Focus to infinity problem with an adapted lens.

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I asked this in the Sony thread but I might have more luck with a thread...

I've today received an M42 to Sony adapter and tried my M42 mount Takumar 50mm f1.4. All works fine except that when focusing on our local hill I'd expect focus to be achieved just before infinity but in this case I achieve focus between 7 to 10ft or 2-3m going by the lens markings. The lens achieves focus at all distances and the minimum focus distance seems about right so the only issue is that I can't really set the lens to about the right distance using the lens markings before focusing unless I keep in mind that infinity is at about 3m.

Has anyone ever come across infinity being achieved so near on the lens focus scale? I don't know if this is some sort of adapter issue or just that the lens markings are hopelessly inaccurate past a few feet.
 
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Not sure with Sony but with Nikon, to focus to infinity, you generally need an adapter that includes a correctional lens to offset the difference in distance from the rear lens element to the sensor. The Nikon Z mirrorless is easier. Here you can purchase adapters without correctional lenses that simply move the lens element backwards a tad. Which adapter did you buy?
 
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You don't need correction lenses when adapting 35mm SLR lenses to mirrorless. The flange focal distance is always less in the mirrorless (including Sony). Could the adapter be too thin? Do you have other M42 lenses to try?

With Nikon F, the distance is particularly long even by SLR standards, so you need a correction lens for nearly any other system. It's shorter with something like Canon EOS, so there are glassless adapters for several systems, including M42. But mirrorless is really the best choice for adapting lenses. There's a good table of distances here:
en.wikipedia.org

Flange focal distance - Wikipedia

en.wikipedia.org en.wikipedia.org
 
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In answer to your question - this bad: only on one lens, and a modern one at that - a samyang 14/2.8 which I had to recollimate.

Not clear if it only this lens that is causing problems ?

I haven’t myself had any legacy glass with this sort of problem - they have all been pretty much spot on the hard infinity mark.

If it not a collimation problem with that lens, then as retune says, almost certainly the adapter is too short in depth. A common problem with even some midrange adapters as well as the cheap chinese ones. K&F are pretty reliable usually as a midrange brand but they all, in my experience, are built just slightly short by 50-100 um so they guarantee infinity focus but not overdoing things so that you too much lose close focus.

If I am looking for an adapter I try and get it from amazon so that if it is too short or too loose or tight etc I can ( and have ) returned it without fuss.

I have adapted lenses to a nex6, a7 and a z6 - getting a good inexpensive adapter is trial and error I am afraid.
 
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I have the M2 for Canon EF to Micro 4/3 and had the same problem. There was glass in it that I just twisted as advised.. helped but not amazing. but I suppose that's the price you pay for adapting glass! Need an expert to help me really!
 
ebay adaptor or an SRB-Griturn (or other reputable brand) one?

IIRC (and I mat well not!), my old Takumars all had reasonably accurate focussing scales - at least they did when fitted to their native bodies.
 
Retune said:
You don't need correction lenses when adapting 35mm SLR lenses to mirrorless. The flange focal distance is always less in the mirrorless (including Sony). Could the adapter be too thin? Do you have other M42 lenses to try?

With Nikon F, the distance is particularly long even by SLR standards, so you need a correction lens for nearly any other system. It's shorter with something like Canon EOS, so there are glassless adapters for several systems, including M42. But mirrorless is really the best choice for adapting lenses. There's a good table of distances here:
en.wikipedia.org

Flange focal distance - Wikipedia

en.wikipedia.org en.wikipedia.org
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Partially true but there are several adapters, including the Pixco adapters from M42 to Nikon Z that use a correctional glass. I tried one to use in conjunction with the FTZ adapter without realising the adapter had glass in it. I thought it would just recess the lens a tad but that wasn't the case. It was obviously made to go directly from lens to body. My idea was to be able to leave the FTZ in place and have all my lenses Nikon F mount. The better choice, it would seem, is to use a direct to camera adapter without glass like the Urth one, which is naturally a similar length to the FTZ.
 
stickytape said:
I have the M2 for Canon EF to Micro 4/3 and had the same problem. There was glass in it that I just twisted as advised.. helped but not amazing. but I suppose that's the price you pay for adapting glass! Need an expert to help me really!
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Those AF/speed booster adapters are much more complicated, and do have glass, so what I said above wouldn't apply. I assume Alan just has a simple adapter.
 
This will be a non glass, dumb adapter. Alan shoots with a Sony A7.

My Contax Carl Zeiss 80-200mm does focus quite a way past infinity (noticeably more than any other lens I've adapted) but it's not that far out WW.
 
Sorry for missing out some details guys.

It's just a dumb metal adapter from K&F Concept, definitely no lens in it and the camera is a Sony A7 which is a FF mirrorless camera.

