Merging the optics from an A50 mm F1.7 to a M50 mm F1.7?

Friso · 06-01-2021, 11:40 PM

This is my first post, so don't hesitate to let me know if I do something wrong

Out of curiosity I recently purchased an A50 mm F1.7. The lens reviews on this site proofed to be spot on, the aperture ring of this lens is a disaster, almost stuck at F8. The glass elements seems to be good enough although I haven't been able to test the lens yet by lack of a camera, my old istDL only produces black images nowadays unfortunately (now I have to choose between a K-3 III or a K-1 II).

Long time ago I converted a M 50mm F1.7 into a pinhole lens, so I removed the glass elements and replaced them with a pinhole sheet. The glass took some damage in the process. I slightly regret that move now because the M 50 1.7 was a fine lens. So I wonder, would it be possible to insert the smc optics of the crappy A 50 into the M 50? It seems the optics of those lenses are almost the same. I don't care about the A functionality, the M works just fine for me.

Does anybody have experience with this kind of thing?

Last edited by Friso; 06-02-2021 at 11:22 AM.

sfkazimierczak · 06-02-2021, 01:18 AM

I don't recall seeing such a lens here but as you already have both lenses, there is a very simple way of finding out. However if I were you I would try to repair the aperture ring in A version. It should be much easier than changing complete optics.

antipattern · 06-02-2021, 01:21 AM

Originally posted by sfkazimierczak

I don't recall seeing such a lens here but as you already have both lenses, there is a very simple way of finding out. However if I were you I would try to repair the aperture ring in A version. It should be much easier than changing complete optics.

The A50/1.7 has a common fault with the aperuture mechanism, as @sfkazierczak pointed out. I had one in the past with said problem and it was a very easy fix with some epoxy glue. So I agree that that would probably the easier solution if there's nothing else wrong with the A50.

**pepperberry farm** · 06-02-2021, 04:14 AM - **1 Like**

before I sold it off, I just kept the A 50/1.7 in the 'A' position on the aperture ring....

replacing it with the A 50/1.4 or A 50/1.2 was my way of fixing the problem...

bdery · 06-02-2021, 05:33 AM - **1 Like**

I doubt this is possible. It would only work if the two lenses used exactly and perfectly the same optical formula, down to sub-milimeter precision. That's highly unlikely. Unless the optical formula IS identical, you won't get a usable lens, and you might not be able to insert the glass elements in the first place.

Indeed, fixing the A is the easiest option. Otherwise, getting another used M will be cheap and easier.

**sergysergy** · 06-02-2021, 06:11 AM

Based on the review section the optics seem to be the same. If you end up trying let us know how it goes.

Not a Number · 06-02-2021, 06:28 AM

Repair of the aperture ring is minimal. Remove the rear mount (4 or 5 screws). Remove the aperture ring, taking care not to lose the ball bearing, spring and "A" release button. Reattach the leaf spring (drill hole, screw in or just glue with epoxy). Reassemble.

Pentax-A 50mm f1.7 Aperture ring repair - PentaxForums.com

There was just a post recently of someone wanting the exchange the fogged rear element of an 50mm A f1.7 with that from an M 50mm f1.7. You should contact the poster and trade your A with his M.

**gofour3** · 06-02-2021, 07:46 AM - **1 Like**

Originally posted by pepperberry farm

before I sold it off, I just kept the A 50/1.7 in the 'A' position on the aperture ring....

replacing it with the A 50/1.4 or A 50/1.2 was my way of fixing the problem...

Yep that's what I would do.....

Phil.

Friso · 06-02-2021, 11:11 AM

Thx all for your great advice. I will first try to repair the A50 as suggested, but I have to say that I really like the solid feel and handling of the M50, the focus ring of the A50 does feel a bit fiddly compared to the M50, maybe because wear and tear.
I will post the results of this little adventure when ready (can take a while, in my case it can take several years between having a plan and executing a plan

).

---------- Post added 06-02-21 at 12:04 PM ----------

Originally posted by sergysergy

Based on the review section the optics seem to be the same. If you end up trying let us know how it goes.

