[jonathantang86]

About two days ago,I bought a F 35-70 f 3.5-4.5 lens from a shopping site in Taiwan.
https://www.pentaxforums.com/forums/attachments/8-film-slrs-compact-film-cameras/369357d1504904794-some-trouble-about-unknown-matter-my-lens-imgp2446_dxo.jpg
It is a relly nice lens,very steady andaccruate. The depth of field is also suitable for snap shot.However,there is something annoy me.
I found that there are so many dots which look like water droplets in the front of interior lens.I have no idea what is it and i can't also find any useful information on the web.Can anyone tell what is that ?Could I have any chance to elimate this trouble without disassemble my lens?
https://www.pentaxforums.com/forums/attachments/8-film-slrs-compact-film-cameras/369358d1504904794-some-trouble-about-unknown-matter-my-lens-imgp2421_dxo.jpg
https://www.pentaxforums.com/forums/attachments/8-film-slrs-compact-film-cameras/369359d1504904794-some-trouble-about-unknown-matter-my-lens-imgp2412_dxo.jpg
https://www.pentaxforums.com/forums/attachments/8-film-slrs-compact-film-cameras/369360d1504904794-some-trouble-about-unknown-matter-my-lens-imgp2460_dxo.jpg
Here is a photo that by this lens.You can see the street light cause a mystery flare on this photo.https://www.pentaxforums.com/forums/attachments/8-film-slrs-compact-film-cameras/369361d1504904794-some-trouble-about-unknown-matter-my-lens-imgp2374_dxo.jpg

Attached Images

View Picture EXIF

File Date

 

View Picture EXIF

File Date

 

View Picture EXIF

File Date

 

View Picture EXIF

File Date

 

View Picture EXIF

File Date

 

[pschlute]

Doesnt look like fungus. Most lenses will get blemishes on the glass over their lifetime and mostly can be ignored as they dont affect image quality. But in this case I suspect that humidity has cased water to dry on the inside surface of the lens. Any shot taken into a light will have flare but your picture demonstrates these blemishes have dried residue which will affect image quality.

I would return the lens

[jonathantang86]

Doesnt look like fungus. Most lenses will get blemishes on the glass over their lifetime and mostly can be ignored as they dont affect image quality. But in this case I suspect that humidity has cased water to dry on the inside surface of the lens. Any shot taken into a light will have flare but your picture demonstrates these blemishes have dried residue which will affect image quality.

I would return the lens

Thanks for your reply.
I think the cost for transporting the lens back is not cost-effect. (I bought the lens for about 23GBP)
So,if it really is water,it looks still wet now.Is there any way the dry it out?
I already put the lens in a sealing bag and full of desiccant.Is that going to work?

[MarkJerling]

I already put the lens in a sealing bag and full of desiccant.Is that going to work?

I imagine that's your best bet short of disassembly. Can't hurt to give the drying out solution a try first.

[jonathantang86]

I learn a lesson.You can't get a good lens in a cheap price XD.
By the way,the lens selling in Taiwan is comparatively more expensive than others.

[pschlute]

I imagine the lens is dry already and it is residue that is on the lens. Buy yourself a spanning wrench and take the front element out. You should be able to clean it

[Ranchu]

The plain black surface surrounding the front element is a trim ring, use the tinyest screwdriver or a pin to pry it up, starting in the spanner notches. Underneath it you'll find the spanner notches for the entire front group, which you can unscrew with a lens spanner or similar.

[pentaxus]

My guess is that it is condensed lubricant from the focusing system. Water would probably already have dried out. The instructions from PSChlute and Ranchu will work for cleaning anyway.

[jonathantang86]

Thanks you guys!
I found a post and it seems have the same problem.(what's in the lens? How can I clean/fix it? F 35-70 - PentaxForums.com)
The matter is in the same lens alsothe same position.I think I should buy some tools for disassembleing the lens.

[Ranchu]

Here it is with the ring off, mine looks different because an inner lens is removed for cleaning.