Telecentricity in Micro Four Thirds.

Started Oct 30, 2013 | Discussions
Anders W
Forum ProPosts: 18,167Gear list
Like?
Re: Thanks for the info ...
In reply to alatchin, 11 months ago

alatchin wrote:

Anders W wrote:

alatchin wrote:

Steve_ wrote:

I'm not sure this isn't a product of how large and optically uncompromised the 4/3s zooms were. It's hard to correct a lens as fully when compactness and light weight are leading priorities.

Large? I don' think they were too large but I agree that maybe we as users did not appreciate fully how good those lenses were.

Compare the size of the Oly 4/3 7-14 to that of the Panasonic m43 7-14,

A lot of the size savings from the 7-14 seem to be due to the mirror box in this case creating the need for a more complex design... Also the Olympus seems to have little to no issues unlike the Panasonic lens which has had a number o fhtreads about purple flare?

The purple-flare issue is due to the fact that a) the antireflective coatings on at least some of the lens elements of the 7-14 do not fully remove reflections close to the border between ultraviolet and violet and b) the on-sensor UV-filter on most/all Oly bodies, unlike that in most/all Panasonic bodies, does not eliminate these wavelengths. It has nothing whatsoever to do with the issue discussed in this thread. See here for additional details:

http://www.dpreview.com/forums/post/51390321

14-35/2.0 to the 12-35/2.8,

Software correction and a 1 stop aperture difference... Also the 12-35 doesnt even compare well against the 12-60 43rds lens for sharpness, let alone the 14-35.

What directly comparable evidence can you muster in support of your claims regarding sharpness?

http://www.luminous-landscape.com/reviews/cameras/olympus_om_d_e_m5_review.shtml#lumix

Not a thorough review, but there is clearly a difference. As the 14-35 is a better performing lens then the 12-60 it simply is what it is.

There is no free lunch, software correction and slow apertures will make smaller lenses. These smaller lenses will not outperform larger lenses for IQ reasons, they will have different advantages (size portability, comfort in use, price etc.)

What evidence can you muster in support of your claim that the smaller lenses MFT lenses cannot outperform the larger FT lenses, everything else equal (including max aperture).

WHat does all else being equal mean? If I stop the 12-60 down to f5.6 and compare images to the kit zoom wide open i think the results will be obvious. My phrasing was slightly off as I was in a hurry, by larger my contention was that a faster lens such as the 12-60 vs the 12-50 (as brought up by steve) the 12-50 cannot keep up.

Now the 12-40 f2.8 may well be a sharper lens, and it is smaller than the 12-60, but it takes advantage of the mirrorless design, uses digital correction (which I dont hold anything against) and is 20mm shorter at the telephoto end.

So there are real differences beyond just it being a m43rds lens. Plus it is actually quite alot larger than the average m43rds zoom... My guess it to keep the quality higher.

Before going into detail, just a question to make sure we don't debate things we actually agree on: What is the general point you are trying to make? That the smaller MFT lenses are generally optically inferior to the larger FT lenses since the former, on account of being smaller, must by definition perform less well than latter when the two are compared at the same f-stop?

If not, please spell out as clearly as you can what your general point is.

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +21 more
Reply   Reply with quote   Complain
alatchin
Contributing MemberPosts: 759Gear list
Like?
Re: Thanks for the info ...
In reply to Anders W, 11 months ago

Anders W wrote:

alatchin wrote:

exdeejjjaaaa wrote:

alatchin wrote:

Also the Olympus seems to have little to no issues unlike the Panasonic lens which has had a number o fhtreads about purple flare?

that was an issue w/ Olympus design IR/UV cut filtering in sensor assembly - letting too much close to UV spectrum through, not Panasonic fault in lens design... so put the blame where it belongs

I am not blaming anyone. It is a fact. Another fact is the 7-14 olympus lens doesnt exhibit the same flare.

I dont care for the brand bashing, I am simply stating that the smaller lenses, while being perfectly good lenses, are not necessarily the equal of their larger cousins.

