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torbod
Joined: 31 Jan 2010
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 Posted: Fri Dec 09, 2011 9:05 am Post subject: Back focusing mystery with beloved Helios 44-3 MC |
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torbod wrote:
Hi,
What I see in terms of focus point in the WF is correct with all other lenses I have, thus there is no issue with my focusing screen alignment in the camera (Sony A900). How come can the Helios back focus quite severely, I just don't get it?
I can clearly see in the WF where the focus is at (it is a sharp lens from wide open), but when I open the files, the focus is always off. I have tested focusing on a ruler from 50 cm distance, and the real focus is approximately 4 cm behind what I see in the WF. It is so strange, since I don't change aperture or make any other maneuver before triggering the shot after the focus is set. Just as with any other lens.
Previously I have had similar problems with lenses with loose internal elements, but only after shifting the vertical orientation on the lens (from pointing upwards to downwards and vice versa). This lens has no loose elements what I can see.
Any ideas on what it can be?
Is it possible to fix?
Cheers
Tobbe
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peterqd
Joined: 28 Feb 2007
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| Posted: Fri Dec 09, 2011 10:24 am Post subject: |
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peterqd wrote:
If you're certain the camera is OK with other M42 lenses on the same adapter then it has to be an issue either with the lens itself or in combination with this adapter. Does the lens screw properly into the adapter? Sometimes a flanged adapter can cause such problems with some lenses.
I also wonder if the lens actually focuses as sharp as you expect, it could have a defect of some sort. Have you tried bracketting the focussing to find the best it can achieve?
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torbod
Joined: 31 Jan 2010
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| Posted: Wed Dec 14, 2011 5:38 am Post subject: |
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torbod wrote:
| peterqd wrote: |
If you're certain the camera is OK with other M42 lenses on the same adapter then it has to be an issue either with the lens itself or in combination with this adapter. Does the lens screw properly into the adapter? Sometimes a flanged adapter can cause such problems with some lenses.
I also wonder if the lens actually focuses as sharp as you expect, it could have a defect of some sort. Have you tried bracketting the focussing to find the best it can achieve? |
Thanks for the input. I'm by now quite experienced in using manual focus lenses, in fact that is almost all I have been using for the last two years. Setting manual focus, DOF and how incompatible adapters and misaligned focusing screens, etc affect the system is nothing new to me.
Thus, I cannot really understand how the adapter can affect back focusing. On Sony, there is no optics in the adapter like Nikon has. Thus, even if the lens would hit a flange on the adapter (which it doesn't). That situation would just act a s a very short extension tube and just alter the infinity focus and close focusing abilities, and not mysteriously shift the focus from what I see in the VF and what is captured on the sensor.
The lens is very sharp (at least the central part from wide open and edge to edge stopped down). The part of the image that is in focus is very sharp. I can also clearly demonstrate by shooting e.g. a ruler from an angle that the focus I clearly see in the VF is not where it ends up in the image. This way I can count the centimetres the focus is off (and even use trigonometry if I would be picky to get the real value, which is not very important).
It would be interesting to use the lens on a NEX or similar that uses the main sensor for live view and see how it behaves. But I have no such camera within reach.
When I read your answer a new theory came up in my head. Perhaps the lens has some "quality" in combination with the tiny astigmatism in my eyes that in conjunction requires another VF dioptre setting in the camera as compared to all other lenses I have. Worth testing, but I suspect that it will not be the solution.
BR
T
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Spotmatic
Joined: 18 Aug 2008
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| Posted: Wed Dec 14, 2011 6:43 am Post subject: |
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Spotmatic wrote:
I don't have a solution for you, but I can assure you that I have exactly the same problems with ~58mm f/2 lenses on my Pentax K-5. For instance the 58mm f/1.9 Primoplan and the 58mm f/2 Biotar. I think these lenses are not contrasty enough wide open to facilitate manual focusing on stock focusing screens (as you know any focusing screen has a DOF all by itself), so it's more or less hit or miss.
