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02-20-2011, 10:53 PM   #16
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QuoteOriginally posted by silverelantra Quote
None are cropped??? WOWWW... they really are sharp, especially the last one. I can see dirt and water on its eyes clearly.

May I add another setup? Not as good as yours though.

DFA100/f2.8 + Internal flash -2 + FGZ 360

ISO 400. 1/125,f11
either that is a MASSIVE jumping spider or a significant crop

02-21-2011, 12:16 AM   #17
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QuoteOriginally posted by yeatzee Quote
either that is a MASSIVE jumping spider or a significant crop
I'll take your last guess..
03-03-2011, 11:36 AM   #18
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So today I fould out that I can stack my lenses, too.
Did it before but I didn't see a way to connect my 50mm to the Sigma 105mm Macro. Turns out my lens hood for the Sigma just holds the SMC Pentax 1.4/50 securely in place.
Maximum magnification of this set-up is ~2.3:1 (pictures when it's brighter again...).
My question is: which lens should I stop down?
Stopping the main lens (Sigma) down gets me the benefit of not having to care about the stacked lens since it's fully automatic.
Sharpness doesn't really differ either way. What is different is distortion (the f/1.4 lens has rather strong field curvature) and CAs (again, pictures later).
With the stacked lens stopped down I get some vignetting.

Stopping both lenses down to f/11 results in a highly vignetted but very sharp image. Stopping down both but only slighly gives the best sharpness but also strong vignetting.

So what is the best way?
1. Leaving the stacked lens wide open and using the main lens only,
2. Stopping the stacked lens slightly down (like to f/2.8) to eliminate distortion and CAs and still using ther main lens' aperture,
3. Stopping the stacked lens down and rely on the superior resolution capabilities of the main lens?

I tend to favour the "only stop stacked lens down"-option.

Great comparison, btw.
03-03-2011, 12:25 PM   #19
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Main lens is the PRIMARY. Stacked lens is the SECONDARY. Magnification is PRIMARY / SECONDARY so if they're 105mm and 50mm, MAG = 105/50 = 2.1x. I like using a 35mm secondary, for 105/35= 3x magnification. Stopping-down the primary is what causes vignetting. I leave the primary wide open and only stop-down the secondary. But whatever works for you, is fine. Have fun!

03-03-2011, 01:29 PM   #20
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Does the Primary/Secondary rule still apply if there is additional extension between them?
The Sigma has a deeply recessed front element and the Pentax sits even further from the Sigma's front element.
If I could I'd allso use my 28mm but that's not possible since I can't fix it on the other Sigma. For now it's 50 reversed, 50 reversed + some extension or 50 reversed and extended on the 105mm lens.
Magnification was calculated by simply measuring - there are 10,x mm visible. With a sensor length of 23,4mm that gives: 23,4/10,x mm=2,3x

Back to my initial question: Is there a reason why I should stop down on the secondary lens?
Results seem to get better but no consistently better - it varies.
03-04-2011, 11:56 AM   #21
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QuoteOriginally posted by yeatzee Quote
A wide angle macro? Like a macro landscape?
I've been somewhat impressed by the images from the Sigma 24mm 1.8 macro, although the sharpness seems pretty weak at larger apertures. I wouldn't mind duplicating the wide-angle macro look if possible with stacking.

I've been considering using a Sigma 30mm 1.4 with a Raynox 250 as of late. That would give an effective focal length of 24mm and Magnification ratio of ~1:3.
03-04-2011, 10:47 PM   #22
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QuoteOriginally posted by Egg Salad Quote
Does the Primary/Secondary rule still apply if there is additional extension between them?
All the calculations I've seen ignore separation between primary and secondary. I haven't tried measuring exact magnification. The separation *does* contribute to vignetting. I use lenses with shallow insets to prevent that.

QuoteQuote:
Back to my initial question: Is there a reason why I should stop down on the secondary lens?
Because stopping-down the primary causes vignetting. Try it and see.

QuoteOriginally posted by jeffshaddix Quote
I wouldn't mind duplicating the wide-angle macro look if possible with stacking.
I have tried my fishy K-mount Zenitar 16/2.8 on about 12mm of tube extension and yes, it's macro and no, I didn't find it satisfying. The problem with short-focal-length macro is the VERY tight working distance. I've also used a fishy Vemar 12/8 that's unfortunately built so it doesn't reach infinity focus. As is, it is necessarily a close-up lens, and also not satisfying, with very shallow focus.