Schemes like these brought me to this idea.

Not a Number · 06-02-2021, 05:59 PM

Originally posted by Friso

the focus ring of the A50 does feel a bit fiddly compared to the M50, maybe because wear and tear.

Probably needs to be re-greased. Search for Helimax-XP helicoid grease on Amazon or eBay for a nice grease to use on camera lenses.

bdery · 06-03-2021, 05:21 AM

Originally posted by sergysergy

Based on the review section the optics seem to be the same.

These drawings should never be taken as proof that the lenses are the same. If I was a designer, there's no way I'd give away my design secrets to competitors by displaying my exact designs for all to see. Let them work for it

Friso · 06-03-2021, 05:52 AM

Originally posted by gofour3

Yep that's what I would do.....

Phil.

Taking a lens apart is part of the fun for me. And I'm investigating the performance of old glass out of curiosity at the moment. I'm working on a cityscape project (spanning multiple months already) using my beloved Nikon D7000, and I like to compare it with a still to buy modern Pentax camera equipped with an old 50 mm lens. The challenge I gave myself is to make a series of the same cityscape under different weather conditions using only a 50 mm lens and photo stitching. The goal is to produce at least one "wall worthy" picture. For me that means enough pixels and a resolution that I'm satisfied with. What I like about this site is the posts with examples but I guess I can't post my results so far because they were made with a Nikon.

---------- Post added 06-03-21 at 06:23 AM ----------

Originally posted by bdery

These drawings should never be taken as proof that the lenses are the same. If I was a designer, there's no way I'd give away my design secrets to competitors by displaying my exact designs for all to see. Let them work for it

Yes, I can understand that. I guess that's why I posted this question. I don't want to end up with another damaged lens by trial and error. When I disassembled the M50 I was surprised how easy it was, the construction was rock solid but still easy to take apart.

That is... until I reached the last element to remove. The metal ring that held the glass in place wouldn't turn, no matter what I tried, so I ended up using a small drill to open it. That's when the glass got damaged, as well as that metal ring of course. One of the lessons learned for me is that I will make sure to get my hands on the right tooling when I make another attempt to open a lens. I'm still tempted to open this one as well one day, because I spotted a small spec (I hope dust, not damage) at the inside of one of the glass elements at the back. Before I do that I will make some test pictures to see whether or not it does affect image quality. But in order to be able to make test pictures I need to buy a camera first (I guess my istDL is beyond repair). APS-C or FF, what to do... shuttershock, resolution, dynamic range, tilting display... so many dilemmas

This is off topic for this thread, but I guess that for the type of photos that I like to make (stitching) an APS-C suits me more then a FF because of the higher resolution.

Friso · 06-03-2021, 12:50 PM

Originally posted by Not a Number

Repair of the aperture ring is minimal. Remove the rear mount (4 or 5 screws). Remove the aperture ring, taking care not to lose the ball bearing, spring and "A" release button. Reattach the leaf spring (drill hole, screw in or just glue with epoxy). Reassemble.

Pentax-A 50mm f1.7 Aperture ring repair - PentaxForums.com

There was just a post recently of someone wanting the exchange the fogged rear element of an 50mm A f1.7 with that from an M 50mm f1.7. You should contact the poster and trade your A with his M.

Great info, but first I need to purchase a Pentax camera because I don't have one in a working condition at the moment. Then I will make some test pictures with the A 50 and the M 50 pinhole

Can't wait to see the results of the pinhole experiment because my old istDL decided to go black before I had a chance to experiment with it (maybe the fact that I managed to drop it on the floor with a magisterial hyperbolic trajectory had something to do with that : ) Depending on the results I will decide how to proceed, I'm not in a hurry. Maybe I will start saving for this new wonder lens of 85 MM as well : )
I have a hard time justifying big expenses on a new camera because I still like my Nikon and only take pictures when I have some sort of project in mind. But for some reason I've always liked the Pentax brand and I like to explore its pixel shift and other shift options.... oh and the weather sealing attracts me soo much. So the successor of the Nikon will be a Pentax (I have more Pentax lenses (4) then Nikon (1)).

