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03-03-2012, 05:04 PM   #16
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The Tamron SP 60-300 has a fixed rear block that does not move during normal focus and zoom operations. It is one-touch design where you rotate for focus and pull out to zoom. To get it into its macro mode, you must focus to its closest distance (1.9m), push the zoom ring all the way back to the 60mm (shortest lens length) and then twist it to lock it. Once locked at 1.9m and 60mm, you can now pull the zoom ring out and it moves all the elements (including the rear block) just like having a variable length extension tube. You cannot focus or zoom once locked. The maximum magnification 1:1.55 is achieved when the lens is fully extended.

The Pentax implementation of "macro" on the F 35-70 and F 35-105 is quite different. The lenses have a 2-ring design, one for focus and one for zoom. On both lenses, the rear block moves away from the body when zooming toward the longer focal lengths. Both can be switched to macro at their longest settings (70mm or 105mm) and you can still use the focus ring (or AF) in macro mode. The F 35-70, moves the front elements further away to increase the macro ratio while the F 35-105 move the rear block toward the body to increase the ratio. It is interesting also that the F 35-70 is physically shorter at the 70mm setting while the F 35-105 is shorter at the 35mm setting.

The Pentax M 40-80 which also has a twist macro mode, behaves like the F 35-70.

Bottom line is that there are many designs to implement "macro" capabilities on a zoom lens.

03-03-2012, 07:45 PM   #17
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I've got two SMC-A mount lenses a 70-210 f4, which does close focusing at 70, and a 35-105 which will do close focusing throughout the range (and has been my main shooting lens since I got it for exactly that reason). Both will only get you to 1:4 magnification, but for the work I've been doing that has been enough.
03-03-2012, 09:05 PM   #18
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I was thinking this was a more common design but it turns out it may be a vivitar thing. Basically, you know how when you turn the focusing ring, the front group of elements turn and screw closer or further away to focus? This one just allows the focus collar to turn further moving the front group more. It is capable of moving the whole range at any focal length with the bar removed. I also have vivitar 28-200mm, 28-210mm and 35-210mm lenses that have the same kind of macro (my vivitar 70-210mm isn't like that though). As far as other designs, I have a soligor that has a separate ring at the rear of the lens that extends the entire lens except the mount area forward, and works at any focal range. Basically its an adjustable built in macro tube. I also have a takumar that the zoom ring goes to the highest focal distance (70mm I think), and then the zoom ring turns a bit further to go into macro mode. It looks like its only effecting some of the front and middle glass but not rear groups.

If it is a vivitar thing, perhaps some engineer has some reason for it or didn't even think to allow it in the whole range, and they just kept using that design in different lenses?
03-03-2012, 11:46 PM   #19
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QuoteOriginally posted by ripit Quote
The Tamron SP 60-300 F3.8/5.4 that demp10 posted about goes to show you can have some macro ability on the short end.
Yes, but that lens is very painful to use at its maximum magnification. With the hood on, you cover the subject with it. It's the best example of why you *don't* want macro at the shortest focal length.

QuoteOriginally posted by ripit Quote
My 70-300mm has macro at 200-300mm so maybe that is the part of the range that could do macro to the advertised spec.
That lens still achieves its maximum magnification at 300mm. Magnification is determined by focal length + closest focusing distance. The macro mode on the Tamron/Sigma lenses just allows you to focus closer in a certain focal length range. Why they chose that particular range depends on the intricacies of each optical design. They could have allowed you to focus closer across all range, but I expect that the results would have been embarrassingly poor outside the macro range.

