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Bigma with 2x and 1.4x converter for moon shots?

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AlYousuf

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I think I crammed the whole question in the subject line but here goes.

ive been experimenting with moon shots, with good results so far using my 50-500 Sigma and a Kenko 2x conveter. I bought the Kenko years ago, and reason being it works on Canons and Sigma's. I dont know much about converters so I was told Canon TC's arent compatible with Sigma and vice versa.

This time around I need to get even closer shots, so im thinking of new converters in this case both a Sigma 2x and a Sigma 1.4x and stack them on the Bigma.

That should give me a focal lengh of 1400mm to work with vs the current 1000mm. Should be challenging, but thats what this is all about :D

now the main question is, with a min aperture of f/6.5@ 500mm and 2.8x worth of converters that would translate into into a widest aperture of f/17.5 @ 1400mm. Im wondering if this doesnt sound like a good idea, diffraction? The whole point of going longer focal length is to capture more detail, dont want to be doing the opposite thing.

suggestions?
 
If you can take very sharp images in wide open shot at 500mm then why not. For "full moon" then it's bright enough for stack TCs.
 
Try it with a 2x, and then with a 2.8x and see if there is increase in detail captured. With careful technique, I believe you can squeeze out a bit more detail with the extra 1.4x behind the 2x, provided your Bigma is a good copy.

Shoot at 1 stop from wide open, forget the effects of diffraction in the meantime. The lessening of aberrations due to stopping down will likely outweigh the softening due to diffraction, resulting in a net gain in IQ. You can easily verify this by taking shots wide open and 1 stop down.

Here are more moonshooting tips I've posted before:

http://romyocon.wordpress.com/2011/04/06/moonshooting-with-birding-lenses/
AlYousuf said:
I think I crammed the whole question in the subject line but here goes.

ive been experimenting with moon shots, with good results so far using my 50-500 Sigma and a Kenko 2x conveter. I bought the Kenko years ago, and reason being it works on Canons and Sigma's. I dont know much about converters so I was told Canon TC's arent compatible with Sigma and vice versa.

This time around I need to get even closer shots, so im thinking of new converters in this case both a Sigma 2x and a Sigma 1.4x and stack them on the Bigma.

That should give me a focal lengh of 1400mm to work with vs the current 1000mm. Should be challenging, but thats what this is all about :D

now the main question is, with a min aperture of f/6.5@ 500mm and 2.8x worth of converters that would translate into into a widest aperture of f/17.5 @ 1400mm. Im wondering if this doesnt sound like a good idea, diffraction? The whole point of going longer focal length is to capture more detail, dont want to be doing the opposite thing.

suggestions?
Click to expand...
--
Romy



PHILIPPINE WILD BIRDS (Over 260 species captured in habitat, and counting.)
http://romyocon.wordpress.com/
 
Get as high as possible . I know it sounds dumb , but the higher you are , the less smog , haze - etc you deal with .
You a remote with mirror lock up .

The new canon 2X and 1.4 extenders have more and better glass - maybe rent before you buy or buy , try and return if they suck .
--
1st it's a hobby
7D gripped XTI gripped
Canon - efs 10-22 , 17-55 , ef 18-55 IS
EF 28-90 , 28 @ 2.8 , 50 @1.8 , 28-135 IS
L's 35-350 , 70-200 MK II IS
Quantaray lens 70-300 macro
Sigma 135 - 400
2X III , Life Size converter
KSM filters for all
kenko auto tubes , EF 25
 
tonyjr said:
Get as high as possible . I know it sounds dumb , but the higher you are , the less smog , haze - etc you deal with .
You a remote with mirror lock up .

The new canon 2X and 1.4 extenders have more and better glass - maybe rent before you buy or buy , try and return if they suck .
--
1st it's a hobby
7D gripped XTI gripped
Canon - efs 10-22 , 17-55 , ef 18-55 IS
EF 28-90 , 28 @ 2.8 , 50 @1.8 , 28-135 IS
L's 35-350 , 70-200 MK II IS
Quantaray lens 70-300 macro
Sigma 135 - 400
2X III , Life Size converter
KSM filters for all
kenko auto tubes , EF 25
Click to expand...
I agree that makes sense, im in Dubai, and when I shoot the moon from my home I see ALOT of atmospheric crap, so my current moon shots are limited by how clear the skies are. For starters you cant see stars which tells alot.

Now on the other hand, about an hour's drive from Dubai, a little into the desert the skies are brilliantly clear, this time I might shoot from an elevated location as well, some roads that go through the mountains, but I dont want to make all this effort before knowing how well my equipment work and what I need, skills etc....
 
liquidstone said:
Try it with a 2x, and then with a 2.8x and see if there is increase in detail captured. With careful technique, I believe you can squeeze out a bit more detail with the extra 1.4x behind the 2x, provided your Bigma is a good copy.

Shoot at 1 stop from wide open, forget the effects of diffraction in the meantime. The lessening of aberrations due to stopping down will likely outweigh the softening due to diffraction, resulting in a net gain in IQ. You can easily verify this by taking shots wide open and 1 stop down.

Here are more moonshooting tips I've posted before:

http://romyocon.wordpress.com/2011/04/06/moonshooting-with-birding-lenses/
AlYousuf said:
I think I crammed the whole question in the subject line but here goes.

ive been experimenting with moon shots, with good results so far using my 50-500 Sigma and a Kenko 2x conveter. I bought the Kenko years ago, and reason being it works on Canons and Sigma's. I dont know much about converters so I was told Canon TC's arent compatible with Sigma and vice versa.

This time around I need to get even closer shots, so im thinking of new converters in this case both a Sigma 2x and a Sigma 1.4x and stack them on the Bigma.

That should give me a focal lengh of 1400mm to work with vs the current 1000mm. Should be challenging, but thats what this is all about :D

now the main question is, with a min aperture of f/6.5@ 500mm and 2.8x worth of converters that would translate into into a widest aperture of f/17.5 @ 1400mm. Im wondering if this doesnt sound like a good idea, diffraction? The whole point of going longer focal length is to capture more detail, dont want to be doing the opposite thing.

suggestions?
Click to expand...
--
Romy



PHILIPPINE WILD BIRDS (Over 260 species captured in habitat, and counting.)
http://romyocon.wordpress.com/
Click to expand...
thanks Romy,

I see you stacked 2 2x converters on the 400, and ive seen people stack much more than that on other super telephoto lenses with good results, so im more or less aiming for the same.

I cant be too sure whether my Bigma is a good copy, I know my 5DII is a BAD copy that doesnt focus well, so whenever I tried using the Bigma with autofocus the results werent as I expected, so im not sure about that.

Moon shots were quite soft out of the camera, but with alot of PP turn out to be pretty nice, but not nice at 100%, say 70-80% crops are perfect :) With that said there was ALOT of atmospheric crap (heat refraction?) and it was VERY obvious as he moon "wobbles" badly in 10x live view.
 
I would suggest doing it on the camera with MFA and MFA it first on far away object like somebodies roof in a good light.
--
Eugene

The only time a smaller sensor with the same pixel count is superior to a larger sensor (aka higher pixel density) is when you are focal-length limited.

Quote by Lee Jay

 
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