I have quite a few adapters for different lenses and bodies and I have had one which couldn't focus to infinity but this is the first time I've seen infinity occur too close.

I'm very tempted to think it's an adapter problem as I've never seen a lens with markings this far out. The only thing which is phasing me is the question of if an adapter can cause this and sill focus throughout the range from minimum focus distance to infinity, all be it a too close infinity.

Unless one of you guys stops me I may just return this adapter and try another but I really don't want to return it if there's any chance it isn't at fault.

PS.
I'll hang on until I get another lens which is due on Friday and if that one is way out too I suppose it must be an adapter issue.

Thanks all. I'll report back when the other lens arrives.
 
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THIRTYFIVEMILL said:
Partially true but there are several adapters, including the Pixco adapters from M42 to Nikon Z that use a correctional glass. I tried one to use in conjunction with the FTZ adapter without realising the adapter had glass in it. I thought it would just recess the lens a tad but that wasn't the case. It was obviously made to go directly from lens to body. My idea was to be able to leave the FTZ in place and have all my lenses Nikon F mount. The better choice, it would seem, is to use a direct to camera adapter without glass like the Urth one, which is naturally a similar length to the FTZ.
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Is that a focal reducer or speed booster or something, perhaps intended for a DX Z camera like the Z50? A straightforward M42 to (FX) Z adapter shouldn't need glass. An M42 to Nikon F adapter would need glass and should work with the FTZ, but then you're adding an extra lens that wouldn't be needed with a simple direct adapter, and won't help with image quality.
 
woof woof said:
I'll hang on until I get another lens which is due on Friday and if that one is way out too I suppose it must be an adapter issue.
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Would have been a good excuse to get another lens if there wasn't already one in the post, for 'testing purposes'. :)
 
Retune said:
Is that a focal reducer or speed booster or something, perhaps intended for a DX Z camera like the Z50? A straightforward M42 to (FX) Z adapter shouldn't need glass. An M42 to Nikon F adapter would need glass and should work with the FTZ, but then you're adding an extra lens that wouldn't be needed with a simple direct adapter, and won't help with image quality.
Click to expand...

Actually you're right. Darn, I'm too tired to be posting. Yes, it's M42 to Nikon F.
 
woof woof said:
Sorry for missing out some details guys.

It's just a dumb metal adapter from K&F Concept, definitely no lens in it and the camera is a Sony A7 which is a FF mirrorless camera.

I have quite a few adapters for different lenses and bodies and I have had one which couldn't focus to infinity but this is the first time I've seen infinity occur too close.

I'm very tempted to think it's an adapter problem as I've never seen a lens with markings this far out. The only thing which is phasing me is the question of if an adapter can cause this and sill focus throughout the range from minimum focus distance to infinity, all be it a too close infinity.

Unless one of you guys stops me I may just return this adapter and try another but I really don't want to return it if there's any chance it isn't at fault.

PS.
I'll hang on until I get another lens which is due on Friday and if that one is way out too I suppose it must be an adapter issue.

Thanks all. I'll report back when the other lens arrives.
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Shame about your k&f ( if it is an adapter issue ). I have a couple of Urth adapters but not the m42 to FE and have found them pretty good. Anyway, cheaper than a Novoflex.

This one has some sort of helicoid.

Urth x Gobe Lens Mount Adapter: Compatible with M42 Lens to Sony E Camera Body (Extendable): Amazon.co.uk: Electronics & Photo

Shop Urth x Gobe Lens Mount Adapter: Compatible with M42 Lens to Sony E Camera Body (Extendable). Free delivery and returns on eligible orders.
www.amazon.co.uk
 
I'm sure I've seen some M42 adapters with a separate central core that the lens screws into held in place by grub screws. If that's the case here then you might be able to adjust it by screwing the core a little further in and re-locking it.
 
ancient_mariner said:
I'm sure I've seen some M42 adapters with a separate central core that the lens screws into held in place by grub screws. If that's the case here then you might be able to adjust it by screwing the core a little further in and re-locking it.
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That sounds like the Urth one I posted a link to a few posts back
 
ancient_mariner said:
I'm sure I've seen some M42 adapters with a separate central core that the lens screws into held in place by grub screws. If that's the case here then you might be able to adjust it by screwing the core a little further in and re-locking it.
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I've seen those but this one isn't one of them and there's no adjustment.

TBH I did think that the adjustment was to get the centre of the lens to line up correctly when the lens and adapter are mounted on the camera.
 
woof woof said:
I've seen those but this one isn't one of them and there's no adjustment.

TBH I did think that the adjustment was to get the centre of the lens to line up correctly when the lens and adapter are mounted on the camera.
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They are actually simple helicoids to move the lens flange nearer or further from the sensor plane.

