Panny 45-200 not a Zoom but Varifocal?

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I had an interesting experience shooting the Vintage Motorcycle Festival at Barber Motorsports park yesterday with my 45-200 lens. Earlier in the summer I was using the much smaller 45-150 panny lens for the Superbike races and while it wasn't the best lens I had used for motorcycle racing, the focus kept up reasonably well once I got used to it. I found I would like a little more reach so I sold the 45-150 and got the 45-200 I have now. Using it at the track yesterday was at first very disappointing. The lens would lock and then lose focus seemingly at random and was performing much worse than the small 45-150. I still got the shots I needed but was puzzled and was beginning to feel I had made mistake, however...

I went out again in the afternoon to my usual corner at the track and while I was waiting for the race to start, I was playing around with the lens and focus points to see if I could fine tune things. One thing I noticed gave me an "Ah HA!" moment. If one focuses on a spot and then zooms, the focus is lost for a moment and then the lens re-focuses. This happens with the finger off the shutter and whether or not you have Single or Continuous focus selected, neither of which should matter with the finger off the shutter.

This leads me to the conclusion that this particular lens is not a true "zoom" but rather a varifocal (or vari-focal) lens. A true "zoom" or design maintains the focus point (or pretty close anyway) as the focal length is changed or "zoomed". Discovering this helped me understand that I WAS the problem as I tend to zoom a bit when tracking motorcycles at races and I used to do this with my D200 and 80-200 2.8D without an issue. This meant I had to change my approach.

As I would track bikes around the turn in front of me I was leaving the zoom ring fixed until I turned back to catch the next pass. This made a huge difference and I imagine that with any lens, not zooming while tracking would give the AF system less to deal with but in this case it was a world of difference. The bonus is that many of the shots were very sharp and contrasty (for a lens at this price) and I feel a bit better than the 150 that is said by some sites to be a bit sharper. Maybe I have a good example but in either case once I met the lens halfway as it were, I was pleased with the results.

Some might suggest I get the 40-150 2.8 and I agree, if I had the budget right now I would have it (and the 12-40) but since I only need that serious firepower a couple of times a year for those events I don't think so (but I still want it). I plan on renting one next year so I can see if I MUST have it though.

Just FYI, here at the setting I used for the AF in case anyone is interested:

C-AF
Tracking Off
OIS on the lens, not the IBIS - seemed to maintain focus just a little better using lens OIS
Shot at continuous Low set for 4fps
9 box AF point size moved one click to the left of center

F6.3 at 1/800 ISO200 shot as jpeg
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Full size jpeg can bee downloaded from here: www.jacksonphotoworks.com/images/VintFest2014_0488.jpg
 

dougjgreen

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I've found that, nowadays, MANY a lens that claims to be a zoom is actually a varifocal. Since I don't shoot video, I don't really pay it much mind, but I can see that it would be an issue.
 

pellicle

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Hi
firstly, great shot!!

...One thing I noticed gave me an "Ah HA!" moment. If one focuses on a spot and then zooms, the focus is lost for a moment and then the lens re-focuses.

This leads me to the conclusion that this particular lens is not a true "zoom" but rather a varifocal (or vari-focal) lens.
I think this is a semantic point, and most certainly the earlier zooms I had (and I bought my first zoom in 1976) were exactly that (vari focal). Eventually they modified designs to allow the focal point to remain fixed. But if you think about the word "vari-focal" it could also mean that the focal length varies.

I seem to recall that when "one touch" zooms came out that this became an issue ...

When it comes to picking the point and catching it I'd always use manual focus to confirm the focus on that spot and then grab. None the less your camera has done an outstanding job there!

PS: I notice a little vignetting on your image there (which works in that case) and its something I noted in my copy. I did a quick comparison with the new FD200f4 and found that it worked for me much better than the Pana45-200mm (which I've subsequentially sold). Not only did the FD give me f4 over f5.6 I found that the transmission of the lens was better resulting in another stop of shutter speed ...

http://cjeastwd.blogspot.com/2010/02/panasonic-45-200mm.html

PPS: I see (looking at your EXIF) that you were not at 200mm ... so the flexibility afforded by the zoom would be of course desirable. You must have been close to the action on your point on the track.

