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KUBOTEK Nikon Rayfact 80MM F/3.5 Line Scan Lens Test Saga
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RobertOToole



Joined: 17 Jan 2013
Posts: 916
Location: United States

PostPosted: Thu Jul 05, 2018 9:04 pm    Post subject: KUBOTEK Nikon Rayfact 80MM F/3.5 Line Scan Lens Test Saga Reply with quote

Even though there is no information online about this lens, and the little information out there is (China) is not correct, I have been looking for a good buy on one of these private label Rayfact lenses branded Kubotek for awhile.

A few weeks ago I found a good looking unit complete with a camera for a good price, $250, and most importantly the seller accepts returns.

This is the Kubotek Rayfact 80mm f/3.5



Click on any image to launch a new window with a larger version. You can right click, or two-finger click with a Mac and select the open in a new tab or new window options.

This is what I know about the lens so far.

Kubotek Rayfact 80mm f/3.5
Part Number: KLN-80-F3.5-4
Type: Industrial Large format 12K Line-scan Lens
Magnification range: 1/4x to 1x
Kubotek camera sensor pixel pitch: 4 micron
Focal length: 80mm
Aperture range: f/3.5 - f/11
Sharpest aperture: f/4
Lens mount: This lens has M41 P=0.5 threaded mount
Filter thread: M61mm, unknown pitch.

First the bad news:

The Kubotek camera that this lens was made for has a 36mm register or FFD. First time I tried the lens on my D850 I had to use way too much extension and the F-mount register of 46mm didn't help. It was too far past 1x and the results were not good.

The lens had a fungus issue.

The lens tube interior is not flocked, the shiny black interior flares (like most industrial extension tubes I own).

The good news:

On my Sony A6300 I was able to set the lens up with a 36mm register and this gave me a 1/4x to 1x magnification range.

This is what the lens looks like at 1/4x and 1x magnification settings.

Click on any image to launch a new window with a larger version. You can right click, or two-finger click with a Mac and select the open in a new tab or new window options.





Its seriously sharp at 1x, even wide open at f3.5 although f/4 is slightly sharper.

Click on the image below for a 2000px version in a new window. You can right click, or two-finger click with a Mac and select the open in a new tab or new window options.



This is line scan lens so the image quality is consistent from edge to edge.

Placing a sheet of rolled up flocking material into the rear of the lens stops the flare.


The fungus issue

This was resolved by the the seller crediting my payment once I asked Ebay to step in. Once I received the credit I pulled the lens apart.

There are two sealed lens cells inside that mount to the cam sleeve. best of all, only one surface of the front cell had any fungus and there was no coating damage.

Fungus before cleaning.



Tripod mount

This lens does not have a mount so you will have to use the camera body to attach a quick release plate but I did find that this old Tamron ring works perfectly. There is one on Ebay right now for $18 BTW.

Kubotek Rayfact lens with Tamron tripod ring.



Image quality at 1x

Click on any image to launch a new window with a larger version. You can right click, or two-finger click with a Mac and select the open in a new tab or new window options.

Camera: Sony A6300
Sensor size: 23.5 × 15.6 mm. APS-C. 28.21 mm diagonal. 3.92 micron sensor pitch
Flash: Godox TT350s wireless flash x 2 with one Godox X1s 2.4G wireless flash transmitter
Vertical stand: Nikon MM-11 with a Nikon focus block

These are all single images.



Click on the image below for a 2000px version in a new window. You can right click, or two-finger click with a Mac and select the open in a new tab or new window options.


The sharpness is impressive. The lens has almost no detectable drop off across the frame on APS-C and CAs are very well controlled even in the corners.

I will be updating this project with more images and comparisons once I am back from a 1 week trip next week.

Also I will update this post once I get a custom made adapter tested.

You can see more images and more info on my website:

https://www.closeuphotography.com/nikon-rayfact-kubotek-80mm-lens/

Questions and comments welcome.
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mjkzz



Joined: 01 Jul 2015
Posts: 946
Location: California/Shenzhen

PostPosted: Thu Jul 05, 2018 9:22 pm    Post subject: Reply with quote

wow, I was looking at it just yesterday on taobao, it is 1700RMB, or about 255.55USD without mold issue. The (slightly) molded ones are only 900RMB or about 135USD.

Without Mold

Molded One
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RobertOToole



Joined: 17 Jan 2013
Posts: 916
Location: United States

PostPosted: Thu Jul 05, 2018 9:51 pm    Post subject: Reply with quote

mjkzz wrote:
wow, I was looking at it just yesterday on taobao, it is 1700RMB, or about 255.55USD without mold issue. The (slightly) molded ones are only 900RMB or about 135USD.