Usually used to get closer focus. Cosina voigtlander and others make ones for m mount to whatever but I haven’t seen one before in a non rangefinder adapter.
 
greyowl said:
They are actually simple helicoids to move the lens flange nearer or further from the sensor plane.

Usually used to get closer focus. Cosina voigtlander and others make ones for m mount to whatever but I haven’t seen one before in a non rangefinder adapter.
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I think we may be talking about different things.

I have a helicoid Leica M mount adapter so I'm familiar with those and that one operates without an adjustment screw and Allen key set up. I have seen some M42 adapters which come with an Allen key and clearly have an adjustment screw but I don't know what it's for. I had just assumed that some screw mount lenses don't line up correctly and the adjustment was just to get it to line up? Maybe not.
 
I've had a very short focal length lens that only started to look infinity focused at 2.4m on the scale (nearly the MFD).
A quick measurement with some calipers indicated the adapter was about 0.5mm shorter than it should have been.

For a 50mm lens to be so far from scale would require the error to be significantly worse.
 
greyowl said:
They are actually simple helicoids to move the lens flange nearer or further from the sensor plane.

Usually used to get closer focus. Cosina voigtlander and others make ones for m mount to whatever but I haven’t seen one before in a non rangefinder adapter.
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My but quite likes macro/close up & as he has one of my ML50 lenses I bought him a Sony E-C/Y helicoid adapter for his birthday last year. Works quite well actually. I bought a E-Leica M one for my Voigtlander 40/1.4 Classic in my early Sony A7 days.

woof woof said:
I think we may be talking about different things.

I have a helicoid Leica M mount adapter so I'm familiar with those and that one operates without an adjustment screw and Allen key set up. I have seen some M42 adapters which come with an Allen key and clearly have an adjustment screw but I don't know what it's for. I had just assumed that some screw mount lenses don't line up correctly and the adjustment was just to get it to line up? Maybe not.
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I think that's more for rotation Alan so that the 'top' of the adapted lens sits at the actual top when on the adapter.
 
LeeRatters said:
I think that's more for rotation Alan so that the 'top' of the adapted lens sits at the actual top when on the adapter.
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That's what I was trying to say. This adapter doesn't have any adjustment and lining up wise it's slightly off but not enough to complain about.
 
woof woof said:
I think we may be talking about different things.

I have a helicoid Leica M mount adapter so I'm familiar with those and that one operates without an adjustment screw and Allen key set up. I have seen some M42 adapters which come with an Allen key and clearly have an adjustment screw but I don't know what it's for. I had just assumed that some screw mount lenses don't line up correctly and the adjustment was just to get it to line up? Maybe not.
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ok sorry - I misunderstood - apologies
 
It's me not being clear Richard, and thanks for your input, everyone else too.
 
I don't think that you've said how the lens focus ring markings tally with actual focus distance through the range apart from infinity?

Got a tape measure?

Adapters (not Novoflex ones) can be a bit sloppy, but this sounds miles out which makes me wonder whether the lens barrel has been wrongly reassembled after some diy maintenance.
 
It looks OK at min focus distance but beyond that it's increasingly out.
 
I had another look at this this morning.

The lens extends to achieve close focus and as it is retracted it focuses further away. This would seem to point to the lens not being able to retract enough so maybe the adapter is too long?

Looking at it there's the black body of the adapter and then a bright metal insert or lip which sits proud of the body and then another bright metal insert or lip which is again proud of the first insert / lip.

yNmHNz4.jpg


I suppose the simple explanation is that one or both of these bright metal inserts or lips is too proud. If that's the case the K&F quality inspector must be having a week off as this is the second one I've had a problem with. The first was the wrong adapter in a correctly labelled box and now this one which achieves infinity way too early. I'll hang on until I get another lens but at the moment I'm convincing myself that this is an adapter fault. I do have a K&F Nikon to Sony adapter and that one works but the mark to line the lens up is off... So that's potentially three K&F adapters and all with some sort of issue. Time for me to give up on K&F as a brand maybe.

I have three Novoflex adapters but I had convinced myself that the cheap ones were ok as I have several and the only one I've had a problem with was a Leica M adapter which wouldn't allow focus to infinity, actually it only allowed me to focus to about 25ft.
 
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sounds like you have sussed what’s up with it - great !

With you on k&f - was my standard and no issues for me but I did treat myself to a c/y novoflex when i switched from my a7 to a z and are coming to the conclusion that you get what you pay for - absolutely spot on for all my c/y lenses.

richard
 
Yes, Novoflex are expensive (I have Minolta, Olympus and Canon FD to Sony Novoflex adapters and they're all fine) but I do have a number of cheap ones which have also been perfectly fine.

I've just checked Speedgraphic and a Novoflex M42 to Sony adapter is £78 so that's actually a bit cheaper than the others I've bought. I will wait until the other lens turns up to confirm it's an adapter issue.

