Makinon 28mm F2.8 Auto Optical formula

Bouchama · 11-30-2019, 04:32 PM

Dear friends

I need your help to repaire a K lens Makinon 28mm F2.8 Auto, I found it completely blurred, and I think that the lenses are wrongly assembled.
can you provide me optical formula in order to reassemble it correctely.
Many thanks in advance

Last edited by Bouchama; 11-30-2019 at 04:43 PM.

**mroeder75** · 11-30-2019, 09:50 PM

Originally posted by Bouchama

Dear friends

I need your help to repaire a K lens Makinon 28mm F2.8 Auto, I found it completely blurred, and I think that the lenses are wrongly assembled.
can you provide me optical formula in order to reassemble it correctely.
Many thanks in advance

I have one of these lenses I obtained in 1983. It has always functioned fine. I cannot tell you how to repair it.

These lenses are so inexpensive. They were commonly marketed in the U.S. at K-Mart under the brand name Focal. An eBay search under Focal 28mm Pentax will produce a lot of results with low pricing.

**TwoUptons** · 12-01-2019, 08:36 AM

Originally posted by Bouchama

Dear friends

I need your help to repaire a K lens Makinon 28mm F2.8 Auto, I found it completely blurred, and I think that the lenses are wrongly assembled.
can you provide me optical formula in order to reassemble it correctely.
Many thanks in advance

For a number of the simpler lenses I’ve taken apart, where each element went was fairly clear. Which side of the element pointed where, however, was often a tricky question, and not always one easy to answer, even with a lens diagram.

If you can easily take it apart, there may be some obvious candidates for flipping over...

-Eric

tvdtvdtvd · 12-01-2019, 10:21 AM

Originally posted by TwoUptons

For a number of the simpler lenses I’ve taken apart, where each element went was fairly clear. Which side of the element pointed where, however, was often a tricky question, and not always one easy to answer, even with a lens diagram.

If you can easily take it apart, there may be some obvious candidates for flipping over...

^This is more or less what I was going to say.

It is highly unlikely any of the lenses are out of order, but the possibility of a lens being reversed in its position in not unrealistic.
Heck, I've done it myself when reassembling a lens.

Bonus points: You can create your own 'effects' lenses by reversing elements, removing elements and/or swapping elements.

**TwoUptons** · 12-01-2019, 12:38 PM

Originally posted by tvdtvdtvd

Bonus points: You can create your own 'effects' lenses by reversing elements, removing elements and/or swapping elements.

That’s, uh, exactly what I was doing... sure...

-Eric

Bouchama · 12-02-2019, 01:38 AM

Hi Friends
Many Thanks for your feed-back, I understood that i have to swap elements one by one and test, but what is helpfull is to have something like the below attachement

https://pentaxklub.com/test-expresstakumar-a-28mm-f-2-8/

Thank you in advance

**.a.t.** · 12-02-2019, 10:40 AM

Originally posted by Bouchama

Hi Friends
Many Thanks for your feed-back . . .

Does your lens look like this one in the P.F. lens review database, Bouchama?
Makinon 28mm F2.8 Auto Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database

I have a M42 mount version of that lens shown in the database, but I don't have an optical diagram for it. If you have a specific question about orientation of an element, I might be able to help.

Occasionally, some manufacturers used to print optical diagrams on the outside of the lens box. If you're (really!) lucky, there may be an ebay sale for your lens which includes a box and good photos.

Bouchama · 12-02-2019, 05:05 PM

Originally posted by .a.t.

Does your lens look like this one in the P.F. lens review database, Bouchama?
Makinon 28mm F2.8 Auto Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database

I have a M42 mount version of that lens shown in the database, but I don't have an optical diagram for it. If you have a specific question about orientation of an element, I might be able to help.

Occasionally, some manufacturers used to print optical diagrams on the outside of the lens box. If you're (really!) lucky, there may be an ebay sale for your lens which includes a box and good photos.

Thanks .a.t.

yes this is the lens that i have, i have K mount version. can you draw me or send me photo of un orientation of the optical elements, i think that some of thems are swap specianly the cental ones

Thank yu in advance

**.a.t.** · 12-02-2019, 09:59 PM

Originally posted by Bouchama

Thanks .a.t.
. . .

My apologies, Bouchama! I'm sorry to disappoint you, but I can't help you after all.

I tried my best to get the elements free, but they were solidly cemented into assemblies which I couldn't get apart.
And I don't want to risk trying any harder.

Good luck and I hope you'll have success in finding your answer.