03-04-2012, 10:00 AM   #20
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QuoteOriginally posted by ripit Quote
I get that you get the best magnification/focus ratio at the longest focal length. Do you always in every case want the maximum magnification? Wouldn't it be limiting for closer work if you only had the option of 1:1 focusing?
No, of course not. My point was, if you don't need that much magification, why not just use it at the end but not at the closest distance? That is, if you only want 1:5 magnification, why try to get it by focusing extremeley close at at the wide end when you could get the same magnification at the long end without needing to focus so close. I don't know the specific lenses being discussed, but I have to image that all possible magnification ratios from 1:infinity to whatever the maximum is would be possible without needing to use to short end at extra-close focus distances. Are you saying something about the design causes some specific magnification ratio to not be achievable?
03-04-2012, 06:00 PM   #21
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QuoteOriginally posted by Marc Sabatella Quote
No, of course not. My point was, if you don't need that much magification, why not just use it at the end but not at the closest distance? That is, if you only want 1:5 magnification, why try to get it by focusing extremeley close at at the wide end when you could get the same magnification at the long end without needing to focus so close. I don't know the specific lenses being discussed, but I have to image that all possible magnification ratios from 1:infinity to whatever the maximum is would be possible without needing to use to short end at extra-close focus distances. Are you saying something about the design causes some specific magnification ratio to not be achievable?
That actually makes sense to a point. Why would you want to have to get really close up when you can go to a longer focal length and get a little distance. Might the opposite be true in some shooting conditions though? If you can only use the longest focal length and its a 200mm or 300mm lens, wont you have more issues with camera shake and focusing etc than if you were at a wider angle with less magnification? If it were an inanimate object where getting close up wouldn't be an issue, might you get a better shot at a wider angle?

It's may be irrelevant to the lens in question though at least as it pertains to my question. The lens I specifically posted about is a vivitar 35-105mm 3.2-4. It only goes into the additional macro focus range at 105mm. It achieves this by allowing the focusing collar and the front group of glass to turn further at 105mm (in other words you turn the focus ring to focus and it hits a stop at the end of its range, unless you are at 105mm, and then it can turn past that stop). I removed the bar that stops it from going past that point at other focal lengths (it was bent and dragging a little). It can now focus into that extra macro range at any focal length as the stop is removed. This does not change how it operates at 105mm. It still has the same identical mechanical operation, magnification etc at 105mm. It now has that extra macro focusing range at all focal lengths now that the stop is removed. Why put that stop in there in the first place? It doesn't improve function in any way I can tell but limits function.
03-04-2012, 10:10 PM   #22
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QuoteOriginally posted by ripit Quote
Why would you want to have to get really close up when you can go to a longer focal length and get a little distance. Might the opposite be true in some shooting conditions though? If you can only use the longest focal length and its a 200mm or 300mm lens, wont you have more issues with camera shake and focusing etc than if you were at a wider angle with less magnification? If it were an inanimate object where getting close up wouldn't be an issue, might you get a better shot at a wider angle?
Then a longish 'macro'zoom is the wrong lens for the task.
03-05-2012, 07:42 AM   #23
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QuoteOriginally posted by ripit Quote
That actually makes sense to a point. Why would you want to have to get really close up when you can go to a longer focal length and get a little distance. Might the opposite be true in some shooting conditions though? If you can only use the longest focal length and its a 200mm or 300mm lens, wont you have more issues with camera shake and focusing etc than if you were at a wider angle with less magnification?
Again, I'm talking about achieving the exact same magnification, regardless of whether it is achieved with a shorter focal length and shorter working distance, or longer focal length and longer working distance. While there might be some advantage in terms of shutter speed requirements, the simplistic 1/focal-length rule of thumb for estimating minimum shitter speed kind of breaks down at macro magnifiations.

QuoteQuote:
If it were an inanimate object where getting close up wouldn't be an issue, might you get a better shot at a wider angle?
Again, we're talking the same magnification of the subject either way, but it is true different focal lengths will affect the background. So sure, there is some difference. But I think you are getting into territory where people who care about such subtleties generally are not going to settle for a quasi-macro zoom in the first place.

QuoteQuote:
Why put that stop in there in the first place? It doesn't improve function in any way I can tell but limits function.
Good question. Could be that IQ was judged to degrade too much.

03-05-2012, 06:00 PM   #24
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QuoteOriginally posted by Marc Sabatella Quote

Good question. Could be that IQ was judged to degrade too much.
There has to be some type of reason like that. Why else would they design and install extra parts? I just briefly tested my lens and it seemed to have better iq at shorter focal lengths but it was just comparison of a couple of snapshot (that does include in the new macro focusing range). As there are several vivitars like this, I'm kind of wondering if at some point, a lens was designed and there was a good reason for it, then they just kept using that same design even though the limiter wasn't always necessary?
03-29-2012, 01:08 PM   #25
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I was looking for repair info on a tamron lens and discovered a youtube video that removes this limitation on the sigma 70-300mm similar to the on I have. It seems that lens can go into the macro range at any focal distance but has been limited from doing so.

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