FAQ like Info about 35mm lenses

[ChainSmoker]

Very informative! Outstanding job Timur!

Rich

[Gordon JL]

I have this really old PENTAX photography lens from my dad when he had his own camera. The lens is a prime lens (non-zoom), and I'm assuming the focal length of it is 50mm. Now, I've noticed that the lens hood says 49mm; and the UV filter it has on also says 49mm -- this leads me to think that maybe the 50mm on the lens actually refers to the diameter of the lens, not the focal length (since 49mm fits 50mm). How the hell do I tell what the focal length of the lens is? Also; any way to check to see the value of the lens (so I could tell how the quality is)? And, how would someone come about cleaning the lens? Should I use microfiber cloths, with regular glasses-cleaner liquid, or just an air-blower? It's a really old lens (10-30 years ago); but the lens part itself seems to be in good shape, although I see a lot of dust. I'm thinking that because the lens is so old, that it wouldn't be as crisp or sharp as the newer lenses. Should I just upgrade to new ones?

[TimurCivan]

the focal length should be written on the inner lip of the lense in the front. Next to its Fstop rating. it should say something like "PENTAX--Opticamax---50mm F1.8 ----" etc. ( i made up the opticamax part just to give an example o whats probably on it.)

the 49mm is the filter thread size. the focal length is different.


Pentax lenses, (my dad had, and still swears by Pentax) are really good. if its a brand name one, like the pentax company made it, its probably very good. But like i said look through it backwarsds to see if the dust and crap is inside the lens or outside the lens. Or take a picture with it, if your dad still has the body and then examine the prints, see if the sharpness is acceptable. Or go buy a body, and use it for stills too. ( nothing makes your composition better than taking lots of pictures)

You see once you build up a collection of lenses, and you buy a decent camera body to go with it, suddenly youre a very well equipt Photographer.

Enjoy

[Bobaristheguy]

my guess is that your pentax is a bayonet mount not their screw mount. If that is the case I recommend picking up a K1000 body to test the lenses out. It is cheap, has one of the best light meters ever in a camera, (I know professionals who still have a couple k1000s as backup cameras because of this), and that camera is a tank (meaning you can throw it up against a brick wall, put the lens back on and take a picture with it). Why I say this is because it is the perfect first camera because of its simplicity. It will allow you to learn the basics of exposure and dof that alot of newer cameras automatically do for ya. This will also help you out when you transition that lens into video.

As for cleaning the the lens, use a microfiber cloth and a lens cleaning solution after you have removed as much dust as possible with blowers and compressed air. If you don't you can still make scratches with the microfiber. Also if they are fairly nice lenses you can take them to a camera shop and have them calibrated and polished, this can drastically improve the quality because old lenses that have been sitting unused can grow a haze from dust an oils and many other things. They can also check for any fungus and sometimes can treat it so it is less likely to spread. The camera shop in my area does all this for $15 a lens.

[slinks]

timur! thank you so far! I'm one of those "somewhat lost" people on lenses lol.

[Ed Kishel]

great info!

[Brandon Rice]

Excellent read! I am in line to be getting a Brevis35... so all this info is very helpful for me.

[dougspice]

Good post Timur. I just came back from lens shopping today, and I've been taking stock of my old gear, so I'll throw in a few notes. I used to do a lot of still photography, primarily with Nikon gear, so I feel like I have a pretty good handle on this.

Desireable optical characteristic

Definitely, not all lenses are created equally. In general, you are looking for the same characteristics in all lenses: SHARPNESS, SPEED, and image QUALITY. I've been a bit of a Leica snob from time to time, but the good news that for using these lenses with a video adapter, you don't really need to worry about SHARPNESS. Most lenses out there, even cheap Tamrons and Tokinas, will probably still resolve more sharply than your camera is capable of recognizing.

SPEED, on the other hand, becomes critical. How much light does the lens need? For this sort of application, you want the fastest lenses you can get. Realistically, this is an f/1.4, but for most lenses it'll be more like a f/2.8. In my opinion, anything slower than an f/4 or so risks being useless in anything but an outdoor setting with these cameras. Cheap zoom lenses will have variable speed... for instance quite a few will be f/3.5 at the wide end and more like f/4.5 at the telephoto end. This is something I like to avoid... I work strictly with constant-speed lenses. But on the other hand, variable speed lenses will often be MUCH cheaper.

QUALITY is a pretty broad term to describe all the other little things that go into the image. Chromatic Aberation is the big one: does the lens produce artificial color fringing when looking into highlights or under other circumstances? Some lenses (including the stock lenses on both the HVX and the HD100) will do this at the edges of the frame, but not the center, and it will also occur more often at the telephoto end. Generally, this is considered a bad thing, but it's also an aesthetic. Maybe you like it. There are cheap sorts of very long telephoto lenses known as Mirror Reflex, which operate differently from normal lenses. They are generally not of great quality, slow, and produce very curious focus bokeh. But I personally have used them on several projects, precisely because I thought that weird "bad" bokeh was good for it. This stuff is all subjective, really.

