Why no long telephoto zoom lenses specifically for cropped frame DSLR's

[GerrySiegel]

<p>Correction, meant to say 'internal zoom' vs 'internal focus' in Olympus zoom teles. I understand that the EOS lineup has more internal zoom mechanism. A nice feature I imagine.</p>

[James G. Dainis]

Sensitivity doesn't vary with sensor (or film) size. I can make an exposure at f/32 with an 8x10 camera then slap a 4x5 reducing back on and make another exposure at f/32 on the 4x5 film. A 4x5 inch area of the 8x10 inch film will be the same as that of the 4x5 film.

[richardsperry]

Why doesn't the image circle matter?

 

One would need a ~600mm f4 lens on the FF camera for the same apparent image as the 400mm f4 on the DX.

[scott_ferris]

<p>Richard,</p>

<p>That is what the sales teams have convinced everybody, the truth is if you use the 400 f4 on the FF and crop it to match the crop camera there is an insignificant difference in the actual images if your ff and crop camera are same generation sensors.</p>

<p>I understand you said apparent image, but lets face it, in the end we are after actual images.</p>

[richardsperry]

I wrote apparent to account for the cropping that you mentioned at the beginning. If you're cropping then that means

the image circle matters; you're throwing away pixels that you paid good money for.

 

Just like James' example of shooting 4x5 on a 8x10. He has 3/4s of the sheet that he can't use and has to throw away.

 

In the same way if you mount that same 400mm lens on his 8x10, you are going to get a small little circle in the

middle of the sheet, and the balance of the film is waste.

 

I don't know what sales teams have to say about anything really. It is what it is. The DX has a smaller sensor area,

the image produced with the same lens on it as on a FF will have a narrower angle of view. Producing an apparent image of larger tele lens.

 

I suppose this is all academic, if the OP wants a 400mm equivalent image on his D300 he can get a smaller cheaper

250mm lens. If he gets the 400mm then he is getting the equivalent of a 600mm lens image that the FF might

produce. A Nikkor 600mm f4 is $10,300, the 400mm 2.8 is $7,500; it is obvious that is a savings in cost and size.

It's also obvious that it seems kind of silly to put that kind of glass in front of an $1,800 camera.

[James G. Dainis]

The image circle is the same. Just less area falling on the crop sensor than on the full frame sensor. <P>

 

<img src="http://jdainis.com/tree3.jpg"><P>

 

BTW, unless you are using about a 50mm lens on the full frame sensor it is a crop sensor also. The image circle of a normal 600mm lens would be about 2 feet. The sensor is cropping out all of that except what is falling on the 36x24mm area of the sensor.

[joseph_wisniewski]

<blockquote>

<p>James Dainis - Sensitivity doesn't vary with sensor (or film) size. I can make an exposure at f/32 with an 8x10 camera then slap a 4x5 reducing back on and make another exposure at f/32 on the 4x5 film. A 4x5 inch area of the 8x10 inch film will be the same as that of the 4x5 film.</p>

</blockquote>

<p>Of course it does. One of your examples has 4x as many silver grains as the other. If you want to have anything resembling the same picture at the same print size, you need to use a slower film on the smaller format.</p>

<p>I've always been amazed at how many experienced photographers seem to forget all their shooting experience when they start making those "you can't change the ISO" arguments. It's like they never shot fine grained film on a 35mm and Tri-X on a 8x10. Or they've never used a teleconverter, that little device that changed both focal length and aperture by exactly the same factor. Heck, even Ellis Veneer forgot all his shooting experience and got snarky about it.</p>

 

[richardsperry]

If you take a FF sensor and cut it into 4 equal pieces.

 

None of the pieces are more or less sensitive than the full sensor. No more than a quarter of the 8x10 sheet is more

sensitive than the other 3/4s of it, per his example. The density of the film does not change respective to the size of

the film.

 

If you take a FF sensor and cut it to DX size, they both will have the same sensitivity, the density of the pixels does

not change nor does the sensitivity.

