Extension tubes with Wide angle lens

DorsetDude

DorsetDude

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Showing myself up for the n00b that I am can I ask - If I used an extension tube with a 10-20mm lens on a 1.6 crop canon, will the angle of view still be the same as without the tube on?
What I want to do is get right up close to my cats nose with wide angle on to take a humorous photo of them. Ive tried it with just the wide angle but I cant get close enough to fill the frame because the minimum focussing distance of the lens is too long.

Cheers!
 
As you say, using an extension tube will allow closer focusing, assuming it will fit OK on your Wide angle, another factor could be vignetting.
 
It's a little difficult to explain in words but I'll give it a try...appologies for the odd bit that state the obvious.

Adding a tube will do two things;
1)Move the plane of focus towards the image plane
2)Compress the range achievable between the lens' MFD and infinity focus positions.

Most modern lens designs reduce the focal length as the lens is focussed towards MFD (focal length, and hence AOV, is specified at infinity).

Therefore, if you left the focus ring in the same position then the AOV would be the same but the tube would have moved the plane of focus closer. If you focus at the same distance (may not be possible) then the AOV would be larger!.....hmmm, I hear you say :thinking:.

Think about it. You've moved the range closer therefore to focus in the same place you would have to move the focus ring towards infinity and hence towards the maximum AOV of the lens.

All that said, the range compression with a tube on a wide angle is so severe that there may be little more than a few mm's difference between MFD and infinity and the infinity position is likely to be only a few mm's from the lens surface.

In short, I suspect that the cat's dignity will remain intact until you suss out another way of achieving your goal.

Bob
 
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Bob, how far up my cat's nose would I need to be using a fisheye (8mm) with a tube (assorted lengths)? Not really intending to assault her in this way - although I'm sure she'd be up for it!
 
Nod said:
Bob, how far up my cat's nose would I need to be using a fisheye (8mm) with a tube (assorted lengths)? Not really intending to assault her in this way - although I'm sure she'd be up for it!
Click to expand...
Ah, we've moved from wide angle to fisheye....an added complication.
I'm going to say that I doubt you'll get a tube short enough to work with an 8mm fish. Give me a while to think about but you could start flattening the moggies' nose to improve your chances.

Bob
 
Canon Bob said:
Ah, we've moved from wide angle to fisheye....an added complication.
I'm going to say that I doubt you'll get a tube short enough to work with an 8mm fish. Give me a while to think about but you could start flattening the moggies' nose to improve your chances.

Bob
Click to expand...

:lol:

I think the easiest thing will be for me to try!

MAISIE!!!!!
 
Sorry Bob I dont really understand your explanation.

Asking the question another way how would I take a photo like this one?

Wide Angle Dog

Thanks
 
DorsetDude said:
Sorry Bob I dont really understand your explanation.

Asking the question another way how would I take a photo like this one?

Wide Angle Dog

Thanks
Click to expand...

Wide lens, used close. You'll get within a few inches of the front element at min focus. Focusing distances are measured from the sensor plane, so they're much less than stated from the front of the lens.
 
DorsetDude said:
Sorry Bob I dont really understand your explanation.

Asking the question another way how would I take a photo like this one?

Wide Angle Dog

Thanks
Click to expand...

At a guess, I would say that's more likely to be a cropped fisheye image than just a wide angle. I have a couple of similar shots but not on flickr and TBH, I can't be bothered PPing them (resizing and cropping) and uploading them as examples. Sorry! I even have one of Yv but it's too unflattering for even ME to post!!!
 
Apologies - I only have a few crude snaps taken in the garden available to post but these are just taken using the wide end of a 10-20mm lens on a 1.6 crop camera.

Looks like I used f5.6 here so depth of focus could certainly be increased by using a smaller aperture and more thought given to the focal point than in these examples.

Depending what software you use for PP - it's worth remembering that you can always adjust the perspective of a shot afterwards if you want to push the effect further.

3407060063_745a9a2c4b.jpg


3407057331_6ed4e6909d.jpg


3457277592_182fd4557b_z.jpg
 
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Nod said:
Bob, how far up my cat's nose would I need to be using a fisheye (8mm) with a tube (assorted lengths)? Not really intending to assault her in this way - although I'm sure she'd be up for it!
Click to expand...

Our poor animals. I recently got my first new flash and of course I needed to figure it out so.... here Kitty Kitty.. now the poor guy closes his eyes every time he hears the focus beep go off. Wahahah!!!
 
dinners said:
Apologies - I only have a few crude snaps taken in the garden available to post but these are just taken using the wide end of a 10-20mm lens on a 1.6 crop camera.

Looks like I used f5.6 here so depth of focus could certainly be increased by using a smaller aperture and more thought given to the focal point than in these examples.

Depending what software you use for PP - it's worth remembering that you can always adjust the perspective of a shot afterwards if you want to push the effect further.
Click to expand...

I really like the first one.
 
shaylou said:
Our poor animals. I recently got my first new flash and of course I needed to figure it out so.... here Kitty Kitty.. now the poor guy closes his eyes every time he hears the focus beep go off. Wahahah!!!
Click to expand...

Yup! I try not to use flash on mine - cats do have rather sensitive eyes and while I don't think it causes any lasting damage, I know the I get a persistent image of a flash if someone snaps me! I'm lucky in that I have a D700 - great in low (or almost no!) light, coupled with a fast lens, single bulb artificial light is usually enough to get a useable shot. My fisheye is f/4, so should be fast enough during daylight hours.

I'll post a shot or 2 if I get around to doing the fisheye + tube(s) experiment!
 
Which 8mm and tubes were you trying? Mine is a Sigma and the tubes are an old set of manual ones (no electrical contacts).
 
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