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HELP ME PLEASE!
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PostPosted: Mon Aug 08, 2016 2:07 am    Post subject: HELP ME PLEASE! Reply with quote

Hello to everybody. I have a Minolta 58mm 1.2, but a little time ago, in a fungus cleaning, the last convex optic element -the closest to the camera- fell off. I love this lens, and I really need to repair it. If anyone knows how I can supply it, where can I buy it - Im from Colombia, South America, but I can pay the oversea shipping if its necessary- or the focal distance of this last optic element, I would be very grateful. Thanks to everyone.



PostPosted: Mon Aug 08, 2016 3:25 am    Post subject: Re: HELP ME PLEASE! Reply with quote

ceare258 wrote:
Hello to everybody. I have a Minolta 58mm 1.2, but a little time ago, in a fungus cleaning, the last convex optic element -the closest to the camera- fell off. I love this lens, and I really need to repair it. If anyone knows how I can supply it, where can I buy it - Im from Colombia, South America, but I can pay the oversea shipping if its necessary- or the focal distance of this last optic element, I would be very grateful. Thanks to everyone.



Hi ceare258. Welcome! Friday past I heard some fantastic musicians from your wonderful country at the Reggae On The River festival in Northern California.

A question for you have you put the broken element in the lens to see the effect in photos? You may have pleasant surprise the effect may be much less than suspect looking only at damage.

There are lens manufacturers, however you will need the measurements for both sides. Then to find that prescription among their stock, if they have it. If they do not have it, the possibility of getting them to make a one-off is probably low, unfortunately.

Sometimes simply using a clear glue to replace the broken-off piece repair may not see in photos.


PostPosted: Mon Aug 08, 2016 4:50 pm    Post subject: Re: HELP ME PLEASE! Reply with quote

ceare258 wrote:
Hello to everybody. I have a Minolta 58mm 1.2, but a little time ago, in a fungus cleaning, the last convex optic element -the closest to the camera- fell off. I love this lens, and I really need to repair it. If anyone knows how I can supply it, where can I buy it - Im from Colombia, South America, but I can pay the oversea shipping if its necessary- or the focal distance of this last optic element, I would be very grateful. Thanks to everyone.



I suppose the rearmost optical element broke but you kept the pieces. If so, most likely a competent optician could measure the optical power of a piece and perhaps could fabricate a lens to replace the broken element. However, I don't know if it's worth the effort. The simplest is to buy a lens of the same type on eBay and save the broken lens for parts.


PostPosted: Mon Aug 08, 2016 5:19 pm    Post subject: Re: HELP ME PLEASE! Reply with quote

Gerald wrote:

However, I don't know if it's worth the effort. The simplest is to buy a lens of the same type on eBay and save the broken lens for parts.


Probably cheaper too, since these seem to sell for at least USD300 in average condition.


PostPosted: Mon Aug 08, 2016 7:20 pm    Post subject: Reply with quote

Thanks to everyone. But nope. First, I dont keep the broken lens. It was a very desafortunate accident, and for some reason I dont keep it. Buy another Rokkor 58mm isnt an option for me. Probably you dont know, but with actual prices; 300 dollars is a lot of money right here in Colombia. Plus, Im 15 yo. My last optIon is, if anyone knows the focal distance of this last element, I think I can probably buy a similar magnification lens at surplus shed, a page that someone recommended.


PostPosted: Mon Aug 08, 2016 8:46 pm    Post subject: Reply with quote

if you had the pieces, or the dimensions, then maybe someone could find a lens close enough that might work. I have a boxfull of lens elements that have come from broken lenses, some I even know what lens they came from. But I know I don't have the 58 / 1.2 glass.


PostPosted: Mon Aug 08, 2016 10:05 pm    Post subject: Reply with quote

The rearmost element of a Pentacon 50mm, which is also a Double-Gauss lens like the Minolta 58mm, has a focal length of approximately 40mm, which corresponds to an optical power of +25 diopters. My educated guess is that the combined power of the TWO rear elements of the Minolta 58mm F1.2 is around +20 diopters. Therefore, the optical powers of the Minolta's rear elements are about +10 diopters each. If this is true, a +10 diopter close-up lens could be tried as a substitute for the missing element of the Minolta 58mm F1.2.

