[kurt1968]

Hi , i will be collecting a Pentax SMC-A 50mm f2.8 Macro , i didn't wait to bite when i saw this one coming along.
I will be on the outlook for extension tubes .
But here is my question : i 've read that A lenses make it possible for the camera to meter, right?
So the best for me is to buy automatic extension tubes?
Also , is there a dedicated like macro extender excisting for this lens?
I have no experience with macro extension tubes whatsoever so please inform me what i should be looking for ....thx !!

[Adam]

So the best for me is to buy automatic extension tubes?

If you can find some, then yes. There are no genuine Pentax tubes with A contacts.

You could also get a bellows unit:
PENTAX Bellows Unit III (K) reviews - Pentax Camera Accessory Review Database

[kurt1968]

Is it very difficult to do macroshots without automatic metering (using plain axtension tubes).
What about difference in magnification , tubes vs bellows?
In town there is a very old shop , i actually saw Pentax bellows new in the box !

[LesDMess]

Is it very difficult to do macroshots without automatic metering (using plain axtension tubes).
What about difference in magnification , tubes vs bellows?
In town there is a very old shop , i actually saw Pentax bellows new in the box !

Without aperture priority, you can manually calculate it.

Bellows offer flexibility in magnification and best if you need a lot of it. Probably obvious but you can also stack bellows as you can tubes and the view gets very dark the more you do.

[Scorpio71GR]

You can meter I manual mode. I use manual mode a lot including macro shots. There are some excellent guides here in the forums, here is one of them.

https://www.pentaxforums.com/forums/53-pentax-dslr-camera-articles/100260-man...ic-lenses.html

[LesDMess]

BTW, the M50mm f4 and M100 f4 macros - in good condition, are capable of delivering outstanding resolution and sharpness. The former can be reversed for more magnification and the latter giving you more working distance.

[baro-nite]

Congratulations on getting a copy of this excellent little macro lens. I removed the glass from an old KAR (Ricoh mount) 2x TC to make an A-type 25mm extension tube. Unfortunately I don't get good results using it with this lens; the combination produces a lot of flare. I can't figure out why; I've tried lining the tube with black flocking but it didn't help. So if you want 1:1 magnification with this lens while retaining full metering, I think your best bet is to reverse another 50mm lens onto it with a macro coupling ring. The A50/2.8 macro is itself an excellent lens for reversing, either on a bellows (or tubes) or onto another lens. Of course with a bellows or plain K-type tubes you are down to stop-down metering (or chimping) only.

[Giklab]

That looks disturbing.

[Not a Number]

You should learn stop-down and manual metering techniques. I've been in lighting situations that stopped down was below the sensitivity range of the meter. In this case I had to meter wide open and manually adjust the shutter speed to the f-stop I wanted.

The Pentax K-mount auto-bellows have no electrical contacts so you have to use stop-down metering techniques even with "A" lenses.

Make sure the bellows are K-mount and not screwmount or else you'll need screwmount lenses and an adapter to the camera body.

[slowhands95128]

Pentax has not made KA extension rings ever. I've seen a few sets of old Pentax K extension rings with exposure coupling on ebay, none with KA contacts. The sets were expensive ($150+), so I am still looking for a deal. If you really want A contacts, you can drill them into the mount of the extension rings, but they not will be accurate as you vary extension. However, the camera will permit you to use PTTL flash and auto exposure with compensation; those are locked out by camera firmware with pre-A lenses.

I think it is better to use a high quality achromatic close up filter lens from Canon, Nikon, Marumi or Raynox. I use the Canon 500D and 250D close ups, and all the Nikon 3T-6T close ups. With the close up filters you retain the automatic capability of your 50 FA lens and you don't lose Fstops. These better makers use achromatic lenses for the higher powers and I don't see image degradation.

[Kerrowdown]

I will be collecting a Pentax SMC-A 50mm f2.8 Macro

Enjoy that sweet wee lens, I picked one up this Summer and she has just been a joy to use, has now been promoted to “Femme Fatale” Lady status.