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Double-Reversed-Lens Macros
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PostPosted: Sat Jun 23, 2012 2:48 pm    Post subject: Reply with quote
Interesting lens combinations Tobias!
My question is: why did you shoot at f/16-22?
At that magnification the difference between f/5.6 or f/8 and f/22 is unnoticeable DOF related.
Instead, you lose sharpness and contrast due to difraction.


PostPosted: Sat Jun 23, 2012 3:56 pm    Post subject: Reply with quote
@Himself
Quote:
Interesting lens combinations Tobias!
My question is: why did you shoot at f/16-22?
At that magnification the difference between f/5.6 or f/8 and f/22 is unnoticeable DOF related.
Instead, you lose sharpness and contrast due to difraction.



There're main 2 reasons for that:
- First reason: If I let the reversed lens at wide open, and I set the aperture of the
main lens between f2.8 and f 11: the flash diffuser will overexpose the
photograph. I already down regulated the internal camera flash
with -2.0 which is most I can do and set on ISO 100. I can't
do high speed flashing with the inbuilt camera flash, it's always set
to 1/180 with my cam.

So what to do against that: I can stop down the reversed lens to let less
light in. That's actually a solution and works, BUT viewfinder gets significantly darker
so working does get really awkward.

- 2nd reason and comment on your statement:
Quote:
At that magnification the difference between
f/5.6 or f/8 and f/22 is unnoticeable DOF related

don't underestimate DOF with macro photography.
it's there and it's a lot from what I can tell from my little experience.

check out this photograph, it's the only one from the series which was done at f6,3 (main lens)
and a little stopped down reversed lens to avoid to over exposing.
DOF is very thin there, just compare it to the others which were done at f16 and f22:




Cheers
Tobias


PostPosted: Sat Jun 23, 2012 4:48 pm    Post subject: Reply with quote
I see no difference. Even if there is a 1/20th of a mm difference, it doesn`t ad up to the image.
THE only way to have bigger DOF at that magnification is the stacking way.


PostPosted: Sat Jun 23, 2012 4:53 pm    Post subject: Reply with quote
I see some difference, actually.
On the other hand, DOF is really tiny even at f22, so, in many cases, focus stacking is necessary regardless of the aperture.
But I definitely see some difference between the one shot at f6.3 and the others.


PostPosted: Mon Jun 25, 2012 8:33 pm    Post subject: Reply with quote
@Himself

Quote:
I see no difference. Even if there is a 1/20th of a mm difference, it doesn`t ad up to the image.
THE only way to have bigger DOF at that magnification is the stacking way.



I think we still have very different opinions Very Happy Very Happy

Let me explain from my point of view,
(which is more based on my eyes then on science Wink
... because I am not really into this Macro topic)

Just made some sample shots with one of this combos
(so one with a high magnification value, which is 4,2 : 1)


SMC A 100 /2.8 with a 24mm/2.8 on top

I did a comparison between f 5.6 and f22 on same subject,
same distance, angle lens to object = ~45°
I didn't made f2.8, because I think it's unusable because of
extreme narrow DOF


_____________
1 cent coin:

f5.6



f22



_______________

ruler: angle of view = 5mm

f5.6



f22



__________________
I think difference is obvious, so the argument
Quote:
THE only way to have bigger DOF at that magnification is the stacking way

is not really confirmed Wink

I think you just overestimated the magnification with these combos. it's just ~4:1, so
I can still fill 5mm vertically on the frame with this combo.

____________
____________
My personal opinion about this stacking way:
there a 2 major disadvantages about it:

- it only works satisfying on not-mooving subjects
- one gets very limited and bulky with daily practise due to tripod use

For example:
with these type of shots that I showed here it is impossible to apply:
Just imagine these plants are up to 2 meters tall, so they are constantly in
motion. --> motion and stacking doesn't go along with each other.
(I know there are some crazy guys doing stacks on living animals, but I think
it's not a efficient way for daily use, especially with these
super-macro combos Wink )

I am 99% of an outdoor photographer; when I am doing macros it's mostly
plants or living animals. So I was choosing for myself to be the stack way not my way.

I did once a stack with creeping grubs and it was hell of a work
to align and reconstruct this moving animals:

CZJ Flektogon 35mm/2.4



Cheers
Tobias


PostPosted: Wed May 15, 2013 3:54 pm    Post subject: Reply with quote
yeah I made some of these 3:1 too
(the front of some lens, I believe Super Albinar, came off,
underneath a 50 mm or so thread which with a little force went into 49 mm or so I remember, was some time ago)

The ratios are impressive indeed, but it's really hard to focus and get the plane align with object, and DOF is nonexistent.
Also, the resulting contrast just sucks.
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