Friso · 06-03-2021, 11:56 PM

Originally posted by Not a Number

Probably needs to be re-greased. Search for Helimax-XP helicoid grease on Amazon or eBay for a nice grease to use on camera lenses.

Thx for the suggestion, I wonder is this a stopgap solution or do old lenses really need to be re-greased? I guess you can make everything temporarily run smoother with a big blob of grease, but if it actually is part of the design specifications I certainly will try to apply some when I choose to go for the repair route.

**yucatanPentax** · 06-05-2021, 12:57 AM

Originally posted by Friso

Thx for the suggestion, I wonder is this a stopgap solution or do old lenses really need to be re-greased? I guess you can make everything temporarily run smoother with a big blob of grease, but if it actually is part of the design specifications I certainly will try to apply some when I choose to go for the repair route.

Older greases tend to dry out over time. The grease collects dirt. It tends to harden or get sticky.
The solution is to re-grease with a modern grease which holds up better. Then you'll be ready for another 40-50 years of usage.

06-01-2021, 11:40 PM	#1
Friso New Member Join Date: May 2021 Photos: Gallery Posts: 14	Merging the optics from an A50 mm F1.7 to a M50 mm F1.7? This is my first post, so don't hesitate to let me know if I do something wrong Out of curiosity I recently purchased an A50 mm F1.7. The lens reviews on this site proofed to be spot on, the aperture ring of this lens is a disaster, almost stuck at F8. The glass elements seems to be good enough although I haven't been able to test the lens yet by lack of a camera, my old istDL only produces black images nowadays unfortunately (now I have to choose between a K-3 III or a K-1 II). Long time ago I converted a M 50mm F1.7 into a pinhole lens, so I removed the glass elements and replaced them with a pinhole sheet. The glass took some damage in the process. I slightly regret that move now because the M 50 1.7 was a fine lens. So I wonder, would it be possible to insert the smc optics of the crappy A 50 into the M 50? It seems the optics of those lenses are almost the same. I don't care about the A functionality, the M works just fine for me. Does anybody have experience with this kind of thing? Last edited by Friso; 06-02-2021 at 11:22 AM.

06-02-2021, 06:11 AM	#6
sergysergy Site Supporter Join Date: Jan 2011 Photos: Gallery Posts: 5,175	Based on the review section the optics seem to be the same. If you end up trying let us know how it goes. Attached Images

06-02-2021, 11:11 AM	#9
Friso New Member Join Date: May 2021 Photos: Gallery Posts: 14 Original Poster	Thx all for your great advice. I will first try to repair the A50 as suggested, but I have to say that I really like the solid feel and handling of the M50, the focus ring of the A50 does feel a bit fiddly compared to the M50, maybe because wear and tear. I will post the results of this little adventure when ready (can take a while, in my case it can take several years between having a plan and executing a plan ). ---------- Post added 06-02-21 at 12:04 PM ---------- Originally posted by sergysergy Based on the review section the optics seem to be the same. If you end up trying let us know how it goes. Schemes like these brought me to this idea. Last edited by Friso; 06-02-2021 at 02:01 PM.

