front and rear lens bubble

I have a 70mm ltd DA f2.4 Pentax lens which I have been using for 6 months now so it is still under guarantee. I recently meticulously cleaned the front and rear glass only to find a bubble in each lens. I am not an experienced photographer so it is difficult to tell if this has had an effect on my images in any way. If there is an effect it certainly is not obvious to me in the images I have taken. Mainly Street scenes, cropped landscapes or portrait and I am happy with the results.

I first noticed the bubble in the front glass and after a bit of research I found out that a bubble wouldn't have any effect on my images so all things considered the inconvenience of going to Pentax, the replacement might be worse etc, I decided to stick with it. Now I have discovered a bubble in the rear glass also. I am a bit annoyed. This is advertised as a high quality lens made to high tolerances and yet there are faults not in one lens but two.

Should I go to Pentax and see if they will replace it or should I keep it as the lens, in my limited experience, seems to perform as it should.

Any comments on this would be much appreciated.

Kiwao

could we see some pics of it

Suppose if the images are o.k. then it dosn`t matter.
However what will happen if you decide to sell it?

Davex.

Exactly davex if you come to sell it in the future you won't get much money for it because of the bubbles

I have never heard of bubbles in the glass before. New one on me.

Bubbles should have no effect on image quality nor, for that matter, on resale value. I've never had a bubble in a Pentax lens before but I have seen them in other-brand lenses.

Of course, if there's anyone out there with a FA31, FA200 Macro or DA*300 that has bubbles let me assure you it's totally worthless and you should forward it to me for disposal - I'll give you a token tenner for it.

Given it is a Ltd lens under guarantee I would get it changed. Won't cost you anything and will give you peace of mind.

Cheers, Kris.

Bubbles in optical glass are very common and the higher the quality of the glass the more prone it becomes to bubbles forming.

There is nothing that can be done about this and it has no effect whatsoever on the image quality.

I've a couple of Russian (Helios) lenses with bubbles in the glass, they make no difference at all to the image clarity.

If your not too sure contact Pentax and talk it over with them.

I'm sure they would replace it if your not happy.

I'll give you £20 hefty1 you are tight

So generous Hefty1, I would charge at leat £15 to dispose of a bubbeled Lens.

Davex.

I once bought a Sigma 24-70 lens from Jessops which had a bubble. I took it back and they replaced it with no quibble.
I would suggest that you should return your lens for replacement. I am sure there is no small print that allows for occasional bubbles in the lens specification. Especially a high spec lens.

I have never heard of bubbles forming in the glass or ever seen it.
How big is the bubble and how is it possible for a bubble to form inside the glass:

"Normal" glass is quite susceptible to bubbles as it is a liquid when manufactured although one would expect the QC to reject lens elements ground from glass which had bubbles.

Funny thing about glass is that it will still flow with time. Very old church glass is thicker at the bottom of the window than the top!

Oh dear now that I know this if I do return the lens I will constantly be comparing images and probably will convince myself that the original lens was better and wish I had never changed it!

Is there any info on bubbles having no effect?

Does this mean that the glass 70mm is of higher quality than a 70 without bubbles. Then the resale value must be higher. Oh dear no chance of my dream FA 31mm at a cut price is there

I am very happy with the performance of this lens so why replace it? A brand new lens is one reason but knowing Penax they probably would keep it for weeks and replace the glass. The saying if it ain't broke don't fix it is running through my mind.

I am still not sure what to do

Thanks for your comments