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Objective Advice Needed—New Member
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peterf



Joined: 12 Aug 2010
Posts: 18

PostPosted: Tue Aug 17, 2010 10:05 am    Post subject: Objective Advice Needed—New Member Reply with quote

Greeting,

I'm new to the forums and have been lurking about for a while enjoying every minute of it. I've read a lot, trying to discern which objective to buy for my purpose but still come away a bit confused. I would like to be able to figure this out for myself but so far am unable to so I am asking for your advice. My main goal currently is to photograph the emerging buds of a particular flower that has taken me quite some time to grow in my garden. The individual buds shown below measure about 1mm in dia. and 2 to 3mm in length. I'm trying to get about 3 or 4 of them on the sensor and possibly even get in a little closer. I have tried a number of old Pentax screw mounts reversed, a Companon-S, a 50mm El_Nikkor and various others but so far have had the best results with a 60mm Nikon Macro fully extended (or close) on Novoflex bellows but of course realize that it can be MUCH better. My problem is that the flowers will be going away soon and so time is crowding in on my learning curve. I have a very rigid setup using a metal lathe milling head for advancing the camera for z-stacking using a D300 (5.49 micron pixel pitch) and studio strobes. Stacking is with Helicon Focus and I have been testing Zerene which I like very much. Can anyone reccomend something specific I can buy on ebay (or elsewhere) quickly in the under $600 range or there about. I am most grateful for the forum and looking forward to your comments. Thank you!

Peter




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rjlittlefield
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Joined: 01 Aug 2006
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PostPosted: Tue Aug 17, 2010 11:43 am    Post subject: Reply with quote

peterf, welcome aboard! Very Happy

The field size you need is too big for a 10X objective, so I'm thinking 4X is the best you can do for a single stack.

NikonUser has posted images and some test results for various 4X objectives, see HERE and HERE. Highest quality should come from the apochromat.

But I am not optimistic that the quality will be hugely better than what you are already getting. The apertures of 4X objectives are not much wider than high end conventional lenses. You are already capturing detail at close to the level of individual pixels, as shown by the pair of highlights around X=394,Y=121 in the crop. When I run my usual test of shrink to 50%, expand by 200% to restore the original size, then layer and flash, it's clear that significant detail is lost in that area by reducing the pixel count.

A sharper lens will give you higher contrast at that same level of detail.

You could also get higher contrast at the same level of detail by careful sharpening, except that in the image as posted this also increases pixel noise to an uncomfortable level.

Looking critically at this image, the noise level seems higher than I would expect. I don't know your workflow or how the stack was shot, but I wonder whether there is opportunity for improvement in these areas.

Given your short time frame, I recommend that as "insurance" you review your settings and workflow to be sure that you have captured the best possible source images. Be sure that you have the sharpest aperture setting on your best lens. Use lots of light, set the camera on its lowest ISO, shoot in raw, process in 16 bits. This will give the lowest noise and finest gradation, which preserves the most options for later processing.

To make big improvement in resolution, I think you would need to switch to a 10X objective. These will not cover a field as large as you are talking about. Tiling to cover the wide field is an option, but if you haven't ever done that, I don't recommend starting now. An alternative is to think in terms of a pair of images: one wide field like you have now, and a second image showing a smaller field at higher resolution, shot through a 10X objective.

As to which 10X objective, I can recommend two approaches, as described HERE and at the links posted later in the same thread.

I hope this is helpful.

BTW, I am the author of Zerene Stacker. Thank you for the kind words. If you run into any issues or want tips on how to get the most out of it, just ask. I especially recommend watching the retouching tutorials that are linked from the online documentation HERE. Some of the most effective techniques are not obvious on first contact with the software.

--Rik
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Charles Krebs



Joined: 01 Aug 2006
Posts: 5805
Location: Issaquah, WA USA

PostPosted: Tue Aug 17, 2010 11:46 am    Post subject: Reply with quote

Peter,

Are you sure about the dimensions? Is the first picture a considerable crop? If the first picture you posted is "full frame" from a D300 (15.8 x 23.6mm sensor), the prominent complete bud shown would be about 6mm wide and about 14mm high. This is important to know, because that's 6x larger than you mentioned and could make a big difference as to the best lens choice.
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peterf



Joined: 12 Aug 2010
Posts: 18

PostPosted: Tue Aug 17, 2010 12:07 pm    Post subject: Reply with quote

Mr. Krebs,

Thank you for having a look at this. I just re-measured the large bud in the image with a dial caliper and find the diameter to be closer to .080" (2mm) and the length around .130" (3.5mm) but that is the largest of the group. It is a slight crop but not much. The stack was 24 images with the camera advanced .003" at the closest focus to .005 at the farthest.