[scott_ferris]

<p>" <em>it is obvious that is a savings in cost and size</em>"</p>

<p>No it is not. My point is that if you need a 400 f2.8 on your crop camera to get the image you want, then you DO NOT need a 600 f4 to get the same image on a FF, just use the 400 f2.8 and crop it, the resulting images are identical, including image quality, to a very very small degree.</p>

[James G. Dainis]

So I'm outside with my 8x10 view camera and with 100 ISO film my exposure meter calls for 1/100sec at f/16. I use that and get a good negative. Now I decide to slap my 4x5 reducing back on the camera with 100 ISO film. I check my exposure meter and it still indicates 1/100 sec at f/16. I use that and get a good negative. Then I can pick up my 35mm camera with 100 ISO film. The exposure meter still reads 1/100 sec at f/16. I use that and get another good negative.

 

There is no setting on the exposure meter for film size. Set the meter to 100 ISO and it will give the correct exposure no matter what size of 100 ISO film you are using. I can use the same meter with digital. Again there is no setting for sensor format size. If it calls for 1/100 sec at f/16 with the camera set to 100 ISO I use that whether I am using full format or APS-C format or 4/3 format.

 

Perhaps the confusion is coming from looking at enlargements. An 8x10 photo made from contact printing an 8x10 negative will be virtually grain free. There is no enlarging of the grain. Make an 8x10 photo from a 35mm negative and it has to be blown up 64X in area resulting in enlarging of the grain clusters making them more noticeable.

[joseph_wisniewski]

<blockquote>

<p>Perhaps the confusion is coming from looking at enlargements.</p>

</blockquote>

<p>Yeah! You're almost home!</p>

<p>It's more correct to say that your (take ownership of it, and you're even closer to understanding) confusion comes from not looking at enlargements.</p>

<blockquote>

<p>An 8x10 photo made from contact printing an 8x10 negative will be virtually grain free. There is no enlarging of the grain. Make an 8x10 photo from a 35mm negative and it has to be blown up 64X in area resulting in enlarging of the grain clusters making them more noticeable.</p>

</blockquote>

<p>Now you're starting to catch on. Grains are how we see critical numbers of photons. They're the measure of light. f-stops are a measure of nothing, at all. An arbitrary ratio that makes exposure meters easier to use, when they're also arbitrary and have little to do with the task at hand. You don't normally shoot the 35mm and the 8x10 at the same f-stop. You don't normally shoot them with the same film, either.</p>

<p>Film is annoyingly non-linear in its relationship between grain and sensitivity. Digital sensors are a lot more linear, and my earlier argument about doubling the sensor size with equal technology results in a 2 stop increase. That pretty much exactly compensates the 2 stop difference in the lens capability for a given size of lens at 1/2 or twice the focal length, and viola, you can take the same picture. ;)</p>

[richardsperry]

<p>"No it is not."</p>

<p>It is not the same apparent image if you need to crop it to make it look the same.</p>

<p>Besides, I am working from the OP's point of view. He has a DX camera, he does not get the option to crop to make his image look like your FF image with the same lens. His image is smaller in field of view than your image, with the same lens. His DX camera sees less of the world, at a greater apparent magnification, than your FF camera with the same lens. Every non DX lens he uses has an additional tele factor proportional to the size differential to the FF sensor added to every shot he makes.</p>

<p>I am glad that you have the FF camera, and <em>can</em> crop. He can't crop, his camera already cropped for him. But he can get the same image with his DX camera with a shorter focal length lens, that is lower in cost, smaller in size, and lighter in weight, than you can. Which is really what he was asking for, wasn't it? I don't know why you are so quick to throw away very expensive FF pixels, to make your image look like a DX image. Why did you buy the FF in the first place if that's what you were going to do?</p>

[richardsperry]