Not that this really helps; I just wanted to let you know my own experiences.
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ludoo
Joined: 18 Sep 2009
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| Posted: Wed Dec 14, 2011 6:47 am Post subject: |
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ludoo wrote:
I had the same exact problem on my Pentax with a Rikenon 50mm: custom focusing screen calibrated with shims, all lenses focused great apart from that one which was consistently off by the same amount. I could never understand why and I sold the lens in the end, so I'm curious too.
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martinsmith99
Joined: 31 Aug 2008
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| Posted: Wed Dec 14, 2011 7:00 am Post subject: |
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martinsmith99 wrote:
Most of the DSLRs I've used are only able to show DOF at F4 or smaller, so I would expect a number of les contrasty lenses so show a missed focus. I used to get really frustrated by it, but it's just the limitations of DSLRs; we are using lenses on them that weren't designed to be used. My 5Dii is much better but still difficult with fast lenses wide open. Use live view if you have it when situations present themselves.
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torbod
Joined: 31 Jan 2010
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| Posted: Wed Dec 14, 2011 7:21 am Post subject: |
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torbod wrote:
Good input from everyone 
Then I guess that it is just the way things are until a better explanation comes around. Regarding contrast and this Helios lens. It is in fact a very contrasty lens (that is why I love it. I has a Zeiss-like contrast pop for virtually no money and very saturated colors). So the lens has both contrast and sharpness. I usually use it between f/2.8 and f/4 when setting the focus.
So I don't think it is due to only low contrast or low sharpness. It must be some other factor(s) in this mess. I should try stopping down to at least f/4 and test the correctness, although the VF starts to get somewhat dark past f/5.6.
Also, I don't want to "mask" a missed focus by increasing the DOF by stepping down. I want composition adopted DOF and perfect focus simultaneously
Perhaps I should change the focusing screen from the standard to the darker SONY exchange screen with better DOF and manual focus abilities. But I'm not very tempted to have a darker VF. I shoot macro on free hand with flash aid with manual glass stopped down to f/8-f/16 and the VF cannot become very much darker that it is today during this condition. Has anyone experience with this other screen?
(On my A700 I had a microprism/split screen focusing screen that was great for increasing the hit-rate with manual focus, but quite annoying in other ways. It obscured the "scene" and composition since the focusing assist parts took too much room in the smaller aps-C VF. So I don't want that type of "look" again.)
BR
Tobbe
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ludoo
Joined: 18 Sep 2009
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| Posted: Wed Dec 14, 2011 9:06 am Post subject: |
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ludoo wrote:
| martinsmith99 wrote: |
| Most of the DSLRs I've used are only able to show DOF at F4 or smaller, so I would expect a number of les contrasty lenses so show a missed focus. I used to get really frustrated by it, but it's just the limitations of DSLRs; we are using lenses on them that weren't designed to be used. My 5Dii is much better but still difficult with fast lenses wide open. Use live view if you have it when situations present themselves. |
Depends on the focusing screen. The Canon EE-S for example is designed for fast lenses and shows oof correctly up to about f1.8-f1.4.
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peterqd
Joined: 28 Feb 2007
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| Posted: Wed Dec 14, 2011 9:22 am Post subject: |
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peterqd wrote:
| torbod wrote: |
| peterqd wrote: |
If you're certain the camera is OK with other M42 lenses on the same adapter then it has to be an issue either with the lens itself or in combination with this adapter. Does the lens screw properly into the adapter? Sometimes a flanged adapter can cause such problems with some lenses.
I also wonder if the lens actually focuses as sharp as you expect, it could have a defect of some sort. Have you tried bracketting the focussing to find the best it can achieve? |
Thanks for the input. I'm by now quite experienced in using manual focus lenses, in fact that is almost all I have been using for the last two years. Setting manual focus, DOF and how incompatible adapters and misaligned focusing screens, etc affect the system is nothing new to me.
