Can a $30 lens beat the UV-Nikkor?

[nfoto]

Spoiler alert. No, it cannot. However, as seen below, the differences can be much smaller than one would think in advance.

 

The said $30 lens is an old Petri CC 135mm f/3.5, for which I paid the princely sum of $30 incl. shipping. It has the old Petri Breech lock mount, for which adapters to various other formats can be had nowadays. It cannot work directly on a Nikon F-mount body as the register distance is shorter than the Nikon, but there is no such problem on say the Z series, m43, or Sony E-mount.

 

I recently got a Petri-Z adapter and thought it interesting to see what the lens could do against a UV-Nikkor, which is a famous golden reference for UV. It is also very expensive with asking price seen up to $6000 or higher. I purchased my first UV-Nikkor back in the early '90s and have added others along the way, all of which continue to work flawlessly on digital cameras as they are modified to have an internal CPU.

 

Captures are 100% crops. Run straight through Photo Ninja with the usual minimum of processing apart from setting "UV white" balance.

 

UV was done with my modified Z6 and the Baader U filter. Illumination by 2*800 Ws studio flash and exposure is the same in both cases, thus the UV response level-wise is about equal. Aperture f/11 and ISO 200, with the flashes about 2m away.

 

Alas this was to be the only comparison shot as one of my flashes literally exploded soon thereafter with a bang that made me deaf for hours. All fuses blew of course. It must be the condenser that failed. Until the studio flash is repaired I have to postpone other testing, or wait until I can break my C-19 quarantine and seek the big outdoors.

 

Centre of the frame.

 

 

Left corner of the frame

 

 

It is easy to see the difference here for the peripheral part of the frame, much less obvious for the centre which is very surprising. Do keep in mind the enormous price difference and the fact that also the cheap lens was almost parfocal visible to UV, which is a feature very rarely observed apart from the expensive specialist UV lenses. In case one wonders, yes the infamous UV striping of the Z6 is present as I did not run the NEFs either through a dedicated plugin (Topaz) or a raw converter capable of dealing with the issue (RawTherapee). This was done in Photo Ninja.

 

My Petri is the oldest generation with chrome focussing barrel. I still see them on eBay for $30-40 plus shipping thus they are not expensive. In fact, the bespoke adapter to your camera mount of choice likely will cost more. Filter thread is 52mm.

[bvf]

I expect the price of the Petri will rocket above $30 now!

 

Have you tested, or are you intending to test, how far into UV the Petri reaches?

[nfoto]

Will do when I'm able to move outdoors again, and/or my studio flash is repaired. I don't expect it goes way down in UV; however the fact that I did not need to alter the exposure re UV-Nikkor is unusual, to say the least. Also remarkable was the near parfocal performance vis-UV, which also is highly unusual.

 

Maybe the price rises, who knows? One has to keep in mind the added cost of the required adapter. As of today, I found several samples on eBay at very low prices, one in fact well below $30.

 

There is another slower version f/3.8 instead of f/3.5 seen in black, it might be younger. No idea of its performance. The Petri 35/3.5 is a genuine Kuribayashi clone, by the way. I have several of them and they are decent performers in UV, a replica of the Kyoei branded version of the same specifications.

[Cadmium]

Note: There are at least 3 versions of the Petri 135mm f/3.5, I have 3, and I think there are more.

 

The Petri 35mm f/3.5 ("genuine Kuribayashi clone") transmits UV like the Kuribayashi 35mm f/3.5 version, the elements are probably made by the same company (Kyoei) as the actual Kuribayashi 35mm is,

and the front and back elements look the same to me, however I have never dismantled the Petri version to see how the other elements compare or are positioned, which I have with the Kuri.

It should be pointed out that the Kuri and The Petri don't have the same mechanical build. For example, the Kuri has the focus ring in the rear, the Petri in the front. The Kuri has the (two) aperture rings in the front,

the Petri has the (one) aperture ring in the rear.

I also find the breech-lock mount rather inconvenient, because to convert it requires more space,

so if you want to use the lens for infinity it is easier to use the Kuri on an infinity converter because its M42 threads will mount directly with the infinity converter.

I have not yet compared the sharpness of the Kuri (or the Petri version) with the UV-Nikkor.

I do know that the Kuri version has extremely low focal shift, but I have not compared that aspect to the Petri version.

I have also not compared a Petri breach lock 135mm to a Kuribayashi 135mm. However, I know that the Kuri 35 has better lack of focal shift than the longer Kuri lenses.

Here is is a comparison of the Kuri 35mm f/3.5 and the Petri 35mm f/3.5 lenses.

