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Focusing beyond infinity
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PostPosted: Sat Oct 10, 2009 9:51 pm    Post subject: Focusing beyond infinity Reply with quote
I spent a while playing around with my cameras and adapters this afternoon and to my horror found that all my M42 adapters allow focusing beyond infinity! While not the world's worst problem, by focusing just a little short of the infinity mark, I am getting far better detailed images.

So now the question...I know you can sand down an adapter that DOESN'T reach infinity, but what can you do to one (or three!) that run past it?

Any advice is much appreciated Smile


PostPosted: Sat Oct 10, 2009 10:10 pm    Post subject: Reply with quote
It's hard to say without seeing the way the adapter is constructed, but you might be able to cut out a piece of shim stock of the appropriate thickness and attach it to the flat side of the adapter. Super glue might work.

How to find out correct thickness? I dunno offhand. Trial and error most likely.

I used to own a couple of Canon FD telephotos, and I still own a couple of old T-mount teles that all focus past infinity. True, it does make for focusing on distant subjects somewhat touchy, but the way it was explained to me, this "feature" was there to counteract lack of achievement of infinity focus when the optic expanded due to increases in ambient temperature.


PostPosted: Sat Oct 10, 2009 10:16 pm    Post subject: Reply with quote
On my Zorki Camera the register plane is aligned by little sheets of paper (with high density of course).
I would try with such material to find out correct thickness. Then glue with material that does not develop / change it’s own thickness while hardening.


PostPosted: Sat Oct 10, 2009 10:19 pm    Post subject: Reply with quote
you have to find how to calibrate your lenses
here is the way to fix contax lens
http://forum.mflenses.com/infinity-tune-for-contax-lens-t7011.html


PostPosted: Sat Oct 10, 2009 10:21 pm    Post subject: Reply with quote
Wow, such quick answers! I'll try sticking a shim on first then and will update you with progress.


PostPosted: Sun Oct 11, 2009 2:06 am    Post subject: Re: Focusing beyond infinity Reply with quote
Shrek wrote:
I spent a while playing around with my cameras and adapters this afternoon and to my horror found that all my M42 adapters allow focusing beyond infinity!


Chinese stuff... manufacturing tolerances are non-existent. Try Russian-made adapters called Poisk-Foto. I know www.filmprocess.ru sells them. Look like this: http://filmprocess.ru/photo_m42_poiskfoto.html



Infinity is at hard-stop at all my Russian and German (Jena) lenses; all of my Russian lenses are within about 4 degrees off upright position (Germans are top notch). Note that SMC and S-M-C Takumars will not mount (physically) on these adapters due to the flange and aperture link collision issue. They do cost some $50 with an AF chip though. Other than that, they are just perfect.


PostPosted: Sun Oct 11, 2009 6:51 am    Post subject: Reply with quote
Thanks but I am not able to deal in kyrillic ... Embarassed


PostPosted: Sun Oct 11, 2009 9:35 am    Post subject: Reply with quote
The main problem is;THE REGISTER --

unfortunately it must be accurate.

One example:
EOS -- 44 mm register
M42 -- 45.46 mm
The difference is 1.46 mm

1.46mm is NOT A PROBLEM AT ALL,
the problem is 0.06mm

So, tuning something like + - 0.06 mm -- oops! that's a big problem while drilling an adapter..

tf

Last edited by trifox on Sun Oct 11, 2009 1:20 pm; edited 2 times in total


PostPosted: Sun Oct 11, 2009 10:17 am    Post subject: Reply with quote
Going 'past infinity' might be a nuisance but provided the on-screen image is in focus so will be the result. It just means that for landcapes and the like you need to judge sharpness rather than whacking the focus mount back to its stop.


PostPosted: Sun Oct 11, 2009 10:33 am    Post subject: Reply with quote
trifox wrote:
EOS -- 42 mm register


44 mm ?


PostPosted: Sun Oct 11, 2009 10:42 am    Post subject: Reply with quote
All my M42 adapters allow focusing past infinity. I don't mind that. What is annoying me now is my M42 lenses that don't reach infinity on my film cameras....GRRRRRR!


PostPosted: Sun Oct 11, 2009 1:17 pm    Post subject: Reply with quote
sichko wrote:
trifox wrote:
EOS -- 42 mm register


44 mm ?


yes -- John !! I have been stuck in FD measures for last month!! Very Happy Very Happy

EOS = 44 mm
FD = 42 mm

THANKS!! Smile

tf


PostPosted: Sun Oct 11, 2009 1:26 pm    Post subject: Reply with quote
I didn't know that FD was 42 mm. I see now why it is so difficult to work with.


PostPosted: Sun Oct 11, 2009 9:00 pm    Post subject: Reply with quote
Another point to consider -- unless you're shooting wide open, more than likely hyperfocal distance will take care of subjects at infinity.


PostPosted: Mon Oct 12, 2009 6:22 am    Post subject: Reply with quote
I did have good luck with one HK AF confirm m42 adapter... I'm trying to figure out which one it was. It was black & brass.


PostPosted: Mon Oct 12, 2009 2:02 pm    Post subject: Reply with quote
sichko wrote:
I didn't know that FD was 42 mm. I see now why it is so difficult to work with.


