macro questions

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Archive 2009 · macro questions

aFrIcanSH
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p.1 #1 · macro questions

Hope this is in the right section. I've been shooting macro for just over 2 years now but feel the 'need' for some more magnification. I've got the D300, 105mm VR and plan to pick up an R1 macro flash kit. But i'm a little confused about magnification. Right now i'm thinking my 2 favored options would be kenko extension tubes (12, 20, 36mm) or a macro filter and i've heard some things about this raynox DCR250 or something. Which of the two would give me more magnification? Thanks a million. I may crop a little of the picture if necessary but I think i'd want to avoid doing so.

I might combine both the filter and tubes in the future. Or add more tubes. But the working distance in the first place isn't much is it?

Oct 30, 2009 at 08:56 AM

LordV
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p.1 #2 · macro questions

Hi,
I'd go for a set of extension tubes first will give you a max of 2:1 magnification with all the tubes.
The Raynox will give you around 1.84:1 max mag. Raynox plus tubes would give 2.84:1 mag.

If you have a 50mm prime lens you can reverse that on the front of the macro lens and get 3:1 max mag and in combination with the ext tubes, 4:1 mag

Brian V.

Oct 30, 2009 at 09:54 AM

aFrIcanSH
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p.1 #3 · macro questions

How'd you do those calculations? Would be easier for me to have some idea if possible

I realised that with the tubes I could get around 1.6x with the tubes (apparently 105 + 68/ 105) I want to get the most out of the 105. Apparently macro filters get more magnification with longer focal lengths or something, so is it safe to say a 55-200mm at 200mm would get greater mag than a 105? I know the 12mp sensor of the D300 might give me some leeway to crop 2x, say until 6mp ish

I probably won't get a macro filter. I'm actually a bit worried about working distance too. What's a good compromise? I know a costlier alternative would be a 1.7x teleconverter. I'm rather confused actually. Thanks

Oct 30, 2009 at 10:02 AM

LordV
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p.1 #4 · macro questions

Hi, - actually knew these because I have a sigma 105

But macro lens with extn tubes isn't quite as simple as you show.
Normal calc is as you use = exist mag + ext tube mm/focal length mm
but unfortunately a macro lens shortens it's focal length at min focus and this together with some other errors leads to an under estimate of the magnification.
You will get 2:1 mag with your lens and a full set of kenkos- trust me

Other calcs are just reversed lens calcs.
First focal length of a dioptre lens = 1000/dioptre no
DCR-250 is + 8 dioptre= 1000/8=125mm focal length

Mag of macro lens with dioptre or reversed lens on front = exist mag + focallength macro lens/focal length reversed lens

so for DCR-250 = 1+ 105/125 - for reasons I do not undestand this calc works accurately without taking into account the shortened focal length of the macro lens

with a reversed 50mm lens = 1+ 105/50 approx 3:1 and with ext tubes = 2+ 105/50

You are correct that ext tubes give higher mags with shorter focal length lenses and add on dioptres higher mags with longer focal length lenses.

The shortening effect on the focal length at min focus = approx min focus distance/4 which I suspect for your lens will be around 78mm but even using this figure in the ext tube calc gives a slight under-estimate of the actual mag achieved

Brian v.

Oct 30, 2009 at 10:33 AM

aFrIcanSH
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p.1 #5 · macro questions

So my best bet would be tubes and the 105. I don't think i'll use a TC cause its costly. I'll skip the filter too. 2:1 should be fine i guess i could crop a bit and get 3:1 or 4:1?

A reversed 50mm would also be a good option cause i found the cost of the 50 and BR-2A or something is almost the same as the 105 and the 3 tubes plus id get a 50mm f1.8 to play with. But working distance is another thing i have to take into account. Which of the two would give a better working distance then?

Oct 30, 2009 at 11:15 AM

Kenj8246
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p.1 #6 · macro questions

You can always snap a shot of the mm side of a ruler as well. Divide the sensor size of the D300, 23.7mm by the number of mm marks showing in your image and the result is the magnification factor.

This image is copyrighted by the owner

The quick image above was taken with my D300, older Nikkor 105mm lens 80mm of extension (Nikon PN-11 and PK-13) and a Raynox DCR150, a +4 diopter. My math shows 23.7 / 8 = 2.96. Pretty darn close to 3:1. Granted, the working distance is slim and the DOF is very thin, but high mags can be achieved with your 105VR and enough 'help'.

Kenny

Oct 30, 2009 at 11:27 AM

LordV
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p.1 #7 · macro questions

aFrIcanSH wrote:
So my best bet would be tubes and the 105. I don't think i'll use a TC cause its costly. I'll skip the filter too. 2:1 should be fine i guess i could crop a bit and get 3:1 or 4:1?

A reversed 50mm would also be a good option cause i found the cost of the 50 and BR-2A or something is almost the same as the 105 and the 3 tubes plus id get a 50mm f1.8 to play with. But working distance is another thing i have to take into account. Which of the two would give a better working distance then?

I'm not a fan of using TCs for macro - I'm too much of a detail junkie.
To reverse a 50mm lens onto the 105 you would need a male/male reverse coupler guessing with 52mm/58mm thread sizes - this is not the same as a BR2A which is a reverse lens to body coupler. The advantage or reversing a lens onto another lens is you maintain complete aperture etc control via the main lens (the reversed lens is used wide open and normally focused on infinity).
Any of the higher mag systems will obviously shorten the min focus distances. Think with the 105 + ext tubes you will be around 3" in front of the lens. With a reversed 50mm on the front around 2" in front of the lens.
Brian V.

Oct 30, 2009 at 11:30 AM

aFrIcanSH
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p.1 #8 · macro questions

I'll probably go with tubes first then. I came across a male/male coupler thing today for around $10 which is not that bad but tubes seem like a decent option.
Thanks for the idea about the mm ruler thing.

Oct 30, 2009 at 12:01 PM


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