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03-19-2010, 11:45 PM   #1
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Macro performance on long vs. short lenses

I own a Tamron AF 90mm f/2.8 Di and it is my only Macro lens. I find the macro difficult to focus hand-held, and I'm wondering if I may have better luck with a DA 35 Limited Macro. More generally, how does the focal length of the lens alter macro performance?

03-20-2010, 12:26 AM   #2
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QuoteOriginally posted by harmonica2 Quote
I own a Tamron AF 90mm f/2.8 Di and it is my only Macro lens. I find the macro difficult to focus hand-held, and I'm wondering if I may have better luck with a DA 35 Limited Macro. More generally, how does the focal length of the lens alter macro performance?
you need a tripod for macro for steady focus, not a different macro lens.
03-20-2010, 12:43 AM   #3
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the answer lies in depth of field

Depth of field is the part of the photo that is sharp. Aperture controls this depth. Focal Length also changes Depth of Field. For example: your 90 mm lens at f2.8 has a shallower Depth of field than a similar 50 mm f2.8 lens. This is due to focal length.

tip 1 don't shoot macro without a tripod and remote unless you have to.

tip 2 increase your aperture to make focus easier if you are handheld.
03-20-2010, 01:01 AM   #4
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If you want great depth of field (DOF) in macro work, you NEED a tripod. "Razor-thin" just barely describes the DOF when you're at magnifications of 1:2 and greater. So you need very small apertures; and with lens extension, your effective aperture shrinks; and for a clear sharp shot, that means long tripod exposures. Here's where I describe what happens to effective aperture at extension: https://www.pentaxforums.com/forums/pentax-beginners-corner-q/94262-quick-mac...tml#post961588

QuoteQuote:
More generally, how does the focal length of the lens alter macro performance?
Without invoking too much math, magnification is a function of focal length and distance. You increase magnification by adding extension, i.e. by putting the lens further from the sensor or film plane. The formula is: MAG = EXT / FL where EXT is the amount of extension, and FL is the focal length of the lens.

Macro lenses work by extending the lens out. You get the same effect by adding extension tubes or bellows to a standard lens. And it's the lens' focal length that determines the extension needed for any specific magnification.

What's that mean? For 1:1, you can extend a 35mm lens by 35mm, a 50mm lens by 50mm, a 90mm lens by 90mm, etc. And at shorter focal lengths, you must be closer to the subject to reach any specific magnification. So a 105mm lens at 1:1 lets you work three times further from the subject than you would with a 35mm lens, also at 1:1. Shorter lenses are good for small stuff you can close in on. Longer lenses are usually considered better for field work.

Those are the basics. Now, don't get me started on trap-focus...

03-20-2010, 01:02 AM   #5
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Yeah, it doesn't really matter what your focal length is when you're looking at reproduction ratios. You need to stop down to get depth of field which means you need more light to get shutter speeds up to an acceptible picture.

Photography is about comprimise and macro is no exception!
03-20-2010, 01:25 AM   #6
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When you are looking for the sharpest lens for the lowest price you might end up with a 50mm macro lens. If bugs are what you're hunting for the two times bigger working distance of the 90/100/105 mm is your thing.
DOF is not changing by the focal length of your lens compairing the same magnification.
Getting something small in focus is a matter of practice in the field.
Setting your camera in AF and using the lens MF you can press the release button in advanche
and trigger the shutter by moving your camera in position "target in focus".
I hope my bad English is not blurring my point of view, but basically : don't buy another lens
untill you understand what your "problem" is.
Macro is laying on your belley in the grass for hours and mayby coming home with one or two fine pics...
and having lots of contact with nature. Have fun.

Last edited by freewheeler; 03-20-2010 at 01:36 AM.
03-20-2010, 04:18 AM   #7
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I do a lot of macro, mostly hand held (insects, for plants I use more frecuently the tripod), with my Tamron 2,5/90, with and without the 1,4x TC. You have to adjust very well the diopter at the eyepiece (if you need to), find the right angle to get the focal plane exactly in the best orientation, and it is normally better to close diafragm to 5,6-8 for plane objects, and 11-16 for more tridimensional. A good way for nice backgrounds is measuring exposure for the background and subexposing one or two steps, using the flash for fill in ilumination of the main object (in M-Mode, if you subexpose the pttl flash will complete the difference).

Cheers - Klaus
03-20-2010, 05:26 AM   #8
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All that said, speaking as a hobbyist, and as a mostly weekend family photographer, the DA 35 allows you to use it as a walk-around lens and easily go from landscape shots, to people shots, to colorful and sharp macro shots. It is easier to hand-hold compared to the longer macro lenses, and it is not like I walk around with a tripod when I go on a walk with my family, or to a playground or a pool, etc. The DA 35 may be certainly worth a shot for what you are looking for. It's no mystery why it is as highly regarded a lens as it is.

03-20-2010, 06:28 AM   #9
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I'm using a long lens currently for macro (Sigma 70-300) and extension tubes on other lenses. There are advantages sometimes with the longer lens, especially with insects which would be difficult to get close to. I also find it a great lens for getting close ups along the shorelines when I'm paddling my kayak. I can shoot without getting out. It also works well getting shots of subjects such as butterflys which move a lot and don't let you get too close. While not a true 1:1 macro, the lens does an excellent job. The long length doesn't work well inside however. I don't do a lot of indoors macro work but when I do, it's usually my 55/f2 Tak and an extension tube. What you need for a length really depends on what your are shooting and where. As for focusing, I always focus manually. For macro, you have to be right on the money, slow and patient. If money was no object, I could come up with several good reasons to own a bag full of macros, a 35, 50, 100, and 200.
03-20-2010, 09:05 AM   #10
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Thanks for the responses! Still confused about DOF in macro mode.