Some of them are really worth the effort though, for example, the FL 55mm f1.2.
I have a lathe so after removed the FL mounting plate I simply machined 2mm of the mounting boss at the base of the lens (Bringing the rear element 2mm closer to the sensor and therefore allowing infinty focus)and fitted an SA mounting plate to it. To keep the A/M ring fixed at the M setting (so I could stop down manually) I added a brass shim from an old Sigma lens and by tightening the three mounting plate securing screws it also clamps the A/M ring tightly in one position.
Some pics:








Of course as Sigma SA and Canon EF have the same registration distance you can just as easily fit an EF mounting plate instead and you will have infinity focus without having to use an optical adapter which can compromise on image quality. Wink


PostPosted: Mon Oct 12, 2009 4:46 pm    Post subject: Reply with quote
Wow, that's a really clean conversion and machine job. You taking orders? Very Happy


PostPosted: Mon Oct 12, 2009 7:00 pm    Post subject: Reply with quote
Hey DSG,

I have some questions about your conversion, if you don't mind.

I too have a lathe (and a milling machine), and I also have an FL 55mm f/1.2. Plus I shoot EOS film and digital. So I appreciate your showing how you converted your FL 55mm.

When you chucked your lens up in your lathe, did you remove the focusing ring first? I'm also wondering how you avoided marring the lens's metal surface with the chuck jaws.

My lathe -- and all the others I've used -- has no measurement scale for longitudinal movement (parallel to the axis). Did you use a dial indicator or something to determine exactly how much material you were removing?

Is the brass ring strictly necessary? I'd just as soon omit that step if possible.

You also indicate at the end of your post that an EF plate can also be fitted. I don't have any spare EOS back plates handy. I wonder if I dismantled an adapter for, say, Nikon F to EOS, if it would be the right thickness? Any feel for that?


PostPosted: Mon Oct 12, 2009 7:08 pm    Post subject: Reply with quote
fates wrote:
Wow, that's a really clean conversion and machine job. You taking orders? Very Happy


Hi fates ..

We are taking orders for conversion, if you wish Wink

please, don't hesitate to contact us on:
info@cameraserviceone.com

or visit our website:
http://www.cameraserviceone.com

cheers..

Tf


PostPosted: Mon Oct 12, 2009 7:53 pm    Post subject: Reply with quote
cooltouch wrote:
Hey DSG,

I have some questions about your conversion, if you don't mind.

I too have a lathe (and a milling machine), and I also have an FL 55mm f/1.2. Plus I shoot EOS film and digital. So I appreciate your showing how you converted your FL 55mm.

When you chucked your lens up in your lathe, did you remove the focusing ring first? I'm also wondering how you avoided marring the lens's metal surface with the chuck jaws.


The only part I removed before machining was the A/M ring and the inner rotating ring it connects to but then I obviously I took precautions to prevent the lens getting scratched during machining.
First I cut some cardboard from a toilet paper roll and wrapped it tightly around the rear element tube, with about 1/2"-3/4" longer than needed. I pushed a bit of scrunched up toilet paper into the end of this to cover the rear element itself and then I snipped around the end so the end could be folded over. This was then secured and wrapped with tightly wound PVC electical tape.
A clean rag was wrapped around the rest of the lens and more cardboard was wrappped around the focus dial and all secured with tape.
The focus dial has 12 knurled idents so the three jaws of the chuck will perfectly lock into any three of them. Note: Dont do the chuck up too tight!...Use just enough pressure to hold the lens tight and secure.
Then you can start machining.
Dont use any coolant!...The rear boss is only Aluminium so its very easy to dry machine...Besides, soluble oil would play absolute havoc with the optics!
Its better to take many shallow passes across the boss than a couple of deep ones or you could easily overdo it.

cooltouch wrote:

My lathe -- and all the others I've used -- has no measurement scale for longitudinal movement (parallel to the axis). Did you use a dial indicator or something to determine exactly how much material you were removing?


The inner rotating ring sits in a depression in the rear of the lens and as I recall is normaly flush with the boss so you can use it as a depth gauge


cooltouch wrote:

Is the brass ring strictly necessary? I'd just as soon omit that step if possible.


In my case it was...Without it the A/M ring turns increadbly easily and its all too easy to accidentaly turn it to A setting almost everytime you touch the lens, say to focus it...It will only stop down manually on the M setting so it makes a lot of sense to lock it on the M setting...The shim does this job neatly and efficiently.


cooltouch wrote:

You also indicate at the end of your post that an EF plate can also be fitted. I don't have any spare EOhe M setting S back plates handy. I wonder if I dismantled an adapter for, say, Nikon F to EOS, if it would be the right thickness? Any feel for that?


An M42-EF adapter should make a good substitute, but make sure the bore is big enough to allow the 40mm diameter rear element tube to pass through it when focussing to infinity.
Machining it is relatively easy but the difficult bit it is accurately drilling the three tiny (About 1-1.5mm) securing holes. After drilling them you need to carefully countersink the holes on the face that mates to the camera so the screwheads of the securing screws are flush.
As shown in my pics I aligned the red mounting position dot on the SA plate with the pin on the A/M ring when set to the M position but it might be slightly different on an EF plate so to find out where to drill the holes you will first need to mark the "up position" on the EF plate or M42-EF adapter (Thats the point around the edge of the new mounting plate that faces upwards when its mounted to your camera) and once found and marked you have to find the point on the rear of the lens that faces up when mounted to the camera (f numbers upwards) then you can work out where to drill you three new mounting plate securing holes by using the old FL plate as a drill template.
Hint: Its essential you accurately centre then clamp the FL plate and the new plate tightly together before drilling (make sure the inside face of the FL plate faces the outer face of the new plate). A drill press should be used for accuracy.


PostPosted: Mon Oct 12, 2009 8:45 pm    Post subject: Reply with quote
Thanks much! I've printed this out for my archives.
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