<p>"take ownership of it, and you're even closer to understanding"</p>

<p>You were the one who said that a 4x5 sheet of film had less sensitivity than an 8x10 sheet of the same film. When you meant that the print(the enlargement) made from it had less resolution. You brought enlarging into the discussion without actually saying that you were now discussion prints, and not the film negative.<br>

"Film is annoyingly non-linear in its relationship between grain and sensitivity"<br>

The same film has the same sensitivity whether it is 35, 120, 4x5, or 8x10 in size. That is very linear, such that it is equal.</p>

<p>"If you want to have anything resembling the same picture at the same print size, you need to use a slower film on the smaller format."<br>

He did not say a smaller format, he said a smaller section of the film with the same camera(using a different back). And he was not discussing same print size. If he used the same camera and lens on his 8x10 camera to capture an image on 4x5 film, he could use the same film, the same ISO, the same shutter speed, and the same aperture as if he were exposing the whole sheet of 8x10. They would all remain constant(linear even). Except that the image would be smaller, and with a smaller field of view being exposed. <br>

Introducing "same print size" in there as a variable which changes the comparisons radically, and where the confusion originates. So radically, it makes the whole comparison of sensor sizes useless(not just confusing).</p>

[James G. Dainis]

I use the photo enlargement aspect to perhaps provide a guide as to why Joseph is so wrong in his thinking and he takes that as proof that he is right. <P>

 

<I>"f-stops are a measure of nothing, at all. An arbitrary ratio that makes exposure meters easier to use, when they're also arbitrary and have little to do with the task at hand. You don't normally shoot the 35mm and the 8x10 at the same f-stop. You don't normally shoot them with the same film, either.</I></P>

 

Everything there is wrong. The f/stop is the lens focal length divided by the aperture opening. The light intensity coming through an f/4, 300mm lens is the same as that coming through an f/4, 50 mm lens. An exposure meter is not arbitrary. An incident exposure meter measures the light falling on a subject and gives the correct indicated exposure. 1/100 sec at f/16 is the same whether using an 8x10 camera, a 4x5 camera, a medium format camera, a 35mm camera, a full frame digital camera, an APS-C camera or a 4/3 camera. I am not about to go out and buy 6 different light meters, one for each camera, when when I use them in the same scene they will all indicate 1/100 sec at f/16. I could certainly shoot 35mm and 8x10 at f/16 if I wanted. I used to use both Plus-X in both sheet and roll film. Lots of people shoot both Velvia 35mm 100 ISO film and Velvia 100 ISO sheet film.

[Mike D]

<p>To quote Richard "But he can get the same image with his DX camera with a shorter focal length lens, that is lower in cost, smaller in size, and lighter in weight, than you can." Precisely. My cropped frame D7000 with Sigma 50-150 F2.8 lens is comparable to my full frame D700 with a 70-200 F2.8. I guarantee my Sigma 50-150 is smaller and lighter than the Nikon 70-200. (However, I don't own a 70-200.) What I was trying to get at in my original post is that there are no very long cropped frame telephoto zooms that take advantage of this factor. I am getting older and need to lighten up on my gear and really don't see the absolute need for all full frame equipment in my particular case. I can't believe I'm alone in this situation. My D700 is an excellent body, but so is my D7000, and I would like to take advantage of smaller and lighter lenses that are used on cropped frame cameras, especially long telezooms. BTW, I use a Sigmonster on a regular basis, but that's primarily for surf images.</p>

[scott_ferris]

<p>Richard,</p>

<p>I was referring to your specific point <em>"If he gets the 400mm then he is getting the equivalent of a 600mm lens image that the FF might produce." </em>not Michael's, the OP's, original question. But again, your comment is incorrect. And repeating it ends up giving people the impression that this subsiquent comment has merit, <em>"But he can get the same image with his DX camera with a shorter focal length lens, that is lower in cost, smaller in size, and lighter in weight, than you can." </em>and it doesn't have merit.</p>

