Infinity Alpha 50 Manual

This is a standard 50mm f/1.4 autofocus lens for Sony Alpha-mount cameras, which includes every autofocus Minolta MAXXUM or DYNAX, 35mm or digital, on which it. View and Download Agilent Technologies 1290 Infinity II user manual online. Preparative Open-Bed Fraction Collector. 1290 Infinity II Laboratory Equipment pdf manual.

There are to adapt manual lenses to the Sony A7 series cameras. To do so you need an adapter and this article will help you to choose the right one. We are three guys from Germany who have adapted manual lenses for many years now. By using several dozen adapters over the years we have learned the hard way, that not all adapters are created equal. We hope that the money we spent on bad adapters will help you to avoid annoying miss-buys we experienced. In the following two parts we tell you why you need an adapter in the first place, and which issues can arise with adapters. If all you need is the right adapter for your lens you can simply jump to ].

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If you want to support our manufacturer independent work please consider using them. Contents • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Why you need an adapter This image was taken with the awesome using a Novoflex adapter The first reason is that every camera manufacturer uses a different mount and with a few exceptions these are not compatible. Let’s assume you want to use an old on your Sony A7II. The Minolta physically doesn’t fit your Sony. Here the adapter comes into play: on the side facing the camera it has the Sony E-mount and on the side facing the lens the Minolta SR-mount, so with the adapter your old manual focus lens now fits your new A7 series camera.

There is a second issue which needs to be overcome and that is the. This is the distance between the mounting flange of the lens and the sensor. If the flange focal distance between the lens you want to adapt and the camera isn’t maintained you will either lose infinity focus or won’t be able to focus on anything at all. Your camera needs to have a shorter flange focal distance than your lens or it is impossible to make an adapter. That is one reason why you can adapt almost any lens to the Sony E-mount cameras with their very short flange focal distance of just 18 mm. Let’s have a look at the Minolta SR 1.7/55 again. It has an SR-mount so its flange focal distance is 43.5 mm.

Your Sony Alpha 7 has an E-mount with a flange focal distance of 18 mm. Therefore the adapter needs to be 43.5 mm – 18 mm = 25.5 mm thick. Adapter Problems Adapters can cause several issues which we want to discuss briefly to give you a better basis for an educated buying decision.

Mechanical fit Optimally a lens would fit your camera so well that there is zero play and camera and lens feel like one unit. In practice even native E-mount lenses don’t fit perfectly and you can notice a tiny bit of radial play. The reason for that is that it is more expensive to machine mechanical parts very exact with tight tolerances and therefore a small amount of play is often allowed to keep costs down.

With adapters we have seen very different amounts of play. • Our Novoflex and Rayqual adapters fit very well and we notice zero play with them. • Our experience with cheaper no-name adapters is all over the place.

We have owned adapters which fit almost as good as a Novoflex and we have had adapters from the same source which where unusable because of their very bad fit. • Our cheaper adapter brand of choice is K&F, their adapters usually show a tiny bit of play. It is so minimal though, you only notice it when you look for it. Adapter thickness We gave a brief explanation of how an adapter needs to span the difference between the flange focal distance of lens and camera in the previous paragraph. In theory any adapter, mount and lens would have exactly the same flange focal distance as specified.

In reality there is variance in each component: • Lenses might be miscalibrated so that they reach infinity before the infinity hard stop or can’t be focused at all on a well calibrated camera. • Sony’s E-mount cameras – especially the ones from the first generation – show a significant amount of variance regarding their mount parameters.

• Adapters are subject to variation as well. The amount depends on the manufacturer’s quality control and production process. So this is a big game of tolerance. If you manufacture your adapter exactly it will work well on most lens/camera combinations, but some people won’t be able to reach infinity with their lens.

So most adapter manufacturers make their adapters a bit shorter. This guarantees that the adapted lenses reach infinity but it also has several unwanted consequences: • The focus scale of the lens becomes inaccurate. The shorter your focal length, the more it will be off.

