All equivalent field of views are equal....(birders lament)

Started Aug 28, 2014 | Discussions thread
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Brandon birder Veteran Member • Posts: 4,112
All equivalent field of views are equal....(birders lament)

...but some are more equal than others.
Those of you that know me must realise that I have had many cameras straddling the range from FX high megapixel to ultra super zooms, with DX M4/3 and CX in between. I am an avid birdwatcher and bird photographer as well as fascinated with cameras and how they use the rapidly changing technology to give us consumers so many more options within the the photography niches we all live within. Indeed this has opened up bird photography to the masses who are interested, where before it was an extremely elitist group of people with big pockets, SAS weather resilience and infinite patience to get images we today can get in the comfort of a hide.
To this end I have come to recognise that field of view and light are key to getting bird images with feather detail. I also recognise that for me personally a field of view of about 800mm (FX equivalence) is optimal. Shorter than this and the reach isn’t enough, longer and the technical requirements to get a sharp handheld image are not acceptable. I have tried tripods with Wimberley heads and absolutely hate the effect they have on my birdwatching pleasure and on my physique. So my goal in the last few years has been to get the best 800mm FOV equivalent for the conditions. So if walking the dog a light combo, walking around a reserve on foot especially in the summer a Blackrapid carrying combo and for winter (UK) because of the light and weather dictate hide work then a system that I can use on a monopod and extracts the best of the light is best for me.
For this reason I have rationalised my camera combo’s to a V3 and 70-300cx lens for dog walking, a D7100 and Nikkor 80-400VR for reserve walking and a D810 and 500mm f4 or 300mm f2.8 and TC’s for winter.
So what do I mean by by FOV equivalence?It is the field of view equivalent to that found when looking through a 800mm lens in an FX camera whether it is achieved by lenses, tele-converters or cropping that image. Often combinations of all of the above. The current benchmark for me is to get a good 12 megapixel image with a field of view of 800mm equivalent. In 2008 when I first started my goal was 6 megapixels but technology has raised what is possible.
So for examples a 60% crop of a 36 megapixelx D810/500mm f4 image is around 12 megapixels. A 50% crop of a D7100/80-400@400mm is 12 megapixels. Furthermore and this is different here a downsample of a V3/70-300cx image from 18 to 12 megapixel gives the same.
So why 12 megapixels? For me it will produce with minimal processing a good A3 print. It will also downsize well for current web output and be more than enough for future 4K HDTV output. It is also with the current technology the minimum size that I can achieve with good handheld technique with the current combo’s I have.
So what has this got to do with the title?
My aim a couple of years ago when I was using a 10megapixel V1 and a D800 was to try and get equivalent image quality with all my combo’s. So idealistically whether I used a V1, D7000 or D800 the image quality of the final output image would be roughly the same. I thought it would be nice to have a lightweight system without IQ loss especially as I am not getting any younger.
This hasn’t turned out to be the case. Equivalent field of views do not produce equivalent images even with the best post processing I can do. The CX images always need more post processing and can’t be cropped much further at all. On the other hand the 800 field of view image from the D810/500mm and 60% crop can be cropped a further 50% and produce a very good 6 megapixel image. The D7100/80-400 sits between but is closer to the D810 derived image in terms of crop ability. So the FX combo’s at same field of view equivalence actually have more reach than the CX.
I guess this could be self evident and derived from the dynamic ranges of these sensors but of course the DR of a cropped FX sensor is less than that of the uncropped sensor by a factor equivalent to the area size of the crop. So a CX sensor which is essentially letting the camera do the cropping should be comparable to an FX sensor cropped down to the same size as a CX sensor.
I have come to the conclusion it is not. Which is a shame for me but means that I couldn’t rely on the CX system all the year round without IQ loss. Nor can I rely on an FX system all the year round due to it’s weight. Hence the reason I have three systems.
I am not sure whether this is down to the technology or just that I am at the limits of my ability with the small sensor cameras and not with the larger sensor cameras.
I realise that this is a very bird centric point of view but there are a lot of bird photographers now that it can be done more easily. I also choose to post these thoughts first on this N1 forum as it is with the CX system that is the most exciting in offering great reach and light weight, that the shortfalls lie. I have dealt with these differences by relegating my CX system to travel and dog walking, though also to places where I can get really close and have good light too. I still need to carry my larger systems for bird watching on reserves. I would love to promote the CX system to a primary system, but either can’t or don’t know how to
I wonder what other bird photographers think about these issues?I also would love to know what those photographers who regularly exceed my capabilities do to eek out the extra quality from their images. Whether this be ÔÇťoptimal" post processing techniques, sheer skill or just good heavy support for their equipment.What is your optimal field of view?

Nikon 1 V1 Nikon 1 V3 Nikon D7000 Nikon D7100 Nikon D800 Nikon D810
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