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120 macro or 180 with extension

macmx

Member
I have the 120 CFE right now, but I am considering changing it for the 180 CFE, since I've heard nothing but good things about this lens.

How does the 180 work with extension tubes for close up shots?

Marcus
 

polypal

New Member
The 120 Makro-Planar is designed for close range and macro jobs.
The 180 is an excellent lens but optimised for infinity.

Can you explain why you want to change the 120 for the 180 lens?
 

jerry

New Member
Marcus,

When I bought my V-system, I had the opportunity to test several lenses during one afternoon. I opted for the 120 instead of the 180 mainly for 2 reasons: 1) The 180 is topheavy, making the balance when used handheld more awkward and 2) The 120 is pinsharp at close range AND at infinity. Also, according to the salesperson, it is more suited for packshots when used with digital backs. (Not that I own one)
 

macmx

Member
I mainly want to go with the 180, because I don't do that many macro shots, bit I want to buy a 2X converter and use it with the 180 for nature shots, which I do a lot more. It is also my impression that the 180 is a good portrait lens.
 

emilgil

New Member
Is a macro lens such as the 120mm makro-planar better at close ranges than a "normal" tele lens with extension tubes focused at or near infinity?

According to the common theory (or fact) that the 120mm is more or less useless at long ranges, would the macro-planar focused at infinity with extension tubes yield a less sharp image than if it was focused at close range without the help of tubes? And, in the same way, would a 180mm focused at infinity with the appropriate extension tubes yield a sharper image than it would when focused at close range to achieve the same depicting scale?

I'm perfectly happy with my CF120 at all ranges but I'm looking to get a 180mm. I'll be very intrested to see if I can spot any difference!
 

jerry

New Member
Emil Gildebrand (Emilgil) wrote on January 06:

' 2008 - 11:30 am,According to the common theory (or fact) that the 120mm is more or less useless at long ranges, would the macro-planar focused at infinity with extension tubes yield a less sharp image than if it was focused at close range without the help of tubes?'
I am a bit confused here, Emil. For focussing at infinity, one does not need extension tubes for the 120mm makro-planar. The beauty of this lens is that it is a very, very good light telephoto lens which is also optimised for close range makro work. One can debate whether the focal length is more or less suitable for portrait work, but certainly not the image quality. And as I said in an earlier comment, I dislike the unbalance a 501CM gives me handheld with the 180, therefore chose the 120.
 

polypal

New Member
Jerry,

I think what Emil means is: Is there a difference in quality when using extension tubes instead of using its own helicoid to focus at close range.
As far as I can see there will be no difference.

Focusing at infinity with an extension ring between the lens and the camera is not possible.
 

kommini

New Member
Focusing at infinity with extension tubes is possible, in the sense that, = the barrel of the lens can be set at infinity with the extension tubes conn= ected !

Krish
 

polypal

New Member
Of course you can set the lens distance scale at infinity when an extension ring is used.
This does not mean you are focusing at infinity meaning get a sharp image from objects at large distance.
 

arjuna

New Member
My understanding of Emil's question is: given that the 120 MP is optimized for closer distances (when it is on a camera), where, for best results, should you place the lens' focus when you are using extension tubes - on a close distance, e.g. 3 m / 10 ft, where it is normally optimal, or at infinity? or does putting the lens on an extension tube alter the optical path so much that this becomes an irrelevant question, and you just use the lens' focus to focus on the subject, within the new focusing range? I confess that I have never used an extension tube, so maybe this isn't a very good question.
 

emilgil

New Member
Sorry for being a bit unclear, Kommini and Arjuna are not far from getting my point but I'll try to rephrase my previous post.


When using the 120mm for close range work, you may use the internal helicoid or add tubes to get the extension you need.

Let's say I want to shoot at 1:6, requiring 20mm of extension from either the internal helicoid or a tube. If using the helicoid only, I would focus at about 1m. Using 20mm of tubes, I would focus at or very near infinity. According to popular belief, the second method would yield an image inferior to the one taken with helicoid extension only.

Using the 180mm would on the other hand yield a superior result when using tubes rather than helicoid as this lens is reputedly better at infinity than at close range.

Is this correct?
 

polypal

New Member
Arjuna,

Welcome at the forum.

As soon as an extension tube is fitted the distance scale on the lens is no longer valid.
You answered that question more or less yourself: "or does putting on an extension tube alter the optical path so much...."

After fitting an extension tube you adjust the distance between lens and subject to come within the changed range of focussing of the lens and tube combination.
Once there you can fine tune the focus with the helicoid, the focussing system of the lens.

Ex&le:
An 80 mm lens fitted with a 32 mm extension tube will focus an object at 18,5 cm from the front of the lens.
An object not larger than 11 cm will completely fill the filmframe.
 

emilgil

New Member
Polypal, I don't know if your post is aimed at Arjuna only or at me as well. I guess I have to rephrase myself again; by "focusing at infinity" I mean "reducing the helicoid extension to a minimum as if focusing at infinity under normal circumstances when not using extension tubes". I know that the scale on the lens is pretty useless if one is using tubes but I'm merely using it as a tool to indicate the helicoid setting.

My point is to ask if the results will be different if I use a lens optimized for infinity, such as the 180mm, with tubes and minimal helicoid extension instead of focusing the same lens without tubes, using only the helicoid to achieve the desired extension.
 

emilgil

New Member
Yes, but will a 120mm with tubes give a result inferior to that of a 120mm without tubes when covering the same area?
 
Emilgil,
I understand your question, and it is an interesting, not to mention, a legitimate concern.
I am not familiar with the optical design of the 120 lens, which, I presume, has changed over the years. However, I believe the answer to your question lies in whether or not the lens elements move simultaneously together in the same direction when focusing, OR whether or not they move at different rates, or in different directions when focusing.

1. If the entire glass configuration moves simultaneously when focusing, then using the extension tubes would be no different than using the helicoid.

2. If there are lens elements that move at different rates or directions while focusing (as most modern 35mm macro lenses do), then you should experience a difference, however slight.

Ex&le, assume for the moment that the elements move at different rates and directions while focusing - if you add 30mm worth of extension tubes with the lens "focused" at infinity, it would yield a 1:4 magnification, but the optical elements would be in their "infinity" position, which would yield different quality results than if you used the helicoid to focus the lens out to 1:4, since then, the optical elements would "adjust" to different positions, most likely better optimized for that particular distance.

In either case, I would use the lens' helicoid to focus out as far as I could, and then add extention tubes after that.
Michael H. Cothran
 

polypal

New Member
The 120 Makro-Planar is at its best at minimal focusing distance.
Meaning fully extended.
Planar designs are largely symmetrical where the front lens group moves as one part.
Michaels suggestion to make use of the helicoid as far as possible will give best results.
 

jerry

New Member
The MP120 has less distortion and is more uniform from center to edge in light distribution, according to the CZ data, even at large distance. Indeed, the 180 Sonnar has a better MTF curve at large distance than the MP120.
Unfortunately, I do not own the 180 so I can not perform a real life test to see the actual difference between the two, someone can?
 
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