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Ultra-Achromatic-Takumar 85mm f4.5
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PostPosted: Sat Feb 25, 2012 11:03 am    Post subject: Reply with quote

I cannot imaging that another higher bid will appear. So I think it is better to leave it as the seller is using such tricks to get a higher bid?
Otherwise I can bid for you. But I am not that fortunate that I can go much higher on my own account Embarassed - and I cannot do anyhing usefull with the lens myself, that specialism is far over my ambitions Rolling Eyes


PostPosted: Sat Feb 25, 2012 11:28 am    Post subject: Reply with quote

I'm considering to withdraw my private offer, as this "procedure" leaves any room for potential fraud.

It should be mentioned that when I was presented higher resolution images, I saw possible haze inside.
This image is not shown on the dutch auction site.


PostPosted: Sat Feb 25, 2012 11:45 am    Post subject: Reply with quote

UA Takumars 85mm have two weak spots from the few I have had in my hands in my life:
a) the front lens is made of CaF2 (Calciumfluorite) hence is very soft, so wipe makes and scratches can easily happen if not used with utmost care (a really clueless seller in teh US once used a high pressure air can to "blow it clean" and cracked the front lens due to the temperature shock
b) the lens is prone to internal haze and I have seen a few having that, calling for service, if it can be cleaned. For UV work, internal haze is a very bad thing, as UV light anyway tends to scattering on any particles

So have a look at these images:

for a)


for b)


I won't further comment, form your own opinion please.


PostPosted: Sun Feb 26, 2012 4:37 pm    Post subject: Reply with quote

im not trying to fraud anyone here...

maybe i could meet up with spotmatic if hes willing and he could inspect it.
the haze on those pics to me looks like out of focus reflections in the lenses further down the barrel.

i have made pictures this morning where i ran my focus through the barel of the lens and made a pic of every spec of dust that i found
i also made a video of that.

people who are interested could ask for them in fullres

#1

#2

#3


PostPosted: Sun Feb 26, 2012 4:47 pm    Post subject: Reply with quote

These pics don't help at all to see if there is haze Robbert. I had descibed how to make darkfield shots to make that visible. So here is the method:
- place the lens with fully open aperture before some dark background
- place a strong light behind the lens, so that its light shines through it, but at a slight angle and a little to the side, so that it does not shine directly into the camera
- take a picture from the front, focusing to the inside of the lens.

That usually reveals such stuff as haze, mold, fungus, separations etc.

I'll give you an example, this is a lens that looks perfectly clear if you look through it to the sky or a white paper etc. - and here is the darkfield result. The seller had no clue of that before I showed that to him and was quite in shock. It needs some experience to discover that:


Don't get me wrong, I'm not directly or indirectly implying anything bad. I'm just saying that it is hard to find such stuff without having had experiences yourself with many lenses. I certainly hope that it is NOT there!!

Having Peter (spotmatic) inspect it, would also be a good idea!


PostPosted: Sun Feb 26, 2012 8:05 pm    Post subject: Reply with quote

Unfortunately I seem to lack the funds for this lens, but the least I could to is inspect it for a prospective buyer. PM replied!


PostPosted: Mon Feb 27, 2012 9:51 am    Post subject: Reply with quote

It would be great Peter, if you could shed some light onto the condition of that lens! Unfortunately you won't have the means to test it out in IR and UV, as especially UV performance is very unforgiving in my experience. Too bad it is too far far away from me.


PostPosted: Mon Feb 27, 2012 12:35 pm    Post subject: Reply with quote

Btw. if anyone wonders how that lens performs in visible light, I made a test a while ago with mine against the famous SMC Takumar 1.8/85mm http://photographyoftheinvisibleworld.blogspot.com/2009/08/test-pentax-smc-f1885mm-vs-ultra.html
Not surprisingly the 1.8/85mm is the clear winner, especially when it is not about closeup work, which the UA Tak 85mm is optimized for.


PostPosted: Tue Feb 28, 2012 12:27 pm    Post subject: Reply with quote

Well, the owner of the lens is here now and here are the photos I took of it and with it...

I found the lens pretty sharp with absolutely no CA and PF at all, remarkable! Shocked

1.


2.


3.


4.


5.


6.


6b. 100% crop of the above:


PostPosted: Tue Feb 28, 2012 12:48 pm    Post subject: Reply with quote

Thanks for your effort Peter + Robbert! In these darkfield shots, the light source should not be visible in the images, but shine from the back and just so much from the side through the lens, that it stays invisible. Bit hard to explain.

But I guess I see what I wanted to see, the halo around the LED lamp reflections is obvious.


PostPosted: Tue Feb 28, 2012 1:40 pm    Post subject: Reply with quote

I know Klaus, but it was harder than I thought it was... The led light kept showing in the glass.

Anyway, I found the lens VERY contrasty and also VERY sharp, remarkable... despite it being not coated at all.

Focusing is also very smooth, and the diaphragm is clean and snappy too.

All in all I would not mind using it for regular photos. Of course, scientific applications are much more demanding...


PostPosted: Tue Feb 28, 2012 1:54 pm    Post subject: Reply with quote

Thanks Peter.

Yes, it is a sharp lens overall, but if used for UV, that "light" behaves very differently than normal visible light, that's why I was so "hard" about checking it out. Using such a lens for normal visible light would be a bit sad actually, as it was not really designed for that, but mainly for UV and also IR.