• The hard infinity stop of your manual lens no longer works, as lenses will focus past infinity. • You will see a negative effect on performance with lenses which use floating elements (most modern wideangle lenses including zoom lenses do). So how much of an issue is it if an adapter is too short? It is a big issue if you use a fast wide-angle lens with floating elements. Phillip once tried to use the legendary Zeiss Milvus 2.8/21 with a cheap Nikon F to Sony adapter on his A7 and it had very weak corners while the showed very good performance with the same adapter. Bastian also had issues with a cheaper adapter and the and even with more expensive (but still too short) adapters and the. Phillip once tried the Canon EF 4/16-35 with a cheap electronic adapter and this combo had serious field curvature issues.

To show you how big the differences can be Bastian made this comparison using his Nikon-F Samyang 14mm 2.8 and a K&F and a Rayqual adapter. Let us first look at the center of the frame. Before: K&F adapter After: Rayqual adapter Samyang 14mm 2.8 on Sony A7rII, focus on center, 100% crops Here the too short K&F adapter leads to abyssmal image quality in the corners with the floating elements Samyang lens and the Rayqual adapter looks significantly better. I (Phillip) have used legacy lenses with too short adapters for years and saw no reason to fix these adapters.

But that’s just me, and I don’t use the focusing scale nor the infinity stop. Now that I own several legacy wide-angle lenses with floating elements, I am more cautious and have for correct infinity. In theory adapters could also have uneven thickness which would lead to a tilted image plane and therefore degrade the image quality. Personally we have never run into such issues though, even with otherwise badly made adapters.

Adapter length is also an issue you can. Adapter Reflections a reflective adapter on the left vs a well designed Novoflex on the right Another issue is light reflected by the adapter to the sensor. Adapter reflections do not happen often.

I (Phillip) used adapted lenses with cheap adapters for years before I ever noticed them. They seem to happen only with some lenses and in specific scenarios but then they often destroy an image.

Here is an example for that. Sony A7rII Nikon Series E 50mm 1.8 NiSi ND1000 Filter Before: Pixco adapter with light leak After: K&F adapter Durability Not all adapters are made to last. So far I (Phillip) have had to throw four cheap no-name adapters away because they no longer held the lens safely. In one case I had to spend over an hour to get it off my lens. Adapter Issues – Conclusion By reading about these issues one might get the impression that adapters are a huge headache and one would be much better served by staying away from them and choosing native lenses straight away. But if you look at Sony’s native lenses regarding tolerances this is a as well. Internet forums are full of reports of people who had to go through many copies to get a well centered one and we have had to return a significant proportion of the Sony lenses we have bought for oursevles as well.

Our list of issues is so detailed because, as reviewers, we think it is our job to take a really critical look and identify any potential issues. In practice many people buy a random $20 adapter and never notice any of these issue. But if you run into an issue our article should help you to understand and fix it or to avoid it right away by choosing the right adapter. Adapter manufacturers There is a large number of adapter manufacturers and on top of that adapters from the same manufacturer might show some variation as well. We would have to test several hundred adapters to get reliable information on their average thickness and variation. We can’t do that. But we use certain brands a lot so we have a large enough sample size to give you more detailed information on them.

We have also summarized other people’s (that we trust) reports on brands we have less experience with. K&F At around $20 they are very affordable but we have experienced much less issues with them than with other cheap adapters in the same price bracket. They usually fit well with only a small mount of play and their locking mechanism seems to be durable enough. Reflections can be an issue though, because the inside is rather reflective, but as said you won’t run into them often. The fact that they are usually rather short weighs heavier and will affect image quality with some lenses.

Still they are our budget manufacturer of choice and each of us owns several of their adapters. Recently K&F has released a second generation of adapters. The new adapters are much better at controlling reflections and the camera facing mount is now chromed. We still have only a small sample size but it seems that they only go a little beyond infinity, less so than the earlier version. The adapters are also noticeably heavier than earlier versions. Novoflex At $140-250 they are among the most expensive adapters but they are made in Germany with very tight tolerances and very good build quality. All the Novoflex adapters we have used so far showed zero play and the adapters suppress any flare issues effectively.

