Two Basic Questions

Started Jun 11, 2013 | Discussions
fbwap
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Two Basic Questions
Jun 11, 2013

This may not be the right forum for these two questions, but it is the forum I am familiar with. I have read this forum every day for well over a year. I have come to respect the great technical knowledge among the Sony Alpha community and I am looking for technical answers.

1. I have an OM2 setup with four lenses back from the early 80s. How come my Sony APS-C lenses are bigger? And Full-Frame are even bigger than that? The OM system was full frame and the lenses were nice and small. I find it hard to believe the auto-focus hardware alone makes things that much bigger.

2. I have a circular polarizer now. When I rotate it, I find it hard to see the difference in my EVF. I know about being 90 degrees to the sun. It was extremely easy to see the difference when I turned my linear polarizer on my old Olympus gear.

Thanks

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Chimere
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Two Basic Questions
In reply to fbwap, Jun 12, 2013

Interesting post:

1 - The only difference would be the focus motor & chips installed in the modern lenses. However, I personally (Pentax fan converted to Sony) did not see a noticeable increase in sizes). Can you give optical data and dimensions of the lenses you are comparing ?

2 - the OM's optical view finder will process light waves differently than the electronic sensor of the EVF. So it would be expected that the sensor recording - according to your observation - may be less influenced by the polarisation filter. Shoot some pictures (with and without filter) for comparison and let us know ?

Chimere

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rio911
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Re: Two Basic Questions
In reply to fbwap, Jun 12, 2013

fbwap wrote:

2. I have a circular polarizer now. When I rotate it, I find it hard to see the difference in my EVF. I know about being 90 degrees to the sun. It was extremely easy to see the difference when I turned my linear polarizer on my old Olympus gear.

Thanks

I'm not sure about the rest, but I think this has to do with the EVF showing the current exposure all the time!  I mean when you use an optical viewfinder and rotate the front element of the circular polarizer, you will see directly the influence of the filter in your viewfinder: it will go darker as you approach maximum effect and will be lighter at minimum.  While the EVF is by default setup to show the current exposure taking into account aperture, shutter speed and in this occasion the filter.

rio

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Chimere
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Two Basic Questions
In reply to rio911, Jun 12, 2013

I'm not sure about the rest, but I think this has to do with the EVF showing the current exposure all the time! I mean when you use an optical viewfinder and rotate the front element of the circular polarizer, you will see directly the influence of the filter in your viewfinder: it will go darker as you approach maximum effect and will be lighter at minimum. While the EVF is by default setup to show the current exposure taking into account aperture, shutter speed and in this occasion the filter.

rio

You might have a point there. However, the filter cuts out only & always 1/2 of the polarized light waves only, not of the total amount hitting the lens. So the change in EV value might not be that much noticeable with the filter applied.

Perhaps the OP can provide the exposure data with and without filter, and with the filter turned 90 degrees ?

Chimere

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seilerbird666
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Re: Two Basic Questions
In reply to Chimere, Jun 12, 2013

All filters only do one thing, they remove light. As you rotate the ring on the polarizer it changes the amount of light it removes. As it becomes parallel to the light it removes more light. The OVF display does not change when you change the exposure, an EVF display will change when you change the exposure.

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tboydva
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Re: Two Basic Questions
In reply to fbwap, Jun 12, 2013

Alas - I sold my OM-1 several years ago (and purchased an NEX - with additional funds obviously). It was tough to let go. I used and use a polarizer frequently and you are correct - it's much harder to "see" the effect through an EVF. I'm mostly shooting shots with sky, so if you look at the very top of the EVF, you can see darkening while spinning the CP filter. It's not nearly as pronounced as with an OVF. For shots "through" water, the effect is easily visible through the EVF for me. I generally do not see a change in the ISO (I typically shoot A with auto ISO) through the filter rotation.

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fbwap
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Re: Two Basic Questions
In reply to rio911, Jun 12, 2013

rio911 wrote:

fbwap wrote:

2. I have a circular polarizer now. When I rotate it, I find it hard to see the difference in my EVF. I know about being 90 degrees to the sun. It was extremely easy to see the difference when I turned my linear polarizer on my old Olympus gear.

Thanks

I'm not sure about the rest, but I think this has to do with the EVF showing the current exposure all the time! I mean when you use an optical viewfinder and rotate the front element of the circular polarizer, you will see directly the influence of the filter in your viewfinder: it will go darker as you approach maximum effect and will be lighter at minimum. While the EVF is by default setup to show the current exposure taking into account aperture, shutter speed and in this occasion the filter.

rio

So I guess if I want to make it easier to see the effect, I need to switch off any auto-exposure settings and leave things completely manual. I will try that.......the next sunny day that comes around.

I wonder if there are any ways to see the effect other than going completely manual with the exposure.

Thanks!

