Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
06-12-2014, 03:58 PM   #1
Pentaxian




Join Date: May 2012
Posts: 2,962
Best Lenses for Reversal?

This is a discussion about Macro but also specifically about lenses. I am not sure if this belongs here or there so I just picked one.

If the Mods desire to relocate the thread, please by all means put it where it fits best.

---

For macro I am wondering if there are any specific lenses that are better/best for macro when used reversed?

Now for a little background so we can 'point' the discussion.

Despite what I have heard to the contrary you 'can' use lenses without an aperture ring for reverse macro... I have used a 21mm limited a number of times for it. The technique is to turn the camera on, set the desired aperture in camera, pull the "preview" switch (on my K-5 it's right on the shutter button), and while holding it (with the camera on) remove the lens, turn the camera off, reverse the lens, etc. It works just fine although I am not sure if it's good practice for the gear or not to do that. So far it doesn't seem like it hurts anything. That said, a lens with an aperture ring is just a lot more convenient.

I have come to really like a reversed 28mm focal length. A reversed 28mm with no stacking or tubes gives about a 3:1 magnification. A reversed 50mm gives about a 1:1 magnification. From what I can tell the lower the focal length the higher the magnification, so if you start at 50mm and work your way down you get more magnification with about a 3:1 happening around 28mm.

I have yet to figure out how much (numerically speaking) adding various lengths of tubes adds to the magnification, or if say a reversed 50mm on tubes would be more sharp or 'better' than a 28mm without. If anyone has opinions or experience please chime in.

Now, my lenses that I use for reversal are a couple of different things, but sometimes I use an F50 f1.7 or an F28 f2.8. I have another 50mm that is pure manual that I like too. The difference with that last one though is at it's smallest setting it only stops down to f16 whereas the others can stop down to f22. I am not sure if this makes any difference, but this is the realm I have been working in f stop wise to get my lighting right and depth of field right and so on and so forth.

What I want to do is get input from people with experience as to which lenses specifically are sharpest when used for reverse mounting. I also want to be able to know the best ways to get beyond 1:1. I find most of the macro lenses for Pentax (35mm, 100mm, Tamron 90mm) are all 1:1.

Are there any dedicated Pentax lenses that go beyond 1:1 out of the box or is there nothing except reverse lenses to get (up to) my 3:1 range?

I am thinking about (instead of using my F28 and F50) for macro work that I get something that is non AF or maybe optically better... those two lenses in my opinion are just too good the other way around to wallow down in the dirt with them... but I am (among my other questions) really wondering what are some very specific options for otherwise manual lenses that I can reverse and get at least as good if not better results from them?

06-12-2014, 04:21 PM   #3
Veteran Member
OregonJim's Avatar

Join Date: Mar 2009
Location: Willamette Valley, Oregon
Posts: 1,327
QuoteOriginally posted by alamo5000 Quote
I have yet to figure out how much (numerically speaking) adding various lengths of tubes adds to the magnification
Extension tubes and bellows do not increase magnification (hold on guys...). What they do is decrease the minimum focus distance of the lens. If you add enough extension, you can get the actual plane of focus to exist somewhere inside the lens, which is less than useful.

The magnification comes from moving closer to your subject.

So, the only things that affect magnification are the focal length and the distance to subject.

I've never tried to calculate mag with a reversed lens, because a reversed 28mm is no longer 28mm. Not sure what it is.

Last edited by OregonJim; 06-12-2014 at 04:35 PM.
06-12-2014, 05:27 PM   #4
Loyal Site Supporter
Loyal Site Supporter
blackcloudbrew's Avatar

Join Date: Mar 2009
Location: Cotati, California USA
Photos: Gallery | Albums
Posts: 4,460
I think from just empirical use, a 50 lens with an aperture ring is the best. I like my old FA 50 f1.4 a lot just for this purpose.

06-13-2014, 03:20 AM   #5
Master of the obvious
Loyal Site Supporter
savoche's Avatar

Join Date: Jun 2011
Location: Lowlands of Norway
Posts: 18,309
I'm not aware of any lens that, mounted normally, will give more than 1:1. Bellows to get closer, or reversing or stacking to increase magnification is the way to go, I think. An easy way of stacking is to use a close-up lens like the Raynox DCR-150 (+4.8 diopter) or 250 (+8 diopter) on a tele lens.

I found a PDF on this site explaining how to calculate magnification ratios with extensions or stacking.
06-13-2014, 04:23 AM - 2 Likes   #6
Loyal Site Supporter
Loyal Site Supporter
baro-nite's Avatar

Join Date: Aug 2011
Location: North Carolina, USA
Photos: Gallery | Albums
Posts: 5,294
The only consumer lens that goes significantly beyond 1:1 without accessories is the Canon MPE-65.

The SMC Pentax 1:3.5 28mm (i.e., "K series") is particularly good reversed.

Re extension and magnification, it's just like with the lens mounted forward -- each unit of focal length you add in extension increases the magnification by a factor of 1.

With magnifications this high, at f/16 you are losing so much detail to diffraction that it isn't really worth doing. I mean you could upscale a lower magnification shot and get about the same result. At 3:1 the effective f-number is about 4 times the nominal (i.e., the setting on the aperture ring) f-number, so you want something you can use below f/8. Yes, DOF will be incredibly thin. So this is why the K28/3.5 is so good -- it's quite sharp stopped down just one click from wide open (f/4.3 or so).

You'll often read that reversing on plain extension is better than reversing onto another lens, because you aren't adding any extra glass. I believed this until I actually tested it. I've found that stacking generally gives better results, if you have appropriate lenses to use as primaries.

This is a stack shot with the K28/3.5 reversed on the #2 Pentax manual tube:

06-13-2014, 04:34 PM - 2 Likes   #7
Loyal Site Supporter
Loyal Site Supporter
baro-nite's Avatar

Join Date: Aug 2011
Location: North Carolina, USA
Photos: Gallery | Albums
Posts: 5,294
Another stack (6 shots, handheld) with the same lens, reversed on the Pentax helicoid extension tube at full extension (around 4:1 magnification):



07-05-2014, 05:52 PM   #8
Senior Member




Join Date: Aug 2013
Photos: Gallery
Posts: 150
El nikkor 50/2.8
Period! :-P
07-06-2014, 03:58 AM   #9
Loyal Site Supporter
Loyal Site Supporter
baro-nite's Avatar

Join Date: Aug 2011
Location: North Carolina, USA
Photos: Gallery | Albums
Posts: 5,294
QuoteOriginally posted by rp_dxn Quote
El nikkor 50/2.8
Period! :-P
A good lens for reversal (make sure to get the newer "N" version, though) and an extremely good value, but hardly a 28mm! For a 50mm lens the Pentax-A 50/2.8 is also very good reversed, and then of course you can turn it around and mount it the normal way too, so it beats out the El-Nikkor on versatility in a K-mount system.
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!
28mm, 50mm, aperture, camera, f28, lens, lenses, macro, magnification, tubes
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Best lenses for the K5-IIs kuau Pentax SLR Lens Discussion 21 11-30-2014 08:24 PM
DXOMark - Best lenses for K-3 audiobomber Pentax SLR Lens Discussion 46 01-17-2014 04:08 AM
best small lenses for K-01 kevwil Pentax K-01 69 04-29-2013 09:29 AM
Best Lenses for Northern Lights? Skipper74 Pentax K-5 & K-5 II 9 09-12-2012 06:43 PM



All times are GMT -7. The time now is 11:13 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