Marv Loc: Crisfield Md

would cropping a picture be same as using a teleconverter to get the same close up or what would be the difference I hope I am phasing the question right I know that when using a teleconverter you lose a couple of f-stops and autofocus does not work on some lens but was wondering if cropping would give you the same effect

Zookeeper Loc: Texas

It depends on what you are doing with the image. If the final use of the image requires fewer pixels than remain in a cropped image then there is no difference. If the final use is to print the image for display then usually there would be a difference, especially as the size of the printed image increases.

Basically a teleconverter adds optics to the light path that increase the focal length of the lens system. As a result the image takes advantage of the full sensor pixel count.

For the Nikon 1.4x and 2x teleconverters this may not work out so well. I did a test with a D800 using the 200-400 Nikon lens at 400mm on a robust tripod sitting on a concrete pad in the mirror-up mode to see if the results improved when adding a teleconverter to achieve a higher resolution image. In my tests I found that the 200-400 lens without a TC produced as good an image when upscaled to match the resolution of the same lens with the 1.4x and 2x TCs.

As a result I don't bother with TCs anymore.

MT Shooter Loc: Montana

Absolutely not. TC's will allow you to use the entire sensor array of pixels for the image. When you "crop" an image you are throwing away pixels. Never a good idea unless you have a large surplus of them to spare, like on the Nikon D800's.

Chefneil

I see an afternoon of experiments ahead.

This is how I would do (kinda like what zookeeper did)
--Take an image at a certain range, say 100mm
--Take the same image with a nifty fifty and TE eqaulling an equivalant mm
--Then take one with only the the nifty fifty and crop to the same image as the 100mm. print them all and see for yourself.

Wish I had a TE for my rig so I could do this.

If ya' do this, lets see the results! It could make for an interesting essay


olc

Zookeeper Loc: Texas

Chefneil…

The idea is to use the same lens with and without a TC. Set the camera body on a tripod and select a subject that has fine detail, like a brick wall or even the LensAlign target if you have that.

At max aperture shoot the subject with the lens on the camera, no TC. If using a zoom lens images can be taken at specific focal distances, such as 120mm, then 85mm, then 24mm …what ever range the zoom supports.

Next add the TC between the lens and the camera, refocus and shoot another image. If using a zoom make sure the lens is set the the same focal length(s) it was without the TC.

In post processing, without any sharpening applied to the images, up-scale (enlarge) the image shot without the TC by a percentage that will result in an image that displays the subject at the same size as the one shot with the TC. For instance, using a 1.4x TC you would upscale the image that did not use the TC by 140%.

This will also increase the pixel count in the upscaled image but we are only concerned with a 100% crop comparison from each image.

At this point, at 100%, both images should display the subject matter at the same size on the computer. If a brick measures 2" on screen in one image at 100% it should measure 2" in the other image at 100%.

Now compare 100% crops from each image to see which one has sharper details. In my test of the 200-400 Nikon lens and the most recent 1.4x and 2x TCs the up-scaled image had as much detail when viewed at 100% as did the images using the TCs. Therefore the TCs were not providing increased resolution, just increasing the effective focal length of the lens system. In this situation up-scaling the images was as effective as using a TC.

Photoshop CS6 was used to up-scale the images where no TC was used.

I also did this test years ago when I was shooting Canon and as I remember the Canon TCs did provide more detail than up-scaling an image.

I've seen comments that the Nikon TCs work better with some lenses than with others, so they may be an option with other lenses.

It is best to do this with raw files, not JPEG files, so the camera does not skew the results by applying in-camera sharpening.

Bugfan Loc: Toronto, Canada

I'm not sure I will explain this well but here goes anyway ...

The short answer is yes it will be the same. But it's more complicated than that.

The teleconverter gives you a full resolution image on your camera so if you're trying to create a bill board odds are you'll have a high res images to use.

But the teleconverter can cost you two stops (assuming you're using a 2x) or one stop for a 1.4x. If you're working in poor light that means a less than optimal image particularly if you're forced into a high ISO.

Cropping the images instead works in that low light situation, you'll still have a quality image but by now taking the middle out of it you'll find it's no longer the high res you had to begin with but the quality at least is there. Maybe that will get you half a bill board instead.

Of course if you're looking at a 44x6 print you won't really see any difference at all.

Basically it depends on what you want to do with the image when you're done and it depends on the shooting conditions that create the image. There are trade offs to be made regardless of what you choose to do.

I hope this makes some sense. If not just ask again.

JimH123 Loc: Morgan Hill, CA

There is another factor. There are dedicated, expensive teleconverters that work with a limited set of lenses. These are the best and will produce excellent results.