I love this forum - lots of thoughtful responses! I do in fact have a tripod, but it's macro hand-held where I experience focus problems that are bad enough I am considering another lens.

So far, there seem to be two reasons I would have better luck in macro mode with the DA35 Limited: The focus distance is almost 2/3 shorter, so perhaps I will have the ability to hold the subject still (like a flower or my baby's hand) with my left hand, while the camera body will be easier to hold steady due to the more compact limited lens.

There seems to be some disagreement as to whether DOF is different in Macro mode between these two lenses under the same lighting conditions. How does one compute the DOF in macro?
03-20-2010, 09:19 AM   #11
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I have better results hand holding my DA 35mm compared to the Sigma 105mm or either of my Tamron 90mm lenses. One of reasons is that the focal length is shorter. When hand holding the rule of thumb is 1/focal length for minimum shutter speed not taking SR into account because I may or may not have it on depending on the situation.
03-20-2010, 09:52 AM   #12
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QuoteOriginally posted by harmonica2 Quote
I love this forum - lots of thoughtful responses! I do in fact have a tripod, but it's macro hand-held where I experience focus problems that are bad enough I am considering another lens.

So far, there seem to be two reasons I would have better luck in macro mode with the DA35 Limited: The focus distance is almost 2/3 shorter, so perhaps I will have the ability to hold the subject still (like a flower or my baby's hand) with my left hand, while the camera body will be easier to hold steady due to the more compact limited lens.

There seems to be some disagreement as to whether DOF is different in Macro mode between these two lenses under the same lighting conditions. How does one compute the DOF in macro?
there were some previous discussions regarding DOF and FL. people say that the FL of a lens has an influence on the DOF. or that a 35mm at f2.8 has a different DOF view compared to the 90,100, 105, 150, 180, 200mm at f2.8. is it really different or is it due to field perception? however, people must consider the 1:1 magnification ratio, focusing distance, actual subject dimensions and FOV of certain focal lengths. if one were to replicate the same center subject dimension, the DOF would still be the same but not the image's FOV.

Last edited by Pentaxor; 03-20-2010 at 10:17 AM.
03-20-2010, 09:58 AM   #13
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Besides working distance, another advantage of longer focals is that they give you a more beautiful background (more uniform). I even would prefer a 150 or 180 then the 90 + 1,4x TC I mostly use. With enough practice I am shure you will get sharp results with longer focals. On this site you can see a lot of my macros (lens, exposure and diafragm are indicated with the shots):
Mirada Natural. Galería fotográfica de Klaus Kamppeter

Cheers - Klaus
03-20-2010, 10:19 AM   #14
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QuoteOriginally posted by harmonica2 Quote
So far, there seem to be two reasons I would have better luck in macro mode with the DA35 Limited: The focus distance is almost 2/3 shorter, so perhaps I will have the ability to hold the subject still (like a flower or my baby's hand) with my left hand, while the camera body will be easier to hold steady due to the more compact limited lens.
If you want one-handed macro close-ups, you will need a ringflash, or a carefully crafted multiflash setup like a metal bracket with the camera in the middle and angled flashes at each end. A ringflash is simpler.

And your working distance might get closer than you want. I just measured, using my 90mm macro at 1:1, and a 35mm on 36mm of extension (also 1:1). The 90 worked around 5 inches. The 35 worked around 1.5 inches. That's lens-front to subject. For comparison, I put a 50mm lens on 49mm extension (also 1:1) and got a working distance of 3 inches.

QuoteQuote:
There seems to be some disagreement as to whether DOF is different in Macro mode between these two lenses under the same lighting conditions. How does one compute the DOF in macro?
Ha. [pause] Ha.

The Online DOF Calculator (which is buggy as hell) is about right here: with a 35mm lens on your Kx at f/32, focused at 2 inches, your DOF is 0.03 inches, from 1.98 to 2.02 inches. And that's when you're stopped down to f/32. (Why do I say this Calculator is buggy? Because it gives your hyperfocal distance as 76.7 inches!) Change the lens to 90mm and the calculated DOF is just the same: 0.03 inches. Less than 1mm. Even assuming that better calculators are around, that's pretty close to the DOF you'll get with ANY lens setup at 1:1.

Last edited by RioRico; 03-20-2010 at 10:24 AM.
03-20-2010, 10:22 AM   #15
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QuoteOriginally posted by Klaus Quote
Besides working distance, another advantage of longer focals is that they give you a more beautiful background (more uniform). I even would prefer a 150 or 180 then the 90 + 1,4x TC I mostly use. With enough practice I am shure you will get sharp results with longer focals. On this site you can see a lot of my macros (lens, exposure and diafragm are indicated with the shots):
Mirada Natural. Galería fotográfica de Klaus Kamppeter

Cheers - Klaus
OOF FOV of a longer focal length macro looks more uniform due to a much closer FOV. I believe that there is no contest that an independent longer macro would be better than a shorter macro with a TC. besides, you lost a stop there.

and yes, a longer telephoto macro is a joy to use.
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