Is fine tuning the focus of my lenses necessary?

**Larrymc** · 02-25-2022, 01:13 PM

Originally posted by 87Duckfan

Can focus adjustment be made to a SMC-A manual focus lens?

Actually no there is no need to focus tune a manually focused lens, you merely turn the focus ring and evaluate the focus while looking through the viewfinder. Unless you just enjoy trying get the green dot to display when you sense the focus is correct.

**UncleVanya** · 02-25-2022, 01:15 PM - **1 Like**

Originally posted by 87Duckfan

Can focus adjustment be made to a SMC-A manual focus lens?

Only via “apply all” since the lens doesn’t have a data pin and ID.

**c.a.m** · 02-25-2022, 02:01 PM

Originally posted by 87Duckfan

Can focus adjustment be made to a SMC-A manual focus lens?

Yes, and the Green Hexagon may be used effectively to achieve accurate and precise focus.

One approach is described in this article: Achieving Better Manual Focus with the Green Hexagon - PentaxForums.com

However, calibrating a manual focus lens, i.e., 'AF fine tuning', can be time-consuming and tedious, as suggested in the article.

Originally posted by Larrymc

Unless you just enjoy trying get the green dot to display when you sense the focus is correct.

LOL. One needs to enjoy setting up a calibration lab in the workshop... and being patient in the field to coax the focus ring to stop just when the Green Hex first lights.

- Craig

**87Duckfan** · 02-25-2022, 02:39 PM

I seem to be having difficulty focusing to infinity with the 400mm SMC-A on both the K70 and K10. Seems a little blurry to me (at infinity). Any suggestions?

**UncleVanya** · 02-25-2022, 06:17 PM

Originally posted by 87Duckfan

I seem to be having difficulty focusing to infinity with the 400mm SMC-A on both the K70 and K10. Seems a little blurry to me (at infinity). Any suggestions?

Are you hitting the hard stops or are you just unable to get it in focus despite having adjustments on both sides of actual infinity.

**87Duckfan** · 02-25-2022, 06:27 PM

Originally posted by UncleVanya

Are you hitting the hard stops or are you just unable to get it in focus despite having adjustments on both sides of actual infinity.

I can focus fine at any distance, just when set to infinity (hard stop as you call it), things still look a bit blurry. Is that normal?

**Lowell Goudge** · 02-25-2022, 06:50 PM - **1 Like**

Originally posted by 35mmfilmfan

I intend to purchase a bottle of red wine tomorrow to facilitate the fine tuning of my lenses, having tried other methods with indifferent success. I look forward to revealing the results of my investigations. I may even mention how I get on with the lenses.

I think that’s the wrong approach, the more you work the blurrier your images become, both literally and figuratively.

If, and it is a really big if, you manage to get the optimum result, you will have absolutely no recollection of how you achieved it

**UncleVanya** · 02-25-2022, 07:04 PM

Originally posted by 87Duckfan

I can focus fine at any distance, just when set to infinity (hard stop as you call it), things still look a bit blurry. Is that normal?

The infinity stop can be misaligned. It probably needs adjustment.

**rogerstg** · 02-26-2022, 08:36 AM

Originally posted by 87Duckfan

I seem to be having difficulty focusing to infinity with the 400mm SMC-A on both the K70 and K10. Seems a little blurry to me (at infinity). Any suggestions?

IMO, it's only a problem if you can't focus on something a great distance away. For me, it's OK and not unusual for the stop be just past focused infinity; definitely not before. I assumed lenses were calibrated this way to account for use in extreme hot and cold conditions as well as to account for manufacturing variances.

**pschlute** · 02-26-2022, 01:21 PM

Originally posted by 87Duckfan

I seem to be having difficulty focusing to infinity with the 400mm SMC-A on both the K70 and K10. Seems a little blurry to me (at infinity). Any suggestions?

You would do best posting this as a new thread.

Not being able to achieve infinity focus is not directly related to AF/FA menu setting.

Failure to achieve infinity focus can be quite common with older "K", M or A series lenses.Unlike modern lenses which allow the lens to focus beyond infinity, the older lenses have less "give" in the infinity stop. The answer is to have the lens adjusted by an expert, or yourself if you like a challenge.

This subject (infinity focus) has little to do with focus adjustment per se

35mmfilmfan · 02-26-2022, 01:49 PM - **1 Like**

Originally posted by Lowell Goudge

<snip>

If, and it is a really big if, you manage to get the optimum result, you will have absolutely no recollection of how you achieved it

That is a supremely accurate description of the vast majority of my life !! Sometimes, I'm not even sure if I'm dithering properly.

tibbitts · 02-26-2022, 11:28 PM

Originally posted by 87Duckfan

I can focus fine at any distance, just when set to infinity (hard stop as you call it), things still look a bit blurry. Is that normal?

It's pretty common for a lens to focus past infinity, for various reason, so you should determine whether the subject gets sharper (using live view) as you focus toward infinity, but then becomes blurrier again before you hit the focus stop (assuming the lens has a stop.) If so probably the lens focuses past infinity. If it keeps getting sharper but never gets as sharp as you think it should be, then maybe it's not focusing far enough. Some older lenses are easy to adjust (I had a 200/4 SMC Takumar that wouldn't focus far enough toward infinity, but was trivial to adjust); others are more complicated. Sometimes with zooms you might find you have to check at various focal lengths.

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02-25-2022, 01:13 PM	#46
Larrymc Site Supporter Join Date: Jun 2014 Location: Mississippi, USA Posts: 4,872	Originally posted by 87Duckfan Can focus adjustment be made to a SMC-A manual focus lens? Actually no there is no need to focus tune a manually focused lens, you merely turn the focus ring and evaluate the focus while looking through the viewfinder. Unless you just enjoy trying get the green dot to display when you sense the focus is correct.

