Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-25-2018, 08:46 AM - 3 Likes   #1
Loyal Site Supporter
Loyal Site Supporter
Thagomizer's Avatar

Join Date: Jun 2014
Location: London Ontario
Posts: 643
A game of millimeters (or parts thereof)...

There's nothing like a good lens to show up deficiencies in technique. Lately I've been doing a lot of macro work at greater than 1:1 using various reversed lenses. This morning I decided to use my Sigma 50mm f2.8, as I hadn't done much shooting with it of late. It felt a lot harder to get things to work with the sudden step back in perspective. My apparent keeper rate went down; at least that's what it felt like. It's easier to get the eyes of insects in focus when the eyes take up more of the image. There's plenty of wonderfully sharp detail in this shot (check out the plant hairs just in front of the beetle). But not the eyes. These were at f8. Maybe f11 would have been a better choice. Sunlight on the live-view screen certainly didn't help, either. It sounds like a reasonable excuse, but this is a timely (though maybe not welcome) reminder that I have to be more careful and take more time.




Last edited by Thagomizer; 07-25-2018 at 09:00 AM. Reason: fixing typo
07-25-2018, 10:50 AM   #2
Site Supporter
Site Supporter




Join Date: Sep 2014
Location: Bishop, CA
Posts: 180
I know exactly what you mean and have been pushing myself to face the same challenge.
Even with plants and non life forms getting that line of focus (even at 1:1) can determine the image and break it rather than make it.
Eyes just magnify the difficulty even more.

Would be curious to see a mathematical formula showing some proportional ratio of challenge to magnification. At 2x magnification is it twice as difficult?
Often feel it would be an increase of ten (even 100) fold but that is part of the joy when we hit it right on.

I still employ the techniques form my film days and spend some time working a shot, often much of that before i push the shutter.
This past year I have been enjoying projects that give me a keeper ratio of 1 or 2 out of 35 as opposed to 30% or higher.
It feels so good to be pushed again.

Nice to see this post and know others are always working on refining skills too and facing similar challenges.
Thanks for posting.
07-25-2018, 02:00 PM   #3
Site Supporter
Site Supporter
kiwi_jono's Avatar

Join Date: Dec 2009
Location: Christchurch, New Zealand
Photos: Gallery | Albums
Posts: 1,392
I'm no macro expert but for me I get passable results if I:
* Tripod if you are able (I always seem to end up not having a tripod when I see macro opportunities!).
* At least f11 and maybe f16
* ISO that allows a shutter speed faster enough to counter any movement. Even better a macro flash (or make a hood / diffuser / adaptor for a standard flash)
* Take several shots, tweaking focus for each
07-25-2018, 02:34 PM - 1 Like   #4
Pentaxian
photoptimist's Avatar

Join Date: Jul 2016
Photos: Albums
Posts: 3,124
QuoteOriginally posted by pcrichmond Quote
Would be curious to see a mathematical formula showing some proportional ratio of challenge to magnification. At 2x magnification is it twice as difficult?
Often feel it would be an increase of ten (even 100) fold but that is part of the joy when we hit it right on.
One relevant formula is:



From this formula you can see that the DOF @ 2:1 is nearly 3X thinner than the DOF @ 1:1.

But another key issue is that the effective aperture of the wide-open lens grows smaller with magnification. At 1:1 an f/2.8 lens is like an f/5.6 lens and at 2:1 an f/2.8 lens is like an f/8.4 lens. This makes the image dimmer by 2 stops at 1:1 and by 3 stops at 2:1. It also affects the use of the camera's AF system including focus confirmation and catch-in-focus although many only use manual focus for macro work.

07-25-2018, 02:55 PM   #5
Pentaxian




Join Date: Jun 2008
Location: Idaho
Photos: Gallery
Posts: 730
The fact that portions of your image were tack sharp says something for the lens but it's the depth of field that got you. For macro photos at that scale, f8 is going to have an incredibly small DOF which account for the creature's mid-section being in good focus but its head being beyond the DOF range (the portion of the leaf with hairs in sharp focus is the same distance from the lens as the mid-section although it doesn't appear that way). A compromise that looks better is to focus on the head or eyes and let the background parts go out of focus but that is a compromise.

You have few choices - you can stop the lens down further but at some point diffraction will begin to make the image look worse, or you can take several shots, moving the camera (or refocusing the lens) each time, and merge them in a single image where the different planes are all in good focus. The latter can be automated to a degree but you need specialized equipment and software. The former is the most practical approach but you need a good lighting source to overcome the high f values (and not cook your subject). One of the advantages of many macros is that they can be stopped down beyond the usual f16-22 range (which as photoptimist pointed out become even larger f values at higher magnification ratios), but that ability makes them more useful than regular lenses for closeup work.

