Extension Rings

I have a Pentax MZ6 with a 28-90 AF standard lense. What i want to know is want type of extension tubes can i fit while still being able to use auto focus, or will i have to loose the auto focus. I've a chance of a set of Pentax K series.
Richard

As far as I know you will lose all electronic connections with any Pentax tubes. There are some other makes that have contacts, but someone else will have to tell us what they are...

As far as I know there are no extension tubes that continue AF... but I thought I saw some Kenko ones that did.

AF for macro work is of limited use anyway. I have a set of "Triplus" tubes that I got for a snip at Jessops that have the electronic contacts. They work a treat

None of the Pentax tubes have contacts (even the "A" ones).

Matt

Hi,

Kenko make AF tubes with a Pentax fit, but to be honest, if you are going to be doing any serious macro work, then you will probably find that you'll get more accurate results manually focussing. I've taken shots where the depth of field is less than 1/10 mm, although that's at around 5x magnification.

Autofocus is pretty accurate with the pentax lenses that I've used in the big world, but I doubt you'll be that accurate at any sort of macro scale of magnification.. ie anything greater than 1:1.

You might also want to think about a true AF macro lens. I know there are folks here that swear by the PENTAX FA 100mm f3.5 macro lens, but as you can see here..

http://cgi.ebay.co.uk/PENTAX-FA-100mm-f3-5-MACRO-SMC-LENS-PZ-MZ-ist-DL-USED_W0QQ...

you're looking at some serious money, even second hand. No doubt someone will give you more info on the above lens, but as I said, you will probably get more accurate results with manual focussing.

Hope that helps,

Cheers

Liam

This particular macro lens is a low cost one, and it seems to be the same as the Cosina. However, despite the low cost and rather rudimentary barrel contruction it is actually a good performer.

There are better Pentax macro lenses. The SMC Pentax-M 100mm f4 is superb and quite often found on eBay. I have recently purchased a SMC Pentax-FA 100mm f2.8 which is a beast of a lens but looks very promising. One advantage will be its 1:1 magnification.

For serious macro photography, I would choose a proper macro lens every time, but don't forget that even close up lenses (filters) will produce very good results very cheaply.

Just posted a super-macro shot taken with the SMC-F 100mm/f2.8 and a large extension tube. Manually focussed, f/32, twin wireless flash.

http://www.ephotozine.com/gallery/showlargepic.cfm?photoid=667897

Even shooting bugs hand-held with pop-up flash you don't need AF:
http://www.ephotozine.com/gallery/showlargepic.cfm?photoid=469402

Enjoy
Matt

I bought a set Kenko tubes from College Cameras (http://www.collegecameras.co.uk/), but they are not AF. They have all the connections for exposure etc but no drive connection for the focusing. Maybe I have a ‘non AF’ set, but I suspect it is a case of AF compatible being marketed as AF.

They are good tubes though and I doubt I would ever use auto focus for macro work anyway.

what if i had a standard Petax 50mm 1:7 lense using extension tubes

The 50mm f1.7 will be the best choice of standard lens to use with extension tubes as it will maintain good performance close up. It will be much better than a zoom at these distances.

I have found that with macro work you really need to use manual focus because of the very small DOF, and this especially applies when using extension tubes or eversing rings (and if using a reversing ring there is NO way AF can work!) I have only used AF when using my 70-300 sigma which has a macro function.