Chris Bail
Regular Guy
I recently bought a nice user Pentax-L 43mm f1.9 from another RFF'er (little bit of paint loss on the barrel, really nice glass, smooth focus and aperture selection) but I've noticed a problem with it on my M8, and I'm wondering if anyone here can help me sort this out exactly.
I will also say that the seller offered to take it back, but considering the length of time it took to get to me, the relative scarcity, and the fact that I picked up a nice user lens at a nice, user price (and don't want to have to start looking again) left me wondering if anyone here can help me figure out what I need to do with the lens to get it working properly.
As soon as the lens was out of the box, I was shooting pictures with it, and I noticed right away that it seemed to be back focusing, so I did some further test shots and investigation. I noticed when testing it at infinity that the RF patch doesn't quite line up. It stops just short of marrying the two images at infinity. It's not terrible, but it's noticeable. (It needs just a smidge more throw in the focus to make the images in the RF/VF line up) The images at infinity seem adequately sharp and in focus. At least as sharp as my CV 35mm and Canon 50's
After realizing that the images weren't lining up at infinity, I started taking some more test pictures, and intentionally focused just a smidge closer than I wanted to, and my subsequent test shots showed that my sharpness at the point of focus was really good to my eye (for as inaccurate and unscientifically as I was in my "focus correction")
I don't have any similar issues on any other lenses (even the Canon 50/1.2 is sharp at the point of focus when the RF images are aligned) and all of my other lenses have RF images that seem to line up properly at infinity. (Summicron 40, CV 35/1.2, Canon 50/1.2, Canon 50/1.4.)
This leads me to believe that the lens elements are in the right place, (since it is focusing properly at infinity, and everywhere in between, as long as I throw the focus a smidge closer than the RF patch indicates), and everything is working as it should, with the exception of the focusing ring on the back of the lens not quite interacting with the RF cam right.
Does this make sense to those of you that are more experienced with RF lenses? If so, is there a way to fix this problem easily?
The lens doesn't seem to need a CLA, so I'm not inclined to ship it off for repair right away, and I don't mind doing a simple repair myself if it's a matter of loosening a couple screws, making an adjustment and putting it back together again. I'm just not 100% sure where to start.
I'm happy to hear any helpful advice that anyone might have. For now, I'm planning on using it as is and compensating my focus.
I've attached some samples. All were shot wide open, with the first few at close to minimum focus. No PP other than 100% crop.
Focused on the allen bolt at center with RF images aligned (100% crop)

L1011906 by Chris Bail, on Flickr
Same as above, cheated and focused a little forward

L1011907 by Chris Bail, on Flickr
Focus on the light switch slider with RF images aligned (100% crop)

L1011883 by Chris Bail, on Flickr
Same as above, cheated and focused a little forward

L1011884 by Chris Bail, on Flickr
Completely usable as is, so long as I remember to cheat the focus a little...but I'd like to figure out if this is fixable. (Focused on the the sign on the right and cheated the focus forward a little)

Leica M8 - Pentax-L 43mm f1.9 by Chris Bail, on Flickr
I will also say that the seller offered to take it back, but considering the length of time it took to get to me, the relative scarcity, and the fact that I picked up a nice user lens at a nice, user price (and don't want to have to start looking again) left me wondering if anyone here can help me figure out what I need to do with the lens to get it working properly.
As soon as the lens was out of the box, I was shooting pictures with it, and I noticed right away that it seemed to be back focusing, so I did some further test shots and investigation. I noticed when testing it at infinity that the RF patch doesn't quite line up. It stops just short of marrying the two images at infinity. It's not terrible, but it's noticeable. (It needs just a smidge more throw in the focus to make the images in the RF/VF line up) The images at infinity seem adequately sharp and in focus. At least as sharp as my CV 35mm and Canon 50's
After realizing that the images weren't lining up at infinity, I started taking some more test pictures, and intentionally focused just a smidge closer than I wanted to, and my subsequent test shots showed that my sharpness at the point of focus was really good to my eye (for as inaccurate and unscientifically as I was in my "focus correction")
I don't have any similar issues on any other lenses (even the Canon 50/1.2 is sharp at the point of focus when the RF images are aligned) and all of my other lenses have RF images that seem to line up properly at infinity. (Summicron 40, CV 35/1.2, Canon 50/1.2, Canon 50/1.4.)
This leads me to believe that the lens elements are in the right place, (since it is focusing properly at infinity, and everywhere in between, as long as I throw the focus a smidge closer than the RF patch indicates), and everything is working as it should, with the exception of the focusing ring on the back of the lens not quite interacting with the RF cam right.
Does this make sense to those of you that are more experienced with RF lenses? If so, is there a way to fix this problem easily?
The lens doesn't seem to need a CLA, so I'm not inclined to ship it off for repair right away, and I don't mind doing a simple repair myself if it's a matter of loosening a couple screws, making an adjustment and putting it back together again. I'm just not 100% sure where to start.
I'm happy to hear any helpful advice that anyone might have. For now, I'm planning on using it as is and compensating my focus.
I've attached some samples. All were shot wide open, with the first few at close to minimum focus. No PP other than 100% crop.
Focused on the allen bolt at center with RF images aligned (100% crop)

L1011906 by Chris Bail, on Flickr
Same as above, cheated and focused a little forward

L1011907 by Chris Bail, on Flickr
Focus on the light switch slider with RF images aligned (100% crop)

L1011883 by Chris Bail, on Flickr
Same as above, cheated and focused a little forward

L1011884 by Chris Bail, on Flickr
Completely usable as is, so long as I remember to cheat the focus a little...but I'd like to figure out if this is fixable. (Focused on the the sign on the right and cheated the focus forward a little)

Leica M8 - Pentax-L 43mm f1.9 by Chris Bail, on Flickr