<p>Stand in the same place with a FF camera and a crop camera, both have 400mm lenses, the subject, a bird, fills the frame of the crop camera. Shoot both images. Now enlarge both images so the birds are 14" tall in a print, which has been enlarged more? Which has better image quality? Well they have both been enlarged exactly the same amount and from my experience, in real world shooting conditions, there is a very very marginal difference in IQ.</p>

<p>Michael's real question was, why do crop camera users have to carry the size and weight of lenses that create an image circle large enough to cover a much larger sensor? Now that is a good point, but not one to get confused with focal lengths, subject magnification and image quality. A 400mm lens is a 400mm lens, the reproduction ratio is the same on any format sensor. You do not need to use a 600mm on FF to replicate the image a crop camera can do with a 400mm, you just need a 400mm. Crop sensors do not gain you focal length, they steal your field of view.</p>

<p>Why would anybody use a FF and a 400 instead of a 600, to save $9,000! After all, the results are the same as using a crop camera, but you have the FF for when you can use it to fuller benefit.</p>

[richardsperry]

<p>Joseph,<br>

It is not far beyond me. Not beyond at any length.</p>

<p>I know that he and you are talking about two different things. I know what he wrote to be true. And what you wrote to be an obfuscation of what he said, but I know what you are saying to be true as well. That was my point.</p>

<p>I knew what you said before you wrote it.</p>

[richardsperry]

<p>Scott, you are doing the same thing.<br /> "Now enlarge both images so the birds are 14" tall in a print"</p>

<p>Who says the image is going to a paper print. Or going to be enlarged to print media.</p>

<p>It can go to a 22" monitor. A 3" iPhone. A 52" HDTV.<br /> Enlargement does not change what the sensor captures.</p>

<p>"Crop sensors do not gain you focal length, they steal your field of view."<br /> I agree. I have wrote that, and that is why I write "apparent". If you put the 400mm on your D3(whatever) and take a pic from the same spot of the same subject. And I put that same lens on my D300 from the same spot and same subject. The digital images, the NEFs, will be different. My field of view will be smaller, and my apparent resolution at any enlargement is going to be less than yours. Your camera with that lens has a wider angle of view. You have more image on your sensor.<br /> The field of view on a DX camera is smaller(it is stolen as you say) with the same lens on a FF camera. To get the same field of view on the FF, you need to move to a proportionally longer focal length lens, and vice versa.</p>

<p>If you and I take the same pic of the same bird with the same lens, same distance. And enlarge the image to the same size. My bird is going to be bigger than yours. It will have a greater magnification factor than your enlargement. For you to have the same size bird on that enlargement, you need a longer focal length; unless you crop and resize in PhotoShop.</p>

[scott_ferris]

<p>It doesn't matter what the method of reproduction. The bird has to be enlarged, on screen, in print, wherever, even on a 3" iPhone screen it is still enlarged. To get the bird the same size on whatever it is you are using the cameras both enlarge the bird the same.</p>

<p>It comes down to a fundamental difference in the way that long lenses tend to be used (and yes this is a broad generalisation but it is appropriate), they tend to be used to maximise subject magnification, as opposed to shorter lenses that are used to achieve a specific field of view. So the 400mm lens achieves the same reproduction ratio on both cameras, there is no need to use a 600mm lens if you have a FF camera. That was all.</p>

<p>My real point was, people understand they "see less" with a crop camera, but the follow on assumption is that the crop camera actually makes things bigger, I was trying to say that is not true. The bird is the same size on both sensors, so it doesn't matter if you crop the ff or use all the crop camera frame, the result is the same, the bird is enlarged the same on whatever medium it is reproduced on/in even if you end up using less of the ff capture.</p>

[richardsperry]

<p>I don't care if its a 400, 600, or 50mm lens.<br /> Throw out the whole 400 lens, the OP is not going to buy one anyway, neither am I. The 400 and 600 is moot.</p>

<p>Let's go back to a 50mm lens for simplicity. If you and I, you with FF, me with DX, use the same lens 50mm lens. At the same capture resolution of the image, of say, 800 by 1200 pixels. Your bird at any enlargement is going to be smaller. Mine is bigger.</p>