They also have very solid springs to maintain pressure on the lens. The only smaller issue we have found is that they usually don’t quite reach infinity. One Minolta SR shows 3m on the focus scale of a Minolta MD 2.8/24 focused at infinity and another one 5m on a. Unfortunately the anodization on Novoflex products isn’t all too durable and after some usage you will see signs of wear on the adapters. One advantage of the Novoflex over the Rayqual is the (Affiliate link) tripod collar.

It is bloody expensive but also rock solid and especially handy for mounting heavier lenses without a dedicated tripod collar. Our recommendation if you want an adapter you don’t need to worry about. Rayqual Rayqual Nikon-G to Sony-E Adapter We have only tested a Nikon-G adapter from Rayqual so far but it might in fact be the best Nikon-G adapter as it even offers click stops (the Metabones doesn’t). Furthermore two loyal readers of this blog, Tim and David, have recommended them in the past and we trust their judgement. They play in the same league as the Novoflex adapters with zero play but they use light baffles which will suppress any flare even better (not that I ever noticed any issues with a Novoflex).

Unlike the Novoflex adapters the Rayqual adapters have no margin to allow for miss-calibrated lenses or camera mounts, as the infinity hard stop will be dead on with most lenses. Lost 5x02 Ita Download Youtube. Therefore it can happen that you won’t reach infinity with them. Furthermore some readers told us when using extension tubes you might run into vignetting issues quite easily.

Our other recommendation if you want an adapter you don’t need to worry about. Metabones Metabones Nikon-G to Sony-E Adapter Metabones is best known for their Canon EF AF adapter (they were the first in the game) which is now available in its fifth generation. Their precision is above that of the cheapest manufacturers but according to they have a high failure rate (they should know because no one has similar sample sizes). The failures will be caused by the electronics most often but none the less they don’t seem to play in the same league as Novoflex or Rayqual. Metabones offers adapters for many mounts, which are also often a bit short (similar to Novoflex). What I (Bastian) really like about the Metabones adapter is the built in yet detachable Arca-Swiss compatible tripod mount, although you might run into difficulties when using very big clamps or an L-bracket mounted to your camera.

Fotodiox Pro Fotodiox offers adapters at different price points, the higher quality ones feature the “Pro” tag in their name. I (Bastian) have already tested 3 different of their Leica-M adapters: the normal one is a little too short but otherwise there is nothing wrong with it. The pro had very nice, solid build quality and acutally a very nice design. The Pro DLX stretch (a helicoid adapter) was unfortunately a little too much on the wobbly side (may introduce decentering to your lenses), I can’t recommend it. Nevertheless, I still have and use two of their cheaper adapters and see them as an alternative to the K&F adapters. So, how much should I spend on an adapter?

So, how much should you spend on an adapter and which brand should you buy? We can only recommend you to stay away from $10 no-name adapters, the saved money isn’t worth the potential issues. But if you spend $20 on a K&F or Fotodiox adapter you have a good chance of never running into any issues.

And if you spend $15 on materials and for an hour you will most likely be able to fix any potential issues as well. So we would recommend to buy one of these if you are getting started with manual lenses or just use a few affordable lenses from one manufacturer. If you never want to worry about your adapter and use some more expensive lenses on a regular basis we would recommend you to spend $150 on a Novoflex or Rayqual adapter.

Adapter Recommendations by lens mount Minolta SR mount with the SR mount are easily identified by the MC or MD engraved into the front. For a full list of all the models visit. Identifying third party lenses with SR mount is bit more difficult but many have something like MD engraved near the mount and the image of the mount above can help. Our budget recommendation is the K&F II adapter: * * * Our peace of mind recommendation are Novoflex and Rayqual adapters. Their prices differ a lot between the markets and we would recommend the cheaper one.