Thus, I cannot really understand how the adapter can affect back focusing. On Sony, there is no optics in the adapter like Nikon has. Thus, even if the lens would hit a flange on the adapter (which it doesn't). That situation would just act a s a very short extension tube and just alter the infinity focus and close focusing abilities, and not mysteriously shift the focus from what I see in the VF and what is captured on the sensor.
The lens is very sharp (at least the central part from wide open and edge to edge stopped down). The part of the image that is in focus is very sharp. I can also clearly demonstrate by shooting e.g. a ruler from an angle that the focus I clearly see in the VF is not where it ends up in the image. This way I can count the centimetres the focus is off (and even use trigonometry if I would be picky to get the real value, which is not very important).
It would be interesting to use the lens on a NEX or similar that uses the main sensor for live view and see how it behaves. But I have no such camera within reach.
When I read your answer a new theory came up in my head. Perhaps the lens has some "quality" in combination with the tiny astigmatism in my eyes that in conjunction requires another VF dioptre setting in the camera as compared to all other lenses I have. Worth testing, but I suspect that it will not be the solution.
BR
T |
 I admit I was scratching around for the explanation.
If you find it, please keep us posted!
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torbod
Joined: 31 Jan 2010
Posts: 379
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| Posted: Wed Dec 14, 2011 10:03 am Post subject: |
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torbod wrote:
| peterqd wrote: |
I admit I was scratching around for the explanation.
If you find it, please keep us posted! |
No worries mate, I'm glad for all contribution
/T
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poilu
Joined: 26 Aug 2007
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| Posted: Wed Dec 14, 2011 10:28 am Post subject: |
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poilu wrote:
now with liveview those issues should be easily resolved
put the dslr and helios on tripod, focus with the viewfinder
then check liveview, if images are different, matte is faulty
everytime I shimmed my 400D, I always found a lens who didn't work
how it is possible to get focus with a lens and not with another
easy, shimming require less than 0.1 mm tolerance
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Orio
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| Posted: Wed Dec 14, 2011 10:46 am Post subject: |
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Orio wrote:
| poilu wrote: |
how it is possible to get focus with a lens and not with another
easy, shimming require less than 0.1 mm tolerance |
+1
that's it.
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torbod
Joined: 31 Jan 2010
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| Posted: Wed Dec 14, 2011 12:08 pm Post subject: |
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torbod wrote:
Live view is good, at least with the main sensor (I guess that a two sensor system can be as misaligned as a sensor and a focusing screen).
My problem is that I don't have live view in my camera and still want to use the lens.
The remedy may be shimming then... and hoping that the focus is not altered with all other lenses that works fine now. I have a hard time of believing that I can shift the focus some centimeters (shot from 50 cm distance) with the Helios without setting all other lenses I have totally off.
Does anyone have any experience of shimming a Sony a900?
cheers
T
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themoleman342
Joined: 21 Oct 2007
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| Posted: Wed Dec 14, 2011 12:51 pm Post subject: |
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themoleman342 wrote:
Are you using the a900 with manual focus lenses and without the "M" Screen? Before doing anything else, UPGRADE! Seriously, it takes two minutes and it makes shooting with these faster lenses a breeze.
My helios 44-3 is dead-on with my a850. I tried shooting at a ruler too. Is your focus confirmation at the wrong spot too?
I suspect it's with your lens? Or maybe the diopter is doing something funny in conjunction with it?
My inclination is if every other lens works for you and this one doesn't, shimming may correct your helios but it will throw the majority off.
