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-   -   Macro question (https://e-group.uk.net/forum/showthread.php?t=4705)

SkinHead 28th February 2009 08:08 PM

Macro question
 
Hi everyone,
i am new to this forum and consider myself a photo hobbyist. apart from the E-510 and 2 kit lenses(14-42mm and 40-150mm), i also have the 70-300mm lens. i am contemplating on buying a macro lens however i dont know which one yet...
i am looking to buy the Sigma 18-50mm f2.8. i know its a macro but is this a macro in the truest sense? i have been going through a lot of reviews on macro lenses and they are all single focal length lenses which makes sense as they are intended solely for that purpose. but pictures taken by the sigma were mostly wide and close-ups but no macro shots(havent found one). i have also read that this is a considerably fast lens and a good all rounder as well.
has anyone have any experience using this lens?
would this be a good choice to add to my equipment or should i go for the proper macros?
Thanks

mike_j 28th February 2009 08:46 PM

Re: Macro question
 
It all depends on what you mean by macro. Strictly it is 1:1 magnification. A lot depends on what you want to photograph. Flowers and butterflies don't need 1:1, extreme insect close ups etc probably do. The other factor controlling the choice of lens is the working distance. Inanimate objects don't mind the lens a couple of centimetres away, insects do! Longer focal lengths give more working distance.

The Sigma sounds like a decent enough lens but with a maximum magnification of 1:3 is not really macro - just close focus.

The best dedicated lenses for macro on 4/3 are the 35mm and 50mm ZDs with the EX-25 extension tube as required. The former gives very short working distances. There are also various excellent 'legacy' lenses, the problem with these is that they are manual focus and aperture.

Look through this forum and there are endless threads and gallery pictures on macro.

photo_owl 28th February 2009 11:02 PM

Re: Macro question
 
as Mike highlights the sigma won't offer you any more than your 70-300 in terms of magnification - for insects and flowers that lens is pretty good already.

many people in your situation get the 50/2 as it's a great multi purpose lens with stunning sharpness and contrast.

Ellie 1st March 2009 12:02 AM

Re: Macro question
 
Quote:

Originally Posted by mike_j (Post 38719)
It all depends on what you mean by macro. Strictly it is 1:1 magnification.

Ah! Maybe this is the place to ask my question, because this is something I find rather confusing.

Can somebody explain, and if possibly show with pictures, what the difference is between a picture taken with a 50mm lens and a 50mm "macro" lens please. I suppose it would need to be of exactly the same thing, taken from exactly the same position.

Also, why would you (anybody) need a dedicated 50mm lens if you've already got a zoom lens that covers the same - 40-150mm for example - or should it be obvious?

PeterD 1st March 2009 02:34 AM

Re: Macro question
 
Quote:

Originally Posted by SkinHead (Post 38717)
Hi everyone,
i am new to this forum and consider myself a photo hobbyist. apart from the E-510 and 2 kit lenses(14-42mm and 40-150mm), i also have the 70-300mm lens. i am contemplating on buying a macro lens however i dont know which one yet...
i am looking to buy the Sigma 18-50mm f2.8. i know its a macro but is this a macro in the truest sense? i have been going through a lot of reviews on macro lenses and they are all single focal length lenses which makes sense as they are intended solely for that purpose. but pictures taken by the sigma were mostly wide and close-ups but no macro shots(havent found one). i have also read that this is a considerably fast lens and a good all rounder as well.
has anyone have any experience using this lens?
would this be a good choice to add to my equipment or should i go for the proper macros?
Thanks

You have the 70-300 lens already as do I. I use an achromatic screw-on lens, made by Sigma, which gives good performance when used with the 70-300 lens.

http://e-group.uk.net/gallery/data/5...s_-7232818.jpg

The added advantage is that you end up with a zoom Macro. The setup gives a minimum and max focussing distance (focussing window for want of a better expression) for each focal length. This enables you to focus from a distance without disturbing the subject.

Quote:

Originally Posted by Ellie (Post 38733)
Ah! Maybe this is the place to ask my question, because this is something I find rather confusing.

Can somebody explain, and if possibly show with pictures, what the difference is between a picture taken with a 50mm lens and a 50mm "macro" lens please. I suppose it would need to be of exactly the same thing, taken from exactly the same position.

Also, why would you (anybody) need a dedicated 50mm lens if you've already got a zoom lens that covers the same - 40-150mm for example - or should it be obvious?

The problem with the standard lenses is the minimum focussing distance as I understand it. I have another question. If the efl is 2 times does that not mean that a 2:1 Macro on the 4/3 system is the equivalent of 1:1 for a full frame camera?

Peter

mike_j 1st March 2009 07:42 AM

Re: Macro question
 
Quote:

Originally Posted by Ellie (Post 38733)
Ah! Maybe this is the place to ask my question, because this is something I find rather confusing.

Can somebody explain, and if possibly show with pictures, what the difference is between a picture taken with a 50mm lens and a 50mm "macro" lens please. I suppose it would need to be of exactly the same thing, taken from exactly the same position.

Also, why would you (anybody) need a dedicated 50mm lens if you've already got a zoom lens that covers the same - 40-150mm for example - or should it be obvious?

The macro lens is simply optimised for close working and has a wider focussing range, it can focus much closer. Within the focussing range of the 'normal' lens there won't be much difference between them though macro lenses tend to be fairly high performance so will be much sharper than, say, the kit lens set at 50mm.

