"Chinese" 52mm extension tubes

ChrisR · Post by **ChrisR** » Sat Feb 25, 2017 3:54 am

I'd like to know the thickness of these 52mm "filter thread" rings.
Could someone who has some, measure for me?

I realise there's some redundancy in the four dimensions shown:

Dimensions at the male end are more important.

If C or D is radically different at one end than the other, it would be useful to know.

Thanks

mjkzz · Post by **mjkzz** » Sat Feb 25, 2017 6:17 am

Never seen a "52mm" extension tube before, I always use a "standard" dumb extension with 3 segments of 21, 14, and 7, and two ends for camera mount. Both Nikon and Canon versions have larger diameters, 58mm for Nikon and 62mm for Canon.

My usually route for extension is to use these "standard" extension tubes and then use either EOS-to-M42 or AI-to-M42 at the front of extension, then add either reversed lens or Raynox + objectives. Keep the M42 end as short and as front as possible to avoid vignetting.

ChrisR · Post by **ChrisR** » Sat Feb 25, 2017 7:15 am

The do exist - but are inconsistently available from various vendors.
OK this one's just west of China:

I have some of the genuine

Chinese no-name tubes, which aren't either of the diameters you mention.
I'm looking at getting an adapter made and am thinking a pseudo standard size would be useful.

The Nikon K rings were also 52mm.

mawyatt · Post by **mawyatt** » Sat Feb 25, 2017 7:18 am

Chris,

I switched to 52mm for my tube lenses long ago for full frame, they come in 7, 14 and 28mm lengths, but I also use a PB-6 Bellows now.

I don't have micrometers, so just measured with a ruler.

D ~ 55mm
C ~ 49mm

So C +2B ~52mm, then B~1.5mm, and C + 2A = D, so A~3mm

Mike

ChrisR · Post by **ChrisR** » Sat Feb 25, 2017 7:32 am

Thanks Mike!

mjkzz · Post by **mjkzz** » Sat Feb 25, 2017 8:50 am

Thanks ChrisR, I should have emphasized on that I have never seen it. Here is what I use - a dumb, simple extension tube + a M42 lens mount adapter to convert the front part to M42 thread. These "standard" extension tube has larger inner diameter, for example, the Nikon one has 58mm outer diamter and 53mm inner diameter, enough to cover full frame. The Canon one is larger. These are cheap, about 7USD each set.

Once the front is M42, it is easier to work with, as matter of fact, I hate to use a helicoid as I did before, at least mine, it is too loose and hard to position. So I have a variable length extension tube machined for me and it has M42 thread on it.

ChrisR · Post by **ChrisR** » Sat Feb 25, 2017 9:06 am

Thanks Fan
I have two sets of those for Nikon, One for Oly4/3rds and one for Canon. The Oly is the same thread as ONE of the Nikon sets!

mawyatt · Post by **mawyatt** » Sat Feb 25, 2017 9:12 am

Chris,

BTW, if you plan on using these be sure to flock the inside...the ones I have are very reflective!!

Mike

mjkzz · Post by **mjkzz** » Sat Feb 25, 2017 3:22 pm

this is the part I like "standard" extension tubes, they have grooved interior, so far I have not found the need to flock them, even at 50x where light is bound to bounce around. Both components are easy to find.

The only thing I want to caution others is NOT to get the so called "precision" M42-to-Nikon (or Canon) adapter, most of these precision ones are chromed ones, they are highly reflective as seen in the middle of here

The only thing these precision adapters have over normal ones is that its thickness is machined to tight specs so that the registered distance is a perfect match when you mount a M42 lens to Nikon (or Canon) body, so the M42 lens will behave like a native lens (Nikon or Canon), but for the purpose of extending, this is probably not as critical.

dolmadis · Post by **dolmadis** » Sun Apr 02, 2017 4:18 am

Just to add to the knowledge base.

http://www.ebay.co.uk/itm/230998684397? ... EBIDX%3AIT

These inexpensive tubes are 52mm and are compatible with these 52mm from Amazon UK https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1 and my very few Nikon K Series tubes.

Just discard the M4/3 parts

HTH

John

ChrisR · Post by **ChrisR** » Sun Apr 02, 2017 4:51 am

A little more - I ordered one of these, thinking that I have a n M52 to 52mm filter thread somewhere:
http://www.ebay.co.uk/itm/M52-to-M42-Ad ... 2057034731

It's adequate quality, though there's no locking screw. I have no idea what the "shutter button" picture is there for.
I was surprised to find that a 52mm filter, or Nikon K-ring tube, screws perfectly satisfactorily into the front thread. The (Nikon) one I tried has barely a single turn of thread. Longer threads may jam.

ChrisR · Post by **ChrisR** » Thu Apr 27, 2017 3:27 am

Confirmed - John's first link (Title is Macro Extension Tube Ring Mount Adapter For Micro Four Thirds 4/3 E-P5 PL5 GF6 if the listing disappears) has reasonable, and very cheap, 52mm extension tubes.

But I wouldn't want the bayonet end-rings anywhere near a nice camera! They don't go together easily, then jam together - ugh!