So, focus stacking is probably the best option. Or make a pinhole camera from an oatmeal box. Infinite DOF, close-focus, ultra-wide, BINGO! Even better, use a 1-gallon paint can. I think Freestyle sells a paint-can pinhole kit for a few bucks.
03-05-2011, 07:35 AM   #23
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Some images follwing...

The stack set. Huge advantage: you have two lenses for focusing (ok, you usually focus by moving either camera or object). With the long focus throw of the Pentax you can really fine tune your focus easily.
[/URL]" target="_blank">

"Stopping down the primary causes vignetting..."
Sigma: f/11, Pentax: f/1.4
[/URL]" target="_blank">

Sigma: f/2.8, Pentax: f/11
[/URL]" target="_blank">

Another set:

Sigma: f/11, Pentax: f/1.4
[/URL]" target="_blank">

Sigma: f/2.8, Pentax: f/11
[/URL]" target="_blank">

Sigma: f/8, Pentax: f/1.4
[/URL]" target="_blank">

Sigma: f/2.8, Pentax: f/8
[/URL]" target="_blank">

Conclusion: center sharpness about even, edge sharpness considerably better with the secondary (stacked lens) stopped down.
Distortion way weaker with the secondary stopped down.

03-05-2011, 08:01 AM   #24
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Thanks for the comments RioRico. I used to own a sigma 17-70mm macro and really enjoyed the close focus shots at 17mm. I was hoping to duplicate that ability in a nice prime, but the market just doesn't have a nice macro lens with that focal length.

I can understand how extension tubes can get frusrating especially with the setup you mentioned. You'd probably want a sub-10mm tube for the 16mm lens, which are hard to find for sure.
03-05-2011, 12:19 PM   #25
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Original Poster
QuoteOriginally posted by Egg Salad Quote
Some images follwing...

The stack set. Huge advantage: you have two lenses for focusing (ok, you usually focus by moving either camera or object). With the long focus throw of the Pentax you can really fine tune your focus easily.


"Stopping down the primary causes vignetting..."
Sigma: f/11, Pentax: f/1.4


Sigma: f/2.8, Pentax: f/11


Another set:

Sigma: f/11, Pentax: f/1.4


Sigma: f/2.8, Pentax: f/11


Sigma: f/8, Pentax: f/1.4


Sigma: f/2.8, Pentax: f/8


Conclusion: center sharpness about even, edge sharpness considerably better with the secondary (stacked lens) stopped down.
Distortion way weaker with the secondary stopped down.
im pretty sure this is just the result of a HUGE gap between lenses

Here's some samples I've taken with the sigma 105mm macro and a Pentax M 50mm F/1.7 reversed stacked:



















If you want to see more, basically any macro on my photo stream from page 18-22 is with the M 50mm + sigma stacked setup
03-07-2011, 06:22 AM   #26
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So...
I've just looked through you album (all of them!) and now several things became clear to me.
No wonder you have hundreds of critter pics if your house is full of them.
You are putting a lot(!) of dedication into this and you aren't afraid of total cheapskate solutions...there's a lot of paper rolls involved.
Macro solution for single in september | Flickr - Photo Sharing! Rubber bands. WTF?

And seriously - handholding this whole set-up with flash (jumping spider)?
That's not okay morally.

But I have to say they totally screwed you - I mean who would buy a XATNEP?

Ok, but seriously:
are these also taken with the Sigma + reversed 1.7/50?
Budwing female | Flickr - Photo Sharing! This one looks unreal - more like 3D character animation...
Budwing adult female | Flickr - Photo Sharing!
Budwing female's wing | Flickr - Photo Sharing!

And if yes - are they focus stacked?
I can't get nearly that much DOF and frankly the results suck.
Focusing freehand? Impossible.

Seems like I had to get a tripod that actually can hold my stuff, some extension tubes and another 28mm lens...

Question: do those AICO extension tubes offer A functionality?
If found some but they are so cheap I can't believe they aren't fully manual.

Last edited by Egg Salad; 03-07-2011 at 07:02 AM.
03-07-2011, 07:03 AM   #27
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Effect of stacked lens spacing

QuoteOriginally posted by Egg Salad Quote
Does the Primary/Secondary rule still apply if there is additional extension between them?....
Increasing the spacing of stacked positive lenses increases the combined focal length. For macro work this decreases the magnification.