Bouchama · 12-03-2019, 01:19 AM

Originally posted by .a.t.

My apologies, Bouchama! I'm sorry to disappoint you, but I can't help you after all.

I tried my best to get the elements free, but they were solidly cemented into assemblies which I couldn't get apart.
And I don't want to risk trying any harder.

Good luck and I hope you'll have success in finding your answer.

.a.t. I understand, many Thanks for your effort
I think found the correct position of optical elements yesterday. let test today the infinity focus. however i discovred another problem, the aperature is not working fine, it open and close from min to max only even i select any aperature. my question is how disasamble the aperature system ?

Thank you.

**.a.t.** · 12-03-2019, 09:49 PM

Originally posted by Bouchama

. . .my question is how disasamble the aperature system ?

Thank you.

Do you have the elements removed from the barrel, Bouchama? If so, does moving the internal aperture lever show you what might be wrong? Do the aperture blades look wet? If they have oil on them, that can slow the blades or make them erratic. Oily blades can often be cleaned without disassembly.

I really hope you won't need to disassemble the aperture. It appears to me it would be difficult to get all the pieces and springs back in properly. Your PK lens will have some differences from my M42, but I've included two pictures of my lens in case they might be helpful. (Click the photos to see a larger size.)

Bouchama · 12-04-2019, 02:07 AM

Originally posted by .a.t.

Do you have the elements removed from the barrel, Bouchama? If so, does moving the internal aperture lever show you what might be wrong? Do the aperture blades look wet? If they have oil on them, that can slow the blades or make them erratic. Oily blades can often be cleaned without disassembly.

I really hope you won't need to disassemble the aperture. It appears to me it would be difficult to get all the pieces and springs back in properly. Your PK lens will have some differences from my M42, but I've included two pictures of my lens in case they might be helpful. (Click the photos to see a larger size.)

Many Thanks .à
Will Try and let you know

11-30-2019, 04:32 PM	#1
Bouchama New Member Join Date: Sep 2019 Posts: 5	Makinon 28mm F2.8 Auto Optical formula Dear friends I need your help to repaire a K lens Makinon 28mm F2.8 Auto, I found it completely blurred, and I think that the lenses are wrongly assembled. can you provide me optical formula in order to reassemble it correctely. Many thanks in advance Last edited by Bouchama; 11-30-2019 at 04:43 PM.

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11-30-2019, 09:50 PM	#2
mroeder75 Site Supporter Join Date: Sep 2014 Location: Iowa Photos: Gallery Posts: 1,597	Originally posted by Bouchama Dear friends I need your help to repaire a K lens Makinon 28mm F2.8 Auto, I found it completely blurred, and I think that the lenses are wrongly assembled. can you provide me optical formula in order to reassemble it correctely. Many thanks in advance I have one of these lenses I obtained in 1983. It has always functioned fine. I cannot tell you how to repair it. These lenses are so inexpensive. They were commonly marketed in the U.S. at K-Mart under the brand name Focal. An eBay search under Focal 28mm Pentax will produce a lot of results with low pricing.

12-01-2019, 08:36 AM	#3
TwoUptons Loyal Site Supporter Join Date: Nov 2015 Photos: Albums Posts: 4,213	Originally posted by Bouchama Dear friends I need your help to repaire a K lens Makinon 28mm F2.8 Auto, I found it completely blurred, and I think that the lenses are wrongly assembled. can you provide me optical formula in order to reassemble it correctely. Many thanks in advance For a number of the simpler lenses I’ve taken apart, where each element went was fairly clear. Which side of the element pointed where, however, was often a tricky question, and not always one easy to answer, even with a lens diagram. If you can easily take it apart, there may be some obvious candidates for flipping over... -Eric

12-01-2019, 10:21 AM	#4
tvdtvdtvd Veteran Member Join Date: Jan 2010 Posts: 1,665	Originally posted by TwoUptons For a number of the simpler lenses I’ve taken apart, where each element went was fairly clear. Which side of the element pointed where, however, was often a tricky question, and not always one easy to answer, even with a lens diagram. If you can easily take it apart, there may be some obvious candidates for flipping over... ^This is more or less what I was going to say. It is highly unlikely any of the lenses are out of order, but the possibility of a lens being reversed in its position in not unrealistic. Heck, I've done it myself when reassembling a lens. Bonus points: You can create your own 'effects' lenses by reversing elements, removing elements and/or swapping elements.

