Need some help with a lens purchase..

[PeterAM]

I just got a Mamiya 645 45mm lens for use on my 1000s. There is a black speck (larger than pinpoint), inside the lens, that is apparent when looking through the lens at a light source. Since I have an adapter for it, I mounted the lens on a DSLR (Pentax K10D) and shot some pictures of white paper, with some lines to give me something to focus on. I did it so that the paper fills the whole frame. Looked at the image(s) blown up and brightened, on the computer screen and can't find the speck. I remember reading that some lens issues don't effect picture quality; is this that type of thing?
If in fact, this is not an issue, is it possible that it doesn't show up using the DSLR, but might on the 1000S?

 

[Fotoguy20d]

It can be a very disheartening thing to look inside a very expensive lens and see all the dust and junk that's floating around in there. Most of it doesn't matter though. Sounds to me like this is one of those. I'd say try it out with a roll of film and see what you think. FYI - (there was a url link here which no longer exists) didn't make a difference that I could see.

Dan

 

[daleeman]

I've picked up a buch of Mamiya 645 lenses from KEH and at the EX to bargain level there is dust in them and they still crank out a good image. I would not buy the UGLY level of lenses from them, they are UGLY.

 

[PeterAM]

This lens is from KEH also. I don't have the time to have a roll of film processed and make their 14 day (from invoice date) cutoff. Will shoot some more with the lens on the DSLR and then make a decision. Helps to know that there is dust, etc. in their lenses. This looks like its a flat piece of something, maybe paint;I was hoping that it had dislodged from getting banged around in shipping and would settle back somewhere else (off of the glass), but no such luck. Other than that the lens is in nice shape, with caps and case.

 

[bdial]

It's very common for lenses to gain some dust or other sorts of specs. It's very uncommon for it to cause a visible problem if that's the extent of it. Fungus or haze from moisture or lubricants are a different matter.
FWIW, your DSLR is using a much smaller portion of the lens's image circle than your 645 will, but it's unlikely to matter.
If you are near a shop that can sell you a roll of color film, any minilab should be able to process it in an hour.

 

[John Koehrer]

As long as the debris is inside the lens it won't be visible. As above, haze or condensation will be visible.
Don't obsess, but exchange it if they have another one. They're good about that kind of thing.

 

[thisismyname09]

Its also possible to disassemble the lens and remove whatever is inside of it, so long as it's not etched into the glass. Even fungus is removable, I think.

 

[colrehogan]

Some really old LF lenses have air bubbles in them. I have at least one like that, plus another with a scratch on the front element, but I use it and can't tell that it is scratched. Many of my newer lenses have dust in them, but in many cases, I can't get to it and it doesn't affect picture quality.

 

[Pumal]

I've been a couple of years using 2 Super-Takumars full of dust and/or fungus. The pictures come out just fine.

 

[CBG]

If you can't get it in focus ... don't worry. It shouldn't show. When you are shooting into the sun or in other flare producing situations, shade the lens from direct light - which you should be doing anyway.