Reverse adapter, macro tubes

I plan to buy a reverse adapter (to use my Helios (Zenit) lens). I never used the reverse ring before and I don't know what should I look for. Do I mount it onto a body or on another lens (ie my 16-45mm?)

Yesterday I read that it's better to buy an original Pentax M42 / K-mount adapter than a cheap one from eBay. How it is with the ring adapters?

What about extension tubes? Should they be K-mount?

Michal,

Your Zenit lens probably takes a 49mm filter? If so you can look for a 49mm screw to Pentax K adapter ring and reverse mount the Zenit right to your DSLR.

If you really want to play Macro, mount your 16-45 in the DSLR as per normal and buy a ??mm to 49mm reversing ring to mount the two lenses face-to-face. (I don't know the filter size for your zoom).

As for tubes, yes, start with K mount to extend your 16-45, or your Zenit reversed on the 49 - K adapter.

Hope this hasn't confused you even more.

Beware, Macro is adicting!

A reversing ring screws onto the front of your lens and allows it to be fitted to the camera back-to-front. A different adapter is needed if you want to join two lenses together instead.

Extension tubes need K mounts, or K mount adapters. There are manual sets with no electrical contacts, or automatic ones with contacts.

EDIT: Mac's reply wasn't there when I was typing mine

[
EDIT: Mac's reply wasn't there when I was typing mine [/quote]More importantly, Pete agrees with Mac!

There are also 'Auto' tubes which have no contacts. Auto refers to the mechanical diaphragm linkage and not the pass-through contacts.

I have a set of Kenko P-AF tubes and guess what . . . they don't handle AF.

Thanks, so this is as I thought

Are these cheap eBay adapters and tubes OK?

The M42 to K Mount can be cheap for Macro (who cares about no infinity focus in Macro?) but should be the good one for normal use of your Zenit.
Everything else (reversing rings, tubes etc) doesn't matter as long as they're solid and safe connections.

Have fun.

The very cheap tubes I got off Fleabay are shiny on the inside. This is not a good thing. Better tubes have a more matt surface to minimise reflections.

Thanks. Now I have to search Internet shops / eBay a bit