The point here is that the purple flare with the Pany 7-14 has nothing whatsoever to do with the size of the lens or with any other factor generally distinguishing MFT from FT lenses. As I pointed out in a prior reply to you, it is a matter of the choice of antireflective coatings (by Panasonic) along with the choice of on-sensor UV filter (by Olympus). Note that the problem does not appear if you put the Pany 7-14 on a Pany body. It occurs only when using this Pany lens on an Oly body as a result of insufficient coordination between the two companies when it comes to on-sensor UV filtering.

I didnt disagree with you. However lens performance should be taken as a whole.

-- hide signature --

“You don’t take a photograph, you make it.” -Ansel Adams
blog.alatchinphotography(dot)com

 alatchin's gear list:alatchin's gear list
Olympus E-3 Olympus PEN E-P2 Olympus PEN E-PL2 Olympus OM-D E-M5 Olympus PEN E-PL5 +20 more
Reply   Reply with quote   Complain
alatchin
Contributing MemberPosts: 759Gear list
Like?
Re: Thanks for the info ...
In reply to Anders W, 11 months ago

Anders W wrote:

alatchin wrote:

Anders W wrote:

alatchin wrote:

Steve_ wrote:

I'm not sure this isn't a product of how large and optically uncompromised the 4/3s zooms were. It's hard to correct a lens as fully when compactness and light weight are leading priorities.

Large? I don' think they were too large but I agree that maybe we as users did not appreciate fully how good those lenses were.

Compare the size of the Oly 4/3 7-14 to that of the Panasonic m43 7-14,

A lot of the size savings from the 7-14 seem to be due to the mirror box in this case creating the need for a more complex design... Also the Olympus seems to have little to no issues unlike the Panasonic lens which has had a number o fhtreads about purple flare?

The purple-flare issue is due to the fact that a) the antireflective coatings on at least some of the lens elements of the 7-14 do not fully remove reflections close to the border between ultraviolet and violet and b) the on-sensor UV-filter on most/all Oly bodies, unlike that in most/all Panasonic bodies, does not eliminate these wavelengths. It has nothing whatsoever to do with the issue discussed in this thread. See here for additional details:

http://www.dpreview.com/forums/post/51390321

14-35/2.0 to the 12-35/2.8,

Software correction and a 1 stop aperture difference... Also the 12-35 doesnt even compare well against the 12-60 43rds lens for sharpness, let alone the 14-35.

What directly comparable evidence can you muster in support of your claims regarding sharpness?

http://www.luminous-landscape.com/reviews/cameras/olympus_om_d_e_m5_review.shtml#lumix

Not a thorough review, but there is clearly a difference. As the 14-35 is a better performing lens then the 12-60 it simply is what it is.

There is no free lunch, software correction and slow apertures will make smaller lenses. These smaller lenses will not outperform larger lenses for IQ reasons, they will have different advantages (size portability, comfort in use, price etc.)

What evidence can you muster in support of your claim that the smaller lenses MFT lenses cannot outperform the larger FT lenses, everything else equal (including max aperture).

WHat does all else being equal mean? If I stop the 12-60 down to f5.6 and compare images to the kit zoom wide open i think the results will be obvious. My phrasing was slightly off as I was in a hurry, by larger my contention was that a faster lens such as the 12-60 vs the 12-50 (as brought up by steve) the 12-50 cannot keep up.

Now the 12-40 f2.8 may well be a sharper lens, and it is smaller than the 12-60, but it takes advantage of the mirrorless design, uses digital correction (which I dont hold anything against) and is 20mm shorter at the telephoto end.

So there are real differences beyond just it being a m43rds lens. Plus it is actually quite alot larger than the average m43rds zoom... My guess it to keep the quality higher.

Before going into detail, just a question to make sure we don't debate things we actually agree on: What is the general point you are trying to make? That the smaller MFT lenses are generally optically inferior to the larger FT lenses since the former, on account of being smaller, must by definition perform less well than latter when the two are compared at the same f-stop?