12-01-2019, 12:38 PM	#5
TwoUptons Loyal Site Supporter Join Date: Nov 2015 Photos: Albums Posts: 4,213	Originally posted by tvdtvdtvd Bonus points: You can create your own 'effects' lenses by reversing elements, removing elements and/or swapping elements. That’s, uh, exactly what I was doing... sure... -Eric

12-02-2019, 01:38 AM	#6
Bouchama New Member Join Date: Sep 2019 Posts: 5 Original Poster	Hi Friends Many Thanks for your feed-back, I understood that i have to swap elements one by one and test, but what is helpfull is to have something like the below attachement https://pentaxklub.com/test-expresstakumar-a-28mm-f-2-8/ Thank you in advance

12-02-2019, 10:40 AM	#7
.a.t. Site Supporter Join Date: Mar 2011 Location: yesterday Photos: Gallery Posts: 1,261	Originally posted by Bouchama Hi Friends Many Thanks for your feed-back . . . Does your lens look like this one in the P.F. lens review database, Bouchama? Makinon 28mm F2.8 Auto Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database I have a M42 mount version of that lens shown in the database, but I don't have an optical diagram for it. If you have a specific question about orientation of an element, I might be able to help. Occasionally, some manufacturers used to print optical diagrams on the outside of the lens box. If you're (really!) lucky, there may be an ebay sale for your lens which includes a box and good photos.

12-02-2019, 05:05 PM	#8
Bouchama New Member Join Date: Sep 2019 Posts: 5 Original Poster	Originally posted by .a.t. Does your lens look like this one in the P.F. lens review database, Bouchama? Makinon 28mm F2.8 Auto Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database I have a M42 mount version of that lens shown in the database, but I don't have an optical diagram for it. If you have a specific question about orientation of an element, I might be able to help. Occasionally, some manufacturers used to print optical diagrams on the outside of the lens box. If you're (really!) lucky, there may be an ebay sale for your lens which includes a box and good photos. Thanks .a.t. yes this is the lens that i have, i have K mount version. can you draw me or send me photo of un orientation of the optical elements, i think that some of thems are swap specianly the cental ones Thank yu in advance

12-02-2019, 09:59 PM	#9
.a.t. Site Supporter Join Date: Mar 2011 Location: yesterday Photos: Gallery Posts: 1,261	Originally posted by Bouchama Thanks .a.t. . . . My apologies, Bouchama! I'm sorry to disappoint you, but I can't help you after all. I tried my best to get the elements free, but they were solidly cemented into assemblies which I couldn't get apart. And I don't want to risk trying any harder. Good luck and I hope you'll have success in finding your answer.

12-03-2019, 01:19 AM	#10
Bouchama New Member Join Date: Sep 2019 Posts: 5 Original Poster	Originally posted by .a.t. My apologies, Bouchama! I'm sorry to disappoint you, but I can't help you after all. I tried my best to get the elements free, but they were solidly cemented into assemblies which I couldn't get apart. And I don't want to risk trying any harder. Good luck and I hope you'll have success in finding your answer. .a.t. I understand, many Thanks for your effort I think found the correct position of optical elements yesterday. let test today the infinity focus. however i discovred another problem, the aperature is not working fine, it open and close from min to max only even i select any aperature. my question is how disasamble the aperature system ? Thank you.

12-03-2019, 09:49 PM	#11
.a.t. Site Supporter Join Date: Mar 2011 Location: yesterday Photos: Gallery Posts: 1,261	Originally posted by Bouchama . . .my question is how disasamble the aperature system ? Thank you. Do you have the elements removed from the barrel, Bouchama? If so, does moving the internal aperture lever show you what might be wrong? Do the aperture blades look wet? If they have oil on them, that can slow the blades or make them erratic. Oily blades can often be cleaned without disassembly. I really hope you won't need to disassemble the aperture. It appears to me it would be difficult to get all the pieces and springs back in properly. Your PK lens will have some differences from my M42, but I've included two pictures of my lens in case they might be helpful. (Click the photos to see a larger size.)

12-04-2019, 02:07 AM	#12
Bouchama New Member Join Date: Sep 2019 Posts: 5 Original Poster	Originally posted by .a.t. Do you have the elements removed from the barrel, Bouchama? If so, does moving the internal aperture lever show you what might be wrong? Do the aperture blades look wet? If they have oil on them, that can slow the blades or make them erratic. Oily blades can often be cleaned without disassembly. I really hope you won't need to disassemble the aperture. It appears to me it would be difficult to get all the pieces and springs back in properly. Your PK lens will have some differences from my M42, but I've included two pictures of my lens in case they might be helpful. (Click the photos to see a larger size.) Many Thanks .à Will Try and let you know