There are a lot of cheap close-up lens offers on eBay:
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.Xclose+up+lens+%2B10.TRS0&_nkw=close+up+lens+%2B10&_sacat=0

You can combine two or more close-up lenses to obtain optical powers other than +10 diopters. To know the optical power of the set, simply add the respective optical powers.

Another possibility is to try spectacle lenses for hyperopia (far-sightedness) with optical power around +10 diopters.

An optical technician should be able to cut the lens(es) to the appropriate diameter(s).


PostPosted: Mon Aug 08, 2016 10:10 pm    Post subject: Reply with quote

Maybe you can find a damaged 58/1.2 somewhere and swap the rear element...

I have a broken (front element heavily damaged) 85/1.7 lying around here but I can't help you with the 58.


PostPosted: Tue Aug 09, 2016 2:28 am    Post subject: Reply with quote

Gerald wrote:
The rearmost element of a Pentacon 50mm, which is also a Double-Gauss lens like the Minolta 58mm, has a focal length of approximately 40mm, which corresponds to an optical power of +25 diopters. My educated guess is that the combined power of the TWO rear elements of the Minolta 58mm F1.2 is around +20 diopters. Therefore, the optical powers of the Minolta's rear elements are about +10 diopters each. If this is true, a +10 diopter close-up lens could be tried as a substitute for the missing element of the Minolta 58mm F1.2.

There are a lot of cheap close-up lens offers on eBay:
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.Xclose+up+lens+%2B10.TRS0&_nkw=close+up+lens+%2B10&_sacat=0

You can combine two or more close-up lenses to obtain optical powers other than +10 diopters. To know the optical power of the set, simply add the respective optical powers.

Another possibility is to try spectacle lenses for hyperopia (far-sightedness) with optical power around +10 diopters.

An optical technician should be able to cut the lens(es) to the appropriate diameter(s).



Well, thats pretty much better. I have heard that, if you have the correct focal distance of the lens and the diameter, you can buy it at surplus shed. This is the only option I have. You also can help me a Lot if you know another optic shops where I can buy it. And also, I think that I can kill two birds in one shot. Well, Im planning to use this lens in my Nikon D3300. The flange focal distance of Minolta SR mount is 43.50 mm. Nikon F is 46.50 mm. If you can help me to find the exact focal distance of the rearmost element, I think that it problably work in my Nikon if I add 2 of this lens. Thanks for all your help.


PostPosted: Tue Aug 09, 2016 5:20 am    Post subject: Reply with quote

except there are two sides to the element, with different measurements...each side needs to be correct curvature to accept the rays ahead...

Lowest cost fabrication is begin buy eye glasses with the lens element prescription, online, like $20 -- these have coated acrylic lenses which are easy to hand-machine into the round shape identical to the old element -- and you get two in case you think you can do better next time. (like me) Laughing


PostPosted: Tue Aug 09, 2016 4:02 pm    Post subject: Reply with quote

Dear OP, you might be in luck!

https://www.flickr.com/groups/805805@N25/discuss/72157655707226659/

Post is 1 year old but no replies, although the author is still an active member, so it's worth a shot contacting them. Wink


PostPosted: Thu Aug 11, 2016 8:55 pm    Post subject: Reply with quote

Teemō wrote:
Dear OP, you might be in luck!

https://www.flickr.com/groups/805805@N25/discuss/72157655707226659/

Post is 1 year old but no replies, although the author is still an active member, so it's worth a shot contacting them. Wink



Dear Teemō, I really dont have enough words to thank you. For you, I will use my precious lens again. I wish I had friends like you.


PostPosted: Fri Aug 12, 2016 10:40 am    Post subject: Reply with quote

ceare258 wrote:
Teemō wrote:
Dear OP, you might be in luck!

https://www.flickr.com/groups/805805@N25/discuss/72157655707226659/

Post is 1 year old but no replies, although the author is still an active member, so it's worth a shot contacting them. Wink



Dear Teemō, I really dont have enough words to thank you. For you, I will use my precious lens again. I wish I had friends like you.


That's great to read. Smile