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Old Sep 5, 2018, 11:17 PM   #1
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What do you think? Monarch butter caterpillar munching away on milkweed. Canon EOS Rebel T6, EF-S18-55mm f/3.5-5.6 IS II with +10 diopter lens, aperture priority f18, manual focus, ISO 2000, partial metering, cloudy WB, unedited
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Old Sep 6, 2018, 5:24 PM   #2
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G'day Linda


Hungry little blighter ain't s/he

I think that your image is 'pretty good' for the equipment you have at your disposal. Bright sun might show colours and allow more fine detail to be seen, but with that lens combo I reckon you've done okay

Keep playing / experimenting and find what the camera / lens setup can deliver before spending too much on other things

Phil
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Old Sep 6, 2018, 11:34 PM   #3
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Oh yes! All they do is eat and poop! I love to play and experiment. The only problem is there is never enough time. Alas! Thinking about extension tubes or macro lens. Thinking, thinking . . . . . . . . add them to my wish list!

Linda
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Old Sep 7, 2018, 4:02 PM   #4
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G'day Linda

re- extension tubes ...

You will have noticed how your zoom lens 'grows' as you zoom from 18 to 55 or 55 to 200 with the bigger lens ... this is called the 'trombone effect' while zooming. The focus module of the lens does something similar but not to the same degree. Basically, a lens starts off focussing at infinity and as it is moved away from the film / sensor, the focus point comes closer & closer

An extension tube is a hollow tube, one end clicks into the camera body, the other end receives the lens - and the size of the tube varies from 10mm to 30mm. They often come in a set of 3, each 10mm, 20mm & 30mm - and you can double them up if you want - 10+30 = 40mm sort of thing

As a general rule - with your dSLR, whatever mm's of lens you are using is added to an extension tube of 2/3 those mm's, then you will be viewing the object at 1:1 life-size. So if your 18-55 lens was at 30mm and you inserted a 20mm tube, your image on screen would be life-size. BUT- your depth of field becomes very, very small ... maybe 1/4" when using F22, so the focus must be very accurate

The downside of using tubes is that you cannot zoom when the tube is in use, as it alters the focus point dramatically and makes it unusable. Most people using tubes also use them on a single focal length lens to avoid zoom issues

Hope this helps
Phil
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Old Sep 9, 2018, 10:34 PM   #5
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Yes, I really appreciate all the info, Phil, since I am so green. I don't have any prime lenses yet, so all I have to work with for now are my zooms. I have a lot to think about. Just off the top of my head after you've explained the mechanics of the tube and the incredible narrow depth of field at f/22, perhaps my best option (albeit more expensive) would be a macro lens.

Cheers,

Linda

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Old Sep 11, 2018, 4:45 PM   #6
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G'day Linda

There are some 'laws of optics' that are with us all the time -

Using your 18-55 at 55 and selecting F22, say, the DoF will be identical to that of a good macro lens of 55mm single focal length also at F22. The real difference will be in the sharpness - the macro lens is designed for maximum sharpness during closeups, the zoom is designed to give a 'nice' image over a variety of zoom settings

Another law of optics says ...
"no matter what focal length of lens is in use, when the image size is the same, the Depth of Field will be the same"

So- if you had your 18-55 at 40mm and with an extension tube say, and moved in real close to get a beaut view of something, and someone else was using a 100mm macro lens alongside you and juggled their tripod to get the same image size as you were getting - even though the lenses were different distances from the subject, when the image sizes are the same, the DoF will be the same.

Differences will be seen in the sharpness of the image and the convenience of a greater lens-to-subject distance ... ie: you're not intruding into the spider's web for example

Hope this helps
Phil
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