Longer lense vs. Smaller sensor and insufficient cash?

I have a 5D & 5D MK II body with full size sensors. My longest glass is the F/4.5-5.6L IS 100-400 zoom. I would love to have a 600mm fixed focus lens for wildlife imaging but do not have the cash. What is the best way to work around this.

1. Buy a 60D body with the 1.6 APS-C sensor? Does this effective extension of the 400mm on my 100/400 give me a true 640mm or is this really smoke and mirrors? Am I better off using my 70/200 F/2.8L IS with my 2X teleconverter on it on a 60D to gain the 640mm. My understanding is that I would retain the AF feature doing that while I would lose that feature on the 100/400 with the teleconverter. Does it matter which way I go in the final analysis?

2. Buy a $240 800mm Vivitar manual focus mirror lens? What is the image quality of these type lenses?

3. Just stay with what I have and only take images of the subjects I can get close enough to to fill a sufficient percentage of the frame to forgo large scale cropping.

I would appreciate any input to this dilemma.

Thanks - Alan

I wouldn't bother with a mirror lens if you are concerned with image quality. In particular the bokeh you get with such lenses pretty awful (google it ant you'll see).

The 60D will give you extra "reach" as the pixel density is higher on a smaller sensor. However, you will lose some of the benefits of the larger sensor (e.g. low light performance). I use a 7D for bird photography (with a 500mm prime) and a 5D for other purposes. The image quality I get from the 7D small sensor is just fine, and I get "closer" to my subjects.

I am not sure where you are going with the 100-400 vs. 70-200 with 2x TC? Both gives you the exact same reach (640mm equivalent). The latter option will degrade AF speed and image quality.

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Originally Posted by Fredrik Backman

I wouldn't bother with a mirror lens if you are concerned with image quality. In particular the bokeh you get with such lenses pretty awful (google it ant you'll see).

The 60D will give you extra "reach" as the pixel density is higher on a smaller sensor. However, you will lose some of the benefits of the larger sensor (e.g. low light performance). I use a 7D for bird photography (with a 500mm prime) and a 5D for other purposes. The image quality I get from the 7D small sensor is just fine, and I get "closer" to my subjects.

I am not sure where you are going with the 100-400 vs. 70-200 with 2x TC? Both gives you the exact same reach (640mm equivalent). The latter option will degrade AF speed and image quality.

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Fredrik - Thanks for your input. I guess the real issue here is whether I will get the same image size with the 100/400 @ 400mm on a 60D as I would with a 640mm (if there was one) on a full size sensor. I'm sure the image quality will be acceptable as the 60D & 7D I believe both use the same sensor. I never used my lens on an APS-C sensor so do not have first hand experience with this. While I would love to have the Prime lens I just don't have the funds for that at this time.

Alan

Canon makes a 300 and a 400 mm that are in a lower price range and they are both very adequate. They are about $1500 each.

EF 300mm f/4L IS USM

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EF 400mm f/5.6L

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Alan, one way to think of reach is 'pixels per duck'. If you are shooting from the same spot with the same lens, then, yes, 60D/7D will give you more 'pixels per duck' than the 5D markII. In good light, since the performance of the current APS-C sensors is good, you will definitely get the benefits. However, as Frederick mentioned, in low light you will see the degradation in image quality.

You asked: whether I will get the same image size with the 100/400 @ 400mm on a 60D as I would with a 640mm (if there was one) on a full size sensor

The size of the subject will be same. However, since 5D mark II sensor has higher MP count, you will get more pixels-per-duck with 5D markII.

DOF will also be more shallow on the 5DmarkII-640mm rig at the same aperture and same subject distance. DOF depends on focal-length( when aperture and distance-to-subject are constant). With the 60D-400 rig, although the effective focal length is 640, at a given aperture and subject-distance, the DOF range will be that of 400mm lens. With the 5D-640mm rig, the DOF range( at the same aperture and subject-distance) will be that of 640mm lens.

Lots of wildlife Pros on the canon side shoot with APS-H sensor( 1.3x crop factor) as that gives a sweet spot between reach and IQ with excellent AF and fps.

You're posting on a bird forum, so I assume that you want to shoot birds. If so, then by the 7D, which has the close to ideal pixel-pitch for cropping pix and maintaining detail without undo noise. I own the 5D2 and the 7D, which is a fantastic combination. The 7D has great detail.

Also, don't forget the EF 1.4x TC to grab a little more reach. It'll slow down your AF terribly (that lens is a little too slow) but it'll be great for grabbing reach on relatively static subjects.

Here's an example of detail potential from a 7D, using a 500mm plus the 1.4xTC:
http://farm6.static.flickr.com/5143/...b1f22acb_b.jpg
European starling on signpost by dcstep, on Flickr

7D, 60D, T2i, T3i all appear to have the same noisy sensor with the same high pixel density. Nikon, Pentax, and Sony all have considerably less noisy crop sensors on the market right now. Canon is hopefully going to catch up. Thus, if you're considering buying a more pixel dense camera to get more pixels per duck (or per starling etc.), I would recommend buying a T2i so as to leave cash for a body with the next generation sensor when it comes out. I do find the 7D sensor's pixel density to be quite helpful as long as the light is good. (I bought my 7D before the latest generation sensors from the other camera makers came out, otherwise I would have gotten a T2i myself.)