There's a few other serious considerations that have to be added in when adapting still lenses to motion pictures, which you would never have to worry about on your regular 35mm body. The first is breathing, which is the tendency for objects to shift size as they move in and out of focus. Lenses with bad breathing problems can look like you're doing a small zoom even when all you're doing is a focus rack. Everyone can pretty much agree this is a bad thing. So make sure you test out a lens you're thinking of buying and watch what happens to a subject carefully as you rack through the focus range. Some lenses breath a lot, some hardly at all.

Secondly, is the travel of the focus ring. Most modern lenses worth their salt will have internal focusing, meaning the lens doesn't change shape or size physically as you change zoom or focus. But others may actually significantly change length as you focus. That's bad because if you are trying to use your lens with a follow-focus, you can't! The focus ring moves not only rotationally, but also up and down along the length of the lens barrel... bad news. Today I was playing with two fairly identical Nikon 180mm lenses. Same lens, just a few years apart, but one had travel to the focus ring and the other did not. So even though the one with consistent focus ring position was in slightly worse condition, I had to buy it instead.

I guess the last thing to consider would be size and weight. If you have an adapter that's not rail-mounted, you'll probably be limited in how big and heavy the lenses you're getting can be, because you'll be putting a lot of strain on your camera's filter threads. I'd recommend you find a rail system.

That was a lot more than I intended to write, really. I'll talk about some of my own lenses in a second.

[dougspice]

Here's my own collection of lenses at the moment, and some general comments:

Nikon 17-35mm AF-S f/2.8 - This is a top-notch lens. Way overkill for this sort of thing. Probably the sharpest lens I own for my Nikon, fast autofocus, and plenty of other features that are irrelevant to 35mm adapters. It cost over $1300. If you happen to also shoot stills, though, get one. It's great. The range is awesome and it doesn't have many of the weaknesses of zooms. It is a bit big and heavy (about 5x bigger than my 50mm, most non-photographers automatically assume it's the longer of the two!)

Nikon 50mm AF f/1.4 - This is the bread-and-butter standard lens. Fast, small, light, well-built, and with no distortion. It cost about $200 new. Everyone should have one. Mine is a few years old, and I'm told the new ones aren't as good. You might want to compare it with the current f/1.8 version, which is also cheaper. You could also save some money by going for an older manual focus version.

Nikon 55mm AI Micro f/2.8 - Awesome manual focus macro lens. I got this dirt cheap years ago. It's taken some serious abuse. I'm not sure it has much use on a 35mm adapter, but who knows?

Nikon 180mm AI f/2.8 - Very sharp manual focus telephoto. Much less breathing than the used 200mm lenses I compared it against. I got this one for about $300. Fixed-length, but other than that it's great. Fast and good feel to the focus.

Other lenses I have owned in the past or often borrow/rent:

Nikon 80-200mm AF f/2.8 - An absolutely great lens that I wouldn't hesistate to recommend to any photographer. The 70-200mm AF-S is essentially the same, but even nicer. Any of these lenses will run you well over $1000, though, even used, so if you're doing adapter work, I recommend an old manual focus or fixed-length lens.

Nikon 85mm AF f/2.0 - Really great lens for portraits. Tack-sharp, nice bokeh, nice feel to it. Not too cheap, though, and it's easy to find other lenses that will take you through similar focal lengths, so I might call it a bit of a luxury item. Check it out, though.

Nikon 20mm AF f/2.8 - A good sharp and fast wide-angle. It definitely causes some noticeable wide-angle distortion, but maybe you're into that. Once I got my 17-35mm, which seems to be superior in pretty much every regard, there was no reason for me to use this anymore.

Nikon 500mm f/8 Mirror Reflex - This is the most compact, lightweight 500mm lens you are likely to find. It is incredibly limited by the fact that it operates at a fixed slow speed of f/8... pretty much useless once it starts getting dark. It also has that quirky "halo" bokeh of reflex lenses which stands out. All that aside, it's the cheapest way to get this close to your subject, and it produces some interesting effects. I picked up a similar f/5.6 lens in Russia for about $200, which was unfortunately stolen. Note to amateur lens thieves: bigger doesn't necessarily mean better.

Tamron 28-200mm AF f/3.5-f/4.8 - This was the first SLR lens I ever owned. It's a piece of crap, as is any lens that goes from 28-200mm, but it was dirt cheap and great for travel when I didn't know any better. Aside from the huge focal range, there is nothing about this lens that would be called "good". The good news is, a lens this soft sucks for stills, but probably holds up just fine for video. Not that I'm recommending it, of course.

Pretty much everything else I've shot has been with Leica gear. Absolutely top-rate and absolutely overkill for this application, so I won't go into it here.

[TimurCivan]

Thanks for the info on Nikons.
I really have little experience with them.