06-03-2021, 12:50 PM	#13
Friso New Member Join Date: May 2021 Photos: Gallery Posts: 14 Original Poster	Originally posted by Not a Number Repair of the aperture ring is minimal. Remove the rear mount (4 or 5 screws). Remove the aperture ring, taking care not to lose the ball bearing, spring and "A" release button. Reattach the leaf spring (drill hole, screw in or just glue with epoxy). Reassemble. Pentax-A 50mm f1.7 Aperture ring repair - PentaxForums.com There was just a post recently of someone wanting the exchange the fogged rear element of an 50mm A f1.7 with that from an M 50mm f1.7. You should contact the poster and trade your A with his M. Great info, but first I need to purchase a Pentax camera because I don't have one in a working condition at the moment. Then I will make some test pictures with the A 50 and the M 50 pinhole Can't wait to see the results of the pinhole experiment because my old istDL decided to go black before I had a chance to experiment with it (maybe the fact that I managed to drop it on the floor with a magisterial hyperbolic trajectory had something to do with that : ) Depending on the results I will decide how to proceed, I'm not in a hurry. Maybe I will start saving for this new wonder lens of 85 MM as well : ) I have a hard time justifying big expenses on a new camera because I still like my Nikon and only take pictures when I have some sort of project in mind. But for some reason I've always liked the Pentax brand and I like to explore its pixel shift and other shift options.... oh and the weather sealing attracts me soo much. So the successor of the Nikon will be a Pentax (I have more Pentax lenses (4) then Nikon (1)). Last edited by Friso; 06-03-2021 at 11:59 PM. Reason: Clarification and style adjustment.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Merging RGB layers in Paintshop Pro 2019	RobG	Digital Processing, Software, and Printing	7	09-05-2019 04:02 PM
Quick Lens Comparison (Voigtlander 58/1.4, A50/1.7, A50/2.8 Macro)	jeffshaddix	Pentax SLR Lens Discussion	25	06-09-2014 04:29 AM
SMC M50 f1.4 vs. SMC M50 f1.7	gamgee	Pentax SLR Lens Discussion	8	06-13-2008 04:41 PM

06-02-2021, 01:18 AM	#2
sfkazimierczak Forum Member Join Date: Nov 2014 Photos: Gallery Posts: 56	I don't recall seeing such a lens here but as you already have both lenses, there is a very simple way of finding out. However if I were you I would try to repair the aperture ring in A version. It should be much easier than changing complete optics.

06-02-2021, 01:21 AM	#3
antipattern Senior Member Join Date: Apr 2012 Location: Berlin, Germany Photos: Albums Posts: 232	Originally posted by sfkazimierczak I don't recall seeing such a lens here but as you already have both lenses, there is a very simple way of finding out. However if I were you I would try to repair the aperture ring in A version. It should be much easier than changing complete optics. The A50/1.7 has a common fault with the aperuture mechanism, as @sfkazierczak pointed out. I had one in the past with said problem and it was a very easy fix with some epoxy glue. So I agree that that would probably the easier solution if there's nothing else wrong with the A50.

06-02-2021, 04:14 AM - 1 Like	#4
pepperberry farm amateur dirt farmer Join Date: Dec 2014 Location: probably out in a field somewhere... Photos: Gallery \| Albums Posts: 41,766	before I sold it off, I just kept the A 50/1.7 in the 'A' position on the aperture ring.... replacing it with the A 50/1.4 or A 50/1.2 was my way of fixing the problem...

06-02-2021, 05:33 AM - 1 Like	#5
bdery Pentaxian Join Date: Mar 2008 Location: Quebec city, Canada Photos: Gallery Posts: 9,362	I doubt this is possible. It would only work if the two lenses used exactly and perfectly the same optical formula, down to sub-milimeter precision. That's highly unlikely. Unless the optical formula IS identical, you won't get a usable lens, and you might not be able to insert the glass elements in the first place. Indeed, fixing the A is the easiest option. Otherwise, getting another used M will be cheap and easier.

06-02-2021, 06:28 AM	#7
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Repair of the aperture ring is minimal. Remove the rear mount (4 or 5 screws). Remove the aperture ring, taking care not to lose the ball bearing, spring and "A" release button. Reattach the leaf spring (drill hole, screw in or just glue with epoxy). Reassemble. Pentax-A 50mm f1.7 Aperture ring repair - PentaxForums.com There was just a post recently of someone wanting the exchange the fogged rear element of an 50mm A f1.7 with that from an M 50mm f1.7. You should contact the poster and trade your A with his M.

06-02-2021, 07:46 AM - 1 Like	#8
gofour3 Site Supporter Join Date: Oct 2008 Location: Vancouver, Canada Posts: 8,092	Originally posted by pepperberry farm before I sold it off, I just kept the A 50/1.7 in the 'A' position on the aperture ring.... replacing it with the A 50/1.4 or A 50/1.2 was my way of fixing the problem... Yep that's what I would do..... Phil.

