Help! I'm having Perar lens issues.

[douglasf13]

Hi. I have been battling with my little MS Optical Perar for the last 7 months, and I'd love to hear your insight on my situation, even if you don't own the lens.

Last February, after owning the lens for a month or two, I began noticing that my Perar's corner resolution was incredibly asymmetric. While I didn't expect the corners of this tiny lens to be world-beating, I am using it on an aps-c NEX camera, so I'd expect the corners to be reasonable. Regardless, it isn't the lack of corner resolution that I'm concerned about. It is the unevenness of the corner resolution. In using a liveview camera, I'm obviously able to accurately focus into each corner with high magnification, and I've been stunned at how much sharper one corner is compared to the others. It seems like this lens has heavy decentering. If I extend the collapsable lens barrel upside down, with the aperture markings facing downward, the sharp corner moves with it, and I've tried multiple adapters, so I've ruled out that it is an issue with my setup.

So, I sent the camera back to Dirk at Japan Exposures, so that he could take a look, as I'm apparently the first Perar user to complain of this. Dirk inspected the lens, tested it on his M9, and he found nothing wrong with it. The horrible Japan earthquakes ended up happening during this time, so Dirk sent the lens back to me while he could, and, while I was skeptical of his tests, I was in the middle of a house and business move, so I left the lens in the box, and I didn't retest again until Aug. Well, the same issues were very apparent to me, so I sent the lens back to Dirk for a second time for him to test.

This is where things get interesting. Now, Dirk claims that not only does he see my lens issues on his M9, but his copy of the Perar apparently does this as well! So, now I'm being told this lens isn't designed for very sharp corners, and this could be a product of field curvature, and it isn't a modern aspherical design, and I should try not to shoot things perpendicularly, etc. Huh? As I mentioned before, I didn't expect ZM 35/2.8 corners at f5.6 or anything, but the resolution asymmetry is hard for me to ignore. While I know that I could probably just sell the lens on ebay, and maybe even make a profit, I feel strange listing a lens that I believe has a major issue, despite it being ok'd twice by the retailer.

All that I really want at this point, despite spending over $100 to ship it back to Japan twice, is a refund of my original purchase price, but Dirk refuses to oblige my request. Do you think I'm out of line here? If you're a Perar owner, have you noticed the same issues? Even if you're not a Perar owner, have you ever heard of asymmetric corners being part of a design? Even on an aps-c camera?

Below are a few samples to give an idea of what I'm talking about. This was on a tripod shot at f5.6, and I liveview focused into each corner. This certainly isn't a perfect, technical test, but I can reproduce it over and over again, and have more examples that jive with this.

p.s. I apologize for cross-posting this on a bunch of forums, but there aren't a lot of Perar owners, so it's tough locating them.

Full shot (ignore the red circle I added.)

Top right corner crop

Bottom right corner crop

Bottom left corner crop

Top left corner crop

Am I being unreasonable to ask for a refund or repair? I've personally never seen this kind of corner disparity in a lens before. Thanks!

 

[250swb]

Oh no, you've cross posted here as well. I'll paste what I said on LUF and RFF here as well

"Its a niche lens, I don't think anybody but you could have bought it for its corner sharpness. For corner to corner sharp imaging you don't want an old Tessar design, never mind one that collapses. Enjoy the unsharpness in the corners and the way the lens renders. I hadn't even looked closely at corner sharpness on mine until you posted your concerns, I just knew it was soft, and yes, it is, so what? The lens design is from another age you need to leave modern expectations behind."

Anywhere else I need to reply?

Steve

 

[douglasf13]

Yes, if you'd read my post, I mentioned that I cross posted in various forums, because there are so few Perar users.

The problem isn't corner sharpness. The problem is that the sharpness is wildly asymmetrical, seemingly meaning the lens is de-centered. Are all of your corners similar in resolution?