Novoflex: * * * Rayqual: * * Canon FD are very affordable and Canon made a few outstanding (at least in their time) lenses like the. They can be identified by the engraved FD and use a rather complicated and unusual mounting mechanism which makes it a bit more complicated to mount them.

Our budget recommendation is the K&F II adapter: * * * Our peace of mind recommendation are Novoflex and Rayqual adapters. Their prices differ a lot between the markets and we would recommend the cheaper one. Novoflex: * * * Rayqual: * * Canon EF/EF-S The EF mount is the successor to the FD mount and is purely electonical, so Canon EF(-S) lenses, even most of the manual focus ones, need an adapter with electronics in order to being able to change the aperture. Most of these adapters also offer AF and support the lenses’ IS (if available). They range from ~70$ (Commlite, Viltrox, Fotodiox) to ~400$ (Metabones T Smart) with the Sigma MC-11 in between for ~250$.

I (Bastian) have tested Commlite, Viltrox and Sigma MC-11. When it comes to controlling the aperture they all worked quite well, but when it comes to AF I can only recommend the Sigma MC-11 of these three, the other two were quite unreliable, especially above 150mm. Furthermore the two cheaper adapters showed way more radial play than I can tolerate. When it comes to the flange distance the MC-11 was also the best match.

The latest Metabones adapter is said to be at least on par with the Sigma MC-11, but it is also significantly more expensive and the guys over at with their reliabilty. Some additions to your useful article. First I would like to add Leitax, who have started to make direct E-mount adaptors for several mounts. Apart from reduced tolerances (at least that’s my experience with several XX->EF mount adaptors) a rock-solid stability, they offer a kind of spacer ring, which in combination with a cheap Canon (copy) tripod ring allows to put a tripod ring on the adaptor similar to the ASTAT-NEX from Novoflex. While the ASTAT-NEX can be used on any XX->E-mount adaptor from Novoflex the Leitax seems to be different for every mount type, which is much less flexible when you use lenses with different mounts. For people who like to have EXIF data with their adapted manual lenses there is the possibility to use an adaptor with programmable chip for the respective mount to Canon EF and then use a second adaptor from EF to E-mount. Of course your issues with tolerances become even worse when using two adaptors, which is why I recommend to use it with Leitax mount conversions only.

It’s not cheap though, when you convert many lenses. Very nice article!

Ever since I found your blog, I was unsure if the cheaper Adapters would degrade image quality (in earlier articles you often recommended novoflex adapters). But novoflex was out of my price range. The K&F Koncept adapters work for me, although I can focus past infinity with most lenses.

I would like to add that there is a cheaper speed booster alternative to the metabones adapters: Zhongyi II Speed Booster. I own one (EF-Nex) and it works quite well.

Zhongyi Adapters don’t have electrical contacts, so no aperture control or AF through the camera, but with manual lenses you don’t need it anyway. One should look out to buy the second version of their adapters, the first version had issues with flaring. The Zhongyi speed boosters are also quite close to the image quality of the Metabones speed boosters according to Matthias Proske, a camera and lens tester from germany (Test of several Speed Boosters: ): Central sharpnes seems to be very similar. Edge sharpness is a bit better, although the crop factor of the Zhongyi is only x0,72 and not x0,71 as the Metabones (though it is said they would be almost the same sharpness if the Metabones Image would be cropped in post production to match the x0,72 crop factor of the Zhongyi). A comparison of a speed boosted wide angle lens an a crop camera and the same wide angle lens on a fullframe camera would be very interesting! I guess the would be a difference in image quality, but I’m not sure how much the speed booster would affect the IQ.