If not, please spell out as clearly as you can what your general point is.

My point to Steve was that there were reasons the bigger lenses are bigger. You can't just make a blind comparison between the 12-50 and the 12-60 as if they are the same thing. YOu cant just say "look at that, it is bigger" without trying to understand why they may be so.

Aside from that, nothing. I quite enjoy the m43rds lenses and am in a quagmire of selling my 43rds gear and getting the 12-40 and 40-150 (f2.8) or just getting the E-M1. The focus of the E-M5 has spoiled me and anything less than instant can be irritating.

-- hide signature --

“You don’t take a photograph, you make it.” -Ansel Adams
blog.alatchinphotography(dot)com

 alatchin's gear list:alatchin's gear list
Olympus E-3 Olympus PEN E-P2 Olympus PEN E-PL2 Olympus OM-D E-M5 Olympus PEN E-PL5 +20 more
Reply   Reply with quote   Complain
Anders W
Forum ProPosts: 18,167Gear list
Like?
Re: Thanks for the info ...
In reply to alatchin, 11 months ago

alatchin wrote:

Anders W wrote:

alatchin wrote:

exdeejjjaaaa wrote:

alatchin wrote:

Also the Olympus seems to have little to no issues unlike the Panasonic lens which has had a number o fhtreads about purple flare?

that was an issue w/ Olympus design IR/UV cut filtering in sensor assembly - letting too much close to UV spectrum through, not Panasonic fault in lens design... so put the blame where it belongs

I am not blaming anyone. It is a fact. Another fact is the 7-14 olympus lens doesnt exhibit the same flare.

I dont care for the brand bashing, I am simply stating that the smaller lenses, while being perfectly good lenses, are not necessarily the equal of their larger cousins.

The point here is that the purple flare with the Pany 7-14 has nothing whatsoever to do with the size of the lens or with any other factor generally distinguishing MFT from FT lenses. As I pointed out in a prior reply to you, it is a matter of the choice of antireflective coatings (by Panasonic) along with the choice of on-sensor UV filter (by Olympus). Note that the problem does not appear if you put the Pany 7-14 on a Pany body. It occurs only when using this Pany lens on an Oly body as a result of insufficient coordination between the two companies when it comes to on-sensor UV filtering.

I didnt disagree with you. However lens performance should be taken as a whole.

When you decide whether or not to buy a lens yes. When you are debating the reasons for, and consequences of, size differences between FT and MFT lenses, no. In that case, the purple flare of the Pany 7-14 when used on Oly bodies is completely irrelevant.

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +21 more
Reply   Reply with quote   Complain
Anders W
Forum ProPosts: 18,167Gear list
Like?
Re: Thanks for the info ...
In reply to alatchin, 11 months ago

alatchin wrote:

Anders W wrote:

alatchin wrote:

Anders W wrote:

alatchin wrote:

Steve_ wrote:

I'm not sure this isn't a product of how large and optically uncompromised the 4/3s zooms were. It's hard to correct a lens as fully when compactness and light weight are leading priorities.

Large? I don' think they were too large but I agree that maybe we as users did not appreciate fully how good those lenses were.

Compare the size of the Oly 4/3 7-14 to that of the Panasonic m43 7-14,

A lot of the size savings from the 7-14 seem to be due to the mirror box in this case creating the need for a more complex design... Also the Olympus seems to have little to no issues unlike the Panasonic lens which has had a number o fhtreads about purple flare?

The purple-flare issue is due to the fact that a) the antireflective coatings on at least some of the lens elements of the 7-14 do not fully remove reflections close to the border between ultraviolet and violet and b) the on-sensor UV-filter on most/all Oly bodies, unlike that in most/all Panasonic bodies, does not eliminate these wavelengths. It has nothing whatsoever to do with the issue discussed in this thread. See here for additional details:

http://www.dpreview.com/forums/post/51390321

14-35/2.0 to the 12-35/2.8,

Software correction and a 1 stop aperture difference... Also the 12-35 doesnt even compare well against the 12-60 43rds lens for sharpness, let alone the 14-35.