 

[Godfrey]

From what i've seen of this lens, it's a bit of a Lomo lens for a Leica. Variable, for effect and aesthetic, not precision. Shooting with a Holga is the same thing: no one looks at the asymmetry or optical issues, they marvel at the images when they're good.

 

[douglasf13]

From what i've seen of this lens, it's a bit of a Lomo lens for a Leica. Variable, for effect and aesthetic, not precision. Shooting with a Holga is the same thing: no one looks at the asymmetry or optical issues, they marvel at the images when they're good.

I was one of the first to order this lens, and nowhere on the Japan Exposures website does it imply that this $800 lens is lomo-like. http://www.japanexposures.com/2011/05/25/ms-optical-super-triplet-perar-3-535-mark-ii/

Corner sharpness is one thing, and I didn't expect the world (even though I'm using a crop camera,) but de-centering is another issue altogether.

 

[Jan Brittenson]

Looks decentered...

 

[Godfrey]

... Corner sharpness is one thing, and I didn't expect the world (even though I'm using a crop camera,) but de-centering is another issue altogether.

Well, if you think it's de-centered, I'd suggest sending to a camera repair shop with an optical bench and having it collimated. It's not that hard for a good technician with an optical bench to take care of, given that we're talking about a four element lens, and shouldn't cost as much as shipping it back and forth to Japan.

John Van Stelten at Focal Point (http://www.focalpointlens.com/) can do this work (as well as lots of other lens restoration stuff). He's at the high end of this type of work, but I know he's reliable.

 

[douglasf13]

Well, I've already made the mistake of sending it to Japan twice. The first time they tell me there is nothing wrong. The second time they tell me that the issue is there, but it is normal. They currently have the lens in their possession. Do you think that, rather than getting a refund, I should just sell it for more on ebay? It seems to me that, despite the manufacturer and retailer claiming that it is fine, I can't in good faith sell the thing, no? Heck, I could probably get a lot more on ebay for it than I paid.

BTW, thanks for John's email. I emailed him to see what he thinks.

 

[thrice]

Given the incredibly high resolution of modern digital sensors I'm surprised Leica offers any collapsible lenses at all (90 ME). I would say it is a result of the collapsing design not a loose tolerances in construction thing. I imagine the Lens barrel could be redesigned and rebuilt to Leica standards for about double what it already costs.

 

[douglasf13]

Given the incredibly high resolution of modern digital sensors I'm surprised Leica offers any collapsible lenses at all (90 ME). I would say it is a result of the collapsing design not a loose tolerances in construction thing. I imagine the Lens barrel could be redesigned and rebuilt to Leica standards for about double what it already costs.

Yeah, that's a good point. It's just unfortunate how obvious the de-centering is. I'm surely not expecting corner sharpness to be like my ZM 35/2.8 or anything, and I expected to live with soft corners, but having the plane of focus so skewed is pretty disarming...especially on a crop camera. It's practically a mild tilt lens. I'd hate to think that I could throw this thing on ebay and sell it for more than I paid. It's a pretty early serial number from the first batch, so I know it is desirable, but do you all think I should just sell it on ebay without hesitation?

Here are a couple of full sized pics downsized to only about 1000 pixels across, which I would hardly call pixel peeping, and you can still see the corner differences. On each of the shots, I achieved the sharpest focus possible on the "warning" label using a tripod.

 

[edwardkaraa]

Hi Douglas,

From the first sample shots, I would say the lens is decentered, and I personally would expect the seller to exchange the lens for me if not a full refund.

However, if you want to be sure 100% about the decentering, I would advise you to take two oblique shots at infinity, wide open, and compare the corners. Your lens is definitely decentered but the infinity shots will leave no possible doubt.

 

[douglasf13]

Thanks, Edward. This is why I'm so confused. The seller is actually in possession of the lens right now, and even he is telling me that the issue exists. What is frustrating me is that he is expecting me to mark it down as just a characteristic of the lens design, which makes no sense to me.