Dear friends, thanks again for this excellent overview. As I am also a lens junkie (to some extent), AND also a photographer with old eyes and some modern lenses, I can add some experiences with AF adaptors, all valid for A7RII and A6500. I won’t comment manual focus lenses and adaptors, Phillip and Bastian have said enough. Metabones model IV and Sigma MC-11 AF adaptors for Canon EF: As a lazy guy I don’t like to change adaptors and lenses constantly, so I own several (4, to be exact) of the Metabones (some internally flocked, some not) and 2 of the Sigma MC-11 for Canon EF mount, each of them is attached to one single lens – so it is much faster in the field to change lenses regardless of brand, this helps to shorten the time of “open Sony cameras” and minimizes dust collection inside. All Metabones have been purchased in used condition via ebay, so no “positive” selection.

I use these adaptors not only with Canon, but also with Sigma EF mount lenses, especially the Macros. I have very rarely any issues with them, I remember one case when I had to update FW of a Metabones to overcome some sort of not working AF. As I update FW anyway as soon as Metabones announces new ones, no problem. I have also owned for some time the Sigma Sports 150-600 in EF mount, which worked MUCH better with Metabones compared to the Sigma MC-11 (the Sigma adaptors have been purchased new on Amazon, with the 150-600 in mind). The Arca base of the Metabones is a nice feature, but as my Sony’s are equipped with Arca type L-plates, space gets quite limited in case you have a big clamp. What I have to confess: due to the floating elements problem I do not use wideangles with these adaptors anyway, so flange distance is no issue for me. Red Hat Enterprise Linux Server 6 X64 Download Iso here.

My main use are longer lenses and macros. I have exchanged the Sigma 150-600 and replaced it with the latest Canon 100-400, which is MUCH better optically and works fine with the adaptors. With these Metabones and Sigma Macros 150 and 180 and the mentioned Canon 100-400 I have survived 4 macro workshops in the field in 2 years and did not miss one shot due to adaptor related problems.

I also still own one Metabones EF-M4/3 AF adaptor, which works equally well with Olympus OM-D E-M1 (now in possession of my brother). So we can exchange lenses, a fine option, especially as M4/3 had the same missing long lens problem for a long time! To say it clearly: I cannot confirm the Metabones comments of lensrentals. Maybe the lensrentals clients had no time to learn what the adaptors can do and what not (especially the confusing “green” and “advanced” modes). As for the Sigma MC-11: in the beginning there has been much hype around these, which in all honesty I couldn’t understand. My examples had several issues, would focus much slower than Metabones and had big problems in not so bright situations.

After two or three FW updates, I think they are better now and work comparable to Metabones. Mechanical fit is nice, though. I also own one Sigma MC-11 for Sigma SA mount, which I use with a Sigma C 17-70 as a “holiday combo” on A6500 – no complaints, works fine, optically a good solution for a general purpose zoom.

In the beginning however, with first FW version of the MC-11, AF would hunt, miss, fail and make noise as soon as light is not super bright. Now, after FW updates, its just fine. Commlite AF for Nikon: Basically, this adaptor works, again my experience valid only with longer lenses. Main issue is that you need fast lenses. Performance on Nikkor AF-S 1,4/85 was fine, on slower zoom lenses I cannot recommend this adaptor.

Meanwhile I don’t need it anymore, as I have done the step to sell the Nikkor and to acquire a Batis 85. Sony LA-EA3 Works just fine with the Sony ZA 2,8/24-70 and a Sigma 150 Macro HSM OS. Again, all comments only valid for use with the PD-AF-capable Sony e-mount types like A7RII and A6500. General AF issues with Sony E mount.

On Sonyalpharumors, a couple of days ago some photog colleague mentioned the “oszillating AF problem” (but nobody helped him): starting with F/8 and then downwards with slower apertures, native Sony E-mount lenses would hunt for AF and fall into some “pulsing” or “oszillating” behaviour, and stay there trapped. No AF possible.

This may happen in less than optimal contrast scenes (but still far away from dusk or dawn!). I would tend to describe it as some strange kind of interference between AF-point pattern on the sensor and structure of the targeted area. Open up to at least F/5.6 and the AF will work.