The magnification for stacked lenses f' and f" with spacing d (primary lens f' focused at infinity) is:

m.stack.infinity = (f'-d)/f"

Total magnification when primary is extended a distance x to give m.primary.extension magnification before stacking:

m = (m.primary.extension+1)(m.stack.infinity+1) -1 = (x/f'+1)((f'-d)/f"+1) - 1

Dave

The above is because the rule for the focal length of stacked lenses if there's a space d between stacked lenses of focal length f' and f" is:

f = f'f"/(f' + f" - d)

Last edited by newarts; 03-07-2011 at 07:42 AM.
03-07-2011, 07:18 AM   #28
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Somewhat depressing since I should actually know this studying engineering and all..
But this goes well with my findings - couldn't really explain why magnification decreases as I focus to infinity on the stacked lens (infinity focus = stacked lens' elements further from main lens) but now it's clear.
Seems I have to really optimize my set-up if I want to go more of this...

Anyway, newarts...you really rule optics.
Since these rules can't be applied to real lens systems: where would be the center of the lens? How would I determine the additional extension/distance?

Actually, it doesn't matter - I can just measure the given magnification but still...out of interest.
03-07-2011, 08:02 AM   #29
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Where are lenses exactly?

QuoteOriginally posted by Egg Salad Quote
............
Since these rules can't be applied to real lens systems: where would be the center of the lens?
Distance would be measured from the appropriate "principal planes" of the lens... where the "lens" is in space looks different from the front and rear. You'd likely have to determine this yourself by working backwards from experiments ... the manufacturer knows but doesn't bother to publish such details.

QuoteQuote:
....How would I determine the additional extension/distance?...
This one is easy. It is the actual extension of the primary lens. The maximum magnification associated with extending the primary lens is usually in the mfg's specs, like "max mag = 0.2x")

If you are using a bellows just measure the bellows extension.

QuoteQuote:
...But this goes well with my findings - couldn't really explain why magnification decreases as I focus to infinity on the stacked lens (infinity focus = stacked lens' elements further from main lens) but now it's clear...
Thanks for mentioning that, I hadn't thought about it but it seems consistent with predictions.

Incidentally, the equations also work for close-up lenses like the Raynox.

Dave

Last edited by newarts; 03-07-2011 at 03:56 PM.
03-07-2011, 03:43 PM   #30
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QuoteOriginally posted by Egg Salad Quote
So...
I've just looked through you album (all of them!) and now several things became clear to me.
No wonder you have hundreds of critter pics if your house is full of them.
You are putting a lot(!) of dedication into this and you aren't afraid of total cheapskate solutions...there's a lot of paper rolls involved.
Macro solution for single in september | Flickr - Photo Sharing! Rubber bands. WTF?

And seriously - handholding this whole set-up with flash (jumping spider)?
That's not okay morally.

But I have to say they totally screwed you - I mean who would buy a XATNEP?

Ok, but seriously:
are these also taken with the Sigma + reversed 1.7/50?
Budwing female | Flickr - Photo Sharing! This one looks unreal - more like 3D character animation...
Budwing adult female | Flickr - Photo Sharing!
Budwing female's wing | Flickr - Photo Sharing!

And if yes - are they focus stacked?
I can't get nearly that much DOF and frankly the results suck.
Focusing freehand? Impossible.

Seems like I had to get a tripod that actually can hold my stuff, some extension tubes and another 28mm lens...

Question: do those AICO extension tubes offer A functionality?
If found some but they are so cheap I can't believe they aren't fully manual.
First and foremost, I must say im pretty disappointed. I was all excited this morning because of the random influx in views (went from 107 yesterday to 647 when I left to school) only now I know it was from one guy hahahahah

My house usually has some critter in it Family members now know to give me whatever insects they find

im glad you notice my dedication and passion..... and yes I am very cheap Being 17 (my birthday was yesterday ) without a job requires some creativity to get the setups I want Hey man, the rubber bands worked
Not sure what you mean by the morals part though

I would!

No those were all taken with the sigma alone, no stacking. That was my first and only attempt at studio macros

They are fully manually since auto tubes for my purposes are a complete waste of money
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