Apparturesystem Repair: Lensrepair of the Pentacon 300mm f4

[@albancousinie9455]

Thanks a lot for sharing the process, doertepn ! With the help of your video, I could fix my Pentacon 300 blades which had the very same problem.
A point you you do not underline in your video : in mine, the clip that holds the blades alltogether was very relaxed, and eventually the blades could sleep under it : I think that is the source of the problem. I have pushed it against the blades by applying ponctual pressures all around in order to reduce the play, which had likely increased along time. I hope they will stay in place a few more years more now ! Another tip : even though I was using a dry air spray duster, several dusts have found their way into the lens during the operation. I can't imagine what it would have been without. A dry air spray duster is definately advised to have with you for these kind of operations.

[@doertepn]

Hey you are welcome! In my opinion its essential to keep those great lenses working as long as possible! The picturequality of them is amazing! It seems to me that this is a problem of pentacon in general. I had the same problem with a 200mm of them. Your point of pushing the pins in is really interesting and new to me. I thought it was the friction between the blades that forces them out of their position. Did you have good success with your technique?
Thanks for sharing!

[@peterbfeenstra]

Hi thanks for your video. I had the same problem, just worse. Some of the blades were out of their pinhole at both sides. I took them all out and expirimented on how to get them back in place. I succeeded by using the mount of the blades. I put the blades with the downside tip into the long openings along the mount, so "wide open". Then I cut a sticker in the shape of a circle to fit at the inner side of the blades, just along the outer pins. Thus they were fixed and I was able to put them all at once into their place, after putting back the mount. I still needed some time to get all the down pins into their place, but after that everything was fine.

[@doertepn]

+Peter Feenstra this sounds like a great idea! I am not that happy with this lens at the Moment, because i have to pay quite a lot of attention while turning the aperture. They seem to stick even though i cleaned them really well. Maybe i have to loubricate them as well... do you use loubrication? Like oil? If so what product do you use?i am thinking about wepon oil... but not shure yet...

[@peterbfeenstra]

Hello doertepn, I never saw lubricated aperture blades. I just clean them with cigarette lighter fluid until they are dry, then they are snappy. Did you clean yours from both sides? You might try that. Or remove the blades like I did (you have to remove a spring ring first), bathe them in lighter fluid, dry and reassemble them. I can't recommend it though. It is a nerve-racking job. In the factories they must have had special tools to do this. I succeeded with my O-shaped sticker but it was a pain.

[@doertepn]

+Peter Feenstra i never saw lubrication eighter but i am in a forum about old lenses and some people there use weapon oil to lubricate the blademechanics. But i have no experience in this. I just cleaned them from the upside, so my problem might be on the underside but i dont wont to go trough the hasel to go in from the backside. I am not shure how easy this is. It might be easy. I havent looked into it, because it works right now. I am not a fan of putting them completely out. Its not an easy job to get them back in. I can only salut you that you got it back into working condition. Thats not a easy fix.

[@tarzandelosgnomos]

It was not easy, but I managed to put the blades of my 200/4 in place. Thanks again.

[@doertepn]

Your welcome!! Good to hear

[@filippo911]

i had the same problem in Pentacon 200/4
thanks !

[@doertepn]

+filippo911 your welcome! Weapon oil might improve it as well!

[@Ed.Focuss]

Nice

[@mauromarras]

many thanks

[@tarzandelosgnomos]

Gracias, lo intentaré con mi 200/4.

[@simoncheng9631]

Hi, my pentagon 200 f4, the aperture is no working, it is in wide open and cannot be adjusted.it stuck in the wide open position, can you show me how to sort it out for problem.

[@franckbremeault-photograph2112]

Hi there. I had several times the same issue. Now, my blades are all out of their guides so I was forced to remove them (by removing the ring of guides) and I don't know how to place them back 😔

[@invisiblespark]

I have the same lens, took it apart, re-greased it , cleaned it of specs of dust, and re-assembled it. Should i keep it? I am not so satisfied with the results on my Canon 1200D

[@doertepn]

+Deep in the Sky in my opinion its a great lens. But you might have problems because of your cropfactor camera... it was made for a medium format camera... a 6x6 and you are using just a really small fraction of this. I used mine on my sony a7 and the performance was good. But this lens really shines when using it with film. I shoot it a lot with my mamyia 645. Great lens on that. By the way the crop makes it an equivalent focallenght of 400mm... that would be a focallenght i would not use. I do architecture and landscape and sometimes Portraits. So thats not a fit. On my mamyia its more like a 220mm. So portraits work good and you get a lovely background separation. So it really depends what you are shooting

[@asmirprasovic4298]

I'm not sure if you're still active, but I'm curious what do you use for cleaning glass element itself.

[@doertepn]

@@asmirprasovic4298 isopropanol or washing gazolin

Could you do video for Sonnar 180 I am having problem there 😉

[@yonoko6901]

hi doertepn, thanks a lot for your video. I have a problem with my pentacon 300mm f4 and I wish to ask your suggestion please.
the problem is the focus ring, it's not enough fluid in some points when I turn the ring. I wish to open it,clean and oil the focus ring but I have no idea how to disassamble it. can you give me some tips please? thx!

[@doertepn]

Yonoko6 yes i can give you some tips. you have to grease the focusing ring. no oil what so ever. the problem is getting the focusing ring off. i have not done this on this lens, but on another. you basicly have to disassemble the lens entirely to do that. on such a huge lens it Should be easier then on a small 50mm because everything is huge. but anyway its a pain to do. and you have to find the right grease for lenses, which doesnt get hard and doesnt get runny on certain Temperaturs. you will have to look into fotoforums which is the best product for you. i live in germany and the chances are high, that you wont get the product i am using.i would start googeling how to open your lensfocus as well. sometimes its easier from the top, sometimes from the bottom. anyway its one of the hardest repairs to do on a lens. it might be simpler to find a lensmechanic to send it to... but anyway good luck. if you have more questions, just ask. i might do a video if i come around a lens With this problem... but at the Moment they run fine...
Greetings from Germany

[@doertepn]

forum.mflenses.com/pentacon-300mm-f-4-disassembly-repair-t59496.html
you go through the bottom... should be simple

[@yonoko6901]

thanks a lot for your dedication and kindness! I'll try!! ^_^

[@RGeorge2011]

can you please complete the disassembling of the lens?

[@doertepn]

Ramez George you mean the bottom? Its the same procedure as from the top. I dont have to do so because my blades are working fine.

[@RGeorge2011]

it will help if someone wants to clean all the glass elements

[@nx7640]

you should have used a vacuum lens holder

[@doertepn]

Havent Heard about that before. Whats that?

[@ferencbodor]

how is the tool called? :D

[@doertepn]

+Ferenc Bodor which one do you mean? Did i use the wrong vocab?

[@ferencbodor]

doertepn found it! I meant the "Objektiv Schraubenschlüssel"! :D danke ;)

[@doertepn]

Ferenc Bodor ah ein deutscher Zuschauer also ;-)

[@albancousinie9455]

The tool is called "spanner wrench"

[@zorankazinjo6831]

omg you are talking so slow. come on man, get to the point...
Other than that, everything ok. Thanks!

[@doertepn]

Zoran Kazinjo thanks for your comment i try to get faster ;-)
cheers

[@ministryoflies1344]

@@doertepn Yeah...could have sped up the cleaning bit and cut the vid down to 5 minutes! But thanks for posting and good job!!