Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-27-2015, 11:08 AM   #1
Forum Member
chrisca70's Avatar

Join Date: Oct 2007
Photos: Gallery
Posts: 74
Macro advice setup

Reviving this old thread.

I'm looking for an affordable set-up that will render quality images of small moths that are 5mm-15mm. The moths will be pinned and in a controlled environment (this is for Natural History Museum collections cataloging). From some posts I can conclude that I can get a Pentax F 28mm or an M 50mm F/1.7 reversed on extension tubes. Which of these lenses is best? Can you help me check if the items below are the right choices? -Thank you!! BTW I have a K-5IIs

F 28mm on eBay, is this the right lens? LINK

Extension tubes the right ones? LINK

52mm Reverse adapter LINK

05-01-2015, 05:45 AM   #2
Forum Member
chrisca70's Avatar

Join Date: Oct 2007
Photos: Gallery
Posts: 74
Original Poster
Anyone? would really appreciate the input...
05-01-2015, 06:16 AM   #3
Moderator
Loyal Site Supporter
Loyal Site Supporter
photolady95's Avatar

Join Date: May 2009
Location: Cruising PentaxForums and watching your back.
Photos: Gallery | Albums
Posts: 10,752
HI, I've created a new thread for you where you should get better advice. I've placed it in the "Macro Photography" forum.
05-01-2015, 10:12 AM   #4
Pentaxian




Join Date: May 2007
Location: singapore
Photos: Gallery | Albums
Posts: 1,113
Using reverse ring for 28 mm yield about 2.6 X magnification, I think. I have the same ring and used that before. Focus is done thru moving forward and backward to find the point of focus. Depth of field depends on F stop and as you step down to f11 and smaller, viewfinder becomes dim and find the point of focus is a challenge. at f5.6 and f9 I think its ok, normal lighting. Also this set up is prone to glare if flash is used.

Working distance is short too, about 21/2 inches, using my memory and have not do an exact measurement.. But if its a still subject, it should be ok.

Reverse 50 mm lens will probably yield a 1:1 magnification. I have not try reverse 50 mm so its just my guess.

Using the extension tubes on 28 mm will also yield you some magnification but I have never do a measurement on that. I bought one before and have find it not being useful as it has no aperture couplings and viewfinder is dim when trying to find point of focus. The 28 mm on tube will probably touch the subject you are focusing.. 50 mm on tubes will give you additional working distance but lesser magnification compare to 28mm.

In short , I will probably go for 28 mm reverse ring if I want a higher magnification or 50 mm if I want 1:1 magnification. Just my preference but I own both the reverse ring and the low cost extension tube bought many years ago.

marcus

05-01-2015, 05:22 PM   #5
Senior Member




Join Date: Sep 2007
Location: Victoria, BC, Canada
Photos: Gallery
Posts: 160
This is a difficult question to answer without better knowledge of your requirements. You say the moths are 5-15mm long. If all you want is a full body shot then staying with a 1:1 setup (either a true macro lens or a prime lens on extension tubes at f11 to 16) and cropping should provide the depth of field and detail suitable for viewing on a monitor or 8x12 prints. If you are interested in smaller structures like legs or eyes and scale patterns then higher magnification may be warranted but you will lose depth of field. You may want to look into stacking software and hardware approaches to produce the best shots but this will add considerable time to the process. When documenting a collection the time required for each shot is often a crucial concern.

For a wide range of magnifications you may want to consider using bellows instead of extension tubes.

Last edited by Hornet; 05-01-2015 at 08:38 PM.
05-01-2015, 07:17 PM   #6
Pentaxian
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 5,490
See the post linked below on some of the magnification ratios on reverse mounted lens without lens stacking or tubes. This is only effective on lenses with a focal length less than 50mm, With 50mm lenses or longer you should reverse them (on extension tubes or bellows, not lens stacking) with greater than 1x magnification. Refer to he Pentax Auto Bellows K, M and A manuals which give the reason for this and I'm to lazy to find my earlier posts on this.

https://www.pentaxforums.com/forums/22-pentax-camera-field-accessories/287960...ml#post3155624
05-02-2015, 12:12 AM   #7
Veteran Member
old4570's Avatar

Join Date: Feb 2013
Location: Melbourne
Photos: Albums
Posts: 2,524
U-r going to be in a controlled environment :
What is the goal ?

Are the images Portraits ( Macro Portraits ) or some sort of detailed study requiring super close up?

Is speed of concern ?

Buy a Macro Lens , 28mm for 5mm Subjects = Not a good choice ..
Are you going to be image stacking ?

If not , I would recommend a 100mm Macro lens ( 1:1 ) , If you need more macro , you can lens stack a 50mm in front for 2:1 Macro ..
If you have macro skills up the wazoo , then chose tubes or bellows ..
If not , a 100mm Macro lens with Aperture ( A ) control would be the way to go ..

The variables are - Whats required ( pictures ) - the equipment needed ( to get the pictures ) - and your skill ... ( get good pictures )

Sounds like you have a very interesting time ahead of you ..
Is there some where to rent a lens ?
Like maybe a 105 Sigma , or maybe a 150mm Sigma , or a 180mm Sigma , or maybe a Close focus 500mm Sigma .
I would like to know = Whats expected !
Did they provide you with a sample ? ( photo's )
05-02-2015, 07:20 AM   #8
Veteran Member
Aaron28's Avatar

Join Date: Jan 2015
Location: Huntsville, Al
Posts: 1,070
anything old4570 recommends will be of great help......one of the best macro photographers on here that I recognize by name....

05-02-2015, 11:40 AM   #9
Pentaxian
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 5,490
From your equipment choices above it would seem you are working on a practically a non-existent budget. If we had an idea of what your budget is would help on recommendations.

Do the images between specimen have to reflect relative size (i.e. shot at the same magnification) or will a scale be provided and differing magnifications can be used on a per subject basis?

How cramped is the work area where you will be photographing the specimens? Longer focal lengths give you more working distance between the front of the lens and the subject. This make lighting easier but can be a problem in cramped quarters.

How much magnification is needed? Consider the dimensions of the APS-C (crop) sensor in Pentax cameras is usually listed as 23.5 15.7mm.

So at 1x magnification a 15mm long/wide object would take up ~64% of the length of the sensor. A 5mm long object only ~21%.
At 2x magnification the 5mm object would take about 43%

Looking at the manual for the Pentax Auto Bellow-A (all lenses set to infinity):
for the Pentax M-50mm and A-50mm f/1.7 lenses (non-reversed)
values magnification, extension (mm), working distance (mm)
0.8, 42, 93
1.0, 52, 80
The same lenses reversed
1.0, 61, 90
2.0, 113, 64
3.0, 165, 56
M-Macro 100mm f/4 (non-reversed)
0.4, 40, 340
0.5, 50, 290
0.8, 80, 215
1.0, 100, 190
reversed - not given, not recommended.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
New K-3 owner first time setup up advice Stavri Pentax K-3 7 08-21-2014 01:41 PM
Prospective Pentax user requests advice on low light dance photo setup ebouwens Welcomes and Introductions 5 11-15-2013 10:14 AM
Macro Setup Advice Whitewind Pentax SLR Lens Discussion 4 07-21-2012 06:23 AM
Euro trip - kit setup advice? imaspy Troubleshooting and Beginner Help 47 08-12-2011 05:29 AM
Tripod/head setup - advice bpv_UW Pentax Camera and Field Accessories 10 02-12-2011 04:07 PM



All times are GMT -7. The time now is 06:34 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