Thanks to all who've helped and maybe this thread will give others with adapter issues a clue.
 
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I think if the adapter were too long you'd have the opposite problem - you wouldn't get infinity focus. It would be like mounting an M42 lens on Nikon F, where the flange focal distance is too long to use a simple adapter without glass. Or think of an extension tube, where the lens is further away from the sensor/film plane than normal and you don't get infinity focus.
 
You might be right. If you use an extension tube you can focus close up but not at infinity but extension tubes are relatively loooong and maybe this adapter is just a teeny tiny bit too long?

I don't know. I may be wrong. I can certainly focus closely and to infinity it's just that infinity is at less than 10 ft according to the lens markings.

It's either a lens problem or an adapter problem so I'll wait until my next M42 lens turns up, it's due Friday. I'll report back and apologise to K&F if it's not their fault :D
 
woof woof said:
I had another look at this this morning.

The lens extends to achieve close focus and as it is retracted it focuses further away. This would seem to point to the lens not being able to retract enough so maybe the adapter is too long?
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Wrong way round, it's retracted too far & needs to extend to compensate.
Block focusing where all the elements of the lens move together was normal before autofocus. If the relative positions of the elements remain the same the thin lens formula can be applied. The lens needs to be closer to the sensor to focus far away & move away to focus closer 1/focal length = 1/image distance + 1/subject distance (according to the laws of optics).
The adapter & camera body basically effect the image distance. If the adapter is too long infinity focus will be IMPOSSIBLE, the adapter is too short, but extending the lens for close focus compensates for this. To some extent this is normal for all adapters, making them fractionally too long is disastrous so they are deliberately made fractionally short, 0.1mm short would be reasonable IMO.
 
woof woof said:
You might be right. If you use an extension tube you can focus close up but not at infinity but extension tubes are relatively loooong and maybe this adapter is just a teeny tiny bit too long?

I don't know. I may be wrong. I can certainly focus closely and to infinity it's just that infinity is at less than 10 ft according to the lens markings.

It's either a lens problem or an adapter problem so I'll wait until my next M42 lens turns up, it's due Friday. I'll report back and apologise to K&F if it's not their fault :D
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With extension tubes maximum focusing distance is often only a few inches past the lens, even 0.0001mm too long will prevent sharp focus at infinity, though DOF should cover it. The issue becomes more noticeable as the focal length gets less.
 
Ah, which is why I posed it as a question. Thanks.

One way or another it looks like an adapter issue but the lens I thought was coming on Friday is now expected today so I'll try that one when it comes. I could just live with this but I miss being able to set the approximate distance using the lens markings.
 
Oh dear this is confusing me.

I've just received a 28mm M42 lens and looking at the local hill through it it just doesn't look in focus at infinity whereas my other 28mm focus on the hill a little before infinity.

So, my 50mm focuses on the hill at under 10ft and the 28mm doesn't quite manage it. Both are fine at close distance.

I think I'll assume that the lenses are ok, send the adapter back and buy a Novoflex and retest the lenses when it arrives.
 
If the adapter is out so severely that the 50mm needs to be set right down below 3m I wouldn't expect the 28mm to focus at all.
Both 28mm should focus to about the same distances.
Both being 'fine at close distance' further adds doubt on the adapter being the problem.

Just to check, I take it there are no optical elements in this adapter (it shouldn't have them unless it's a focal reducer) & no close up filters on any of the lenses... Something like that or missing elements from at least one of the lenses are I think the only explanations.

Try measuring the distance between the mating surfaces of the adapter (caliper are best but a ruler should do) To go from e-mount to M42 the distance should be 45.46-18mm (about 27.5mm)

If you live close enough to me to meet up (unlikely at the best of times) I could check your lenses on M42 bodies or known good M42 adapters as well as test your adapter with known good lenses... IIRC your from northern climes, which pretty much rules that out :(
 
Thanks for all the help Mike, it's appreciated. There are no elements in this adapter but it's all boxed up ready to go back so I'm not going to unbox it as I'm not sure I could measure it accurately enough to decide anything anyway. And yes, I'm in east Cleveland which is the NE of England.

I'll see if a Novoflex adapter sheds any new light on all this. I'll report back when it arrives and I've tested both lenses.

This is a first for me as the only problem I've had anything like this with adapters in the past is not being able to focus on far objects and in that instance it was obvious. I'll be gutted if it turns out that I've bought two duff lenses though.
 
woof woof said:
And yes, I'm in east Cleveland which is the NE of England.
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Lovely area I've driven through it on several occasions when working at Croft over weekends. Never get time to explore it properly :(
Hope you get it sorted, but I think there's got to be something odd about one of the 28mm lenses (I won't try & second guess which one)
 
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