What directly comparable evidence can you muster in support of your claims regarding sharpness?

http://www.luminous-landscape.com/reviews/cameras/olympus_om_d_e_m5_review.shtml#lumix

Not a thorough review, but there is clearly a difference. As the 14-35 is a better performing lens then the 12-60 it simply is what it is.

There is no free lunch, software correction and slow apertures will make smaller lenses. These smaller lenses will not outperform larger lenses for IQ reasons, they will have different advantages (size portability, comfort in use, price etc.)

What evidence can you muster in support of your claim that the smaller lenses MFT lenses cannot outperform the larger FT lenses, everything else equal (including max aperture).

WHat does all else being equal mean? If I stop the 12-60 down to f5.6 and compare images to the kit zoom wide open i think the results will be obvious. My phrasing was slightly off as I was in a hurry, by larger my contention was that a faster lens such as the 12-60 vs the 12-50 (as brought up by steve) the 12-50 cannot keep up.

Now the 12-40 f2.8 may well be a sharper lens, and it is smaller than the 12-60, but it takes advantage of the mirrorless design, uses digital correction (which I dont hold anything against) and is 20mm shorter at the telephoto end.

So there are real differences beyond just it being a m43rds lens. Plus it is actually quite alot larger than the average m43rds zoom... My guess it to keep the quality higher.

Before going into detail, just a question to make sure we don't debate things we actually agree on: What is the general point you are trying to make? That the smaller MFT lenses are generally optically inferior to the larger FT lenses since the former, on account of being smaller, must by definition perform less well than latter when the two are compared at the same f-stop?

If not, please spell out as clearly as you can what your general point is.

My point to Steve was that there were reasons the bigger lenses are bigger. You can't just make a blind comparison between the 12-50 and the 12-60 as if they are the same thing. YOu cant just say "look at that, it is bigger" without trying to understand why they may be so.

I agree that you can't compare the 12-50 and the 12-60 as if they were the same thing. The first is a kit lens with modest optical ambitions and the 12-60 is a fairly ambitious standard zoom.

In cases where we try to keep the level of ambition reasonably constant, I am inclined to think (without knowing for sure since so little in the way of good and directly comparable evidence exists) that the MFT lenses perform about as well as their closest FT counterparts but are nevertheless smaller. There are at least three reasons why they can be smaller and nevertheless perform similarly: The reduced flange distance of MFT (reducing the need to use retro-focus designs), the use of software correction (which adds another degree of freedom in lens design), and the increased use of various kinds of special glass elements (which makes it possible to achieve the same degree of correction of optical aberrations with fewer elements).

As examples, I would point to the following reasonably comparable MFT versus FT pairs:

Olympus FT 7-14/4 versus Panasonic MFT 7-14/4

Olympus 12-60/2.8-4 versus Olympus 12-40/2.8 (the latter reaching less far at the long end but also being faster)

Olympus FT 14-42/3.5-5.6 versus Panasonic X 14-42/3.5-5.6

Pansonic FT 14-150/3.5-5.6 versus Panasonic 14-140/4-5.6

Olympus FT 35-100/2 versus (the yet unreleased) Olympus MFT 40-150/2.8 (the latter reaching further at the long end but being slower)

Olympus FT 8/3.5 FE versus Panasonic MFT 8/3.5 FE

Panasonic Leica FT 25/1.4 versus Panasonic Leica MFT 25/1.4

Olympus FT 25/2.8 versus Panasonic MFT 20/1.7

Aside from that, nothing. I quite enjoy the m43rds lenses and am in a quagmire of selling my 43rds gear and getting the 12-40 and 40-150 (f2.8) or just getting the E-M1. The focus of the E-M5 has spoiled me and anything less than instant can be irritating.