Edit: Sorry I just read the post over:
| Quote: |
| Perhaps I should change the focusing screen from the standard to the darker SONY exchange screen with better DOF and manual focus abilities. But I'm not very tempted to have a darker VF. I shoot macro on free hand with flash aid with manual glass stopped down to f/8-f/16 and the VF cannot become very much darker that it is today during this condition. Has anyone experience with this other screen? |
Yes, I have experience. I upgraded a week after I got my sony and couldn't be happier. It's as bright and as accurate as any native m42 camera I've had in the past. Spotmatic, Fujica, Chinon, Yashica, everything. It just doesn't have any focusing aids. |
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torbod
Joined: 31 Jan 2010
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| Posted: Wed Dec 14, 2011 1:09 pm Post subject: |
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torbod wrote:
| themoleman342 wrote: |
Are you using the a900 with manual focus lenses and without the "M" Screen? Before doing anything else, UPGRADE! Seriously, it takes two minutes and it makes shooting with these faster lenses a breeze.
My helios 44-3 is dead-on with my a850. I tried shooting at a ruler too. Is your focus confirmation at the wrong spot too?
I suspect it's with your lens? Or maybe the diopter is doing something funny in conjunction with it?
My inclination is if every other lens works for you and this one doesn't, shimming may correct your helios but it will throw the majority off.
Edit: Sorry I just read the post over:
| Quote: |
| Perhaps I should change the focusing screen from the standard to the darker SONY exchange screen with better DOF and manual focus abilities. But I'm not very tempted to have a darker VF. I shoot macro on free hand with flash aid with manual glass stopped down to f/8-f/16 and the VF cannot become very much darker that it is today during this condition. Has anyone experience with this other screen? |
Yes, I have experience. I upgraded a week after I got my sony and couldn't be happier. It's as bright and as accurate as any native m42 camera I've had in the past. Spotmatic, Fujica, Chinon, Yashica, everything. It just doesn't have any focusing aids. |
Thank you, very interesting reading.
I'll shop for an M-screen then to live even happier with all my fast MF lenses. Althogh I must say that the standard screen is very good also as a compromise between focusing aid and brightness for slower lenses, stepped down action or dark conditions.
Cheers
T
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themoleman342
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| Posted: Wed Dec 14, 2011 1:18 pm Post subject: |
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themoleman342 wrote:
I never found the M-screen to be THAT much darker. Only by a stop or so. The contrast is greater, however, like true matte ground-glass. Focusing f1.4 lenses is EASY.
The screens are made to be interchangeable. If you're expecting to be in dark conditions or have slow lenses, just switch back to the standard. No harm done. |
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torbod
Joined: 31 Jan 2010
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| Posted: Wed Dec 14, 2011 1:27 pm Post subject: |
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torbod wrote:
| themoleman342 wrote: |
I never found the M-screen to be THAT much darker. Only by a stop or so. The contrast is greater, however, like true matte ground-glass. Focusing f1.4 lenses is EASY.
The screens are made to be interchangeable. If you're expecting to be in dark conditions or have slow lenses, just switch back to the standard. No harm done. |
Yes, that is smart. Although I donät want to switch tat often with the risk of getting dust in between the sreen and prism.
I you have a macro lens going to 1:1 magnification. Could you set it to max magnification and stop it down to between f/8 and f/16 and see if you can see the focus point in "normal" indoor light (not under a directed spotlight) looking at some bread crumbs or similar? I have no problem with this with the standard screen when I chase bugs and similar. If you can do this with the M screen I would not hesitate to switch ASAP.