One drawback of macro lenses for normal work is that the wide focus range can slow operation down and lead to hunting. Some macro lenses have a focus range limiter switch to reduce this.

photo_owl 1st March 2009 12:27 PM

Re: Macro question
 
Quote:

Originally Posted by Ellie (Post 38733)
Ah! Maybe this is the place to ask my question, because this is something I find rather confusing.

Can somebody explain, and if possibly show with pictures, what the difference is between a picture taken with a 50mm lens and a 50mm "macro" lens please. I suppose it would need to be of exactly the same thing, taken from exactly the same position.

Also, why would you (anybody) need a dedicated 50mm lens if you've already got a zoom lens that covers the same - 40-150mm for example - or should it be obvious?

Slightly different take on the answers given without disagreeing at all with their content

1. the point is that a normal lens won't be able to focus from the same (closer) position a macro lens can. When you are adding extension tubes like the EX25 you are increasing the effective magnification by enabling closer focusing distances. When you add a teleconverter like the EC14 you are increasing the magnification at the same focusing distance.

2. true macro lenses are also 'flat field' in that the focus plane is straight across from the front of the lens. In normal lenses the plane follows a very slight curve so that points at equal distances from the lens are in it. Assuming the focus was at 50cm exactly with a normal lens the edges might be in the focus plane at 49.8cm in front but 50cm when measured in a straight line from the lens.

Ellie 2nd March 2009 12:04 AM

Re: Macro question
 
Aargh!

"flat field" - haven't a clue, but do you mean the front of the lens is less curved? :confused:

Closer focusing distances - means you get closer to the subject? Which is fine if it's a flower, but not so good if it's something that will get up and walk away if it feels threatened

I'm afraid I don't know what achromatic is either. Physics, and optics, were never my strongest point :o

PeterD 2nd March 2009 08:07 AM

Re: Macro question
 
Quote:

Originally Posted by Ellie (Post 38805)
Aargh!

"flat field" - haven't a clue, but do you mean the front of the lens is less curved? :confused:

Closer focusing distances - means you get closer to the subject? Which is fine if it's a flower, but not so good if it's something that will get up and walk away if it feels threatened

I'm afraid I don't know what achromatic is either. Physics, and optics, were never my strongest point :o

Ellie, there are two types of add on lenses which screw to the front of standard lenses. One is a simple sigle lens with various magnifications (x2, x3 etc) and the other type has a lens group of 2 or more sandwiched lenses - see http://en.wikipedia.org/wiki/Achromatic_lens
An example of the MACRO lenses can be found at
http://fuzzcraft.com/achromats.html
I own both types of screw on lenses but the Achromatic lens is the one to go for in Macro work as the articles describe. Combining the Achromatic lens with a zoom lens lets you adjust the minimum focus distance to suit the object you wish to photograph.
Hope this makes sense

Peter

yorky 2nd March 2009 09:17 AM

Re: Macro question
 
One other thing to bear in mind is What are you wanting to photograph in macro! If its just a static subject the Oly 35 is a superb lens and also is useful as a 70 mm lens in its own right. However, should you be thinking of insects etc, you would frighten them away with such a short lens, therefore consider the Sigma 105 (210) This is a very good lens with a good maximum aperture f2.8 which allows to to much further away.

photo_owl 2nd March 2009 09:42 AM

Re: Macro question
 
Quote:

Originally Posted by Ellie (Post 38805)
Aargh!

1. "flat field" - haven't a clue, but do you mean the front of the lens is less curved? :confused:

2. Closer focusing distances - means you get closer to the subject? Which is fine if it's a flower, but not so good if it's something that will get up and walk away if it feels threatened

3. I'm afraid I don't know what achromatic is either. Physics, and optics, were never my strongest point :o

1. I will try and explain again. Huge exageration to make a point - assume you are in Chrischurch and pointing your camera at, and focusing on, Ringwood. With a normal lens Wimborne Minster would also be in focus - with a macro lens Blandford Forum would be in focus instead as it's the same distance North as Ringwood rather than the same distance from the lens. Huge exageration but explains the principle.

2. Yes but I was only highlighting the principle. Generally you have to be very close for high magnification. (Personally the OM600/6.5 with it's minimum focus distance of 39ft if just right for rattlesnakes and scorpions). Between 0.3x and 1x you have a reasonable number of choices in 43rds - hence the discussions.

3. Has been picked up

Ellie 5th March 2009 12:35 AM

Re: Macro question
 
OK, so an achromatic lens is sometimes sold as an add-on "magnifying filter" but isn't cheap because it doesn't distort light/colour. ( I read some of the linked page, but probably misunderstood half of it, and they threw in apochromatic too - just to muddy the waters!)

"flat field" - OK, I understand the analogy. What about at the edges of the lenses? On the 40-150 for example, there is slightly more distortion at the edge than the centre, or is that something completely different?

PeterD 5th March 2009 01:31 AM

Re: Macro question
 
Quote:

Originally Posted by Ellie (Post 38958)
OK, so an achromatic lens is sometimes sold as an add-on "magnifying filter" but isn't cheap because it doesn't distort light/colour. ( I read some of the linked page, but probably misunderstood half of it, and they threw in apochromatic too - just to muddy the waters!)

Ellie,

The achromatic lens ensures two light wavelengths are in-focus at the camera sensor. Apochromatic (Apo) lens ensures that three light wavelengths are in focus at the camera sensor.
Both are designed to overcome colour aberration. The latter is obviously the better solution but is more costly.
Simple magnification lens will not correct for the different wavelengths of light and therefore are not a good solution.
I have looked on the Sigma site where some of the lenses are described as APO to see if they use this technology. What I have found is that they use two SLD lens groups in this design. I guess it is their Apo solution.

Peter


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