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +21 more
Reply   Reply with quote   Complain
amalric
Forum ProPosts: 10,808
Like?
Re: focus breathing?
In reply to Tom Axford, 11 months ago

Tom Axford wrote:

zkz5 wrote:

Tom Axford wrote:

The MFT manufacturers claim that their lenses are near telecentric and I see no reason to disbelieve them.

...

You can use this property to check for yourself whether or not your lenses are telecentric. Put your camera on a tripod and switch to manual focus. Then change from focus at infinity to focus at the closest point possible and see what happens to objects at the edge of the image frame. If they just go in and out of focus without changing position, then your lens is telecentric or nearly so.

So in otherwords, a telecentric lens has no "focus breathing"?

In that case there are definitely MFT lenses that are not telecentric. With the Oly 9-18, the image changes size (like zooming) quite a lot when it focuses.

Yes, the shorter the focal length, the harder it is to make the lens telecentric. Very long focal length lenses are naturally much nearer to being telecentric.

The 9-18 lens certainly isn't fully telecentric, but I suspect it may be closer to being telecentric than many older designs of FF lenses with focal lengths between 18 and 36mm.

Do you mean the 9-18 Micro version, or the 4/3 version? The latter has much better edges, therefore I assumed that it was more telecentric.

When mounted on m4/3 however the price to pay is that with adapter it becomes quite big.

Am.

Reply   Reply with quote   Complain
zkz5
Contributing MemberPosts: 662Gear list
Like?
Re: focus breathing?
In reply to amalric, 11 months ago

amalric wrote:

zkz5 wrote:

With the Oly 9-18, the image changes size (like zooming) quite a lot when it focuses.

Do you mean the 9-18 Micro version, or the 4/3 version?

Yes, the Micro version.

Reply   Reply with quote   Complain
alatchin
Contributing MemberPosts: 759Gear list
Like?
Re: Thanks for the info ...
In reply to Anders W, 11 months ago

I agree that you can't compare the 12-50 and the 12-60 as if they were the same thing. The first is a kit lens with modest optical ambitions and the 12-60 is a fairly ambitious standard zoom.

In cases where we try to keep the level of ambition reasonably constant, I am inclined to think (without knowing for sure since so little in the way of good and directly comparable evidence exists) that the MFT lenses perform about as well as their closest FT counterparts but are nevertheless smaller. There are at least three reasons why they can be smaller and nevertheless perform similarly: The reduced flange distance of MFT (reducing the need to use retro-focus designs), the use of software correction (which adds another degree of freedom in lens design), and the increased use of various kinds of special glass elements (which makes it possible to achieve the same degree of correction of optical aberrations with fewer elements).

As examples, I would point to the following reasonably comparable MFT versus FT pairs:

Olympus FT 7-14/4 versus Panasonic MFT 7-14/4

Fair example, and wides are definitely a strength for m43rds

Olympus 12-60/2.8-4 versus Olympus 12-40/2.8 (the latter reaching less far at the long end but also being faster)

Again starting at the wide end I imagine that created an advantage (along with the other points)

Olympus FT 14-42/3.5-5.6 versus Panasonic X 14-42/3.5-5.6

Pansonic FT 14-150/3.5-5.6 versus Panasonic 14-140/4-5.6

Olympus FT 35-100/2 versus (the yet unreleased) Olympus MFT 40-150/2.8 (the latter reaching further at the long end but being slower)

This would be better compared to the 50-200 in my mind. And one stop faster can mean a big size difference

Olympus FT 8/3.5 FE versus Panasonic MFT 8/3.5 FE

True enough.

Panasonic Leica FT 25/1.4 versus Panasonic Leica MFT 25/1.4

I have both, I will make a comparison

Olympus FT 25/2.8 versus Panasonic MFT 20/1.7

Again, I am not saying there are no good lenses in m43rds or that they do not show a size advantage, but that there are good reasons. The wides will show most of this size savings, I doubt we will see quite so much in the tele end. The 40-150 looks slightly smaller than the 50-200 but has less range... Same story with the 12-60.