Without Mold

Molded One


Hi Peter,

Yes, I did see those auctions but I would not buy from that seller.

I have bought from that guy before, he does a bait and switch, he shows image
of one lens in the ad and ships you another. Also he uses old used boxes and packaging with zero thought he is shipping delicate gear. No care is given about what he is doing.

South Korean or Japanese sellers on the other hand deserve awards for their neat and thoughtful packages. I just bought a Makro Symmar 120 for $295 from a South Korean seller and I they shipped it Fedex express for free and spend a lot of time to carefully box and wrap the lens.

Can you image what those Kubotek / Rayfact lenses sold for originally and to the surplus people? $10K vs $100?

Robert
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Macro_Cosmos



Joined: 15 Jan 2018
Posts: 116
Location: Sydney

PostPosted: Fri Jul 06, 2018 1:48 am    Post subject: Reply with quote

RobertOToole wrote:
mjkzz wrote:
wow, I was looking at it just yesterday on taobao, it is 1700RMB, or about 255.55USD without mold issue. The (slightly) molded ones are only 900RMB or about 135USD.

Without Mold

Molded One


Hi Peter,

Yes, I did see those auctions but I would not buy from that seller.

I have bought from that guy before, he does a bait and switch, he shows image
of one lens in the ad and ships you another. Also he uses old used boxes and packaging with zero thought he is shipping delicate gear. No care is given about what he is doing.

South Korean or Japanese sellers on the other hand deserve awards for their neat and thoughtful packages. I just bought a Makro Symmar 120 for $295 from a South Korean seller and I they shipped it Fedex express for free and spend a lot of time to carefully box and wrap the lens.

Can you image what those Kubotek / Rayfact lenses sold for originally and to the surplus people? $10K vs $100?

Robert


I've bought about 5 lenses from him already, all packed nicely. All purchased through taobao with proper protection and shipped to my relative's address. Perhaps that's the issue? Does buying internationally come with the same protection? I don't think so actually.

He told me that this specific lens without mold is quite rare. He also claims that the lens performs nicely even at infinity. Simply pull it out of the helicoid mechanism.

Edit: My bad, the infinity one should be the 80mm f/4 Rayfact GF
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mjkzz



Joined: 01 Jul 2015
Posts: 946
Location: California/Shenzhen

PostPosted: Fri Jul 06, 2018 2:28 am    Post subject: Reply with quote

Robert, thanks for the warning, I hesitated because I do not know how to mount it. Now after warning, I looked at these two items again, they do not have "7 day return" policy on them, so it might not be a good idea.
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Lou Jost



Joined: 04 Sep 2015
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Location: Ecuador

PostPosted: Fri Jul 06, 2018 7:22 am    Post subject: Reply with quote

I'd like to echo what Robert said about the extraordinary quality of the packing of most lenses I've gotten from Japan. In most cases, I couldn't have done better if I had packed the lens myself. I have also found that the lenses are typically exactly as described. The only problem I have had is that Japanese sellers are so concerned about visible perfection, and have easy access to such good lens repair shops, that they will have lenses "professionally cleaned", which can mean they have taken the lens apart and cleaned off internal fungus. I would distrust their ability to re-assemble the lens with the same alignment and quality control as the original. So I avoid "professionally cleaned" lenses.
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mjkzz



Joined: 01 Jul 2015
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Location: California/Shenzhen

PostPosted: Fri Jul 06, 2018 6:30 pm    Post subject: Reply with quote

Lou Jost wrote:
I would distrust their ability to re-assemble the lens with the same alignment and quality control as the original. So I avoid "professionally cleaned" lenses.


I think if they have done it many times, you can trust them. I just had my heavily molded Canon EF-100 macro cleaned by a guy in a 5 ft by 5 ft shop on Thursday and got it on Friday. The lens was in really bad condition, pictures taken with it were hazy, fuzzy, had trouble focusing. I was using it mostly as prop. Now, I think it is fixed, here is a test shot with cleaned lens.



Of course, I do not think it is a good idea to have them clean an objective.
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RobertOToole



Joined: 17 Jan 2013
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Location: United States

PostPosted: Sat Jul 07, 2018 9:08 am    Post subject: Reply with quote

Good to hear about the saved EF100 Peter.

Some of the older lenses are probably designed to be serviced so I would be okay with it. At one point I owned service manuals for some Nikon lenses like the 200mm Ai-S so this type of lens would be okay.

Modern lenses its a different case I think.