 

 

 

Of the Kuri's, The 35mm transmits the best, I think the 80mm is second best to that...

[nfoto]

Your Kuri has preset aperture, the Petri an automatic. That's the only difference causing the lens casing to appear differently, I think. Otherwise they behave identically, at least my samples of the two do.

 

I had indeed expected the longer focal length to show more focus shift going from visible to UV, so was pleasantly surprised to find this was not the case. Or should I say didn't apply to the lens I have.

 

The breech lock mount never gained much popularity and one can see why as it tends to slow down the swapping of lenses. On the other hand it offers a very robust mount surface and shows little or no wear over time. For today's use, with intermediate adapter(s) to the final mount, this becomes of less concern. You put the lens on the adapter, tighten the breech lock, and mount the package as any native lens for your camera.

[dabateman]

I photo of your petri 135mm would help, Birna.

 

I actually saw one, don't know if would be good a week ago for $10. Almost bought it to test. But have been having too much fun with fused silica single lens elements. So holding off. I am up to 2 elements now with a front biconvex element and rear concave element.

[Stefano]

That lens (Kuribayashi 35 mm) is beautiful! Modern lenses have coatings that block UV, and removing them is difficult. Maybe it is better to build a lens with a single fused silica element, like someone already did.

[Stefano]

I posted at the perfect moment. Two elements? Are you correcting edge effects?

[nfoto]

I photo of your petri 135mm would help, Birna.

 

I actually saw one, don't know if would be good a week ago for $10. Almost bought it to test. But have been having too much fun with fused silica single lens elements. So holding off. I am up to 2 elements now with a front biconvex element and rear concave element.

 

Here is a current listing. There are black models as well. I just assume the chrome is the older, more gut feeling than based upon fact.

 

https://www.ebay.co....IwAAOSwNHZeeNzt

[colinbm]

The Petri bayonet mount has a flange focal distance of 45.50 mm which is large which is large.

I am surprised there are no adapters to M42 with a flange focal distance of 45.46 mm.

[nfoto]

I made my own from an existing Petri bayonet mount and a Minolta MD-m43 adapter, if memory serves. This was for a m43 camera and worked well. Unless infinity focus is of paramount interest, there is plenty of room for makeshift solutions.

 

Recently I got Petri-Sony E and Petri-Z adapters from eBay. I also earlier located a Petri-m43 adapter which I bought to use beside my DIY one.

[bvf]

Here is a current listing. There are black models as well. I just assume the chrome is the older, more gut feeling than based upon fact.

 

https://www.ebay.co....IwAAOSwNHZeeNzt

 

I was tempted by that listing having read your original post, but put off by the cost of an M42 adapter (non-infinity focussing) which cost about twice as much. There are still a couple of Sony E adapters available - cheaper than M42, but still more than the lens. So makes it a bit expensive to have a play without knowing the outcome. Perhaps when Birna has completed the testing - by which time the Sony E adapters will be sold out!

[nfoto]

Decisions, decisions. Life in a nutshell.

 

The female breech lock can easily be scavenged from say a Petri 2X TC, which are easy to get, and combined with many other adapters based on m42 or similar in front.

[dabateman]

I posted at the perfect moment. Two elements? Are you correcting edge effects?

 

Gone both ways. Adding a 75mm Fl concave lens to the back of my 39mm biconvex lens, fully burred out the center and had excellent sharp edges. A 200mm concave element was great for center and ok for edges. I am limited to what I bought to play with. But at $13 each, its been a cheapish fun time. I have too many elements now. But all focal lengths covered.

Biconvex have 25mm, 39mm, 50mm, 100mm, 200mm, 300mm, 500mm

Planoconvex have 75mm, 88mm, 100mm, 125mm, 150mm, 200mm.

Concave have, 50mm, 75mm, 150mm, 200mm, 300mm.

 

Only the biconvex 39mm and 500mm are 50mm diameter and 55mm diameter. All others are 25mm. I think some are actually quartz and some are truly fused silica. But can't test at 200nm, until my cheap Chinese bulb arrives. All these are great at 254nm at least.

Adding a back concave element also helps to increase the back focal distance.

 

To make this relavent. I am over the $30 budget with my elements.

Element cost: $13

Aperture control 1.5mm to 25mm: $32

5mm c-mount ring: $2.25 each

Raf camera 52mm to 25mm adapter: $28

M43rds to dual c-mount/M42 mount $6

Set M52 to M42 and M42 to M52 rings $10

 

So under $100 total. But I can flip various elements into the main lens body. Add a helicoids for the larger focal lengths and it gets more expensive. But I have a set of pentacon six extensions tubes I use. With a m42 tilt to pentacon six adapter and a pentacon six to 67mm adapter. Add 67mm to 52mm step rings to add to lens assembly. Bought those more than 10 years ago.