I've heard nothing but good things about Dirk at Japan Exposure's customer service, but this isn't going well.

 

[edwardkaraa]

Decentering is never a characteristic of the lens design. It's not like spherical aberrations that are purposefully under corrected, it is a fault in lens assembly. I have the feeling the seller is not being honest about this issue. If all the lenses have assembly problems, then this brand must be crappy and the seller should return all his stock to the manufacturer.

 

[ZoranC]

Douglas, with even seller himself saying lens is decentered this is not a question of whether it is decentered anymore but whether seller selling lens that is decentered is OK.

In my personal opinion it is far from OK. It goes without saying that people expect that lens they buy new is centered. Especially when seller asks premium prices for a product.

There was nothing in description of this lens when you purchased it that said something along the lines of "manufacturing tolerances of this lens are such that they can come as decentered to you, treat it as part of it's personality and purchase at your own risk".

Therefore in my opinion seller owes you a full refund and full cost of shipping.

 

[ZoranC]

Decentering is never a characteristic of the lens design ... it is a fault in lens assembly.

Bingo!

 

[Jan Brittenson]

Maybe the seller doesn't speak English too well and doesn't understand what decentering means?

 

[douglasf13]

Maybe the seller doesn't speak English too well and doesn't understand what decentering means?

Interesting thought, but I'm not under the impression that I'm having language issues with Dirk.

 

[douglasf13]

Japan Exposures has decided to send the lens to Mr Miyazaki to inspect and hopefully fix the lens, which is fine by me. Hopefully the issue will be resolved. Thanks for everyone's opinion, and I'll post an update when I receive the lens back from repair.

 

[250swb]

The truth of the matter is that we don't know how the lens resolves the corners of the image because we can't see the corners of the image, these photo's are cropped from the centre of the image.

The Perar is not a Holga lens for a Leica. It is a triplet Cooke design using modern glass, hand made, and in short production runs. It is a very well corrected Cooke design. But as such it has all the characteristics of a Cooke

http://en.wikipedia.org/wiki/Cooke_triplet

It will be sharp on centre bleeding off to the edges and corners at wide apertures (much better stopped down), but since those corners are obscured to the person mounting it onto a camera that crops the image I say its hard to tell by how much the lens is faulty, if at all. The corners may still resolve themselves slightly better than the posted images suggest, particularly at f/stops and DOF at which the lens is at its optimum.

Japan Exposures are a good company, and I'm sure do follow the time honoured business model of 'the customer is always right', so I see no intrinsic value in the terms of them agreeing with you, they will agree with you whatever the problem is. As for cross posting to so many forums, when you get plenty of replies wherever you post, I see that as simply a way to try and brow beat Dirk into giving you your money back after you realised you bought the wrong lens for you. Its the tactic of a mardy person, not somebody searching for expert opinion.

Here is a link to the Perar web page that describes it in detail, showing that it is not a toy lens, or like a Holga, and that it is intended as a serious compact lens to make a pocketable M body combination, even if one copy of it turns out to be faulty.

http://www.japanexposures.com/2011/05/25/ms-optical-super-triplet-perar-3-535-mark-ii/

Steve

 

[D&A]

With regards to Steve's comments (above), I would have liked to have seen the results (images) taken with this particular sample of lens on a full frame camera (M9) and then assess the situation regarding optical asymmetry. Not always does a lens designed for full frame exhibiting certain corner characteristics on a format smaller than full frame, does so in in exactly the same manner on full frame. It could be worse, the same or somewhat different...as I've experienced on many occasions when testing out full frame lenses that were used on both a APS sized sensor vs. Full frame. It's not always a straight translation that if areas away from the center of the frame exhibit a fall off of resolution as seen on APS sensor, that it's a given that it's even worse when used on full frame. I realize we're talking about asymmetry in this particular case but I believe if a lens is designed to be used on full frame, then to assess any possible issues with the lens, it should be tested on full frame....and then take note of any possible issues.

Dave (D&A)