<p>Obviously the image of the bird, projected onto the respective sensors is the same size(we know this already). The sensor sizes are different, thus the image produced, and if enlarged, is different; the bird on the DX image is bigger. Both on any digital format on any digital screen or monitor, or any printed format. All other things besides sensor size being constant, if you get a ruler out and measure, my bird will be bigger. You would need an 85mm lens to approximate the same size bird with a 50mm lens taken with my camera(with everything else constant).</p>

<p>"if you have a FF camera."<br /> I don't, not digital. And neither does the OP.</p>

<p>My point is that if <strong>have you crop</strong> your captured image, to reproduce the same image ratio as mine, your camera is not capturing the same image as mine. I don't know why this is an issue, this is all known information.</p>

<p>"but the follow on assumption is that the crop camera actually makes things bigger, I was trying to say that is not true. The bird is the same size on both sensors, so it doesn't matter if you crop the ff or use all the crop camera frame"</p>

<p>Even in your viewfinder your bird is going to be apparently smaller in the frame, with the same lens same distance. Than in my viewfinder. You will either have to move closer, or crop the image for the birds to be the same size in the image.</p>

[scott_ferris]

<p>Moot or not, you were the one that first mentioned it, and I felt your comment warranted a clarification. Not least of which because Michael has subsequently re-quoted your misconception. </p>

<p>Why should we go back to a 50mm? The title of the thread included the words "Long Telephoto" so that is what I was addressing. But the lens focal length does not matter when you are referring to reproduction ratios.</p>

<p>Now, <em>" Your bird at any <strong>enlargement </strong>is going to be smaller. Mine is bigger."</em> This is wrong. What ever the focal length of the lens used, whatever the resolution, the bird is reproduced <strong>on the sensors</strong> at exactly the same size. If you do a 100 times enlargement of both images, the FF capture is a bigger print, but the birds are the same size. Telephotos are used to maximise the subject size on the sensor. There is no reproduction ratio crop advantage in using a smaller sensor over a bigger one.</p>

<p>If you enlarge both captures to an uncropped 12" x 18" print (or 54" TV screen image) then your bird will be bigger, <strong>but it has been enlarged more</strong>, how is that an advantage? So you are saying, if I enlarge my bird more than you, mine bird is bigger! That is not so surprising!</p>

<p>What is surprising is people saying, and then having others agree, "<em> If he gets the 400mm then he is getting the equivalent of a 600mm lens image that the FF might produce. A Nikkor 600mm f4 is $10,300, the 400mm 2.8 is $7,500; it is obvious that is a savings in cost and size."</em> When all a FF user needs to do to exactly replicate a crop camera users 400mm image is to use a 400mm lens and crop it!</p>

<p>"<em>And neither does the OP</em>." Yes he does, a D700.</p>

<p>"<em>Even in your viewfinder your bird is going to be apparently smaller in the frame, with the same lens same distance.</em>" Not necessarily, it all depends on the viewfinder optics, viewfinder magnification, and hence apparent subject size to the eye, has nothing to do with sensor size.</p>

[richardsperry]

<p><strong>"but it has been enlarged more"</strong></p>

<p>No, it's not. Not if we take the image at the same resolution(you and I can set capture resolution, our aspect ratios are the same). As I said, for example 800x1200, or any equivalent ratio. If you take your 800x1200 image, and I take my 800x1200 image and print them at 20x30, at 300 dpi, your bird is still smaller. With the same enlargement.</p>

<p>""<em>And neither does the OP</em>." Yes he does, a D700."<br /> "I mostly use my cropped frame body for sports anyway so I really don't need a long telephoto lens that also handles full frame."</p>

<p>He is talking about using cropped camera, a DX camera I assume, here in this thread.</p>

<p>"Not necessarily, it all depends on the viewfinder optics, viewfinder magnification, and hence apparent subject size to the eye, has nothing to do with sensor size."</p>