All this leads us to really appreciate the fantastic work some photographers do at the micro level where DOF can be measured in microns.

Still to be said, your photo is a good one and you can gain experience through such efforts.

Last edited by Bob 256; 07-25-2018 at 03:01 PM.
07-26-2018, 06:05 AM   #6
Loyal Site Supporter
Loyal Site Supporter
TER-OR's Avatar

Join Date: Apr 2009
Location: Dundee, IL
Photos: Gallery | Albums
Posts: 6,354
It's tough getting that close. Stopping down is a must, I typically use f16 in the field, but if you have enough light you can go further. A flash will help, a ringflash will help more. A diffused ringflash is ideal. It does make a pretty large rig, though.

Any motion from a breeze will make your image unstable. Welcome to my world.
07-26-2018, 07:03 AM   #7
Loyal Site Supporter
Loyal Site Supporter
Thagomizer's Avatar

Join Date: Jun 2014
Location: London Ontario
Posts: 643
Original Poster
Thank you all for the comments. I was using live view with focus peaking when taking the shot, but that wasn't enough to get the eyes. Focus peaking would have outlined the area that was in focus, but the eyes would have been within that outline, though not outlined themselves. At the higher magnifications I often shoot at, determining when the eyes are highlighted in focus peaking is much easier, as they are proportionately larger on the screen and more clearly distinguished from the rest of the head. The plane of focus is more obvious. At 1:1, the eyes can be lost within the focus peaking highlights of mandibles or antennae, say. Magnified live view would have helped me to distinguish the focus on the eyes, but my hands are not as steady as they used to be and magnified view cuts out as soon as pressure is applied to the shutter release button. For my usual lower light shooting on my front porch, I can often brace myself or the camera against the the same wall on which my subjects are often parked. I can carefully slide the camera along the wall until I've got what I want. For shots like these in the field (as opposed to on the porch) I could try using a monopod again, but I do find it restrictive.

---------- Post added 07-26-18 at 10:13 AM ----------

More macrophotography CSI. Here's another unsuccessful shot, showing either camera or subject movement. Not by much, but still too much.



More flash power combined with a smaller aperture would have killed the ambient light. Using the flash sync. speed of 1/180, instead of the 1/100 sec. shutter speed used would have helped, too. As it is the ambient light was strong enough to register the movement of the subject or camera during the exposure before the flash burst at the closing of the shutter. This is more obvious in the 100% crop, visible as a ghostly trail just to the left of brighter areas. It was breezy at times while I was shooting, so that might be the culprit.



With my usual low-light shooting, ambient light is dim to non-existant, so the flash is the only light source for the entire exposure. Short flash duration acts like a very fast shutter speed, freezing any movement. With my reversed cine lens on extension, the effective aperture at nearly 4:1 is a lot smaller than the indicated f8, much smaller than the effective aperture on this nominal f9 exposure with the Sigma 50mm at 1:1. That goes a long way towards defeating the ambient light of the base exposure before flash. I can also tell the difference between the two lenses in the difference in the appearance of the dirton my sensor, which is much more prominent at smaller effective apertures of the reversed cine lens than the Sigma 50mm.

I do actually have pictures that work, but sometimes duds can be very instructive.
07-26-2018, 08:59 AM   #8
Site Supporter
Site Supporter




Join Date: Sep 2014
Location: Bishop, CA
Posts: 180
QuoteOriginally posted by photoptimist Quote
One relevant formula is:



From this formula you can see that the DOF @ 2:1 is nearly 3X thinner than the DOF @ 1:1.

But another key issue is that the effective aperture of the wide-open lens grows smaller with magnification. At 1:1 an f/2.8 lens is like an f/5.6 lens and at 2:1 an f/2.8 lens is like an f/8.4 lens. This makes the image dimmer by 2 stops at 1:1 and by 3 stops at 2:1. It also affects the use of the camera's AF system including focus confirmation and catch-in-focus although many only use manual focus for macro work.
Very interesting!
I always knew DOF gets thinner with magnification and try to adjust with smaller apertures. Usually starting at 16 and sometimes going down to 32 if I have the light.
Hadn't thought about stops of light loss for a long time, guess I've gotten spoiled with the LV. Will have to start keeping that in mind also.

@Thagomizer, which cine lens are you using?
For 1:1 or so I still use the Raynox 150 on my M200/4 but if I'm wanting to go larger I use either a Rodagon 105 or Omicron 90. Though the Raynox is a descent performer, I always feel I get better results from the reversed lenses. Funny how you mentioned the characteristics of the sensor dust due to different lenses, I've been noticing that too.
I should try to get myself more comfortable using a tripod but find myself such a hand hold addict bracing on whatever I can find as you mentioned.
Ambient light to flash seems to be a constant challenge also. I'm using an of camera diffused flash on an arm and usually have it in the 1/16 to 1/32 power range. Wondering if a tripod might help to bring this ratio closer as there wouldn't be the need to compensate for body shake?

