Camera Lens Question

[Ar-Pharazon]

I have a Canon EOS Rebel XTi DSLR. I got it with 3 Canon lenses and the usual amount of free crap.

Now I'm wanting to get a large telephoto lens. The Canon ones I've seen are thousands of dollars, so those are right out.

There's 2 cheaper brands of these types of lenses: Rokinon & Opteka.

Anyone ever use either one of these brands? Any good?

 

[Galactus]

Canon or Tamron. Nothing else. What are the 3 lenses you have now? Is there something you are not able to do with the lenses you have now?

 

[Michael_One]

Ar-Pharazon, how much photography experience do you have? These kinds of lenses aren't for beginners and the Rebel is an entry- level camera. Other than that I don't know a whole lot about your camera.

Step one: Check your setup menu options. Does your camera have a 'trip shutter without focus confirmation' setting? Most entry level cameras don't have that option and without it you will never be able to take a picture with these lenses.

The lenses attach to your camera with a T-mount which means 'telescope mount'. They don't have connections for the lens to communicate with your camera; these lenses don't have ROM chips in them to tell your camera what kind of lens they are and support ADI ( automatic distance integration ). This is but one of many reasons you aren't going to just point and shoot with these things.

You will have to focus manually and set aperture on the lens. You will need to set exposure manually as well. In other words you do everything yourself.

To get the full 2600 mm focal length you will need the teleconverter. This will make the image quite dim in your viewfinder and it will help to have a lot of experience in focusing lenses under that condition ( that is, murky ).

You will almost certainly need a tripod for good results. At five and a bit pounds the camera and lens are heavy and the focal lengths are such that you probably can't get good images hand holding the camera much past the minimum 650 mm focal length. Remember you are setting everything yourself which is another good reason to use a tripod to hold the thing up while you fiddle with adjustments.

I'm in my late forties and have a touch of arthritis. I certainly couldn't hand hold this lens, there is way too much stuff to do.

I use Minolta cameras, and the longest focal length lens I have is the Tamron 200- 500 mm zoom. It fully integrates with the camera so I can concentrate on composition while the camera takes care of everything else. I use it for photos of birds and animals; I've also used it to take pictures of the Moon on occasion. I don't see myself needing a longer focal length lens, this suits my needs very well. If I needed a tighter image I would simply crop a picture; with 12 mega pixels I can crop quite a bit before image quality suffers. Oh, and the Tamron doesn't weigh all that much which is a big, big plus when spending an afternoon looking for birds to show up.

Hope this helps.

 

[Ar-Pharazon]

Canon or Tamron. Nothing else. What are the 3 lenses you have now? Is there something you are not able to do with the lenses you have now?

The 3 Canon lenses I have are: EF-S 18-55mm f/3.5-5.6, EF 28-105mm f/3.5-4.5 II zoom, EF 75-300mm f/4-5.6 III zoom. These came included in the package. I also have a wide-angle thread-on, a set of macro filters and a remote "clicker".

I would like to do some wildlife photography, hence the desire to get a large telephoto lens. I'd be able to be much further away from the subject and (hopefully) get a good picture.

Ar-Pharazon, how much photography experience do you have? These kinds of lenses aren't for beginners and the Rebel is an entry- level camera. Other than that I don't know a whole lot about your camera.

Step one: Check your setup menu options. Does your camera have a 'trip shutter without focus confirmation' setting? Most entry level cameras don't have that option and without it you will never be able to take a picture with these lenses.

The lenses attach to your camera with a T-mount which means 'telescope mount'. They don't have connections for the lens to communicate with your camera; these lenses don't have ROM chips in them to tell your camera what kind of lens they are and support ADI ( automatic distance integration ). This is but one of many reasons you aren't going to just point and shoot with these things.

You will have to focus manually and set aperture on the lens. You will need to set exposure manually as well. In other words you do everything yourself.

To get the full 2600 mm focal length you will need the teleconverter. This will make the image quite dim in your viewfinder and it will help to have a lot of experience in focusing lenses under that condition ( that is, murky ).

You will almost certainly need a tripod for good results. At five and a bit pounds the camera and lens are heavy and the focal lengths are such that you probably can't get good images hand holding the camera much past the minimum 650 mm focal length. Remember you are setting everything yourself which is another good reason to use a tripod to hold the thing up while you fiddle with adjustments.

I'm in my late forties and have a touch of arthritis. I certainly couldn't hand hold this lens, there is way too much stuff to do.

I use Minolta cameras, and the longest focal length lens I have is the Tamron 200- 500 mm zoom. It fully integrates with the camera so I can concentrate on composition while the camera takes care of everything else. I use it for photos of birds and animals; I've also used it to take pictures of the Moon on occasion. I don't see myself needing a longer focal length lens, this suits my needs very well. If I needed a tighter image I would simply crop a picture; with 12 mega pixels I can crop quite a bit before image quality suffers. Oh, and the Tamron doesn't weigh all that much which is a big, big plus when spending an afternoon looking for birds to show up.

