Extesion tubes

I have just hastily bought 3 extension tubes with k mount bayonet fit for £18 off ebay which I thought was great until I realised that all my lenses except my nifty do not have aperture rings. Will they work if I adjust exposure just by using shutter speed or have I just made a catastrophic mistake? Any help would be appreciated! Thanks, John

If they don't have contacts, then they'll only work wide open !

I believe !?

Thanks stu49. I'l just have to try them out and see if I can compensate with faster shutter speeds. I only ever intended to use them with my 75-300 which has a maximum f5.6 and is mainly used in bright daylight settings anyway. If that doesn't work, they'll be in the classified section here quite soon!

I wouldn't say £18 was a catastrophic mistake ( I have made a lot worse but I suppose it depends on how much you need the £18 ) but anyway .. as Stu said, they will only work wide open. You need tubes with the A contacts so that you can alter the aperture on the camera body.

These do not come cheap.

Is the nifty not the lens you would want to use with extension tubes?

I did wonder that too !

I assume he's looking to reduce the focal range on that long zoom !?

Are they "auto" tubes meaning do they have the mechanical stop down coupler? if so then the body will still stop the lens down to whatever aperture is selected on the body, of course not only will you still have to meter wide open but will also have to compensate manually for the extension tubes.

If however you bought the ones that are devoid of anything other than being a hollow tube with a K mount at either end, then I'm afraid your stuffed with anything other than the fifty

The good news is its a good excuse to buy some more lenses

No it won't stop the lens down ! No electrical contacts means no control over F stops !

Have a look at these, though the latter will probably go for a high price but the first will be worth watching.

link

link

These are both K mount "Auto" tubes, If you look closely you can just see the actuating lever for the aperture, if you want the contacts too then you need to look for KA mount but they'll cost you a pretty penny.

John,

I have a different slighly more radical solution.

Buy yourself another cheap lens with a k mount and manual focusing off e-bay. Anything decent will do: I use 28mm through to 135mm for macro. The longer the lens, the greater the working distance. You'll then have a dedicated macro set up for very little outlay (if that's a concern for you). You also won't feel you've wasted the £18.00.

I find autofocus a waste of time with macro anyway: you're working to such small tolerances it's better to have an old manual lens which was designed with a wide, well damped focusing ring. Of course, you'll have an aperture ring as well and will be able to stop down to ensure depth of field.

Here's one I took earlier today with an ancient Russian Helios 58mm and a narrow tube (these are miniature daffodils!)

[IMG]http://i927.photobucket.com/albums/ad116/ADC3440/Pictures1133.jpg[/IMG]

Best wishes,

Andrew

?? He's already said he has a Fifty (50) !!

Sorry Stu, missed that! Nifty=fifty...mmm. Couldn't be better then, really! I've got one of those(an f2, not one of the really fast ones) and it makes a brilliant close-up lens with the tubes.

A.

Wow, loads of responses, thank you all! Sounds like attaching them to the Fifty may be a good idea. Thanks bwichmawr for the 'macro' tip. I was quite lucky with my 50mm, although it's very old, it is fast with an f1.4 aperture and it only cost me £33 off ebay.

Thanks everyone!

Regards

John

Can anyone give some advise of using those tubes?
I have a three M42 tubes, and Pentacon 50 mm 1.8 M42 lens, and from time to time I use them. In the cameras little screens there always is something, but in the big screen there is always nothing.

Can someone tell me the purpose of each tube? There is three sizes, and two thin plates.

Regards

The different sizes just give slightly different magnifications.

I don't really understand what you mean by little and big screen or thin plates?