A PROMISE KEPT

[mysteryscribe]

I promised to do this experiment a few days ago so here it is....

This is a birdbath in my yard with a 300mm no name lens but since it is the same base lens that makes no real difference. Shot 1 3oo mm lens.

the next image is the same shot with the same lens plus a 2x vivtar extender (doubler)

First shot cropped to approx the same size

These were with a tripod so there was no apreciable camera shake. In my opinion the 2x seems to have done a little better job. However the image increase was done with a simple editor so not as good as a special fractal program might have done. anyway I promised so here it is.

 

[PNA]

Which may be interpret as not needing a 2x extender......

 

[mysteryscribe]

here is the 2x extender after some minor adjustments..

Truth is I thought the extender held up a little better than the enlargement with my program. This combination is 600 mm. I have some more extender glass but I don't think I'm gonna continue this. There should be plenty here to argue about.

Oh yeah this was done of film I have no idea what digital would do...

 

[Alpha]

I don't get it. The experiment is supposed to be, say, a 150mm lens with an 2x extender vs a 300mm lens with no extender. Of course the crop looks worse...

 

[mysteryscribe]

http://www.thephotoforum.com/forum/showthread.php?t=84261 note the arguement is made by more than one person that the extender is useless and the same thing can be done by interpolating the area. It is why I said I don't have a fancy fractal thing so it can probably be done better by someone else.

 

[Alpha]

Oh Jesus. What a wretched idea. You can't accomplish anything by interpolation unless you're viewing from twice the distance. Hold on, let me go look at your shots again from the other side of the room....

...nope.

 

[mysteryscribe]

Hey I just said I would shoot the shot... I have used glass extenders most of my photo career. However I had never used them in shaded light and at first I was having terrible camera shake problems. The tripod shots I just got around to today. I'm not in the discussion anymore.

 

[Seefutlung]

I saw a similar experiment done to test Canon extenders on Canon lenses. The conclusion was that an extender on a L prime had better IQ than cropping the image using the same lens without an extender.

But with consumer grade lenses your IQ was better by cropping than using an extender.

So lens quality definitely affected IQ.

Gary

 

[Garbz]

Which puts us back to the original conclusion that the entire excercise is lens dependant and will not hold true for anything beyond testing 1 lens at 1 focal length with 1 extender :S

Thanks for posting the shots.

 

[mysteryscribe]

Well In my case it's like this...

I have the lens ... I have the glass.., I don't have a fancy interpolating program. The lens quality degraded but it was usable as an image, if not great art with the extender. For me it is the better option with what I have on hand at the moment. I might could get 250 mm with my 135 but I could also get it with my 2x extender. Since I have the glass If it need a 600 mm lens I would rather use the glass than try to blow it up from a 300. That was the conclusion I drew from the experiment not saying that is true for everyone just me.

No matter what the lens, I would expect the loss with THAT extender to be similar if not the exact same amount of loss. Better quality in, better quality out, but still that amount of loss to the image. You can't add glass without loss and you can't blow it up without loss, How much I don't know. As was said it's probably case by case.

 

[fmw]

I don't think the image quality difference between the two is remarkable, just noticeable. I don't use 2X extenders but I do use 1.4X. In my experience it is better to use a 1.4X and crop than it is to use a 2X but that is a less extreme situation than the one you provided here so it would be intuitive, I suppose.

It is also important to use the extenders with fixed focal length lenses. They are noticeably more negative to image quality with zooms than they are with simpler lenses.

I find that a 1.4X extender on a fixed focal length telephoto lens is a pretty good combination.