Arco Tokyo Tele-Colinar 135mm f/3.8

Nordentro · Expire: 2015-01-29

This lens is quite good and one of the sharpest 135mm I have (I have around fifty 135mm lenses). There is some slight mechanical vignetting in the corners on FF, but other than that, beautiful, well built lens with good IQ.

luisalegria · Expire: 2018-01-18

Ditto, I have two of them.
high quality item.

mo · Expire: 2016-07-30

Beautiful samples and colors,and that's what I call a postie bike Cool

Lightshow · Joined: 04 Nov 2011 Posts: 3666 Location: Calgary

Results look impressive, thanks for posting.
The body reminds me of a Canon RF lens.

Nordentro · Expire: 2015-01-29

Yes, it is similar to the early Canons & Canon Serenars. Thx for commenting Wink

Alun Thomas · Joined: 20 Aug 2018 Posts: 661 Location: New Zealand

I just finished a (cough) 'repair' on a copy of this lens. It certainly isn't in the same beautiful state as the one shown futher up thread, the finish is fairly tarnished by age. When I received it I noticed some separation in the cemented element. After successfully disassembling to get to the element, I tried heating and slight pressure to see if the Canada balsam might re-flow successfully. It did not, I tried several times. I was also unable to further disassemble the element despite the separation having spread across most of the surface area. To try to further disassemble the element I submerged it in acetone for the night. In the morning, the evidence of the separation was gone, the element would still not pull apart. My opinion is that the acetone washed the Canada balsam out from between the elements. Due to the manufacture it still would not come apart further. The element seems to be a triple cemented type, and the scheme 5/3.

On testing, the lens is sharp with good contrast even wide open. The pictures are a couple of test shots at center. The flower is a 100% crop, the cat a slightly less extreme crop.

kiddo · Joined: 29 Jun 2018 Posts: 1273

Nice results, I wonder if the separation was only in part of the element surface , and in case it was, after the acetone treatment and cleaning, did it left any border line where the separation was present? Do you think submerging the elements in acetone during the night ,would improve the separation to be less visible ? I've got couple of lenses with separation and still didn't touch em yet

kiddo · Joined: 29 Jun 2018 Posts: 1273

I understand that if there's still any separation visible in the borders of itself ,it would be visible in the bubbles bokeh like highlights etc.,right? But if acetone can cure these issues ,that would be really nice lol

Alun Thomas · Joined: 20 Aug 2018 Posts: 661 Location: New Zealand

You might have to experiment to know for sure. In the past, heating has allowed me to fully disassemble cemented lenses, but the construction would not allow it in this instance. I'm still not sure whether the acetone completely removed the balsam, or re flowed it. I lean towards complete removal. There is now no visible trace of any separation.

pabeu · Joined: 25 Apr 2018 Posts: 72

Alun, I am also interested in fixing separation on a couple of lenses.

Could you describe the heating process you used?
When effective, how do you put/glue the elements back together?

Thank you.

Alun Thomas · Joined: 20 Aug 2018 Posts: 661 Location: New Zealand

To separate I've used 2 methods. One is to heat slowly to boiling in water, this limits the maximum temperature to ~100 degrees C, and the heating process is fairly smooth. This last time I just heated in the oven to about 120C. I recall seeing some info about the correct temperature to heat to, but can't recall now.

I've only reglued an element one time, I used a grade of araldite epoxy glue which was advertised as being optically clear. It worked quite well. You do have to be careful with regards to realignment of the two elements. I used the lens carrier to align them, lacking anything better. With that method you need to reglue, then be careful to remove any excess which squeezes out, I used a rag soaked in acetone to remove it. Then, after 30 minutes, I removed it from the carrier and repeated the cleaning process to remove any last bits and prevent it being stuck in the carrier.

The process is fraught with the high possibility of making mistakes, I generally only do it on lenses I'm prepared to lose if it doesn't work out.

pabeu · Joined: 25 Apr 2018 Posts: 72

Thank you. Really valuable input. Have a great week.