In my case, this happens with the A7RII and the G-Master 24-70, before also with the Vario-Tessar 24-70. NO problem at all with the LA-EA3/ZA Vario-Sonnar 24-70 combination, where the aperture is fully opened and will be closed only after pressing shutter release. Now while all this may be excusable, as SLR’s also don’t AF with F.

When it comes to dumb adapters, I wonder why you always recommend (peace of mind recommendation) the expensive adapters from Novoflex, Rayqual, Metabones and Fotodiox as they still have strong downsides. You can’t focus to infinity with Rayqual. That’s a huge downside, IMO. Novoflex, Metabones and Fotodiox are too short, wobble, have too much play You can get the same or less for much less with K&F. They’re not peace of mind, IMO.

You still need to test them, may return them or live with the shortcomings. And that for a very high price. I have a couple of K&F adapters and they work great.

Twice I needed to re-buy them because they were too short but that was no issue. I just returned them within 14-30 days. You just have to test them asap – but also Novoflex, Metabones & co. In my opinion, if there is no general production problem with this adapter, you can just go with the cheapest, buy a couple of them, test them all, choose one and send back the other ones. K&F is a good start to avoid general production issues.

Somewhere you mentioned that you had had problems with your Minolta SLR adapter, it too short. I wonder if there’s a general problem with Minolta mounts/lenses/adapters because my Minolta adapter also was the only one which was waaaay too off. Maybe the lenses have too much variations because the cameras had too much variations too?

And now the adapters need to compensate for that? I don’t own many Minolta lenses to see if there’re any lenses which need so much play.

For example I have a M42 adapter which has infinity in focus with the lenses I had where the infinity symbol starts, not at the hard stop. I looked for better adapters and was about to fix it myself. But now I have a M42 lens that has infinity focus at the hard stop. So the adapter is absolutely right and I need this kind of play because the lenses have so much variations. Maybe the same is true for the Minolta lenses but even more exaggerated. My cheap C/Y adapter has no play with my Contax/Zeiss lenses.

Maybe they’re build to higher standards and therefore the adapter needs no play. We also recommend the K&F adapters because they usually get the job done but there are certain benefits to the Novoflex/Rayqual adapters which are worth the money in some cases.

Of course you can focus a Rayqual adapter to infinity. As we elaborated in the article there will be cases where you can’t but that’s because your lens and/or camera is out of spec, it is not the adapter’s fault. And the reason that we recommend Novoflex/Rayqual as a peace of mind solution is that they are very well made and have zero play. I own three Novoflex adapters and they have zero play on my a7ii. My half a dozen or so K&F adapters have very little play but they do not fit as well as the Novoflex adapters. I own K&F adapters for Nikon, Canon FD, Minolta SR, Leica M and M42.

They are all quite a bit too short. My noname C/Y adapter has quite a bit of play.

I have no reason to assume, that this is a brand specific issue. Hi, It happens that I’m using FOTGA adapter for my Minolta lenses and I hate it as it has a little play at the mount of the camera and a smaller one in the lens mount. I have one Minolta Rokkor PF 50 1.7 a little wobbly somewhere around the aperture ring, but in conjunction with the adapter feels like a ballerina on my camera mount. I’ve decided to buy the Novoflex adapter for SR mount, but stumbled on Ulata adapters on ebay. They look well built and also have matte black interior.

Has anyone tried these adapters? A couple of forums on the web say that it’s a good adapter but would love to hear one objective opinion about them before my purchase. I’ve also tried Selens for FD and they’re pretty well built and also have that play that you should really look for it to say that it is there. The paint on the exterior looks somehow very expensive, profi-like, but the interior for some reason is a little shinier on the grooves than the exterior, but still better than K&F first generation ones.

