Pentax M 50mm 1.4 With Dust

KPT

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I picked up a 1.4 for my camera today and noticed there is some dust in the lens. Can i clean it myself or do i have to bring it into the shop? I have never tried to disassemble a lens but when i looked at the rear glass it looked like it can be unthreaded so i can clean it myself, could this be possible?


Thanks!
 

Excalibur2

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I don't know what theory says, but I have never been worried by a bit of dust in my lenses, even with a bit of fungus in one of my lens.........I get excellent results.
 
OP
OP

KPT

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I guess i will shoot with it first before i try to clean it.


Thanks!
 

milkplus-mesto

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When you focus as close as possible - when the front of the lens is extended as far as possible, there should be a sizeable gap at the back. If you've got a can of compressed air, you could stick the nozzle of that down there and blow it out.

Just a suggestion.
 

nickandre

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DO NOT TRY THAT! I destroyed a lens thinking I could "just clean it"... btw most primes are sealed so you'd be doing no good. Plus it won't make much of a difference.
 

Steve Roberts

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A few specks of dust probably won't matter most of the time. If they are going to be a problem, it will be when you're shooting into the light.
The can of air probably won't do any harm on the Pentax lens but probably won't do any good either, as the lens assembly is to all intents and purposes sealed, as was mentioned. The dust you see may have been there since the lens was made (holding even new lenses up to a light source can be a levelling experience!). It could be that the dust is a left-over from a previous cleaning or it could be a product of wear on the aperture blades. Most of the time simply knowing that dust/mould is there is far, far worse than the physical effects of it.
If you don't have to dismantle the lens, then I'd suggest that you don't, but if it's really a problem then there's nothing particularly difficult in the mechanical process, only in making sure that you do indeed clean it and don't make it dustier, smeary, etc.. Living in a damp part of England, mould is my enemy and I've made tools specifically to fit the element retaining rings of certain lenses. With prices on eBay being so low it may be cheaper to buy another lens than to pay for one to be cleaned professionally. If you decide to dismantle the lens, there's plenty of guidance on the web and the screw mount Pentax lenses aren't so very different to the K-mounts.

Steve
 

Polybun

tiberiustibz said:
DO NOT TRY THAT! I destroyed a lens thinking I could "just clean it"... btw most primes are sealed so you'd be doing no good. Plus it won't make much of a difference.
Click to expand...

Not only that, you stand a good chance of blowing a big 'ol glob of grease in there too.

Shoot it, if it shows, have it repaired by a shop. Taking a lens apart requires either buying some specialized tools, or making them yourself. You also need a fairly dust free enviroment during re-assembly or you will end up with more dust in the lens than what you started with.

I will say, it isn't hard, but it does require the great attention to detail and infinite patience. If you want to learn, thats fine, just don't learn on a lens you like very much! I can promise you, the first one will go badly!
 

Steve Roberts

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Polybun said:
I will say, it isn't hard, but it does require the great attention to detail and infinite patience. If you want to learn, thats fine, just don't learn on a lens you like very much! I can promise you, the first one will go badly!
Click to expand...

>>don't learn on a lens you like very much!
... offer to repair a pal's lens first.....


>>the first one will go badly
It needn't IMHO, but will likely take much longer than you expect. It's a skill worth acquiring and once you've made any special tools, they are there for next time. Here's a link to the Classic Camera Repair Forum:
http://www.kyphoto.com/cgi-bin/forum/discus.cgi
If you do a search there's plenty of stuff on Pentax lenses and as on APUG, people are always keen to help.

Steve
 
OP
OP

KPT

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Thank you to everyone for all the helpful advice! I will take the lens out today and shoot a roll and hopefully develop it tonight. If the dust causes any issues then i will take it apart and do a cleaning. It will be an experience!
 

John Koehrer

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KPT
Depending on where the dust is, lenses are relatively easy to clean.
On the Pentax, remove the decorator ring, that's the one with the engraving on the front. It unscrews by using the edge of a rubber stopper against it & unscrewing it. With the ring removed there are a couple of sets of spanner slots visible, the outer pair removes the entire front group inner pair allows separation of the elements. Use an inexpensive pair of needle nose pliers with the tips ground to fit.
A couple of tips for you. 1)DON'T sneeze into the lens! damhik. 2)DON'T use common q-tips, they shed.
Use an ear syringe or large squeeze bulb to blow the dust away not your breath, for stubborn particles use the edge of a feather that has been cleaned in alcohol & NOT touched afterwards. It'll pick up oil from your finger & deposit it on the lens & it's a PITA to remove.
 

Polybun


I have had this lens apart. No, no its not easy, it requires some home made tools, an air compressor, in your bathroom, and a bathroom with a shower so you can run the shower and use the humidity to drag the dust from the air! It is 6 elements in 5 groups. It can be done, but I sure wouldn't make it your first repair ever.

That said, IF the dust is between the elements near the apeture, it may possibly be kind of sort of easy, as the front groups can be removed as an entire unit. That is also the only real place for dust to get in.
 

John Koehrer

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Ben,
You never would have made any $$$ doing camera repair working in the bathroom.
 

Polybun

John Koehrer said:
Ben,
You never would have made any $$$ doing camera repair working in the bathroom.
Click to expand...

Hey, it works, don't knock it! And why not, i do all my processing there too! It may not make me any money, but it saves me hundreds.
 

Excalibur2

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Polybun said:
Its not like you leave the thing there!

Heh, it can't be much worse in there than it is outside most days here in portland!
Click to expand...

I'm sure I read somewhere that it takes just 5 days for fungus to start.
 

Polybun

Excalibur2 said:
I'm sure I read somewhere that it takes just 5 days for fungus to start.
Click to expand...

Heh, man, If i'm in the bathroom for longer than 5 days, fungus is the least of my worries!

In all seriousness, maybe your right, I don't know. It may well work for me because I store my lenses in a filling cabinet with a good deal of silica gell packets around them. The running shower trick really does work though, it really will greatly reduce the dust in the air. I'm not saying turn the place into a sauna.
 

Excalibur2

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Just teasing you.....

Might be a good idea i.e quick clean of the lens in a bathroom....... as it might help to reduce static electricity as well.
 

darinwc

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I'd say just shoot with it and forget the dust.
Ive repaired mechanical problems with lenses before and then found it -impossible- to keep the inside clean before reassembly.
Then you have to also consider that you will most definately not assemble the lens back to its factory tuned state.

Unless the dust borders on haze, don't worry about it!
 

Excalibur2

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darinwc said:
Then you have to also consider that you will most definately not assemble the lens back to its factory tuned state.
Click to expand...

Surely in mass production they just put the elements in, and to stop them falling out, hold them in place by screwing down "retainer" rings?
I can't imagine every lens being tested, by hand, by rotating grouped elements a few degrees, before screwing them in place?

Whose knows maybe a machine does it.
 
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