asahi pentax K SMC 24mm 2.8, lot of white dots, cleanable ?

[thebbm]

hello

last week end i get this lens

https://www.pentaxforums.com/lensreviews/SMC-Pentax-K-24mm-F2.8-Lens.html

the lens look pristine so i didn't notice this "white dots" at store. from 5 cm it's crystal clear. but looking thru it from very close up, it's like the moon.
do you think this is cleanable ?





thanks

[kypfer]

This lens is 9 elements in eight groups, so not straightforward to clean, especially if the "problem" is deep into the assembly! Personally, I'd take a few shots with it, especially contra-jour, and see if there really is a problem, then take it from there.

YMMV - Good luck

[Lightshow]

Can you zoom out some, it's hard to tell what it is without some context.
If it's only a small spot, it won't effect the IQ much, it will be most noticeable in the PSF (bokeh balls).
My guess is that it should be cleanable, the big question is if the glass underneath is etched, only one way to find out.

[kiddo]

Most of the time, I've found such lenses cleanable, few times ,dust heve been covering coating damage by fungus or separation and also white spots that would no clean . So, rare lenses ,where normal issues are not frequent, are hard to say until you clean em up. You should contact the seller before starting cleaning the lens and get a discount , or depending of price ,best is to return.

[Teemō]

Probably separation of the cement.

[Sciolist]

[kiddo]

[Teemō]

[Gardener]

[Gardener]

My first guess would be fungus.

[papasito]

In more than 50 years I can't remember any lens with separation that looked like the posted lens.

Seems to be some degradation in the surface lens or in the coated.

Not looks as tipical fungus.

[thebbm]

thank you for all answers.
I never saw fungus like this.

i think the element to clean is just before the aperture (from the front) but i failed unscrewing the metal front ring with my rubber tools.

This is some other pictures :
#1


#2


#3


#4


#5


#6


#7


#8


#9


#10

[Lloydy]

I have seen something similar when I used a very dusty lens outside on a freezing cold day, brought it back in the warm house and condensation formed, the water turned the dust to mud. I didn't notice it for a week or so, but it did clean off.

I've also had fungused lenses that were so bad the element was scrap due to the etching. I think the fungus had been in the lens for a very long time.



this was after cleaning and the surface of the glass was pockmarked totally, it looked like bathroom window glass.

I suspect your lens is fungused, based on your pictures. If it hasn't etched the surface then it should clean to a usable condition. I use cold cream or isoprpyl alcohol.

[thebbm]

i opened the lens from front finaly.
and removed the middle element just after aperture. i hope it's reversible because it felt and i don't know which side it was ( it look the same on each side). i didn't opened it fully because i don't have any thing to clean it. I will get Alcool Isopropylique and try to clean it.
how to you clean it ? what do you use to "dry it" ? thank for all answers

@Lloydy oh the element is very damaged the lens is still usable ?

[kiddo]