Experimental use of Biotar 2/25mm

[Frank Fremerey]

If it is possible to use the Biotar 2/12,5mm as a Super-Macro I thought why not try the 2/25mm?

http://www.fotografikgalerie.de/ExtremmakrosHeliconFocus.pdf

I am currently searching for a Retroring, but I am not sure whether it must be 39mm or 40mm?

sorry, stupid me. It is more in the 50mm range (48? 49?)

I still do not know where to buy.

[Frank Fremerey]

this is how it looks like:

[Bjørn Rørslett]

39 or 40.5 mm filter threads are common, Frank. Get hold of such filter(s) and try what fits. 43 mm is also seen on older lenses.
 
As soon as you have found the correct size, making a reversal ring is a breeze by use of step rings or similar. If the intended host lens is say 52 mm, you add a 52/52 "macro coupler"to the stack of rings.

I believe 40.5-52 direct step rings exist. Not so sure about 39mm, as it is less common. For 43 mm, 43->49 is ubiquitous and 49->52 also is standard size.

[Frank Fremerey]

~50mm front diameter.

[Frank Fremerey]

39 or 40.5 mm filter threads are common, Frank. Get hold of such and try what fits. As soon as you have found the correct size, making a reversal ring is a breeze by use of step rings or similar. If the intended host lens is say 52 mm, you add a 52/52 "macro coupler"to the stack of rings. I believe 40.5-52 direct step rings exist. Not so sure about 39mm, as it is less common.

Thank you

This site got me into experimental mode. Sorry I measured wrong first time.

[Bjørn Rørslett]

Looks like 49 mm could be a better starting point.

You can commence experiments with the reversed lens by using some Gaffa tape to hold it to the BR-2. Results probably improves if you add some extension as well.

[Akira]

Yes, maybe 49mm which is also very common.  I have an old Pentax M42-to-49mm reverse mount adapter.

[Bjørn Rørslett]

Frank, you need a work table looking like this

[bjornthun]

Frank, you will find step rings on eBay.

[Frank Fremerey]

Bjørn. If my place looks like that my wife demands divorce!

I just bought a 49-52-stepup on ebay for 3,61 Euros incl. shipping.

extensions are existing here...

gaffa tape ... how to make a nice lens look ugly in a few seconds...

[bjornthun]

Another thing. 39mm and 43mm are quite common, since these sizes are used on rangefinder lenses and some mirrorless lenses.

[Bjørn Rørslett]

Bjørn. If my place looks like that my wife demands divorce!

You have to sort priorities

Besides, I suppose you have a working space or den somewhere for your own use?

The K-ring sets, photographer's equivalent to Lego bricks, are indispensable when you build experimental setups. Anyone into experimentation should have a few of these. You can pick them up for pocket money on eBay, usually almost in pristine conditions, although prices do seem to increase over time.

[Mike G]

Bjorn, do you ever pick the wrong bit up and attempt to fit it?

[Bjørn Rørslett]

Often, in fact. But never try to pressure-fit anything.

Tinkering with a lot of bits and pieces can be a Zen-like liberation of mind and in fact frequently leads to finding better solutions for the problem at hand.

[Frank Fremerey]

some silk I found...

test shots and making off ... kindoff ... ggg