Aside from that, nothing. I quite enjoy the m43rds lenses and am in a quagmire of selling my 43rds gear and getting the 12-40 and 40-150 (f2.8) or just getting the E-M1. The focus of the E-M5 has spoiled me and anything less than instant can be irritating.

-- hide signature --

“You don’t take a photograph, you make it.” -Ansel Adams
blog.alatchinphotography(dot)com

 alatchin's gear list:alatchin's gear list
Olympus E-3 Olympus PEN E-P2 Olympus PEN E-PL2 Olympus OM-D E-M5 Olympus PEN E-PL5 +20 more
Reply   Reply with quote   Complain
Anders W
Forum ProPosts: 18,167Gear list
Like?
Re: Thanks for the info ...
In reply to alatchin, 11 months ago

alatchin wrote:

I agree that you can't compare the 12-50 and the 12-60 as if they were the same thing. The first is a kit lens with modest optical ambitions and the 12-60 is a fairly ambitious standard zoom.

In cases where we try to keep the level of ambition reasonably constant, I am inclined to think (without knowing for sure since so little in the way of good and directly comparable evidence exists) that the MFT lenses perform about as well as their closest FT counterparts but are nevertheless smaller. There are at least three reasons why they can be smaller and nevertheless perform similarly: The reduced flange distance of MFT (reducing the need to use retro-focus designs), the use of software correction (which adds another degree of freedom in lens design), and the increased use of various kinds of special glass elements (which makes it possible to achieve the same degree of correction of optical aberrations with fewer elements).

As examples, I would point to the following reasonably comparable MFT versus FT pairs:

Olympus FT 7-14/4 versus Panasonic MFT 7-14/4

Fair example, and wides are definitely a strength for m43rds

Olympus 12-60/2.8-4 versus Olympus 12-40/2.8 (the latter reaching less far at the long end but also being faster)

Again starting at the wide end I imagine that created an advantage (along with the other points)

Olympus FT 14-42/3.5-5.6 versus Panasonic X 14-42/3.5-5.6

Pansonic FT 14-150/3.5-5.6 versus Panasonic 14-140/4-5.6

Olympus FT 35-100/2 versus (the yet unreleased) Olympus MFT 40-150/2.8 (the latter reaching further at the long end but being slower)

This would be better compared to the 50-200 in my mind. And one stop faster can mean a big size difference

OK. Perhaps the 50-200 would be even more comparable in this case. Not as fast towards the long end but longer. Remains to be seen what the dimensions of the 40-150/2.8 will eventually turn out to be and how well it will perform relative to the 50-200.

Olympus FT 8/3.5 FE versus Panasonic MFT 8/3.5 FE

True enough.

Panasonic Leica FT 25/1.4 versus Panasonic Leica MFT 25/1.4

I have both, I will make a comparison

That would be interesting, yes.

Olympus FT 25/2.8 versus Panasonic MFT 20/1.7

Again, I am not saying there are no good lenses in m43rds or that they do not show a size advantage, but that there are good reasons.

Yes, and I agree with you that in some cases, at least part of the reason has to do with the level of ambition and the max aperture. However, the point I tried to make is that these are not the only reasons. There are also the three I mentioned.

The wides will show most of this size savings, I doubt we will see quite so much in the tele end.

We agree on that too.

The 40-150 looks slightly smaller than the 50-200 but has less range... Same story with the 12-60.

Aside from that, nothing. I quite enjoy the m43rds lenses and am in a quagmire of selling my 43rds gear and getting the 12-40 and 40-150 (f2.8) or just getting the E-M1. The focus of the E-M5 has spoiled me and anything less than instant can be irritating.

-- hide signature --

“You don’t take a photograph, you make it.” -Ansel Adams
blog.alatchinphotography(dot)com

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +21 more
Reply   Reply with quote   Complain
Keyboard shortcuts:
FForum MMy threads