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-   -   Re: Macros (http://www.velocityreviews.com/forums/t958729-re-macros.html)

dadiOH 03-16-2013 07:39 PM

Re: Macros
 
Alan Browne wrote:
> http://memolition.com/2013/03/15/the...y-27-pictures/


Those are nothing short of EXCELLENT!!

--

dadiOH
____________________________

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Taxes out of hand? Maybe just ready for a change?
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Nige Danton 03-24-2013 05:45 AM

Re: Macros
 
"dadiOH" <dadiOH@invalid.com> wrote:
> Alan Browne wrote:
>> http://memolition.com/2013/03/15/the...y-27-pictures/

>
> Those are nothing short of EXCELLENT!!


They are brilliant aren't they. Can anyone offer recommendations for a
guide (online or a book) as an introduction to the techniques and kit for
this type of photography? Currently have a D7000 and an 18-105 lens.

--
Nige Danton - Replace the obvious with g.m.a.i.l

Tony Cooper 03-24-2013 02:47 PM

Re: Macros
 

On Sun, 24 Mar 2013 05:45:20 +0000 (UTC), Nige Danton
<nige.danton@nospam.com> wrote:

>"dadiOH" <dadiOH@invalid.com> wrote:
>> Alan Browne wrote:
>>> http://memolition.com/2013/03/15/the...y-27-pictures/

>>
>> Those are nothing short of EXCELLENT!!

>
>They are brilliant aren't they. Can anyone offer recommendations for a
>guide (online or a book) as an introduction to the techniques and kit for
>this type of photography? Currently have a D7000 and an 18-105 lens.


I suggest you go to Digital Grin (www.dgrin.com) and follow the forum
on Macros. You'll see the good and the bad, and a lot of tips and
information. Check for new posting frequently.

Pay special attention to the contributions by "Lord Vetinari" and
follow the links to his website. There's no better macro shooting and
teacher around than Brian.

--
Tony Cooper - Orlando FL

PeterN 03-24-2013 08:18 PM

Re: Macros
 
On 3/24/2013 1:45 AM, Nige Danton wrote:
> "dadiOH" <dadiOH@invalid.com> wrote:
>> Alan Browne wrote:
>>> http://memolition.com/2013/03/15/the...y-27-pictures/

>>
>> Those are nothing short of EXCELLENT!!

>
> They are brilliant aren't they. Can anyone offer recommendations for a
> guide (online or a book) as an introduction to the techniques and kit for
> this type of photography? Currently have a D7000 and an 18-105 lens.
>


In addition to Tony Cooper's comments, If you put an extension tube on
your lens, you will be able to move closer to the subject. The tradeoff
is that you will have a smaller depth of field, which you can use to
your advantage.


--
PeterN

Nige Danton 03-25-2013 03:40 AM

Re: Macros
 
PeterN <peter.newnospal@verizon.net> wrote:

> In addition to Tony Cooper's comments, If you put an extension tube on
> your lens, you will be able to move closer to the subject. The tradeoff
> is that you will have a smaller depth of field, which you can use to your advantage.


Great, thanks for the suggestion. I'll have a look and see what's
available. I'll probably be back with more queries.

--
Nige Danton - Replace the obvious with g.m.a.i.l

Nige Danton 03-25-2013 03:40 AM

Re: Macros
 
Tony Cooper <tonycooper214@gmail.com> wrote:
> On Sun, 24 Mar 2013 05:45:20 +0000 (UTC), Nige Danton
> <nige.danton@nospam.com> wrote:


>> They are brilliant aren't they. Can anyone offer recommendations for a
>> guide (online or a book) as an introduction to the techniques and kit for
>> this type of photography? Currently have a D7000 and an 18-105 lens.

>
> I suggest you go to Digital Grin (www.dgrin.com) and follow the forum
> on Macros. You'll see the good and the bad, and a lot of tips and
> information. Check for new posting frequently.
>
> Pay special attention to the contributions by "Lord Vetinari" and
> follow the links to his website. There's no better macro shooting and
> teacher around than Brian.