And there is a cheaper route to go that uses a cheaper, general purpose teleconverter, and it is very likely to not be as good of experience. To add to that, some lenses will do OK with one of these teleconverters, and others will not, especially lower quality zooms. The general purpose teleconverter typically does best with prime lenses.

The result of using the teleconverter is that the picture tends to become what is called "soft". This means that points are spread over more pixels then they are supposed to. And the result is quite noticeable. Most sharpening SW does not overcome this.

So back to the question. The two methods may be equal, but they may not also depending on what equipment you are using.

Chefneil

Zookeeper the way you describe your test, I can only assume it is scientifically and technically correct. But we are talking about photography here and many of us do not know the numbers behind the magic. Like me.

I look for quality of my image without having to go through lab testing procedures. I leave that for those who know more than me.

This is the reason I set the test the way I did. I wanted a true sample of an actual series of photographs without anything between the lens and body, then I wanted to make comparisons using the same real world subjects and equipment most people have.

I know that what you described is the best way to do it but most of us do not have the background nor the equipment, or even the inclination to do lab testing. We just want good results.

In your opinion, could the perimeters I set get a good test of the quality of an image, with and with the TE? If not, how can it be done without going through all the steps you describe?

Please don't misunderstand me, I know your testing procedures are accurate. I just don't have the equipment to do them.

And any how this could be a great excuse to play around with a camera a little.

olc

Zookeeper Loc: Texas

In the last step you need to up-scale the nifty fifty to 200% original size then crop the up-scaled image to 50% in something like Photoshop. Now print each image to the same size and compare. You should find that the up-scaled nifty fifty is rather coarse when compared to the image produced by the nifty fifty with a 2x teleconverter or the one taken with the 100mm lens.

The problem with your methodology is that you are comparing apples and oranges.

In any event what you should be doing is testing any camera/lens combination you choose by shooting the kind of images you prefer (i.e. landscapes or people or portraits) then print the images at the size you like to display. There are many factors that come into play during this process. What you want to achieve is an end product (the print usually) that you find satisfying in all respects.

…and yes, I can be rather technically inclined, after working as a computer programmer I moved on to teach high school math as well as being the designated school photographer. While teaching math I started a photography course as an elective, had about 30 kids sign up, after the first lecture all but about 5 dropped the course, had a great time with those that remained.

Chefneil

As you say the end image is what counts. Your methodology is of course sound. It sets the course for those of us who do not have the technical acumen that you have. Yet it may be the dreams and those round out your square corners, those who can use your science who make beautiful art. I look forward to having more discussions with you.

UtahBob Loc: Southern NJ

For me using the teleconverter gets me a cleaner better image than cropping (i.e upsizing) but that's with tripod and mirror up with remote. If I handhold, I can't get ok results unless I have really good conditions such as full sun because of the light loss. I think you can make the combo work if you are using really high end equipment and then go with something like a 1.4x.

I have an old nikkor 300mm 4.5 all manual. There is a TC-300 that was specifically made to combine with that lens. Although it is called a TC-300 it is only a 2x. The one part of the TC extends into the lens so it can only be used with those lenses that it was really made for although it will couple nicely with my Tokina 150-500, again an old manual lens.

Last spring for kicks I picked up the TC-300 used and shot something tarped in a field. The photo is a shot of a bungie cord at 600mm (300x2) plus the upsized 300mm shot. I did this for myself and saved this image. Not sure if I still have the originals. Again, this is tripod with mirror up. I have gotten decent results with the combo with raptors coming back to the nest with good light and high shutter speeds (with no mirror up). As you can see, the TC is better. There is just more image there. I'm thinking the results here are the effect of the nikkor matching of the lens and TC.

You can always do your own testing on how you shoot and conclude from there. Once you figure out the limitations, you can decide when best to use the TC.

TC verses no TC and Upsized

(Download)

paulrph1 Loc: Washington, Utah

One will get more compression. Whether or not that is a good thing is up to you and the situation. Less depth of field can be good and it can be bad.

naturepics43 Loc: Hocking Co. Ohio - USA

It will give you the same effect but you sacrifice a lot by cropping. For instance, a 36MP image (when cropped to equal the 2X image) becomes a 9 MP image. There are trade-off's either way.

Marv Loc: Crisfield Md

sorry guys I guess I didn't frame my question right what I was asking was it is worth the extra money to buy a teleconverter when If I can get the basically same shot by cropping my apologies to all of you and thanks for all the reply's you folks are great

Robin Poole Loc: Missoula, Mt

Kinda depends on how big you want the subject. blown up a 1.4X gives you a 40% enlargement. Each item in the pic has a certain Number of pixels. If it is very small to begin with and you crop it to8x10 it's gonna be blurry. Lots depend on your subject