Stellar shot - well done
 

SojiOkita

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That's what I didn't like when I used the Olympus 12-50.
When you change the focal length, the focus is totally lost for a short moment and then it refocuses.
I find zooming with such lenses quite annoying.

Anyway, I wouldn't trust a focus made before zooming even on my other lenses. I always refocus after zooming.
It's just the visual aspect (image blurred) that annoys me (it makes composition of the choice of focal length more difficult).
 

dwig

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...
I think this is a semantic point, and most certainly the earlier zooms I had (and I bought my first zoom in 1976) were exactly that (vari focal). Eventually they modified designs to allow the focal point to remain fixed. But if you think about the word "vari-focal" it could also mean that the focal length varies.

I seem to recall that when "one touch" zooms came out that this became an issue ...
More than just a semantic point, it is a matter of proper terminology. It is true that all zooms are varifocals, but not all varifocals are zooms. The term "zoom" began life with the Zoomar lens created for TV work in its early days. It was quickly copied by other optical manufacturers. While variable focal length lenses have a long history, the Zoomar (a brand name BTW) maintained the same focus distance when the focal length changed. The distinction became that "true zooms" maintain focus while "vari-focals" don't. Prior to autofocus, this was an important distinction. When autofocus became ubiquitous, many lenses began to sacrifice "true zoom" characteristics in exchange for other optical advantages, relying on the AF to compensate.

BTW, one-touch designs were the first design used in zoom lenses on 35mm cameras. The two-touch designs were a later simplification, at first usually seen on cheaper lenses. Two-touch designs dominate today because of AF since you rarely need to manually focus.
 

kwalsh

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Indeed, few modern zoom lenses for still cameras are parfocal - most are varifocal. With the stills/video convergence it will be interesting to see if this trend reverses it self.

As to the term "zoom" clearly most stills photographers and manufacturers are perfectly happy calling a varifocal design "zoom" so I think trying to make a distinction of a "true zoom" is going to be fraught and obfuscating. Just call them parfocal and varifocal and remove all ambiguity when discussing the behavior of the focal plane when changing focal length.
 
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I think you'll find quite a lot of "zoom" lenses sold over the years for film cameras were parfocal where the focus point remained true (mostly) with the change in focal length. Some early examples of lenses that were varifocal and in wide use were some (but not all) versions of the Vivitar series 1 70-210's . Pretty much any of my modern (past 10-20 years) Nikon, Pentax, Sigma, etc zoom lenses that I have used maintained focus point while zooming. Not trying to start a debate. I just found it interesting. Still very pleased with the sharpness of the lens but miss being able to zoom as I track a fast moving bike without spoiling the focus.

Oh, and thanks pellicle :)
 
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PPS: I see (looking at your EXIF) that you were not at 200mm ... so the flexibility afforded by the zoom would be of course desirable. You must have been close to the action on your point on the track.

Stellar shot - well done
Yes, I was about 30 feet away at that point.
 
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Interesting post, thanks. I used to have the 45-200 and wish I had it back now. A lot of people dismiss it but I always liked it. Also props for the username, it's good to see MST3K fans still around.
 

wilson

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As others have touched upon, prior to the wide adoption of autofocus, zoom lenses tended to be parfocal for ease of use.
These days, since autofocus is so common, many newer zooms are designed without a requirement that it be parfocal.

Note that the highly regarded $2300 Canon EF 70-200mm f/2.8L IS II USM Zoom is varifocal.
 

pellicle

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Hi

More than just a semantic point, it is a matter of proper terminology.
http://en.wikipedia.org/wiki/Semantics

Semantics (from Ancient Greek: σημαντικός sēmantikós, "significant")[1][2] is the study of meaning. It focuses on the relation between signifiers, like words, phrases, signs, and symbols, and what they stand for, their denotation.
and so proper terminology is indeed semantics. Semantics may or may not be of importance to a topic, but determining proper meaning is indeed an argument in semantics.


It is true that all zooms are varifocals, but not all varifocals are zooms.
Can you explain that?