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Dennis
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Re: Two Basic Questions
In reply to fbwap, Jun 12, 2013

Even in the "good old days" the Oly system was known for being relatively compact.

But it does seem that modern lenses often tend to be bigger.  I just picked up the Nikon 85/1.8 and it's a good bit bigger than an old version (roughly the same size as my Minolta 85/1.4).  Some of it is AF motors.  Some of it may be plastics instead of metal barrels.  But I recall reading a blog post somewhere that said that at the same time mirrorless is satisfying demand for smaller, we'll be seeing bigger lenses satisfying the demand for better (with high MP count sensors demanding more resolution).  50's are getting bigger.  Zooms are sometimes enormous.  The Tamron 28-75/2.8 is a pretty compact lens with decent performance (I found it usable wide open, very sharp from f/4), but better performance (and a critical extra 4mm WA coverage) gets you to the relatively monstrous CZ24-70.

I don't know if it's for angle of incidence with digital sensors or what, but some of the recent increase seems to be for higher resolution.  Some for AF, some for IS.  Maybe some for building with plastics ?

Makes the idea of some old lenses on a NEX via SpeedBooster pretty intriguing.

- Dennis

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rio911
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Re: Two Basic Questions
In reply to fbwap, Jun 12, 2013

fbwap wrote:

So I guess if I want to make it easier to see the effect, I need to switch off any auto-exposure settings and leave things completely manual. I will try that.......the next sunny day that comes around.

I wonder if there are any ways to see the effect other than going completely manual with the exposure.

Thanks!

Yes, you can just switch off the EVF effect in A77 (I don't know about the other Alphas):

MENU button -> Gear 2 ->  [Live View Display] -> [Setting Effect OFF]

Or you can simply monitor your exposure, for example if your camera is in A(perture) Mode, this means that although you will not be able to see any effect on the EVF, your shutter speed should change with the rotation of the CPL element.  With practice, it should be easy to recognize a 2 stop shutter difference (that is the difference a good quality CPL will produce).

Hope this helps,

rio

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fbwap
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Re: Two Basic Questions
In reply to rio911, Jun 12, 2013

rio911 wrote:

fbwap wrote:

So I guess if I want to make it easier to see the effect, I need to switch off any auto-exposure settings and leave things completely manual. I will try that.......the next sunny day that comes around.

I wonder if there are any ways to see the effect other than going completely manual with the exposure.

Thanks!

Yes, you can just switch off the EVF effect in A77 (I don't know about the other Alphas):

MENU button -> Gear 2 ->  [Live View Display] -> [Setting Effect OFF]

Or you can simply monitor your exposure, for example if your camera is in A(perture) Mode, this means that although you will not be able to see any effect on the EVF, your shutter speed should change with the rotation of the CPL element.  With practice, it should be easy to recognize a 2 stop shutter difference (that is the difference a good quality CPL will produce).

Hope this helps,

rio

Excellent idea! I would not have thought of that.

Thank you

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sybersitizen
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Re: Two Basic Questions
In reply to rio911, Jun 12, 2013

rio911 wrote:

With practice, it should be easy to recognize a 2 stop shutter difference (that is the difference a good quality CPL will produce).

That's the difference between a polarizer and no polarizer. The difference between a polarizer at 0° and at 90° is a lot less, and sometimes won't change the exposure value even one notch even though the effect changes visually, depending on the scene. That's the kind of change that can be hard to see with an EVF/LCD.

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EinsteinsGhost
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Re: Two Basic Questions
In reply to fbwap, Jun 12, 2013

fbwap wrote:

This may not be the right forum for these two questions, but it is the forum I am familiar with. I have read this forum every day for well over a year. I have come to respect the great technical knowledge among the Sony Alpha community and I am looking for technical answers.

1. I have an OM2 setup with four lenses back from the early 80s. How come my Sony APS-C lenses are bigger? And Full-Frame are even bigger than that? The OM system was full frame and the lenses were nice and small. I find it hard to believe the auto-focus hardware alone makes things that much bigger.

2. I have a circular polarizer now. When I rotate it, I find it hard to see the difference in my EVF. I know about being 90 degrees to the sun. It was extremely easy to see the difference when I turned my linear polarizer on my old Olympus gear.

Thanks

1- Chances are those lenses were MF, minimalist in design and in addition to Olympus doing a good job with compactness.

2- I have had that issue with my F828, but that is a 9.5 year old EVF. Non-issue on my SLT and NEX.

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dlkeller
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Qualify Removes Light
In reply to seilerbird666, Jun 12, 2013

I feel you response is a bit too general in it's wording. A neutral density filter just removes light. Other filters remove SPECIFIC PARTS of the light, as I am sure you are aware. A polarizing filter removes "glare" which is light which is vibrating on a single plane rather than all planes. Color filters remove specific wavelengths of light, not light in general.

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Dave

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