Constant aperture lens? Beercan F4

robbyrob

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I recently got the minolta beercan lens for my A390. I notice that this lens is a constant F4, yet with my camera I can change to different F-stops as needed. I read through some post on this forum and one poster asked how should I use this lens? The answer seem to be use as you would any other lens. Also most people said the lens was sharper at 2 Fstops than fully open. My question is since the lens is a constant F4 how does that work say when I use F5.6 or F10 or any other Fstop at that matter? Just trying to wrap my head around this.

thanks!
 

Robin_Usagani

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LOL This cracks me up.

Constant f/4 means your max aperture is f/4 regardless whatever focal length you are zoomed in. A lot of kit lenses do not have constant max aperture when you zoom in and out.
 

480sparky

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"Constant f/4" means the maximum aperture is always f/4, regardless of the focal length chosen.

As you stated, most lenses are sharpest when stopped down 2-3 stops from max. aperture. So in this case, f/8 - f/11 will be the 'sweet spot'.
 

EDL

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Most zoom lenses will change the maximum aperture when you change the zoom length. You see this rating when you look at the specs on zooms. For example, the Canon EF-S 18-135mm f/3.5-5.6 IS STM, it gives the focal length zoom range 18-135mm, and the maximum aperture opening of f/3.5-5.6. This means you can open up to f/3.5 at the low end of the zoom (18mm), but once you zoom in to 135mm the maximum aperture is only f/5.6. This spec only indicates the largest aperture settings for the lens in relation to the focal length, you can always change to a smaller aperture, f/8, f/11, etc.

A constant aperture zoom will have the same maximum aperture across the entire zoom range of the lens, but you can still use a smaller aperture if you want to.

Typically, constant aperture is found on higher grade zooms as it takes better optics and design, thus higher cost.
 

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Here's a really interesting side-by-side testing and comparison of a beat-up,old 70-210mm f/4 Minolta "beercan" shot on a Sony Alpha A900, a 24MP FF camera, and a Canon on 5D Mark III with the new Canon 70-200mm f/4L-IS USM zoom lens. The Minolta performs as well as, or better, than the Canon in several different scenarios. The bokeh of the Minolta lens actually looks superior to me, and the test author, in the flower close-up example, with both lenses shot at f/11.

I found this review a few weeks ago, after I happened to examine a MINT condition "beercan" at my local camera specialist pawn shop...I had not seen one in many years, and this example was simply immaculate! And the price was like $129, or $119. Can't recall...I looked at a bunch of lenses that day.

Does the 1985 Minolta 'beercan' stand up against Canon's 70-200mm f4 L? | Photoclubalpha
 

Gavjenks

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I found this review a few weeks ago, after I happened to examine a MINT condition "beercan" at my local camera specialist pawn shop...I had not seen one in many years, and this example was simply immaculate! And the price was like $129, or $119. Can't recall...I looked at a bunch of lenses that day.

Keep in mind that the A900 also costs $1000 more than, say, the 6D, despite having a significantly worse sensor across the board, far fewer features, much clunkier size, and generally more creaky old tech. The image stabilization in-body might have something to do with the price still being so much. Similar for a more modern alpha 99.

So you may be paying $500 less for the lens that ends up working just as well (or occasionally better). But a lot of that cost is probably simply getting shunted over to a more complex and expensive IS-in-body design instead that costs $1000-2000 more than the abilities and features it delivers competitively.

Also note that with the modern L lens, you're paying for weather sealing and a quieter USM motor, so not all of that $500 is accounted for entirely by the IS-in-lens.





Taking into account the camera and lens systems as wholes, the two different approaches probably come out about equal in terms of cost, all told, for a typical photographer who might have up to 1-2 decent lenses bought in a year. Pay more up front for the complicated body every few years, or pay about the same amount extra distributed over a handful of more expensive lenses every few years instead. Whatever. :meh:
 
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Juga

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Here's a really interesting side-by-side testing and comparison of a beat-up,old 70-210mm f/4 Minolta "beercan" shot on a Sony Alpha A900, a 24MP FF camera, and a Canon on 5D Mark III with the new Canon 70-200mm f/4L-IS USM zoom lens. The Minolta performs as well as, or better, than the Canon in several different scenarios. The bokeh of the Minolta lens actually looks superior to me, and the test author, in the flower close-up example, with both lenses shot at f/11.

I found this review a few weeks ago, after I happened to examine a MINT condition "beercan" at my local camera specialist pawn shop...I had not seen one in many years, and this example was simply immaculate! And the price was like $129, or $119. Can't recall...I looked at a bunch of lenses that day.

Does the 1985 Minolta 'beercan' stand up against Canon's 70-200mm f4 L? | Photoclubalpha

I found this review a few weeks ago, after I happened to examine a MINT condition "beercan" at my local camera specialist pawn shop...I had not seen one in many years, and this example was simply immaculate! And the price was like $129, or $119. Can't recall...I looked at a bunch of lenses that day.

Keep in mind that the A900 also costs $1000 more than, say, the 6D, despite having a significantly worse sensor across the board, far fewer features, much clunkier size, and generally more creaky old tech. The image stabilization in-body might have something to do with the price still being so much. Similar for a more modern alpha 99.

So you may be paying $500 less for the lens that ends up working just as well (or occasionally better). But a lot of that cost is probably simply getting shunted over to a more complex and expensive IS-in-body design instead that costs $1000-2000 more than the abilities and features it delivers competitively.

Also note that with the modern L lens, you're paying for weather sealing and a quieter USM motor, so not all of that $500 is accounted for entirely by the IS-in-lens.





Taking into account the camera and lens systems as wholes, the two different approaches probably come out about equal in terms of cost, all told, for a typical photographer who might have up to 1-2 decent lenses bought in a year. Pay more up front for the complicated body every few years, or pay about the same amount extra distributed over a handful of more expensive lenses every few years instead. Whatever. :meh:

Like vinegar and baking soda...please don't turn this thread into another body battle.
 

Gavjenks

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Neither of us shoot Sony, though, AFAIK, so you're probably safe =)
 

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