02-25-2022, 01:15 PM - 1 Like	#47
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 23,027	Originally posted by 87Duckfan Can focus adjustment be made to a SMC-A manual focus lens? Only via “apply all” since the lens doesn’t have a data pin and ID.

02-25-2022, 02:01 PM	#48
c.a.m Site Supporter Join Date: Jan 2013 Location: Ottawa, Canada Photos: Gallery \| Albums Posts: 3,591	Originally posted by 87Duckfan Can focus adjustment be made to a SMC-A manual focus lens? Yes, and the Green Hexagon may be used effectively to achieve accurate and precise focus. One approach is described in this article: Achieving Better Manual Focus with the Green Hexagon - PentaxForums.com However, calibrating a manual focus lens, i.e., 'AF fine tuning', can be time-consuming and tedious, as suggested in the article. Originally posted by Larrymc Unless you just enjoy trying get the green dot to display when you sense the focus is correct. LOL. One needs to enjoy setting up a calibration lab in the workshop... and being patient in the field to coax the focus ring to stop just when the Green Hex first lights. - Craig

02-25-2022, 02:39 PM	#49
87Duckfan Loyal Site Supporter Join Date: Dec 2020 Photos: Albums Posts: 147	I seem to be having difficulty focusing to infinity with the 400mm SMC-A on both the K70 and K10. Seems a little blurry to me (at infinity). Any suggestions?

02-25-2022, 06:17 PM	#50
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 23,027	Originally posted by 87Duckfan I seem to be having difficulty focusing to infinity with the 400mm SMC-A on both the K70 and K10. Seems a little blurry to me (at infinity). Any suggestions? Are you hitting the hard stops or are you just unable to get it in focus despite having adjustments on both sides of actual infinity.

02-25-2022, 06:27 PM	#51
87Duckfan Loyal Site Supporter Join Date: Dec 2020 Photos: Albums Posts: 147	Originally posted by UncleVanya Are you hitting the hard stops or are you just unable to get it in focus despite having adjustments on both sides of actual infinity. I can focus fine at any distance, just when set to infinity (hard stop as you call it), things still look a bit blurry. Is that normal?

02-25-2022, 06:50 PM - 1 Like	#52
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,144	Originally posted by 35mmfilmfan I intend to purchase a bottle of red wine tomorrow to facilitate the fine tuning of my lenses, having tried other methods with indifferent success. I look forward to revealing the results of my investigations. I may even mention how I get on with the lenses. I think that’s the wrong approach, the more you work the blurrier your images become, both literally and figuratively. If, and it is a really big if, you manage to get the optimum result, you will have absolutely no recollection of how you achieved it

02-25-2022, 07:04 PM	#53
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 23,027	Originally posted by 87Duckfan I can focus fine at any distance, just when set to infinity (hard stop as you call it), things still look a bit blurry. Is that normal? The infinity stop can be misaligned. It probably needs adjustment.

02-26-2022, 08:36 AM	#54
rogerstg Site Supporter Join Date: Oct 2007 Location: Rhode Island Photos: Albums Posts: 1,116	Originally posted by 87Duckfan I seem to be having difficulty focusing to infinity with the 400mm SMC-A on both the K70 and K10. Seems a little blurry to me (at infinity). Any suggestions? IMO, it's only a problem if you can't focus on something a great distance away. For me, it's OK and not unusual for the stop be just past focused infinity; definitely not before. I assumed lenses were calibrated this way to account for use in extreme hot and cold conditions as well as to account for manufacturing variances.

02-26-2022, 01:21 PM	#55
pschlute Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 5,635	Originally posted by 87Duckfan I seem to be having difficulty focusing to infinity with the 400mm SMC-A on both the K70 and K10. Seems a little blurry to me (at infinity). Any suggestions? You would do best posting this as a new thread. Not being able to achieve infinity focus is not directly related to AF/FA menu setting. Failure to achieve infinity focus can be quite common with older "K", M or A series lenses.Unlike modern lenses which allow the lens to focus beyond infinity, the older lenses have less "give" in the infinity stop. The answer is to have the lens adjusted by an expert, or yourself if you like a challenge. This subject (infinity focus) has little to do with focus adjustment per se

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02-26-2022, 01:49 PM - 1 Like	#56
35mmfilmfan Pentaxian Join Date: Oct 2016 Location: Norfolk, UK Posts: 2,942	Originally posted by Lowell Goudge <snip> If, and it is a really big if, you manage to get the optimum result, you will have absolutely no recollection of how you achieved it That is a supremely accurate description of the vast majority of my life !! Sometimes, I'm not even sure if I'm dithering properly.

02-26-2022, 11:28 PM	#57
tibbitts Pentaxian Join Date: Apr 2007 Location: Oklahoma USA Posts: 2,131	Originally posted by 87Duckfan I can focus fine at any distance, just when set to infinity (hard stop as you call it), things still look a bit blurry. Is that normal? It's pretty common for a lens to focus past infinity, for various reason, so you should determine whether the subject gets sharper (using live view) as you focus toward infinity, but then becomes blurrier again before you hit the focus stop (assuming the lens has a stop.) If so probably the lens focuses past infinity. If it keeps getting sharper but never gets as sharp as you think it should be, then maybe it's not focusing far enough. Some older lenses are easy to adjust (I had a 200/4 SMC Takumar that wouldn't focus far enough toward infinity, but was trivial to adjust); others are more complicated. Sometimes with zooms you might find you have to check at various focal lengths.