[Michael Piziak]

Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.

---

Can someone suggest some tubes that I can get to use with this lens, and how many tubes would I need (link me to them on ebay if you please will). I would like to take closer in photos of snowflakes and bugs. I don't think this lens goes that close in now, even though it is macro.

SMC Pentax-M 100mm F4 Macro Reviews - M Prime Lenses - Pentax Lens Reviews & Lens Database

[Adam]

Yup, that lens doesn't go to 1:1, only 1:2. Any tubes will work since it's a manual lens.

[smf]

Another option is a Raynox DCR-150 or a Raynox DCR-250. I have used a 150.
Information is at this page: Raynox Macro conversion lenses for Digital SLR camera, our Thirds Mount camera, Micro Four Thirds Mount camera
and also here:
Pertaining to the 150: Projection lens - Raynox USA
Pertaining to the 250:
Projection lens - Raynox USA
I have no commercial relationship with Raynox other than having bought a DCR-150 from a retailer.
And I have not used it to photograph snowflakes.

[dms]

A 50mm tube will get you to 1:1. The tube length divided by the focal length is the increased magnification possible--as it already goes to m=0.5, it has 50mm extension in the lens mount.

[ChopperCharles]

If you want snowflake macros, you'll need more than 1:1.

Best setup for that kind of almost microscopic work would be a Pentax Q, Fotodiox adapter, FA100mm f3.5 Macro with matched adapter (or Promaster AF 100mm f3.5 Macro with matched adapter), which will get you to 1:1. With the crop factor, you're getting 5.5x magnification on top of that, as well as a larger depth of field automatically. I used this setup to get detailed photos of the grooves in a record, down to tiny pieces of dust. Should do amazing for snowflakes (I don't live where it snows, so I have no opportunity to try).


Charles.

[Michael Piziak]

These are empty tubes with no glass, so is there any advantage to buying name brand ones over the metal generic ones offered at bargain prices on the auction site?
like these: Macro Extension Tube Ring for Pentax K10D K20D K100D K7 | eBay

[Doundounba]

Ideally, you want tubes with at least an aperture control lever. It's a whole lot easier to focus with the lens wide-open, using green button metering as appropriate. I can also second the Raynox recommendation - I have had very good results using a Raynox DCR-250 coupled with a Tamron 90mm F/2.8 macro, with or without additional extension tubes.

[dms]

There can be a big difference between name brand and off brand tubes--the tube's inner surface must be well blackened and possibly baffled or flare will be a problem. Also they need to be auto (auto-aperture) or they will be virtually impossible to work at magnification greater than about 0.5--unless you use a tripod and have plenty of time/optimum conditions--not the case for most live bugs, Personally I would (did) go with pentax auto tubes (used from KEH, etc.). Just make sure they really are auto! (lens and tube works on M mode just like lens alone). Pentax was a set of 3 tubes (#1,2,3), w/ combined length of about 50mm.

[Michael Piziak]

I plan to use the tubes only with the manual f4 macro 100mm lens - it has an aperature ring.

[dms]

Your planning to only use lens w/ aperture ring--I assumed that! As you typically are at f/8-f/11 the viewfinder will be darker w/o auto (exposure) tube(s).

i.e., you still need auto tube(s), as otherwise you close aperture before the shot--and it will be near to impossible to do w/o tripod (e.g., you will move slightly and focus is gone), and even w/ tripod it can be tough as you no longer have a good view--when for example the bug has moved into/out of the right position.

[Doundounba]

Exactly, dms and I are saying the same thing: "auto" tubes means tubes that have an aperture control lever. The mechanism holds the lens fully opened until the shutter is released, so you focus wide-open, and then the iris closes down to the dialed-in aperture value when the shot is taken. You need a lens with an aperture ring in order for this to function. If you don't have an aperture ring, you'll need even more expensive tubes that carry the electrical contacts from the camera body forward to the lens. "Auto" tubes are typically around $50-ish, while tubes with electrical contacts are much more expensive...