Whether with a 5D, 5D or other non-1D series Canon camera, a Canon 1.4x tc will not autofocus at all with an f/5.6 lens except in live view. When I use a 1.4x tc with my 7D and 400 f/5.6, I do manual prefocus followed by live view autofocus, on a tripod only. Results are excellent but the bird has to sit still during the live view autofocus. I also tried a third party nonreporting 1.4x tc (one that doesn't tell the camera it's there) and found focusing poor and very slow.

Hi Alan- Just to add to what has been said- it's really is smoke and mirrors, at least as you have defined the issue. Sensor size has nothing to do with the ability to crop an image. The important variable is the density of sensor sites (pixel) on the sensor. Generally, the smaller the sensor site the higher the density because you can pack more into a unit area. Consider a full frame sensor at 12mp (current Nikon D3s, old Canon 5DI). If you cut around the edges of that sensor to match the size of a 1.6 crop factor sensor you would have a 5mp camera. All you lose by going from FF to 1.6 is the four edges of the FF sensor. Both the FF and the cut FF sensor would lay the same number pixels over subjects in your image and therefore both would have the same cropability. The ability to crop is a function of pixel density. Consider the FF Nikon D3s versus the D3x. The former is 12mp, the latter is 24mp. A 500mm lens on a D3s (12mp) would seem like a 1000mm lens on a D3x when it came to cropping the image. To look at it another way, at 100% on your monitor the D3x image would be twice as big as the D3s image. However, the image quality would not be the same because the smaller pixels would produce more noise and be more subject to diffraction softness. There's no free lunch. Your last point is a good one- develop your field skills so that you can get closer to your subjects without affecting them. This will have the biggest impact on your image quality.

The 7D's trade-off between detail and noise is excellent up to ISO 800; thereafter, it can get dicey. When I compare my 5D2, cropped to the same size as the 7D image with the same lens, the 7D has sharper detail. When ISO exceeds 800, then the noise of the 7D starts to intrude too much and the 5D2 looks better overall.

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Originally Posted by Alan Eicoff

I have a 5D & 5D MK II body with full size sensors. My longest glass is the F/4.5-5.6L IS 100-400 zoom. I would love to have a 600mm fixed focus lens for wildlife imaging but do not have the cash. What is the best way to work around this.

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Alan,
There are a couple of factors that point in the direction I would head given your situation (been there). The keys to the image quality, assuming perfect lenses are aperture diameter to collect the light, focal length to magnify the light and pixel size to capture the light. Sensor size only influences total field of view. It is the focal length and pixel size that controls the detail recorded on a distant subject.

The metric for the detail to be recorded is given by the plate scale (dates back to film glass plates):

plate scale = pixel pitch/ focal length.

For a 7D/60D/T2i with 4.3 micron pixels and 400 mm focal length, you will have (the 206265 is the number of arc-seconds in one radian):

plate scale = (4.3 microns/(1000 microns/mm)/400mm) * 206265
= 2.2 arc seconds

It is very very difficult for any current camera + lens combination to do better than 1-arc-second in real resolution due to diffraction. So 400 mm on a 7D/D60 is within about a factor of 2 of what is possible.

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Originally Posted by Alan Eicoff

1. Buy a 60D body with the 1.6 APS-C sensor? Does this effective extension of the 400mm on my 100/400 give me a true 640mm or is this really smoke and mirrors? Am I better off using my 70/200 F/2.8L IS with my 2X teleconverter on it on a 60D to gain the 640mm. My understanding is that I would retain the AF feature doing that while I would lose that feature on the 100/400 with the teleconverter. Does it matter which way I go in the final analysis?

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While not smoke and mirrors, what we lose with small pixels and small lens diameter is light. While we maintain the pixels on subject, there is less light per pixel. Increasing focal length with a small diameter lens does not help increase detail because of diffraction.

To take this to an extreme, buy a superzoom P&S camera. Manufacturers claim 700+ mm "equivalent" focal length. No! It is 700 mm equivalent field of view. The small lens aperture limits image quality due to diffraction and the small pixels collect fewer photons.

Quote:

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Originally Posted by Alan Eicoff

2. Buy a $240 800mm Vivitar manual focus mirror lens? What is the image quality of these type lenses?

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Even if this lens were perfect, the small aperture would limit detail due to diffraction. Then add the bokeh issues. And cheap manufacturing of a $240 lens: it won't be perfect.

Quote:

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Originally Posted by Alan Eicoff

3. Just stay with what I have and only take images of the subjects I can get close enough to to fill a sufficient percentage of the frame to forgo large scale cropping.

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Next to consider is lens image quality. The 100-400 will show more softness with smaller pixels. Better to move to fixed focal length lenses (e,g, 300 f/4 + 1.4x TC or 400 f/5.6). Zooms are not as sharp as fixed (possible exception is the 70-200 f/2.8 II).

More on telephoto reach:
http://www.clarkvision.com/articles/telephoto_reach/

Bottom line, for lighter, lower cost but still pretty good performance: small pixel camera (e.g. 7D/60D) and the biggest fixed focal GOOD lens you can afford. The small pixel need a top lens to get the image quality. Personally, I would choose 300 f/4 (for the IS). I do own the 100-400, 300 f/4, 300 f/2.8, and 500 f/4. I'll take the 300 f/4 when I want to travel very light.

Since you have the 70-200 f/2.8II, I would work with that and get a camera with small pixels (e.g. 7D, 60D).

Roger