An experiment in the absurd...

[cdd29]

First, I want to state that I know better than this and this was primarily done to see if I could actually get any kind of a useable image, and I'm bored. For your amusement....
This is a combined stack of three teleconverters (2 2x, 1 1.5x) with a 150-450 lens focused (sorta) on the moon.
Pentax K-1 (36mp full frame)
lens: Pentax 150-450mm (approx. 400mm used, effectively 2400mm)
teleconverters: 2x, 2x, 1.5
ISO: 3200
shutter speed: 1/6
aperture: I have no idea. Camera is so confused it says f/1.7 (lens is f/6.3 at this length). Taking into account 3 teleconverters, what would that even equate to?

 

[Scott Whaley]

I don't think it worked. Go with the 400 & a 2X teleconverter. I usually just use my Sigma 150-600 with my Canon 7dmkiv. It gives me an extra 300mm.

 

[cdd29]

My goal was to see just how bad of an image would come out of this. It's a little more useable than I thought. It was done all in fun anyway, not as a serious attempt to get a better pic of the moon. I admit, I might use a 1.5x occasionally with the 150-450, but NEVER three.

 

[wfooshee]

Well, a 1.5x is about a stop of exposure lost (a 1.4 converter is a stop,) a 2x is two full stops, so add it up, it's 5 stops. your f:6.3 becomes f:36. Your camera has no idea of the aperture because the teleconverters probably don't communicate exposure information, so the camera defaults to whatever it does for "unknown." Kinda cool that you actually got an image, but the stacking is where that flare in the center came from, basically the original image reflected on some surface inside the glass path.

 

[cdd29]

Surprisingly some of the daytime images I took are fairly clear, though muddy (as I'd expect).

If I feel like wasting a few bucks I might grab one or two more for the hell of it and see what that looks like (K-mount TC's, generic anyway, are pretty cheap on ebay.)

 

[RacePhoto]

My goal was to see just how bad of an image would come out of this. It's a little more useable than I thought. It was done all in fun anyway, not as a serious attempt to get a better pic of the moon. I admit, I might use a 1.5x occasionally with the 150-450, but NEVER three.

Well you succeeded? Both, a relatively ruined image, but what you see is what you got and more than that it was fun. Experimenting and fun, way up top on my list of things to do in photography. My compliments.

What's the line? How to make a great lens into an average lens? Put on a tele extender. LOL

 

[480sparky]

You succeeded in recreating the first photo of the moon.

 

[mrca]

I applaud your testing. The first thing I do when I get a new piece of gear is try to learn not only what it can do, but what it can't, ie it's limitations. It's called trial and ERROR, not trial and SUCCESS. We know a teleextender will degrade the image, but how much? I had a 400 mm 2.8 that was sharp as a tack, attached a 1.7 teleextender and hung a crop sensor d500 off it. Around 1000 mm equivalent. The results were still fantastic. Not as good as without it, but completely useable.

 

[Grandpa Ron]

Welcome to the world of the incessant diddler.

The mind asks what will happen when I do this. Optimism predicts the result. Reality produces the true result.

The "success" of the adventure is of course realtive. But the question of "what if" has been answered.

I think a bit of post processing could product and interesting, little cresant in big cresant photo. It is definatly a study in multiple lens reflections.