question about teleconverters - DPChallenge Forums

07/11/2008 10:58:56 PM · #1

I shoot a lot of prep wrestling (which may end after next year unless my kid comes to his senses and accepts an instate school offer) with a 70-300mm f/4.0-5.6 Di LD Macro (cheap glass). I want to get a better lens when I upgrade to the D300, I'm thinking the 70-200 f/2.8 Nikon VR, but after wrestling I plan to use it for my newest hobby, bird watching, so I need more focal length. I looked into teleconverters and discovered they double the length of the lens, like 300mm would equal 600mm. My question is: Does this take away from the sharpness or quality of the image? Are certain teleconverters better, like made with better glass or something? Links would be appreciated. Thanks!

Canon EF 70-200mm f/2.8L IS USM

07/11/2008 11:08:54 PM · #2

they do take away sharpness and clarity usually--plus you will loose a couple f stops--don't know a lot about nikonbut you could check herelinkor herelink

Mick

Canon EOS-5D

07/12/2008 01:10:14 AM · #3

Originally posted by aerogurl:

Yes, you will loose some image quality through diffraction with any teleconverter. And yes, some are better than others. Telecoverters also reduce the maximum aperture of the lens, usually by one or more f/stops. You should also be aware that not all teleconverters double the focal length of the lens. The amount of magnification depends on the design of the teleconverter. Some are 1.4X, or 1.5X, or 1.7X. To double the focal length, you need a 2X teleconverter. The greater the magnification, the more image quality you loose. Note also that some teleconverters are only compatible with specific lenses. You should make sure that the teleconverter you want will work with your lens before buying it.

Here are reviews of some Nikon teleconverters...

Nikon TC-14E II 1.4x AF-S 1.4X Teleconverter

Nikon TC-17E II 1.7x AF-S 1.7X Teleconverter

Nikon TC-20E II 2x AF-S 2X Teleconverter

Mick

Ann

Olympus OM-D E-M1

Olympus 12-40mm f/2.8 Pro

07/12/2008 12:21:04 PM · #4

Teleconverters are only really useful with fast lenses. With a 1.4x TC you lose 1 stop of light. With a 2x TC, you lose 2 stops. This matters to your autofocus system. Most cameras can't autofocus (or at least not well) if the max aperture of the lens is smaller than f/5.6, because it's just too dark. For your 70-300, at 300mm, your max aperture is already f/5.6. If you put any TC on it, you will lose the ability to autofocus. The view through the viewfinder will also get darker, so focusing manually gets very hard, too.

A cheap TC attached to a cheap lens will just magnify both the lens and the teleconverter's flaws. A good quality TC attached to a good quality lens will produce images that are surprisingly good. Maybe not pixel peeping perfect, but good enough at normal resolutions. That said, in any given situation, longer focal lengths will magnify any problems with your technique. Since you're already using the 70-300D, I'm sure you know all about camera shake and a long, slow lens. My experience is that with my 80-200 f/2.8 lens, my 1.4x TC produces good images easily enough, but I have all sorts of problems with my 2x TC, generally related to lack of skill on my part (camera shake, out of focus, etc).

Anyway, in the Nikon world, the Nikon teleconverters are the best available, if a bit expensive. The Kenko Pro (and Tamron SP, they're the same) are almost as good, and much cheaper.

kirbic

Canon EOS R5

Canon RF 24-70mm f/2.8 L IS

07/12/2008 01:18:13 PM · #5

You probably won't be happy with the 70-200/2.8 VR and 2x teleconverter combination. The lens alone would be a very nice one for shooting wrestling, but of course pretty short for birding. The problem with the teleconverter arises because using it is like blowing up 1/4 of the image to the size of the whole image. The lens is just sharp enough for use on a camera with high pixel density as it is, but not sharp enough to sustain the additional magnification without appearing soft. You'll also lose some contrast. Now, you can recover some sharpness by stopping down, but you're starting from f/5.6 wide open (f/2.8 plus two stops). By f/11 you'll regain much of the lost sharpness, but not the contrast. At f/16 you start losing sharpness to diffraction.
So in the end, you have a combination that:
- Is useful at f/11, and perhaps somewhat at f/8 and f/16.
- Is slower to focus than the lens alone and will hunt in low light
- Has lower contrast than the lens alone
All in all, not that useful a combination. FWIW, I do own the Canon 70-200/2.8, and a 2x teleconverter, so I'm speaking from relevant experience.

Canon EF 24-70mm f/2.8L USM

07/12/2008 04:58:37 PM · #6

Thanks for replying everyone. So, you think I would get sharper shots with a good 300 or 400mm lens over a 200mm + teleconverter? If so, what lens would you recommend for birding? I don't think I can afford the best of the best pro lenses, but I'm not gonna buy cheap glass either. I don;t have my heart set on the 70-200mm f/2.8 VR, its probably more than I can afford.. but I would like something that helps with shake, nice and sharp.. and under a grand, like the Sigma 50-500mm,

Alain has taken some wonderful photos with it.