Hope this helps.

From a long time ago, I have macro photography experience. I did that with a Canon T50 and some macro filters. I was able to photograph (approx.) 1" lead figures from about 6" or less from the subject.

Now it's more of a hobby. I did figure I would need to use a tripod for these longer lenses, but I think I've seen kits where the lens itself can be mounted to the tripod. Also, there are some that have a kind of shoulder brace kit like you'd have on a rifle. I don't know how easy that would be to use.

I have to admit, this camera has a lot of options I still don't know how to use, so I'm unsure if it has the ability to 'trip shutter without focus confirmation'. Gonna have to spend some quality time with it to find out.

I already get some blurry images when shooting handheld with my current large zoom lens, so I understand how it would be harder with an even longer one.

Edit: This is an example of what I'm looking to do, but maybe getting a much "closer" shot. This blue heron likes to summer around the pond at my apartment complex. I took this from the opposite side of the pond. I had to decrease the size of it so I could get it to upload.
http://imagefra.me/view.php?img=/1/12/5/arpharazon/f_mnvpwec9m_59a7b5c.jpg&srv=img38

 

[Michael_One]

Ar-Pharazon, that is one beautiful picture you've taken; congratulations!

To get an idea of what you'll get from a lens in terms of image area captured, consider the angle of view relation:

angle of view = 2*arc tan (d/(2*f))

where d is the width of your image sensor and f is your focal length, both in millimeters.

A Digital Rebel has an APS-C size sensor of about 23 mm width. With that info, here's a quick table of what angles of view you'll get with lenses of various focal lengths:

Focal length...Angle of view
50 mm..........25.3 degrees
100 mm........12.8 deg
300 mm.........4.3 deg
400 mm.........3.2 deg
500 mm.........2.6 deg
600 mm.........2.1 deg
1000 mm.......1.3 deg
2000 mm.......0.6 deg

For comparison, the moon is about half a degree across.

There is a reason Canon telephoto lenses are expensive and it's not just the name; these lenses are complex and made in small numbers ( kind of a vicious circle: they are expensive so few are sold so each costs more to produce ).

A telephoto lens needs additional glass elements to correct for chromatic aberration, think of that as the colors coming apart, this causes the purple fringes you see in pics taken with cheap lenses. You see, different wavelengths of light refract at different angles through a lens, at the more extreme refractions involved at longer focal lengths you need corrective lens groups to herd the photons back on course.

This is the reason that one sample pic in those links is in black and white. Even of a gray subject.

You can get a Sigma or Tamron zoom lens in the 200 to 400 mm range for about US $700, a 200 to 500 would run closer to $850.

My best suggestion is look for a Canon online group, you may be able to get these lenses used at a discount. Also try googling 'camera swap meet' to see if there are any near you. Here in So Cal there is a bi monthly swap meet I've seen that has plenty of used Canon and Nikon lenses.

I wish you well in your search for really good lenses.

 

[Mr. B]

You can't go wrong with the 70-200mm f/4.0 L. Tack sharp with L grade build and avaliable in the $500 range.

Even if the lenses you linked were optically excellent, they would be nearly useless on a crop camera. At f/8, the viewfinder would be very dark... a serious problem since you will have to focus manually... without a split prism.

 

[Ar-Pharazon]

^ What is a split prism exactly, and are you sure there isn't one since there's no using the LCD screen for viewing on a DSLR?

The only way to view is through the viewfinder and I can watch it auto-focus through there as well.

 

[Mr. B]

It's a feature on focusing screens commonly found in film SLR cameras. When both halves of the image in the circle are joined, the image is in focus.

The lenses you linked will NOT auto focus at all. There are no AF motors or "Electro-Focus" interface to communicate with the camera.

 

[Ar-Pharazon]

It's a feature on focusing screens commonly found in film SLR cameras. When both halves of the image in the circle are joined, the image is in focus.

Now that I remember from the 35mm film SLR days.

The lenses you linked will NOT auto focus at all. There are no AF motors or "Electro-Focus" interface to communicate with the camera.

Yeah, I'm aware they are all manual focus. Not a big deal as long as I can, in fact, get the camera to 'trip shutter without focus confirmation' like Michael_One mentioned. I haven't had a lot of time lately, so it's something I still have to look at.

I did tons of miniatures photography years ago, so a lot of manual focusing there. Luckily I had a remote button for that camera too. I had a lot of pics in Dragon magazine for a number of years.

 

[Chaos Descending]

This thread makes my Nikon Corporate Overlords very unhappy indeed.

 

[Mr. B]

If you haven't already, set a lens you currently own to f/8 and hold down the DOF preview button while looking through the viewfinder... that's how dark those lenses will look at their widest zoom and aperture. They will darken further down to f/16 as you zoom in.

How easy was it to manually focus under these conditions?