Cheers
T
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poilu
Joined: 26 Aug 2007
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| Posted: Wed Dec 14, 2011 1:51 pm Post subject: |
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poilu wrote:
| Marc wrote: |
| My inclination is if every other lens works for you and this one doesn't, shimming may correct your helios but it will throw the majority off |
each AF lenses have indeed a different 'micro focus' adjust
but in the manual lenses world, there is only one correct setting
the distance lens-matte_screen must be exactly the distance lens_sensor
| torbod wrote: |
| My problem is that I don't have live view in my camera |
then you must download the chart http://focustestchart.com/chart.html
follow the instruction to check if your A900 is correctly calibrated
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themoleman342
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| Posted: Wed Dec 14, 2011 2:15 pm Post subject: |
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themoleman342 wrote:
| Quote: |
| I you have a macro lens going to 1:1 magnification. Could you set it to max magnification and stop it down to between f/8 and f/16 and see if you can see the focus point in "normal" indoor light (not under a directed spotlight) looking at some bread crumbs or similar? I have no problem with this with the standard screen when I chase bugs and similar. If you can do this with the M screen I would not hesitate to switch ASAP. |
Sorry, I do not have a proper 1:1 setup to really test this. Stopping a lens down to f16 in indoor light and being able to still focus is quite the requirement though. I doubt it would be easy with the M-screen. |
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torbod
Joined: 31 Jan 2010
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| Posted: Wed Dec 14, 2011 3:16 pm Post subject: |
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torbod wrote:
| themoleman342 wrote: |
| Quote: |
| I you have a macro lens going to 1:1 magnification. Could you set it to max magnification and stop it down to between f/8 and f/16 and see if you can see the focus point in "normal" indoor light (not under a directed spotlight) looking at some bread crumbs or similar? I have no problem with this with the standard screen when I chase bugs and similar. If you can do this with the M screen I would not hesitate to switch ASAP. |
Sorry, I do not have a proper 1:1 setup to really test this. Stopping a lens down to f16 in indoor light and being able to still focus is quite the requirement though. I doubt it would be easy with the M-screen. |
Ok.
Well, it is not easy with my screen either, but it is possible. Normally I stop at f/11 since it is easier
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torbod
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| Posted: Wed Dec 14, 2011 3:19 pm Post subject: |
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torbod wrote:
| poilu wrote: |
| Marc wrote: |
| My inclination is if every other lens works for you and this one doesn't, shimming may correct your helios but it will throw the majority off |
each AF lenses have indeed a different 'micro focus' adjust
but in the manual lenses world, there is only one correct setting
the distance lens-matte_screen must be exactly the distance lens_sensor
| torbod wrote: |
| My problem is that I don't have live view in my camera |
then you must download the chart http://focustestchart.com/chart.html
follow the instruction to check if your A900 is correctly calibrated |
No problem so far with AF lenses. The focus is spot on with most of my lenses and I have been using that chart to test most of them.
But this issue I have is only for MF lenses, or in fact only one MF lens
Oh, by the way, I don't use focus confirm in the camera, that is generally way worse with MF lenses than my eyesight. But good tip, I shall try focus confirm with this particular lens
I admit that it is often hard to nail focus with other fast Mf lenses too, but that is down to visibility and contrast of the subject I'm capturing, not any strange optical quality in the lens/camera system like with the Helios.
Thanks
/T
_________________
For Sale or Trade: Pick from the list below.
Manual Lenses: CV 15 4.5 | MIR-20H 20 3.5 | Elmarit-R 28 2.8 | Flektogon MC 35 2.4 | S-M-C Tak 50 1.4 | Rollei 50 1.8 HFT | Helios 44-3 MC 58 2 | MC ROKKOR-X 58 1.2 | MacroPlanar 60 2.8 | Vega-12b 90 2.8 | Tamron 52B 90 2.5 | CZJ 135 3.5 | Jupiter-21A 200 4 | Tair-3s 300 4.5 | KOHBEPTEP K-1 | Takumar x2 |
Camera: Sony Nex 5N |
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themoleman342
Joined: 21 Oct 2007
Posts: 2190
Location: East Coast (CT), U.S.A.
Expire: 2013-01-24
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| Posted: Wed Dec 14, 2011 4:13 pm Post subject: |
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themoleman342 wrote:
| Quote: |
| Oh, by the way, I don't use focus confirm in the camera, that is generally way worse with MF lenses than my eyesight. But good tip, I shall try focus confirm with this particular lens |
I don't really use focus confirm either. I was just wondering if everything is out-of-sync or whether it matches with what appears to be in-focus or the 4cm back. Could lead to an answer... |
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torbod
Joined: 31 Jan 2010
Posts: 379
Location: Sweden
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| Posted: Wed Dec 14, 2011 5:30 pm Post subject: |
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torbod wrote:
| themoleman342 wrote: |
| Quote: |
| Oh, by the way, I don't use focus confirm in the camera, that is generally way worse with MF lenses than my eyesight. But good tip, I shall try focus confirm with this particular lens |
I don't really use focus confirm either. I was just wondering if everything is out-of-sync or whether it matches with what appears to be in-focus or the 4cm back. Could lead to an answer... |
Yes I agree. Will try tonight.