I think once I get the D300, the 200mm would be great for shooting wrestling, the 10mp will give me more space to crop and still retain some sharp images.. but I find birding with my current 300mm challenging as it is, I can't imagine doing it with a 200mm... So I guess I will need to get a 400 or something.. or try a teleconverter.. I dunno, but I'm going to Wings Over Water Festival at the Outer Banks in November and I will be paying for some workshops and such, I really don't want to go there with an inferior lens or something that's not going to give me the zoom length I need.

Message edited by author 2008-07-12 17:19:39.

violinist123

Canon EOS-6D

07/12/2008 05:30:01 PM · #7

Might want to click around the images here art wolfe images to get some ideas. He regularly uses TC's on the 70-200 2.8L, and I think most people would be more than pleased with the results (I realize you are a nikonite). I use a 2x TC on the 100-400 all the time. Apart from having to manual focus and being at F9 out of the gate, shots at 800mm are excellent. And it's a solution that doesn't cost $6,000+ like a super telephoto prime.

MelonMusketeer

Nikon D7000

Nikon MF 50mm f/1.4

07/12/2008 05:57:06 PM · #8

Maybe it would be a good idea to rent a lens for the festival, and that way you will know if you want to buy that model before tying up a lot of cash in a lens that you may not be comfortable with. I would try to have the chosen lens to use for a few days before the festival in order to see if you like the way it shoots.

I do most of my birding with a manual 300mm f4.5 Nikkor. I have found that I can crop from using the lens directly on camera, and have better looking images than using it with a 2X. Also, the focusing and shooting is much easier without the 2X. If you haven't used tele's over 400 mm yet, you will be very surprised at how little camera shake it takes to blur the details in a shot.
I have a 1,000mm Meade reflector, and don't use it much at all for the shake reason. It's good on a sandbag, but almost impossible to keep it stable enough to get the best it has to offer, even on a good heavy tripod.

Olympus 12-40mm f/2.8 Pro

07/12/2008 08:17:01 PM · #9

Originally posted by MelonMusketeer:

Maybe it would be a good idea to rent a lens for the festival

I wouldn't have any idea where to do that? Do you do that locally or online?

MelonMusketeer

Nikon D7000

Nikon MF 50mm f/1.4

07/12/2008 08:32:25 PM · #10

I can't remember who is is, but there is a DPC'er that rents lenses by the week. The last thread I can recall seeing him post in was the one where Cindi

idnic broke her 50mm 1.8 lens.
I see that you are in NC. If you are living near Raleigh or one of the larger places, you may try calling camera stores. Some of the larger ones, and even some of the not so large ones rent lenses. I lived in Garner, near Raleigh in 1975 for about 6 months. I liked NC when I was there.
Back to the TC's. Have a look at

Zeuszen's "Great Blue Heron" collection. A lot of them were shot with the 200/1.4 TC combo.
Linky
I looked back thru the forums, and found the DPC'er that has the rental business. It's Justin, with rentphotostuff.com.

Message edited by author 2008-07-12 21:09:52.

Ann

Olympus OM-D E-M1

07/12/2008 09:40:06 PM · #11

Most larger cities have one or two camera stores that will rent lenses, and I did a search a few days ago, and there seem to be dozens of places that rent lenses online.

Most of the serious bird photogs I know use 400-600mm lenses, usually with teleconverters attached. At that focal length, to get good results, you'll need a very sturdy tripod, and a Wimberley or something like it, because a 500mm lens is about 8 pounds.

I took a bird photography class last year, and decided to stick to birds in my backyard, because a 500mm f/4 lens by itself is more expensive than the rest of my gear combined. And I have nice gear.

07/12/2008 10:08:03 PM · #12

a lot of the people that i've seen on the bird sites talk highly of the nikon 200-400which i think might be cheaper than a 500 or 600 prime which if you really want to do birds is the only!!! way to go--thou very pricy check herelink i think you can regester there for free for at least a bit they have much more than you see when you first log on and many people there have just switched to nikonand would have better advice than i could give. these folks are very serious birders by the way art morris who's site this is is 1 of the canon explores of light

Message edited by author 2008-07-12 22:13:43.

MelonMusketeer

Nikon D7000

Nikon MF 50mm f/1.4

07/13/2008 12:00:24 AM · #13

Thanks

rider. That's a great link. I just registered there.

07/13/2008 09:28:22 AM · #14

Originally posted by MelonMusketeer:

Thanks rider. That's a great link. I just registered there.

your welcome! just remember i didn't twist your arm when you start thinking about buying a 500 !!!!lol

07/13/2008 12:00:15 PM · #15

Originally posted by MelonMusketeer:

Thanks rider. That's a great link. I just registered there.

Thanks for me too.. Looks like a great site, and just the thing I need! :)