Sigma Art and Sports lenses are all individually checked and tuned for sharpness using MTF at the factory in Japan. I doubt you would see the same IQ after a thorough cleaning.

New lenses are not mean to be opened opened even by the factory. MFT - M4/3 lenses for example are not designed to be serviced. Some of the MFT lenses sold in the US, like Panasonic 100-400 cannot be serviced by Panasonic USA, they just return a refurb lens instead. I have read that MFT lenses have no tilt, shimming or centering adjustments built into the lenses like normal DSLR lenses. This means they cannot be tuned at the factory, so you get what you get, and LensRentals says MFT lenses, mostly Panasonic, have by far the highest amount of fails/returns of all the brands they rent.


Robert
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mawyatt



Joined: 22 Aug 2013
Posts: 1595
Location: Clearwater

PostPosted: Sat Jul 07, 2018 9:41 am    Post subject: Reply with quote

Peter,

Wow that looks like a new lens. Hat's off to your lens cleaner Very Happy

Modern lens are probably more sophisticated as are our new electronics. So repair for new electronics is replace the board or just a new one Shocked

I remember as a kid making $ for college repairing TV, audio and music equipment, as well as a research assistant at the university. Replacing blown output transistors, 6L6 tubes and power supply rectifiers & caps was a usual event, not anymore!

Best,
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ray_parkhurst



Joined: 20 Nov 2010
Posts: 1641
Location: Santa Clara, CA, USA

PostPosted: Sat Jul 07, 2018 5:46 pm    Post subject: Reply with quote

Ahh, the good old days!

I did just rebuild my Technics SL10, so the good old days are still here for willing folks.
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mjkzz



Joined: 01 Jul 2015
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PostPosted: Sat Jul 07, 2018 7:51 pm    Post subject: Reply with quote

OK, OK, I get it Very Happy

Those lenses that can not be serviced by 3rd party or even by factory are probably very well sealed/cemented inside the barrel, they are probably less likely to have fungus/dust issues inside the lens. You very well need special tools to open such lenses.

The EF-100 I have does not seem to be well sealed, condensation inside the lens occurs when I take it outside and I have to wait at least 15 minutes under hot sun.

The lens in the picture itself was cleaned, too, it had fungus growing inside, though not too bad as I can hardly notice degradation of image quality.

The point is that if a lens is not well sealed, it probably does not need special tool, nor special assembly procedure, so it can be serviced by third party.

Here is a video showing how to remove fungus.

And a lens spanner wrench is coming my way Very Happy Very Happy Very Happy
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Lou Jost



Joined: 04 Sep 2015
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PostPosted: Sat Jul 07, 2018 8:38 pm    Post subject: Reply with quote

Even old, unsealed, non-automated lenses have potential misalignment issues when being re-assembled. There's a reason for all those alignment marks on good lenses like the Scanner Nikkor.
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mjkzz



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PostPosted: Sat Jul 07, 2018 8:59 pm    Post subject: Reply with quote

OK I do not have that lens and do not know what kind of mark it has. On the other hand, sometimes manufacturer makes a mark to detect tempering.

Anyways, I do not doubt the importance of leaving things as-is, but when you have a problem (fungus, etc), it is better to fix. If the fix is for perfection, it might be over done, but for a skilled person, it MIGHT not that bad.
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mawyatt



Joined: 22 Aug 2013
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PostPosted: Sun Jul 08, 2018 5:41 am    Post subject: Reply with quote

Agree, if you have a lens in such bad shape (fungus) that's it's not usable as a lens and only a paperweight then why not try and fix it. You may end up with a usable lens, or still a paperweight.

I got an old Nikon 200mm F4 for use as a tube lens per Lou's recommendation (thanks Lou) that had the aperture blades stuck together (I didn't read the seller description, so my bad). After discovering such I ordered another "good" one.

Now had 2 Nikon 200mm F4, one useless. So I decided to try and repair it using Richard's wonderful guidance. I had never tried to fix a lens before, so this was all new to me.

https://richardhaw.com/2016/07/24/nikkor-200mm-f4-kai/

Long story short I now have 2 Nikon 200mm lenses, and even modified them for modern Nikon F mount use.

Nothing ventured nothing gained Rolling Eyes


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Lou Jost



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PostPosted: Sun Jul 08, 2018 6:04 am    Post subject: Reply with quote

I absolutely agree, if you already have a lens with serious problems, do whatever it takes to make it better. You have nothing to lose. I do it too.

My comments are directed at people buying used lenses. I think one should try to stay away from "professionally cleaned" lenses, even older ones, if others are available.
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