Stacked converters on a 400 F5.6 IFED Nikkor

[simon_fallon]

Has anyone had any success with photos taken on Nikon equipment through stacked converters? Some years ago I

saw some shots of the moon apparently taken this way; sharpness was more than acceptable and I have since

been trying - on and off - to achieve similar results. I have a 400mm F5.6 IF ED Nikkor with matched TC300 and 14B

converters, also TC200 and 14A for 200mm and shorter lenses. So far results have been less than stunning, although

I suspect camera shake may be partly to blame. What I would like to ask you all is: does anyone know if the order in

which the converters are fitted makes a difference, ie should I fit the TC300 onto the lens, and then the TC14a

between this combo and the camera? Or the other way around, and fit the TC14B onto the back of the 400mm and

then the TC200? The reason for mixing the A and B type is simply that the 14B and 300 won't fit together due to the

protruding front elements, although I have heard of fitting an extesion ring between them to overcome this. As always,

grateful for any experienced advice.

[joseph_smith3]

I have done it successfully with my Nikon 500mm f 4.0 lens. You need a very good tripod, usually with only one leg section extended. With the tc 301, it gets placed into the tele lens first, then you add the tc 14b to the tc 301, w/o an ext tube, then the camera. You should trip the shutter with a release cable. I use this for shots of frogs on ponds and sometimes dragonflies. Sometimes I add ext tubes to get closer and I usually add these to the camera. I have never tried it for anything like a moon shot.

 

The tc 301 is designed to fit inside a long lens so you have to add it to the back of the long lens. In the case of Nikon lenses, this means a 200mm and longer lens and the lens has to be open so the tc 301 can be entered into it. I have never owned a 14a or a tc 200 so I cannot comment on these tcs. Joe Smith

[leif_goodwin8]

The IQ will (obviously) depend on the quality of the individual components, and the way they interact. The Nikon 400m lens is not the sharpest Nikkor, which will not help, and the TC14A is as you say intended for short FL lenses. I doubt that lens is a patch on the 500mm Nikkor.

 

That said, I have never tried the TC14A on the Sigma APO Macro 400mm F5.6 I own, which is optically comparable to your Nikkor. Results are poor on the 200mm AFD micro, acceptable but not great on the 60mm micro, and surprisingly good on the 85mm micro.

[oskar_ojala]

I haven't tried teleconverters with my 400/5.6 IF-ED, but it's quite sharp when focused correctly and supported properly. Especially the support will be very difficult, you will need mirror lock up. Of course result with stacked TCs won't be stellar; even at maximum aperture you have an effective aperture of f16 and that's not even talking about the optical degradation, so it all depends on how high quality you expect-

[simon_fallon]

Thanks for the responses so far; I'll keep an eye on the thread for a while.

[joseph_wisniewski]

First, are you shooting wide open? You've got an f5.6 lens with a 2x and a 1.4x converter. That's f16 wide open. If you stop down two stops, you're at f32, which is more than enough to soften up the image due to diffraction.

 

Next, the moon moves across the sky at a faster rate than most people appreciate. After you've done all the other "common" ultra long lens things (bracket that fastens to both camera and lens, mirror lockup, cable release, sandbag draped across the lens) consider faster film or a higher ISO to get the shutter speed up and eliminate "moon crawl". And don't forget the old 1 pound per 100mm rule on tripods. You've got 400*1.4*2 = 1120mm. That's an 11 pound tripod. If you've got a 2 pound tripod, you are not getting this shot.

[simon_fallon]

Joseph, you know your stuff, but exposures won't be long enough for moon- motion blur, and I'm reasonably happy with my Manfrotto tripod, (though I suppose a bit heavier would be a bit better, and shutter bounce is a concern). However, you have raised an interesting point that I hadn't really considered, namely diffraction. I had always thought-and I'm prepared to be corrected- that this source of image degradation was due to the physical size of the aperture in use, (which is of course set on the prime lens), and that the smaller effective working aperture resulting from the fitting of a converter (or two) had no effect on image quality because the light loss was the result of "lengthening" the lens whilst the actual diaphragm opening remains the same size regardless of any lens add-ons. Hmm... Thanks for posting, you've certainly given me something to think about.

[joseph_wisniewski]

Simon, you're welcome.

 

Oh bother. You're going to make me calculate this again...

 

The earth rotates 360 degrees in 24 hours (we'll ignore terrestrial and sidereal hours for this discussion). That's 360/24 = 15 degrees/hour, 15/60 = 0.25 degrees/minute, 4.1E-3 degrees/second. I assume you're shooting digital. Let's pick on a 12mp, 15.x crop factor DSLR. That has 5.6 micron pixels. The lens and converter stack is 400mm*1.4*2 = 1120mm. A pixel corresponds to an angle of arctan((5.6/1000000)/(1120/1000)) = 2.87E-4 degrees.

 

That means the earth is rotating at 4.1E-3 deg/sec / 2.87E-4 deg/pixel = 14 pixels/sec.

 

What was your shutter speed? At 1/15 sec, each pixel smears onto its neighbor and you lose effectively 1/2 of your resolution. At 1/2 sec, your image gets smeared by 7 pixels of motion blur.

[simon_fallon]

Joseph, I'm impressed, and after you've gone to such thoughtful lengths I hardly dare tell you this, but the truth is I actually never shoot digital at all, except for a few family snaps on my girlfriend's pointandclick. I prefer film, almost exclusively b/w, and for my most recent attempt to reach for the moon I shot a roll of Tri X 400 and a roll of Rollei Pan ISO 25. It wasn't till I was set up and ready to fire that I realised that my 14b teleconverter wouldn't physically fit onto the TC 300 doubler (due to the 14b's protruding front element), so I had to make do with the 400mm doubled. I believe I stopped down to F11, giving me an effective aperture of F22 with doubler attached. I bracketed shutter speeds around 1/60th for the Tri X, and 1/4 sec with the Rollei Pan. I'm temporarily unable to print due to lack of a darkroom (digital users can look smug at this point) but under a Nikon loupe the negs look not bad. Problem is, of course - as you undoubtedly know - with so many variables one could spend a very long time trying to perfect something which may not actually even be achievable. All I can say for certain is that there is no detectable motion blur on the slower negs when compared to the Tri X shots, and that, under the loupe, I cannot see any difference in sharpness between the frames taken with the 2X converter and those shot with the 1.4X. I'm unable to say as yet whether my equipment would have given better results with an even sturdier tripod, or if shooting wide open would have improved things. Obviously a different lens and/or converter might be sharper, my film/dev combo may be less than ideal, and all this is without even adding a second converter to the set up! But I'll persevere, and if I ever discover the magic recipe I will share the results with the forum; just don't hold your breath, guys... Joseph, and all so far, thanks again, very nice to hear from you.

[david_feindel]

As an amateur astronomer, I'd also like to point out a couple other contributing factors that will greatly

influence the sharpness of your photos at that range of magnification. Air currents--arising from nearly

concrete or blacktop as it is cooling down, the neighbor's roof, traffic on highways, the jetstream above you at

30,000 feet--all will reduce sharpness. There's also the humidity in the air--you are shooting through tens of

miles of air. Try looking at the www.cleardarksky.com entry for your location to pick the nights that will

improve your chances. Early morning just before the sun comes up is generally the best time. What you're

attempting to do is not easy; I "cheated" and used my 800mm f/7 telescope as a lens, and still didn't get a high

percentage of keepers. But let us see what you get!