, and yes, I was wondering the same thing. I only bought it and the T a few days ago though, so I have not had extensive testing. But on both Leica and Zeiss M lenses, they are focusing past infinity...the infinity stop is not useful. This is a disappointment.

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My T has been for a visit to Wetzlar with the T-M adapter.

 

After initially emailing and telling me they cannot find a problem I explained in more detail what was going on.

 

They have finally stated it is the adapter and have replaced it.

 

I am a little sceptical about this ..... but I suppose a few thou either way presumably will presumably cause issues once you get into the world of sub 35mm sensors and shorter focal lengths.

 

I will believe it when I see it though .........

 

I have a feeling I will be sitting with a sheet of glass, fine grade emery paper and doing the 'adjustment' myself ........

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It reappeared this afternoon .......

 

Initial testing indicates it is EXACTLY the same ....... with 50mm (various) 75mm and 135mm lenses far distant focus appears a touch before infinity on every lens ..... and using the lens set on infinity results in OOF images.

 

I assume that it means that the adapter needs some shims to increase the distance the lens is from the sensor.

 

It looks like it can be dismantled so I will have a fiddle this weekend.

 

Not impressed.

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It is expected behaviour with any adapter. <shrug>

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Respectfully, I disagree.

It might be almost acceptable for a cheap auction site adapter, and I stopped short of naming the country, as I don't mean disrespect.

But for a genuine manufacturer to produce a fitting which is not able to do what the average normal person expects, I don't believe this is "acceptable behaviour", not at all.

The manufacturer in this case is solely responsible for the lens, the adapter, and the camera, all three are designed and produced by them. To me is it no different to fitting a lens and rolling it to the infinity setting, something we have all done since day one (unless A/F is all you have used). It focuses at infinity, as it should.

Slip this new and not so inexpensive adapter into the optical train and it should do the same.

If this is acceptable behaviour, then the old adage that you get what you pay for is well shot down.

Gary

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I have to agree Gary.......

 

I assume that as the T is primarily AF there is no need for critical sensor placement as in the M where the focussing is entirely mechanical.

 

Whether the camera matches precisely with manual lenses and the adapter is then a complete lottery.

 

As Leica replaced the adapter and the result is basically the same it is not variance in adapter tolerance that is at fault, but the sensor placement in the camera.

 

The front flange of the adapter is removable ..... although the screws are very tight (I will need to get some better quality cross head screwdrivers to tackle it) .... so it may be possible to pack it out underneath to compensate for the error. We will see ......

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Fixed it.

 

Took 20 minutes.

 

The silver front flange comes off easily.

 

Cut some curved pieces of screen protector (0.1mm) which are slightly adhesive and positioned them between the screw holes on the main assembly.

 

By pure 'luck' this completely corrects the problem for my 75/2 and now infinity on the lens produces in focus images on the camera.

 

Will have to check more carefully tomorrow to ensure all the image is in focus and that the whole assembly is still parallel to the sensor in all directions ......

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Well done T/S.

Point is though, that if it were a cheap and nasty camera/lens/adapter you wouldn't have cause to grumble.

But given the cost, the hype as being the best etc, I personally expected better.

I still don't believe it is good enough.

Anyway, enjoy the new found accuracy.

Gary

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I did the same. With a double sided adhesive tape while keeping the covering paper on, to provide a bit more thickness. Works perfectly...

 

This is quite important - and disappointing from LEICA - as when you focus manually, you really want the lens to be focused on infinite when reaching the mechanical stop. I missed a few pictures because of that...

 

Thanks for the tip thighslapper.

Regs

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Focusing just slightly past infinity with a mount adapter is expected behavior. Depending on ambient temperatures, focus distance can change as you are mechanically coupling three disparate pieces of metal together.

 

In certain situations one may not be able to actually reach infinity focus without that built-in leeway.

 

Altering the flange in any way is not recommended as it needs to remain absolutely parallel to the sensor plane.

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The corrected difference is 0.1mm ........ and infinity is way, way off the stop on all of my lenses without it. I find it hard to believe that this discrepancy is a deliberate tolerance to allow for expansion with the normal climatic variations of northern Europe...... it seems far too much. I am not a volcanologist after all ..........

 

I can easily remove the shims if proved wrong ........ and as they are placed completely circumferentially within the flange I am confident the parallel alignment is unaffected... .....and until there is any obvious issue I prefer the convenience of all my lenses acting as they should when used manually on a camera.

 

.... I have just checked .... even if the adapter was all aluminium .... which has a high coefficient of expansion...... and you allow for a 50 deg Celsius rise the difference is 0.01mm

 

Leica have got something wrong with the sensor placement or the dimensions of the adapter.

Edited by thighslapper

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I guess we'll have to agree to disagree.

 

Remember, tolerance stacking involves the lens, the adapter and the body. You mentioned a tenth - a tenth is *huge*. Ideally an optical system will be within a few thousandths tolerance.

 

As background to my point of view, my profession is Quality Control manager at an aerospace machine shop - we fab metal parts for ISO9000 applications.

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The corrected difference is 0.1mm ........ and infinity is way, way off the stop on all of my lenses without it. I find it hard to believe that this discrepancy is a deliberate tolerance to allow for expansion with the normal climatic variations of northern Europe...... it seems far too much. I am not a volcanologist after all ..........

 

I can easily remove the shims if proved wrong ........ and as they are placed completely circumferentially within the flange I am confident the parallel alignment is unaffected... .....and until there is any obvious issue I prefer the convenience of all my lenses acting as they should when used manually on a camera.

 

.... I have just checked .... even if the adapter was all aluminium .... which has a high coefficient of expansion...... and you allow for a 50 deg Celsius rise the difference is 0.01mm

 

Leica have got something wrong with the sensor placement or the dimensions of the adapter.

It is not just the adapter expanding, it is the lens barrel and even the camera itself. Obviously the tolerance is not as tight as the M must be, but it should be something in the order of 1\100th of a mm on the T otherwise the sensor woul be out of line with the optical axis.

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