Macro but which one.

Just to stir the pot a bit, back in the day when money was very tight (70s) I used a reversing ring on a Pentax, model lost in the mists of time, I guess this set-up would still work on modern lens?

I use a Tamron manual focus 90mm f.2.8. and it is superb. I had the Pentax DFA 100mm macro and found the build quality a bit iffy it would not focus with a ring flash on it due to the quick shift clutch,decent images though.Just frustrating to use.
Tamron

I was lucky enough to get a rather tatty copy of the Tamron 90mm macro (adaptall2 - 055B version) for £1. After a bit of a clean it performs rather well

If it's just flowers you'll be shooting a 50mm macro might be OK, but even then the increased working distance of a longer lens is a benefit, it's pretty much essential for insects.

Reversing rings as @takuman suggested can be used with modern lenses but really want a lens with an aperture ring. Extension tubes & a coupling ring (to reverse a lens in front of another) are other budget options, which can also give you even more from a macro lens.

Johan has all the options covered in depth on his excellent extreme macro site: http://extreme-macro.co.uk/

if you have the "Catch in Focus" facility( which is useful for Macro) in your model's menu and wish to use it then you need a Macro lens that can be switched to manual focus. as far as i know you cannot do this with the Pentax, i know you can on the Sigma and think you can on the Tamron

this is the sharpest lens I got, sharper than the 50mm FA 1.4

not bad at all, but I wouldn't dare to use it on a heavy lens like my Sigma 50-150

I have tried a reversing ring on my Pentax M50 f1.7, it works ok but I didn,t like having the rear element exposed. So bought some very cheap extension tubes and that got me into Macro, I have used these extension tubes on the M50 and Tamron 28-75 . Since then I bought a Sigma 105 f2.8 secondhand and found it excellent. The main reason I got the Sigma was that it had an aperture ring which would be useful if I put extension tubes on it. Incidentally I recently used the Sigma on my K-1 at a boxing event and was impressed with its performance.

Reversing rings work well, but are a bit awkward as you lose the aperture contacts. I was lucky enough to find a set of extension tubes second hand that have all the correct electrical contacts for the aperture, these work brilliantly. Also, you may recall threads on here a few years back about butchering an old zoom, i.e. taking out all of the glass and then attaching an enlarger lens to the filter ring. This enables extreme macro and maintains the aperture control on the butchered zoom. I suppose what you use depends entirely on how macro you want to go. If you go down the extreme route you will also need a good flash light source. I use a home-made lightbox attached to a powerful flashgun, which enables decent lighting at apertures of F16 or thereabouts.

Here's one of the 'extreme' examples using the butchered zoom and a Nikon enlarging lens:




Regards
David

many many thanks for all the replies. i think i've got a little more research to do before i take the plunge. there are pro's and cons to each option.

Mike-p took your advice and while i'm deciding ive bagged myself a raynox dcr-250 off amazon. ive got plenty of old glass that it should give a new lease of life too.

One thing no one seems to have mentioned when talking about all this expensive and fancy glass is the questsion of auto focus. It's a pesky nuisance, especially when you want the focus point exactly "there" to optimise the DoF, for example. Manuals are much better and you can use catch in focus and muck about all you want with live view (if the subject isn't about to run away).

Right - butchered lenses.
One ' A' series 50mm f 1.7 lens - unscrew vanity ring on front, unscrew front element; unscrew rear element = no glass but a fully working, camera controlled iris that acts as an extension tube as well !
Put it on the camera
Screw the reversing ring onto the fliter thread
One FA 35 - 80mm zoom. Screw that backwards onto the reversing ring. Set its aperture manually at wide open; set the focus to infinity. (you don't need either of them because the A50 will be operating both focus and aperture.
Stick it on a tripod, get right up close and be amazed. Here is the image my avatar came from ....

There's a Tamron 90mm on for sale on eBay with a buy it now of £145 + postage. That should do very nicely for your needs.