Thanks very much i'll go and register.

--
Nige Danton - Replace the obvious with g.m.a.i.l

Trevor 04-12-2013 02:22 AM

Re: Macros
 

"ruben safir" <dont@email.me> wrote in message
news:kk3dj4$sds$5@reader1.panix.com...
> On Sun, 07 Apr 2013 11:46:26 +0100, R. Mark Clayton wrote:
>
>> A short piece of tube that goes between the lens and the body and means
>> that the lens will focus on nearer objects.

>
> How does that geometry work? The longer the tube the greater the
> magnification? no...


A tube doesn't magnify anything. It does allow you to focus closer however,
which will give you a bigger image at the sensor *if* you move the lens
closer to the object.

Trevor.



Wolfgang Weisselberg 04-12-2013 09:31 PM

Re: Macros
 
Alan Browne <alan.browne@FreelunchVideotron.ca> wrote:
> On 2013.04.10 06:06 , ruben safir wrote:


>> How does that geometry work? The longer the tube the greater the
>> magnification? no...


> You're moving the focal plane further away so the image is "spread out"
> resulting in a smaller area of the scene on the film or sensor. Of
> course there is a penalty in the amount of light received (1/r^2) that
> follows the increased focal length so exp. times are longer.


> eg: 50mm pushed out 50mm (ext. tube length) becomes 100mm


> A 50mm f/1.8 lens has an aperture of 27.8mm


> So at 100 mm it becomes: 100/27.8 = f/3.6.


Actually, it's worse. That calculation of yours is only 100%
true for infinite distances (and close at longer distances).

An extension tube means you're getting really close ... as
otherwise you can't focus. Then the effective aperture is
smaller (depending on the magnification).

Similar with the crop factor: it's only true for long distances;
at close distances the crop factor fades away.

At least that's how I understand it.

-Wolfgang

Trevor 04-22-2013 05:46 AM

Re: Macros
 

"Eric Stevens" <eric.stevens@sum.co.nz> wrote in message
news:ie99n8tj0prr9so3lpevfvsb4oab08flht@4ax.com...
> On Sun, 21 Apr 2013 22:57:07 +0000 (UTC), ruben safir <dont@email.me>
>>On Sat, 20 Apr 2013 21:21:31 +1200, Eric Stevens wrote:
>>>>parrellel rays is not focused on infinity
>>>
>>> Correct.
>>>
>>> Parallel rays are generated by an object at infinity. When you focus a
>>> lens at an object at infinity the rays from that object to the lens are
>>> parallel (until they hit the lens).

>>
>>How is that possible? An object 6 feet wide focused at inifinity can not
>>produce parallel light on the lens, otherwise the light would be too wide
>>to fit on the lens (and a pinhole camera would never work).

>
> It would if the 6 feet wide object was an infinite distance away.


Actually no, the light would be warped by the gravitational field of every
star system between the object and the lens! :-)

Trevor.



Wally 04-23-2013 01:50 AM

Re: Macros
 
On Sun, 21 Apr 2013 22:57:07 +0000 (UTC), ruben safir <dont@email.me>
wrote:

>On Sat, 20 Apr 2013 21:21:31 +1200, Eric Stevens wrote:
>
>>>parrellel rays is not focused on infinity

>>
>> Correct.
>>
>> Parallel rays are generated by an object at infinity. When you focus a
>> lens at an object at infinity the rays from that object to the lens are
>> parallel (until they hit the lens).

>
>
>
>How is that possible? An object 6 feet wide focused at inifinity can not
>produce parallel light on the lens, otherwise the light would be too wide
>to fit on the lens (and a pinhole camera would never work).


The rays are not parallel, but are nearly so... and behave effectively
like parallel rays when they hit the lens.

Here is a little math exercise for you: calculate the difference in
angle for the rays hitting the top and bottom of the lens. (Make
assumptions as necessary.)

W


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