Also I have one no-name M42 adapter that is a perfect fit. Too bad the Russian lenses weren’t made to fit their read-out always vertical. If my Helios lenses fit perfectly with it, my Jupiter 37A is somehow to the side and my Tair 300mm has also a little offset. By the time I figured out what that little hex key is provided for, I’ve lost it. Even so I wouldn’t screw and unscrew those little screws for every lens. All these adapters reach infinity before the mark by a tiny bit, but that isn’t a problem for me, yet:)) Over all I’m staying away from Fotga as the tolerances are way bigger than what I can accept and I’m also open to other cheaper but well built alternatives to Novoflex, Rayqual or Fotodiox since all I’m buying is a metal spacer without glass.

My question has to do with adapting the Minolta Maxxum 70-210mm f3.5-4.5 and the Minolta Maxxum AF Zoom 70-210 1:4 (32) 55mm (beercan) to the Sony A7. Since there is no aperture ring control on these lenses is there an inexpensive adapter available that can control the aperture setting on these lenses? I’m told the Fotodiox Lens Mount Adapter – Sony Alpha A-Mount (and Minolta AF) DSLR Lens to Sony Alpha E-Mount Mirrorless Camera Body adapter has an aperture ring on it although I have not seen or used this adapter before. Hi Phillip, Thanks for sharing your passion and inspiring ohters. You actually made me buy a Sony A7R!

Now I have some nice vintage lenses like the Pentax K 28 f/3.5 that I really would like to use with the Voigtlander VM close up adapter for Sony E mount, but that means I would have to first put a (K&F) Pentax K to Leica M adapter on the Pentax K in the first hand to convert it to a Leica M mount, and subsequently connect it to the Voigtlander VM?Will this work? Have you tried this on e.g. Minolta lenses? In theory it sounds tempting, as it would give close up ability on lots of lenses. I tried the Sigma MC-II adapter on my A7, with Canon 24/2.8 IS USM. Whilst very accurate,(it didn’t miss in over 100 shots), it was also very slow, 3-5sec. I believe though, that on MkII bodies it can be nearly as fast as native, (though it depends on which lens are on.) I’ve just had my first K&F Concept “dud”.

Praktica PB to NEX. It was 0.9mm short! If you Google “Praktica B register distance”, you get a variety of different results,(It should be 44.41mm). I can only assume that they went by one of the wrong distances, or else mine was just a rogue adapter. To the credit of the seller, in China, they were very helpful and immediately offered replacement or refund. As I couldn’t be certain the replacement wouldn’t be any better, I went for refund.

BUYER BEWARE! Nasty things can sometimes happen using an adapter! Above I mention the K&F Concept Praktica B adapter.

The mounts each end were a very good fit, but I had to buy another cheap make to get the length right! (I’m trying out the PB version of the famed Carl Zeiss Jena 135.3.5 Sonnar MC) The PB bayonet mount on the lens, has a row of three, quite substantial round brass, “sprung” contact pins, with straight sides and rounded ends, which protrude 1-2mm beyond the face of the mount. One of these, has “spring-locked” itself, like a lens locking pin, into a deeply recessed screw hole on the adapter mount, and firmly jammed it in place, with no way to remove it, no matter what I do! It took me several tries, over several hours (on and off), with 3 and 4 thou” feeler gauges between the mounts, to work out where and what had jammed. The rounded end of the contact isn’t sufficiently bevelled to “lift” it out again when the lens is turned! That could happen with any make of adapter, and deeply recessed screws are usually a good thing! I still haven’t decided whether to leave it as is, or saw the adapter off!

(After first carefully sealing the rear of the lens against any debris!). Please reread/edit the part about the speed booster. Let us assume, that we use a full frame lens on an APS-C camera. A normal adapter does not change the f-stop. It crops the full frame picture, so one works with a focal length multiplied 1.4, compared to a full frame picture.

A speed booster concentrates the light of the full frame lens on the half frame (APS-C). Herewith the user wins one fstop. The light of the full frame concentrates on the half frame. The focal length is the focal length (angle of view) of the lens, as on full frame.