The reason for not using focus confirm is that it has too much of hysteresis. Thus the confirm light goes on on different places when turning the focusing ring coming from the infinity or mfd directions. It is however consistent when going from the same direction, but I cannot remember the best one, thus I skip it.
/T
_________________
For Sale or Trade: Pick from the list below.
Manual Lenses: CV 15 4.5 | MIR-20H 20 3.5 | Elmarit-R 28 2.8 | Flektogon MC 35 2.4 | S-M-C Tak 50 1.4 | Rollei 50 1.8 HFT | Helios 44-3 MC 58 2 | MC ROKKOR-X 58 1.2 | MacroPlanar 60 2.8 | Vega-12b 90 2.8 | Tamron 52B 90 2.5 | CZJ 135 3.5 | Jupiter-21A 200 4 | Tair-3s 300 4.5 | KOHBEPTEP K-1 | Takumar x2 |
Camera: Sony Nex 5N |
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torbod
Joined: 31 Jan 2010
Posts: 379
Location: Sweden
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| Posted: Wed Dec 14, 2011 7:18 pm Post subject: |
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torbod wrote:
Well, mystery solved, or at least gone.
I tried a focusing confirm adapter and it was fairly spot on coming from one of the directions. Some millimeters off from the other direction. Then I focused on eyesight only, and it was perfectly spot on. Weird...
So now I have perfect focus with the lens no matter what adapter I put it on (I have three and one of them with chip for focus confirm). I can only find three explanations for the focus shift I used to have:
1. A loose lens element. I have tested to gently rattle the lens around and it is still good, thus probably no loose elements.
2. Misplaced matte screen. When I last used the lens, it was a month or so ago. Perhaps the matte screen has moved in place since then. I know that I have had it opened once to blow away some dust, but I thought that was even earlier, and no other lens was that bad earlier.
3. Misadjusted dioptre. When I last used the lens the dioptre could have been off. But I usually don't find dioptre to change focusing position that much and no other lens was that bad earlier.
1 or 2 Seems like the most probable explanation (but I'm not convinced although happy it is fixed).
Anyway, thank you all for the input, this thread is now a good list of checkpoints when focusing shift appears again for anyone.
Now I can start using the lens again. I'm really happy since it is one of my budget favorites and part of my almost complete Russian M42 collection. (20mm, 58mm, 90mm (P6), 200mm and 300mm). I only miss a Mir-24H and perhaps something around 135mm and a macro.
I let you know if the problem appears again, then I'm convinced to solve the mystery once and for all.
Cheers
T
_________________
For Sale or Trade: Pick from the list below.
Manual Lenses: CV 15 4.5 | MIR-20H 20 3.5 | Elmarit-R 28 2.8 | Flektogon MC 35 2.4 | S-M-C Tak 50 1.4 | Rollei 50 1.8 HFT | Helios 44-3 MC 58 2 | MC ROKKOR-X 58 1.2 | MacroPlanar 60 2.8 | Vega-12b 90 2.8 | Tamron 52B 90 2.5 | CZJ 135 3.5 | Jupiter-21A 200 4 | Tair-3s 300 4.5 | KOHBEPTEP K-1 | Takumar x2 |
Camera: Sony Nex 5N |
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GrahamNR17
Joined: 17 Jan 2009
Posts: 1855
Location: Norfolk, UK
Expire: 2012-09-06
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| Posted: Wed Dec 14, 2011 7:42 pm Post subject: |
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GrahamNR17 wrote:
My left eye problem was diagnosed for me by the same lens |
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