06-02-2021, 05:59 PM	#10
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Originally posted by Friso the focus ring of the A50 does feel a bit fiddly compared to the M50, maybe because wear and tear. Probably needs to be re-greased. Search for Helimax-XP helicoid grease on Amazon or eBay for a nice grease to use on camera lenses.

06-03-2021, 05:21 AM	#11
bdery Pentaxian Join Date: Mar 2008 Location: Quebec city, Canada Photos: Gallery Posts: 9,362	Originally posted by sergysergy Based on the review section the optics seem to be the same. These drawings should never be taken as proof that the lenses are the same. If I was a designer, there's no way I'd give away my design secrets to competitors by displaying my exact designs for all to see. Let them work for it

06-03-2021, 05:52 AM	#12
Friso New Member Join Date: May 2021 Photos: Gallery Posts: 14 Original Poster	Originally posted by gofour3 Yep that's what I would do..... Phil. Taking a lens apart is part of the fun for me. And I'm investigating the performance of old glass out of curiosity at the moment. I'm working on a cityscape project (spanning multiple months already) using my beloved Nikon D7000, and I like to compare it with a still to buy modern Pentax camera equipped with an old 50 mm lens. The challenge I gave myself is to make a series of the same cityscape under different weather conditions using only a 50 mm lens and photo stitching. The goal is to produce at least one "wall worthy" picture. For me that means enough pixels and a resolution that I'm satisfied with. What I like about this site is the posts with examples but I guess I can't post my results so far because they were made with a Nikon. ---------- Post added 06-03-21 at 06:23 AM ---------- Originally posted by bdery These drawings should never be taken as proof that the lenses are the same. If I was a designer, there's no way I'd give away my design secrets to competitors by displaying my exact designs for all to see. Let them work for it Yes, I can understand that. I guess that's why I posted this question. I don't want to end up with another damaged lens by trial and error. When I disassembled the M50 I was surprised how easy it was, the construction was rock solid but still easy to take apart. That is... until I reached the last element to remove. The metal ring that held the glass in place wouldn't turn, no matter what I tried, so I ended up using a small drill to open it. That's when the glass got damaged, as well as that metal ring of course. One of the lessons learned for me is that I will make sure to get my hands on the right tooling when I make another attempt to open a lens. I'm still tempted to open this one as well one day, because I spotted a small spec (I hope dust, not damage) at the inside of one of the glass elements at the back. Before I do that I will make some test pictures to see whether or not it does affect image quality. But in order to be able to make test pictures I need to buy a camera first (I guess my istDL is beyond repair). APS-C or FF, what to do... shuttershock, resolution, dynamic range, tilting display... so many dilemmas This is off topic for this thread, but I guess that for the type of photos that I like to make (stitching) an APS-C suits me more then a FF because of the higher resolution.

06-03-2021, 11:56 PM	#14
Friso New Member Join Date: May 2021 Photos: Gallery Posts: 14 Original Poster	Originally posted by Not a Number Probably needs to be re-greased. Search for Helimax-XP helicoid grease on Amazon or eBay for a nice grease to use on camera lenses. Thx for the suggestion, I wonder is this a stopgap solution or do old lenses really need to be re-greased? I guess you can make everything temporarily run smoother with a big blob of grease, but if it actually is part of the design specifications I certainly will try to apply some when I choose to go for the repair route.

06-05-2021, 12:57 AM	#15
yucatanPentax Loyal Site Supporter Join Date: Dec 2009 Location: Dallas / Yucatan Posts: 1,841	Originally posted by Friso Thx for the suggestion, I wonder is this a stopgap solution or do old lenses really need to be re-greased? I guess you can make everything temporarily run smoother with a big blob of grease, but if it actually is part of the design specifications I certainly will try to apply some when I choose to go for the repair route. Older greases tend to dry out over time. The grease collects dirt. It tends to harden or get sticky. The solution is to re-grease with a modern grease which holds up better. Then you'll be ready for another 40-50 years of usage.