[mythguy9]

Hi all, I decided to learn macro the cheap and dirty way before I invest more into a proper macro lens. Below is my setup, a 28mm front lens reversely stacked to a 50mm mounted lens with a male-male adapter. The question is: what shake reduction focal length should I set to???

Should it be 50mm still? When a lens is stacked in front, will the setup's focal length change? I tried to Google but was fruitless...please help




Here's a quick sample from the setup, pretty close-up with almost 2X mag. Vignetting is obvious with the front lens set to f16 (body lens still wide open, I found stopping down the body lens will introduce worse vignette).

[Na Horuk]

Um, I would suggest you turn SR off altogether in those scenarios. Tripod to prevent hand shake blur and if you can, even the 2 sec timer to minimize even mirror slap vibrations.
Good shot btw, looks like youre up to a good start

[Adam]

SR should be off assuming you're on a tripod, which I'm sure you are.

[mythguy9]

SR should be off assuming you're on a tripod, which I'm sure you are.

I wasn't haha. The insect was pinned (I study a bit entomology) so I used the table for stabilisation. Will monopod work too? I plan to shoot outdoors so tripod setup will be a bit slow...

By the way, anybody know what the focal length of my setup (28mm + 50mm) will be equivalent of???

[calculator01]

as mentioned, SR off. But when it asks you what focal length you have, you need to enter a number in there.

Of course, for the life of me, I cannot remember the equation, but ultimately I don't think it would matter since your SR is off (although sometimes I stack and free hand it)

[Adam]

By the way, anybody know what the focal length of my setup (28mm + 50mm) will be equivalent of???

This thread should help you out with the calculation:
https://www.pentaxforums.com/forums/38-photographic-technique/213473-focal-le...e-adapter.html

[mythguy9]

Thanks Adam, with the equation I found FL-combined = 1 / (1 / FL-lens 1 + 1 / FL-lens 2) + close focus compensation

Read more at: https://www.pentaxforums.com/forums/38-photographic-technique/213473-focal-le...#ixzz2rAvTKzWR

Should gives me roughly 18mm for the above setup, but I didn't take close focus compensation into account. Anyway, this is not important at such close range. I will now shoot away and get use to macro!

Thanks guys.

[Na Horuk]

With macro, you will notice 2 big obstacles.
One is thin DoF, so you need narrow apertures. This implies, demands longer exposure times (or higher ISO which means more noise and less dynamic range)
The other is very apparent hand shake. Even at 1:1 macro it is hard to compose while handling the camera. You can try something like those mini tripods - gorillapod? Just be careful, if you use heavy lenses, a small tripod might be prone to tip over. Sometimes even a small beanbag is a good solution, though.
Might be a worthwhile investment if you have such nice subjects and are planning on doing this kind of stuff

A tripod is very useful for any kind of photography, though. Practically only way to maximize sharpness. That, and having good light (flash, strobe, softbox)

[dms]

Actually for the SR it would seem it should be based on an assumption of a distance focused as well as FL. As the distance is less the magnification increases. In the limit adding 100 mm extension to a 100mm lens (simply assuming the extension in the lens mount is not used) gives magnification of 1 [and one can sort of say it's a 200 mm FL] , as does adding 25 mm extension to a 25 mm lens [and one can sort of say it's a 50 mm FL], but in both cases the sensor is recording an identical picture--as regards the focused plane--and thus the SR corrrection (if it was correct for macro--which it isn't!) would be the same. If you want to use SR, I would think the best would be to try some different values and see which works best, for a given lens set up and magnification. But if on a tripod or monopod it should be off (and yes I have observed more unsharpness w/ SR on using either one).

[thechumpen]

Look up Thomas Shahan. He does some amazing stuff with similar low cost set up and from the YouTube vids it all seems to be hand held with a flash.

[arkav]

Thanks Adam, with the equation I found FL-combined = 1 / (1 / FL-lens 1 + 1 / FL-lens 2) + close focus compensation

Can anyone elaborate on that close focus compensation? ( I don't see it explained in the referenced thread )

Back when I used an M series macro lens and had to dial in the focal length, I always wondered if using the lens' nominal focal length was valid when getting near 1:2 ( I almost never added extension tubes
to get additional magnification ). At what magnification does the close focus compensation become significant?

Now that I've got a DFA macro, I don't have to dial in the focal length for SR. Is the camera smart enough to do the close focus compensation? If not, how do I alter the focal length used by the SR ?

( I shoot butterflies in the field, so turning off SR and using a tripod, etc. is impractical )

Cheers

[Doundounba]

Nice shot!

I agree that if you're shooting a still life, a tripod (plus mirror-up and 2s delay or remote) will avoid the whole issue.

But if you're going to shoot handheld - which a lot of subjects pretty much require - I'm going to go against the current of this thread. Why should one turn *down* SR when a diopter amplifies any camera shake? I'd think you'd need more SR (longer effective length), not less.

In any case, my personal experience has been to keep the same FL as the primary in the shake reduction, and that has seemed to work reasonably well so far. I use either a 135mm or 150mm primary. Reversing a 50 on a Pentax-K 135mm F/3.5 - a $50, sharp lens - works very well, and you can leave the 50 wide open and control aperture with the primary without vignetting, which is very convenient.

BTW, you might want to have a loot at the section on coupled reversed technique on Nass's excellent Extreme Macro site.

EDIT: I might as well also point you to the thread where I discuss my own experiments with this technique.