<p>The view finders on the FF Nikon cameras is comparatively larger than the DX cameras. Regardless of that, the image in Live View is going to be different between a FF and DX camera, with the same lens at same distance. Removing viewfinders, computer monitors, and hard copy print outs; your bird on the camera LCD screen is going to be smaller than my bird, all other things being equal. Just get a ruler, if you don't believe me.</p>

<p>If your FF viewfinder is not giving you the same field of view coverage as mine, you might want to take that up with the manufacturer.</p>

<p>If he has a D700, and a D300(200 whatever) and he's complaining about tele lenses; I can not fathom why. The only time that would be an issue is with wide angle FF lenses, on a DX frame. Resulting in not so wide angle images.</p>

[James G. Dainis]

If you are using a larger than "normal" lens on a camera, one whose image circle diameter is greater than the diagonal of the sensor or film, it becomes a crop camera. What we are talking about is the degree of cropping. The FF camera will crop a larger image (36 x 24) than the DX camera (23.7 x 15.6). Let's round that off to 24 x 16 for ease of calculation.

 

Take a bird that falls 24 mm wide on each sensor, using the same lens and distance from the bird. On the DX it will be full width; on the FF it will have 6mm of space on each side. Have a 12 x 8 inch photo printed from the DX capture and the bird will be 12 inches wide, the full width of the photo. You can also have the bird the full width on an 12 x 8 photo made from the FF image capture but you will first have to crop 6mm (or its pixel equivalent) off of each side. Both photos will look identical. It is just more convenient to send the direct image capture of the DX to be printed than to take another crop of the FF before doing so.

[scott_ferris]

<p>Why would you take the same resolution? That is so arbitrary it is worse than irrelevant. So you are now saying if you have smaller pixels than me and we enlarge them so that yours are the same size as mine, your subject is bigger. Again, that is no surprise, <strong>you have enlarged yours more</strong>! </p>

<p><em>"The view finders on the FF Nikon cameras is comparatively larger than the DX cameras. Regardless of that, the image in Live View is going to be different between a FF and DX camera, with the same lens at same distance. Removing viewfinders, computer monitors, and hard copy print outs; your bird on the camera LCD screen is going to be smaller than my bird, all other things being equal. Just get a ruler, if you don't believe me."</em></p>

<p>Believe me, if you took the back off your cameras and measured the subject, as it is projected and recorded onto your sensor, the measurement would be the same. Think about it, your LCD screen is just another end user reproduction. To reproduce a larger field in the same screen space the objects have to be reduced in size, or, to reproduce less subject matter on a screen <strong>you have to enlarge it more. </strong>But the subject is recorded exactly the same size on the different sized sensors, therefore to reproduce a print where the subject is the same size you must have to enlarge them both by the same amount.</p>

 

[richardsperry]

<p>Scott,<br /> My max resolution size of my D300 is 4288x2848 pixels. Which is a 3:2 ratio, at any size. When I do reduce it down to 600 by 400, it actually comes out a pixel less, at 600 by 399. I just resize that additional pixel. For all intents and purposes it's still 3:2.</p>

<p>What is the max resolution size of your D3? I don't know what it is. And don't care to look it up. Tell me what your max resolution size is with your FF camera. We have different sensors, and different MPs(but almost the same), so your resolution has got to be different than mine. But we can both set our cameras to take a set, controlled, resolution size. Your D3 is like 12.1MP, my D300 is like 12.3MPs, right. /shrug.</p>

<p>Resolution is hardly arbitrary or irrelevant in digital. In digital imaging it is one of the most important.</p>

<p>I do think about it, the image on my LCD, is exactly the same as when it is transferred to my computer. In respect to the field of view. If there is a sand grain down at the bottom of my LCD, on the last line of pixels, I see that same sand grain on the image on my comp, down at the bottom.</p>

<p>Like I said, if your more expensive FF camera crops your image from your LCD display, you should take that up with Nikon. Because you are losing something that you should not be losing.</p>