bettis1 Loc: Texas

The two longest lenses which I have are a 55-300 f4.5-5.6 for my D7100 and a 70-200 f4 for my D750. I know that if I use the 70-200 on the D7100 I will have an effective length of 105-300mm. I am most interested at this point in the long end and I anticipate that the higher quality 70-200 lense will give me a better IQ at 300 on the D7100 than the 55-300 will. My question is: Will the difference in IQ between the two lenses at 300mm be significant enough to offset the loss on the short end from 55mm to 105mm? I know that I can set up the two lenses and do some comparisons but I would appreciate any theoretical comparisons from the Hogs.

Thanks,
Bob

rmorrison1116 Loc: Near Valley Forge, Pennsylvania

If you have the light and need the distance then the 300 will out perform the 200. If you don't need the reach and you can "zoom" with your feet, the 70-200 is the way to go. If you have the right light then the IQ difference between the two shouldn't really matter.

bettis1 Loc: Texas

Thanks morrison. The need for the longest possible (300mm) is for birding so the lighting will be variable and "foot zooming" doubtful.

Bob

oldtigger Loc: Roanoke Virginia-USA

i had a 55-300 on my D7100. i ended up giving it away as a body cap because of low IQ.
Stay with the 70-200.

rmorrison1116 Loc: Near Valley Forge, Pennsylvania

The best, relatively inexpensive, birding lens I've found so far is the Sigma 150-600. I have the smaller lighter contemporary model for my Nikon and the larger heavier Sport model for my Canon. The C model costs new around $800-$850 and it does a darn good job for what it is. I've always found that for photographing birds, the more reach you have the better because birds are skittish little creatures and they don't usually like to get to close to people. The S model is also good for building muscles and upper body strength.

Unless you are in a good blind and the birds are up close and personal and your camera has a lot of megapixels, like the Canon 5DSr, the 200 probably isn't going to be adequate enough.

JPL

I am sure the 70-200 is better than the 55-300. But just like the 70-200 has effective length, as you call it, of 105-300 on your D7100 your 55-300 will have effective length of 83-450mm on your D7100. Keep that in mind if you are comparing those two lenses.

martinfisherphoto Loc: Lake Placid Florida

I assume you have never used either lens for birding. The 70-200mm will win hands down every time, even with the lens cap on......

bettis1 Loc: Texas

JPL,

The 55-300 is a DX lens. Unless I am mistaken, on the DX camera the focal length will be 55-300.

Thanks to everyone for the comments. Just to be clear, I know that the 70-200 FX lens (105-300 on the DX camera) will be better at the 300mm end. My question is will the difference be significant enough to offset the loss of the short end loss of focal length.

LarryFB Loc: Depends where our RV is parked

A 300mm lens wil always be a 300mm lens. That is the focal length of the lens. However, on a DX Nikon, it will have the field of view of a 82.5mm to a 450mm lens on a full frame camera.

The focal length of a lens is based on the specifications of the lens. The effective focal length of a lens (read field of view) is a function to the lens AND the size of the sensor in the camera.

JPL

You are rigth and you are mistaken at the same time. The 70-200 is not only a full frame lens but also a Dx lens and always has the same focal length. The 55-300 lens will always be 100 mm longer at 300 mm than the 200 mm lend at 200 mm. Effective focal length will not change that because it has nothing to do with the lens. It is related to the sensor size only. Best way for you to figure this out is to take some sample shots with both lenses at max focal length. Then you will see that your objects will fill much more of the frame with 300 mm lens than 200 mm lens.

Lagoonguy Loc: New Smyrna Beach, FL

If you are birding it is unlikely that you will miss the shorter end IMO. I purchased a Nikon 1.4 teleconverter to use with my Nikon 70-200 f4 and D7100 for this purpose which yielded a 420mm equivalent. The loss of one stop really didn't make any difference in good light but at dusk or dawn it will make a difference. If you can capture your image at that distance it does yield an excellent result. 500 or 600mm would be better but I can't see toting that kind of weight for travel purposes which is my prime focus. I carry a G16 28-140 camera on my belt to capture anything shorter. I keep thinking about the Nikon 300mm FE f4 VR prime that weighs only about 27 ounces but it is just one more specialty lens and $2000. Several members here have stated they really like this lens.

pmackd Loc: Alameda CA

(1) I also have the Nikon 300mm f4 PF prime and it is a fantastic lens. A joy to use. But not enough reach even on a DX camera for small birds, unless you can somehow get really, really close. I can get within 5 feet of a hummingbird at my porch feeder but that is highly exceptional.

(2) As for the comparison the OP asked about, I would set aside the comments here and do my own careful testing, without preconceptions, and with the usual sharpening you use in PP. And do them in varying light conditions and at varying ISO.

imagemeister Loc: mid east Florida

The only thing I will tell you is in a recent testing (using Imatest) by Digital Camera magazine - the Nikon 70-200 f4 had the highest resolution of the lenses tested - which included Canons and third parties. - Not by a huge margin - but the best non-the-less. Put it on the 7100 and crop using pixel enlargement if necessary.

amfoto1 Loc: San Jose, Calif. USA

It sounds as if you are confusing yourself.

The 70-200mm can NEVER be "better at the 300mm end". That lens only goes to 200mm. It doesn't have a "300mm end".

JUST TO BE CLEAR...

That 70-200mm on DX camera will still be a 70-200mm. It doesn't magically "become" a 300mm. If and when it's used on a DX camera, it just "acts like a 300mm lens would on an FX camera".

The 55-300mm on same DX camera will still be 55-300mm and will always have 50% more "reach" than the 70-200mm. On the DX camera the 55-300mm "acts like a theoretical 450mm lens would on an FX camera".

You aren't "comparing two 300mm lenses". You are comparing a 200mm lens to a 300mm lens. Focal length is focal length... irrespective of sensor format or if the lens is marked DX or FX.

Now, I'd bet the 70-200mm is a better quality lens than the 55-300mm. But putting that aside for a moment, most "birders" look for as much focal length as they can afford and carry. 200mm or even 300mm really isn't enough for birding, even when used on a DX camera. The good news is that today there are some very good super telephotos that are relatively affordable... For example the Sigma and Tamron 150-600mm, Nikkor 200-500mm... etc. There also are some recent models that can be found used for less money, Sigma 120-400 OS and 150-500 OS, for example.

Still, they all cost something. There's just no "free lunch".

As to your question about the "short end"... 55mm versus 70mm... That's a negligible and largely meaningless difference. I wouldn't worry about it at all.

And, again, PLEASE do yourself a favor and stop with the lens factor conversions! If you convert one lens, you have to also convert the other in order to make comparisons! If you multiply 70mm to get "105mm", then for a valid comparison you also have to multiply 55mm to get "82.5mm".

Regardless of lens, I'd recommend you primarily use the DX camera for birding. It gives you "more pixels on target" than the FX camera.... i.e., has that "free, built in 1.5X teleconverter effect" with any lens. I think it's also got a faster frame rate, which you will probably find useful. If using flash, if it has a faster sync speed too, that can be another benefit.

imagemeister Loc: mid east Florida

YES