07-26-2018, 10:01 AM - 1 Like   #9
Loyal Site Supporter
Loyal Site Supporter
Thagomizer's Avatar

Join Date: Jun 2014
Location: London Ontario
Posts: 643
Original Poster
QuoteOriginally posted by pcrichmond Quote
@Thagomizer, which cine lens are you using?
For 1:1 or so I still use the Raynox 150 on my M200/4 but if I'm wanting to go larger I use either a Rodagon 105 or Omicron 90. Though the Raynox is a descent performer, I always feel I get better results from the reversed lenses. Funny how you mentioned the characteristics of the sensor dust due to different lenses, I've been noticing that too.
I should try to get myself more comfortable using a tripod but find myself such a hand hold addict bracing on whatever I can find as you mentioned.
Ambient light to flash seems to be a constant challenge also. I'm using an of camera diffused flash on an arm and usually have it in the 1/16 to 1/32 power range. Wondering if a tripod might help to bring this ratio closer as there wouldn't be the need to compensate for body shake?
I've got several, but my favourite, and most used, is the D mount Kinotel 1.5" f1.9 made for 8mm movie cameras. I usually use it with a set of Vivitar AT-22 auto extension tubes (12, 20 and 36mm), giving a total of 68mm of extension. With this combination I can get nearly 4X magnification. The Kinotel came with a filter ring, so it was pretty easy to mount in a hole drilled into a body cap, using an appropriately sized opening sliced from a plastic drafting circle template as a shim betwteen the lens and the filter ring by which to stick it into the cap.

I've also been doing a lot of shooting with a reversed DA 18-55 II, which becomes a serviceable macro zoom lens, allowing me to change magnification by turning the zoom ring. Lots of fun!

I've got a Rodenstock 50mm f4 and Vivitar 50mm f3.5 enlarging lenses, but haven't done much with them. I'll have to give them a chance to audition. I've thought about getting the 150 and 250 Raynox lenses to use as a convenient add-on to regular or macro lenses. The results that others get look very good. I've got so many ways I can get to macro it almost seems like overkill to get more!

I'm usually using the K-S2's built in pop-up flash with a Pringles tin extender/diffuser to get the light out to my subjects. It works very well. I'm thinking of getting an AF 360FGZ II to have a more powerful flash option with adjustable manual power as well as PTTL capability. Adding the flash and bracket would make my rig bigger and heavier, though, and I do like the simplicty and low profile, low weight and low bulk of the built-in unit with diffuser.
07-26-2018, 04:02 PM - 1 Like   #10
Senior Member




Join Date: Sep 2015
Posts: 259
Getting enough light with extreme macro is always a challenge. I sometimes use the Nanoha lens that goes to 4x or 5x and it's hard to get anything in focus, especially anything meaningful. I also use the Venus 2x lens for Pentax and find that is a more reasonable magnification, but even with that the depth of field is tiny. Probably better suited to shooting on a tripod with non-moving subjects, but I like the challenge of having a mini safari in my garden with insects. I'm just prepared for a very low success rate
07-26-2018, 05:03 PM   #11
Site Supporter
Site Supporter




Join Date: Sep 2014
Location: Bishop, CA
Posts: 180
QuoteOriginally posted by Thagomizer Quote
I've also been doing a lot of shooting with a reversed DA 18-55 II, which becomes a serviceable macro zoom lens, allowing me to change magnification by turning the zoom ring. Lots of fun!
I haven't thought about a light weight zoom. Anything above the approximate 2:1 I listed above with the enlarger lenses I've been forced to use a tripod even with flash.
A small zoom might be great for the field. Thanks, I'll have to give it a try.
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!
ambient, aperture, camera, depth of field, exposure, eyes, flash, focus, game of millimeters, light, live view, lot, macro, missed shot, movement, photography, shutter, sigma 50mm f2.8, technique
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Inspiration or the lack thereof? rbefly Photographic Technique 14 10-09-2012 01:25 AM
K5 lcd screen dimensions in millimeters? pakinjapan Pentax K-5 3 09-20-2012 11:51 PM
"The Problem is Demand" (or the lack thereof) dadipentak General Talk 4 07-11-2012 12:05 PM
Lens hoods and use thereof. (take 2) amateur6 Pentax SLR Lens Discussion 34 02-17-2010 01:47 AM



All times are GMT -7. The time now is 05:47 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