Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
02-18-2011, 09:57 AM   #1
Veteran Member
Northern Soul's Avatar

Join Date: Feb 2008
Location: The North of England
Photos: Albums
Posts: 491
Extension tubes & 18-55 1:1 reproduction?

I need to take some product shots for a website - mainly jewellery and so on.

There is no budget for a proper macro lens as yet, although that may change if the website takes of.

In the meantime, I was thinking of getting some extension tubes. It being fully manual is no bother as the photos will be taken in a controlled environment with constant lighting, and besides, what's the point having a screen if you're not going to check the shot?

Extension tube sets seem to be very cheap on eBay - at least for ones with no contacts.

At 8 / $10 or so, are they actually going to fit, do you think? Has anyone bought any? Also, does anyone know what reprodoction ratio I'd get with a set of tubes - the set I'm looking at has 9mm, 16mm and 30mm tubes.

Any input much appreciated.

02-18-2011, 10:22 AM   #2
Site Supporter
enoeske's Avatar

Join Date: Jul 2009
Location: Surprise, Az
Photos: Gallery
Posts: 1,925
You need 50mm of extension tubes on a 50mm lens to get 1:1. However, it isn't a good idea to use the 18-55 lens with extension tubes for a few reasons.

The cheap tubes do not have aperture contacts to pass the aperture data to the camera body. Additionally, the lens does not have a manual aperture ring, it is controlled by the body. Thus, the lens will always be either wide open, or fully stopped down (not sure which). You will either have the tiniest depth of field which is useless for most macros or you will have nice depth of field (from being fully stopped down) but your viewfinder will be pitch black, making focusing impossible.

I recommend picking up a cheap 50mm lens with a manual aperture ring, like the A 50mm f/2, and at least 50mm of extension tubes. That's what I use (until I grab a 28mm, then I'll be using extension tubes, a reverse ring and the 28mm). The A 50mm will let you auto-meter when you aren't using the tubes so its useful for other stuff than macros too.
02-18-2011, 10:27 AM   #3
Veteran Member
Northern Soul's Avatar

Join Date: Feb 2008
Location: The North of England
Photos: Albums
Posts: 491
Original Poster
Ah - didn't think about the lack of aperture ring on the lens - thanks for pointing that out!

The lack of metering isn't a problem, but lack of aperture control would be :-)

I'll keep my eye out for a cheap 50mm.
02-20-2011, 05:31 PM   #4
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
Many threads here cover doing macro without expensive dedicated macro lenses. I love cheap macro. Here are some options:

* A 50mm camera lens on 50mm of extension tubes gives 1:1 magnification, at a working distance of 50mm. A longer lens lets you work further away, with a bit more elbow room. With a 100mm camera lens and 100mm extension you get 1:1 magnification at 100m distance. You get to decide which is best for you.

* If absolute edge-to-edge flatfield sharpness is crucial, use an enlarger lens on bellows. I see PK bellows new on eBay for ~US$40, and M42 bellows used for US$20-30. Enlarger lenses can often be had in the US$5-15 range, or sometimes four for a dime. These are mostly M39, some M42, and a few old USA lenses with weird mounts, etc, so an adapter is needed. Cheapest adapter: a one-buck body cap with a hole cut into it. An enlarger lens longer than 80mm can reach infinity focus on most bellows and can thus also be used for general photography.

* The other way to get great sharpness is to reverse a camera lens. But 1) you still need extension to get magnification, and 2) your working distance will be ~45mm. You can get more magnification by reverse-stacking a camera or enlarger lens onto a camera-mounted lens. But you still have that very close working distance. For any macro setup using camera lenses, they must have aperture rings so you can manually control the exposure.

* Yes, you can reverse-stack a manual lens onto one of your 18-55's. Just be sure to leave your 18-55 wide open, to avoid vignetting. In stacking, the camera-mounted lens is the PRIMARY and the reversed lens is the SECONDARY. Magnification= SECONDARY / PRIMARY. You might look for a cheap 28mm lens as the secondary. With the primary at 55mm, MAG= 55/28 = ~2:1. With the primary at 28mm, it's 1:1. At 18mm it's 18/28= ~0.65/1, etc. But your working distance is still ~45mm.

* If edge-to-edge sharpness isn't necessary, cheap +dioptre closeup screw-in lenses might suffice. Some image quality is lost. If your shots are for eBay-size displays, that really doesn't matter. But at US$10-20 for a set, close-ups don't get much cheaper.

That's an overview. Check the other macro threads here for details. Good luck!

Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
extension, extension tubes, k-mount, pentax lens, slr lens, tubes, website
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Macro w/ m42 Extension Tubes & Takumars bigjonnee Troubleshooting and Beginner Help 13 12-10-2010 11:33 AM
For Sale - Sold: Vivitar Manual 2X Teleconverter and Extension Tubes (12mm & 20mm) sarahfisch Sold Items 1 08-23-2009 08:38 PM
For Sale - Sold: Vivitar AT-22 Extension Tubes Set & Kenko 2x APK Teleplus MC4 hinman Sold Items 7 07-27-2008 08:45 PM
90/100/105mm Macro lens & Extension tubes Ed in GA Pentax SLR Lens Discussion 6 03-08-2008 04:34 AM



All times are GMT -7. The time now is 11:43 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top