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[OM] Re: Mini Macro questions

Subject: [OM] Re: Mini Macro questions
From: Moose <olymoose@xxxxxxxxx>
Date: Thu, 15 Mar 2007 17:43:30 -0700
Scott Peden wrote:
> Moose,
>
> I am interested.
>
> So you used a macro lens, 90/2.8 and then you cropped the images.
>   
Yes, I used the resolution of the sensor, rather than a lens that would 
focus closer, and threw away a lot of the original image area to end up 
with an image with the subject correctly framed.
> It sounds like what you are saying, is get a better lens. 
Yes - if you want better results quicker and easier. And by better, I 
mean both in general performance and in design suitability to the task 
at hand. If this is an exercise to have a lot of fun fussing around with 
cheap ways to use stuff in complex and inconvenient ways, forget I said 
anything. If you are trying to get the best images with the least 
trouble, that's where I'm trying to make suggestions.
> The 90 mm allows for shooting a 1:1 at a further distance away so that more 
> light is allowed in. 
First, I am not suggesting that you get a 90 mm lens. The camera I used 
for my examples has a sensor roughly twice as large as the one in your 
E-500. To get about the same working distance and angle of view on the 
E-500 that I had on the 5D, I am suggesting a 50 mm lens.
> The greater distance gives a better DOF too. 
>   
I don't know about that. There are a lot of factors involved in DOF, and 
I don't know what other lens set-up you would be comparing the 50/2.
> When I get real close, I may only get 10-20% of the frame in focus, yet I
> need that detail but of the whole object. With the Pixie cups, the lighting
> was terrible and when I did have sun it was reflective. The pics that got
> posted were from far away, the ones where I was just getting the cup itself
> in the picture only gave me a portion of the circle in focus.
>   
Yeah, that's a DOF issue, but, once they are cropped so that the cup 
appears large, is the DOF better than the other alternative? The version 
of your shot that I posted isn't as good as if I were working with the 
original image, but shows pretty clearly the DOF.
> I used a tri pod but looking though the view finder is  really a challenge,
> the viewfinder with my glasses is already hard enough to use, 
Using an f2 auto lens, you will find the viewfinder image much brighter. 
For macro, you will be shooting stopped down a lot, but the fast lens 
makes the viewfinder brighter for framing and focusing. Focusing at a 
larger aperture also makes the visual DOF when focusing very shallow, so 
it is easier to set the focal plane at just the right distance.
> but at some
> non comfortable angle, I can only see the center easily, to see the settings
> I have to move in such a way I can see the settings but then can't really
> see what I am shooting. Hence my desire to get back to having a LCD to
> compose with, but we are discussing Macro's.
>   
That is exactly what the E-330 is for. In B live view macro mode, you 
see on the LCD using the actual sensor that will capture the image. The 
LCD is adjustable for angle to make low angle shots easier, you can 
enlarge the image 10x on the screen for precise focus, and the DOF you 
see on the screen is exactly what you will get in the final image.

The E-330 is arguably the finest SLR made to date for macro work. The 
E-510 will lose the adjustable angle screen, but gain anti-shake. It 
looks from the prototype like the new pro model will have it all for macro.
> I'm not quite understanding this paragraph, let me know if my interpretation
> is correct;
> Moose wrote:
> "Absent a change of camera and knowing that you have an EX-25 on the way, 
> I really think you would serve your goal well by saving up some pennies 
> for the DZ 50/2 macro. The 35/3.5 macro is cheaper and doesn't need the 
> EX-25 to go to 1:1, but the 2 stops more speed will make a big 
> difference in manual focus ease and accuracy. It will also have better 
> stand-off distance from the subjects and probably a better lens overall."
>
> I can use the 35/3.5 macro but the DZ 50/2 is 2 stops faster for more light.
>   
More light for focusing, about the same for shooting. You can see better 
through the viewfinder, but will use the same f-stops ans shutter speeds.
> The 35/3.5 does 1:1 on it's own (does the DZ 50/2?)
>   
No, the 50/2 requires the EX-25 to get to 1:1. On its own, it only goes 
to 1:2. With 50/3.5 plus EX-25, you can get even closer. BUT, at the 
cost of being closer to the subject and dimmer viewfinder and more 
difficult focusing.
> Can I use the tube to get the image larger even though they are already
> Macro's, or is it just allowing me to get closer to the subject.
>   
They both happen together. Adding the tube requires you to get closer to 
the subject and also makes the image of the subject on the sensor bigger.
> Let me rephrase that as this is a question of it's own.
> The EX 25 lets me focus closer in, allowing me to get closer to the subject,
> allowing the tiny image I want to capture to be as large on the frame as
> possible, yes?
>   
Yes, with a trade-off or two. As you have mentioned, when you get really 
close, you tend to block the light. Also, as you get closer and the 
image gets bigger, the effective speed of the lens becomes less, and 
longer exposures are needed.
> Does it make a difference if I use a Macro lens or not when I have the EX
> 25, assuming they were, say for instance, both 50 mm lens?
>   
Yes, very much. All optical design is a series of compromises. A normal 
50 mm lens is usually calculated to give its best results at 1:40, and 
worl very well from infinity to about 18 inches, or about 1:10. With a 
25 mm tube, it will make a more magnified image, but the sharpness will 
be poorer than at its normal working distances. Reversing the lesn is a 
way to alleviate this issue at even closer distances with the bellows, 
but still a compromise. A true macro design is optimized for work at 
close distances. (It will have a flatter field as well, but that's of no 
consequence for what you are doing.)

The OM  Zuiko 50 mm macros have a longer focusing helicoid so they can 
focus to 1:2, rather then the 1:10 of the normal 50 mm lenses. My 
testing shows the 50/3.5 to perform exceptionally well at 1:2. It is 
still quite good at 1:1, but not as good. Oly made a whole series of 
macro lenses optimized for different repro ratios, The 80/4 bellows lens 
is designed for 1:1

In summary, a true macro lens will focus closer and perform better at 
higher magnifications than a normal  lens of the same focal length. It 
will also focus closer with an extension tube than will a normal lens on 
the same tube.
> <snip>
> So you now see little flowers too! 
Not entirely new to me, I just haven't done it for a while, nor with 
digital equipment.
> Now start looking at the bugs that make the flower world go round, 
Yup, I am forever noticing bugs I didn't see when I took the picture.
> and with this new equipment on the E-500 I have
> started noticing pollen on the 2 mm wide fruiting bodies. Darn near, at some
> point, I feel like I'll disappear into something looking at what it is made
> up of (remembering the needle head that was shared yesterday) I try to get
> easily recognized objects into much of my smaller photography, it all
> started out looking for a flower in a book that was white and 2 inches
> across, turned out that in the field it is 3/4 ths of an inch across and
> usually purple, by the time we had found one, we had passed thousands of
> them.
>   
Getting accurate color is also possible, but takes yet another area of 
knowledge and technique. Not terribly arcane to do a decent job, just 
more to pay attention to.

Moose

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