 

Also discovered Halex ACC holders, which can be used as tripod colars for a dollar.

[Stefano]

Much cheaper than a pre-made UV lens...

 

what is better, plano-convex or biconvex? A long focal length should improve results as the projected image is big and the sensor crops it.

[dabateman]

I will have to compare my 100mm elements to answer that question. Was actually the purpose of buying both. Too bad he was sold out of 100mm concave elements. I was thinking of building a proper 2 biconvex and 2 concave elements and copy the Wollensak 25mm lens design.

What I don't understand is that both the plan convex and biconvex elements can be reverse mounted in front of my aperture control adapter. I would have thought the plan convex would have needed to stay front mounted.

The concave don't work on their own reverse mounted. So I know I don't understand what is going on. So I just use trial and error to get element distance and attempt at correction.

 

Just looked and the seller I got these from doesn't have anything else listed. Maybe sold out of these things.

[ACRosalino]

Birna, which Petri to Sony E mount adapter are you using, if I may ask?

Thank you.

[GaryR]

Note: There are at least 3 versions of the Petri 135mm f/3.5, I have 3, and I think there are more.

 

The Petri 35mm f/3.5 ("genuine Kuribayashi clone") transmits UV like the Kuribayashi 35mm f/3.5 version, the elements are probably made by the same company (Kyoei) as the actual Kuribayashi 35mm is,

and the front and back elements look the same to me, however I have never dismantled the Petri version to see how the other elements compare or are positioned, which I have with the Kuri.

It should be pointed out that the Kuri and The Petri don't have the same mechanical build. For example, the Kuri has the focus ring in the rear, the Petri in the front. The Kuri has the (two) aperture rings in the front,

the Petri has the (one) aperture ring in the rear.

I also find the breech-lock mount rather inconvenient, because to convert it requires more space,

so if you want to use the lens for infinity it is easier to use the Kuri on an infinity converter because its M42 threads will mount directly with the infinity converter.

I have not yet compared the sharpness of the Kuri (or the Petri version) with the UV-Nikkor.

I do know that the Kuri version has extremely low focal shift, but I have not compared that aspect to the Petri version.

I have also not compared a Petri breach lock 135mm to a Kuribayashi 135mm. However, I know that the Kuri 35 has better lack of focal shift than the longer Kuri lenses.

Here is is a comparison of the Kuri 35mm f/3.5 and the Petri 35mm f/3.5 lenses.

 

 

 

Of the Kuri's, The 35mm transmits the best, I think the 80mm is second best to that...

 

Steve, It's interesting (and confusing) on how many different 35mm kuri/petri versions there are. On the 35mm f3.5 Kuri C.C. Petri that I have, the printing is straight upper, lower case lettering, with an upper case "i". Petri reads as "PetrI", Kuribayashi reads "KurIbayashI".

[nfoto]

Birna, which Petri to Sony E mount adapter are you using, if I may ask?

Thank you.

 

One of those cheap adapters floating around on eBay. For example,

https://www.ebay.co....cEAAOxySoJTQHW4

 

An alternative is getting Petri-m43 and put that on a generic m43-Sony E adapter. I use that approach for many of my various m43 adapters. A bit on the wobbly side, but otherwise a versatile approach.

[ACRosalino]

Thank you for the link with the adapters, Birna: those look quite nice... and colorful, too!

[nfoto]

Hmm. Very few Petri 135/3.5 left on eBay now, and the adapters mostly are gone as well ...

 

Do note there is an MC version, black, that I believe is newer and with multicoating. That version will likely not do.

[ACRosalino]

Yes... those things on evilBay never last long, do they?

Now, supposing I find myself with one Petri adapter too many... are there any other Petri lenses out there which could be UV (or IR) friendly?

[nfoto]

The 35/3.5 Petri is a classic. The equivalent of the often touted "Kuri" 35.

 

Be aware that the internal construction of these lenses may left something to be desired. Lots of pressed metal sheet details, for example. Issues with the aperture mechanism are not uncommon. So if you find one, treat it kindly. They are not Nikkor league in their build.

[Stefano]

Is there a modern UV-capable lens or a way to have it without using a very expensive quartz lens or without building it with single elements? Do you have to use an old lens in order to hope for it to be UV-capable?

[Andy Perrin]

I think those are the options, Stefano? Nobody makes lenses without multicoatings anymore, and the recent ones all have too many elements to be good for UV. And modern lenses that are made for UV are all expensive because it is a small market.