The term "zoom" began life with the Zoomar lens created for TV work in its early days.
I think that like me (when I first replied) you are relying on experience to define that. I had a similar impression although a bit different. Some reading on the topic cleared that up for me (which I did after my post).

for instance http://en.wikipedia.org/wiki/Zoom_lens#History

An early use of the zoom lens in cinema can be seen in the opening shot of the movie "It" starring Clara Bow, from 1927.
well before TV....

Early forms of zoom lenses were used in optical telescopes to provide continuous variation of the magnification of the image, and this was first reported in the proceedings of the Royal Society in 1834
[my bold]

I think problems come from the use of words, such as:
The first true zoom lens, which retained near-sharp focus while the effective focal length of the lens assembly was changed, was patented in 1902 by Clile C. Allen
[italics from original quote]

in my view this use of "true" could be lept upon to disregard the others from being zoom lenses ... I'm not entirely sure thats a proper interpretation, but then that's where argument and interpretation would come in.

I think its also worth considering this: http://en.wikipedia.org/wiki/Parfocal_lens

Zoom lenses (sometimes referred to as "true" zoom) are ideally parfocal in that focus is maintained as the lens is zoomed (focal length and magnification changed), which not only is convenient, but also has the advantage of allowing more accurate focusing at maximum focal length and then zooming back to a shorter focal length to compose the image
which of course makes it clear that its not a simple matter of parafocal = zoom | varifocal != zoom


BTW, one-touch designs were the first design used in zoom lenses on 35mm cameras. The two-touch designs were a later simplification, at first usually seen on cheaper lenses.
also not my understanding of history ... for instance a good many of the early FD zooms (see here) were two touch. For instance
http://www.canon.com/camera-museum/lens/fd/data/zoom/fd_85~300_45_ssc.html
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was released in 1974 and not regarded as a cheap lens ...

http://www.canon.com/camera-museum/lens/fd/data/zoom/fd_24~35_35_ssc_as.html
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released in 1978 and also not a cheap lens.

Of course I'm not sure if you mean earlier 35mm lenses than this...

Two-touch designs dominate today because of AF since you rarely need to manually focus.
that could be right ...

lastly, some history I found interesting

The Kilfitt 36–82 mm/2.8 Zoomar introduced in 1959 was the first varifocal lens in regular production for still 35mm photography.

The first modern film zoom lens was designed around 1950 by Roger Cuvillier, a French engineer working for SOM-Berthiot. It had an optical compensation zoom system.

In 1956, Pierre Angénieux introduced the mechanical compensation system, enabling precise focus while zooming, in his 10x lens released in 1958.
 
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All, I forgot to come back to this thread this past summer and meant to follow up. At the AMA Pro races this past year I rented a 40-150 2.8 (w/the 1.4X tele) to try out. What a great lens! Very well made and very sharp but more than that very contrasty too which makes images look sharper. Did it do well? Yes. Was it leaps and bounds better than the 45-200? Not terribly so, FOR ME. Yes, it is more robust and certainly the lens to get is you are going to do a lot of shooting and need something that can put up with the elements and being tossed into bags and slogged around. The images were sharper and contrasty but not so much that I felt it would matter for web publishing. Frankly a little tweaking in post of the 45-200 images and the images from either lens would be hard to differentiate except to the pixel peepers. Focusing, now here's the thing. Yes, it does focus fast in the sense that the focus mechanism is super quick, however the ability to track (not focus tracking, just C-AF) was not really any better than what I experienced with the 45-200. I'm guessing motorcycle racing, particularly when the bikes are moving away from you, may be a bit to fast for the EM-1 AF system to keep up with. For me, only doing this a couple of times a year, I'd stick with the 45-200 OR simply rent the 45-150 again. I will also say that I'm tempted to just run with 45-200 as the weight is a lot less to carry around all day.
Let me be clear that I'm not putting the 45-150 down. It is exceptional and a pro lens in every sense of the word and working pros should look no further. For me, I was trying to get away from the weight and bulk of my Nikon D200 + 70-200 2.8 and the 45-150 2.8 defeats (some) of that purpose. Next year I'll be taking my new to me 75mm 1.8 to the track and see how it does since I can get pretty close physically. Also I'm anxious to see how the new 4.0 firmware fares against moto racing.
Cheers!
 
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