Here is one of the full captures:





Charles Krebs wrote:
Peter,

Are you sure about the dimensions? Is the first picture a considerable crop? If the first picture you posted is "full frame" from a D300 (15.8 x 23.6mm sensor), the prominent complete bud shown would be about 6mm wide and about 14mm high. This is important to know, because that's 6x larger than you mentioned and could make a big difference as to the best lens choice.
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peterf



Joined: 12 Aug 2010
Posts: 18

PostPosted: Tue Aug 17, 2010 12:37 pm    Post subject: Reply with quote

Rik, thank you very much for the reply and for the welcome! AND, thank you for the software!!! I plan on buying it very soon. Do you give discounts to forum members ;-?

The noise is a little high I agree, it was shot at ISO 160 but the room is quite hot. If I use live view to focus it heats up the cmos and increases noise. The stacking usually compensates so I don't fuss too much over it. I'll look more closely and see if I can determine the cause. I was mostly just rushing to get the capture because these things tend to move around and bloom while I'm trying to photograph them Smile

I do shoot RAW of course but for the test stacks (of which this was one), I just process the jpegs quickly and then find the one I like and do the final images later. Right now I'm just doing the captures while I can get the flowers in front of a lens.

Thanks for the suggestion of tiling. I have done some yes, and my setup is particularly conducive towards this approach but I also wish to learn to work with an objective so have a dual purpose in mind.

I really like Zerene a lot, I used it on this frontal view of the flower (7 images).







rjlittlefield wrote:
peterf, welcome aboard! Very Happy

The field size you need is too big for a 10X objective, so I'm thinking 4X is the best you can do for a single stack.

NikonUser has posted images and some test results for various 4X objectives, see HERE and HERE. Highest quality should come from the apochromat.

But I am not optimistic that the quality will be hugely better than what you are already getting. The apertures of 4X objectives are not much wider than high end conventional lenses. You are already capturing detail at close to the level of individual pixels, as shown by the pair of highlights around X=394,Y=121 in the crop. When I run my usual test of shrink to 50%, expand by 200% to restore the original size, then layer and flash, it's clear that significant detail is lost in that area by reducing the pixel count.

A sharper lens will give you higher contrast at that same level of detail.

You could also get higher contrast at the same level of detail by careful sharpening, except that in the image as posted this also increases pixel noise to an uncomfortable level.

Looking critically at this image, the noise level seems higher than I would expect. I don't know your workflow or how the stack was shot, but I wonder whether there is opportunity for improvement in these areas.

Given your short time frame, I recommend that as "insurance" you review your settings and workflow to be sure that you have captured the best possible source images. Be sure that you have the sharpest aperture setting on your best lens. Use lots of light, set the camera on its lowest ISO, shoot in raw, process in 16 bits. This will give the lowest noise and finest gradation, which preserves the most options for later processing.

To make big improvement in resolution, I think you would need to switch to a 10X objective. These will not cover a field as large as you are talking about. Tiling to cover the wide field is an option, but if you haven't ever done that, I don't recommend starting now. An alternative is to think in terms of a pair of images: one wide field like you have now, and a second image showing a smaller field at higher resolution, shot through a 10X objective.

As to which 10X objective, I can recommend two approaches, as described HERE and at the links posted later in the same thread.

I hope this is helpful.

BTW, I am the author of Zerene Stacker. Thank you for the kind words. If you run into any issues or want tips on how to get the most out of it, just ask. I especially recommend watching the retouching tutorials that are linked from the online documentation HERE. Some of the most effective techniques are not obvious on first contact with the software.

--Rik
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Charles Krebs



Joined: 01 Aug 2006
Posts: 5805
Location: Issaquah, WA USA

PostPosted: Tue Aug 17, 2010 12:55 pm    Post subject: Reply with quote

Peter,

OK... if its 2mm wide, and you want "about 3 or 4 of them" across (vertical as pictured) then you are looking at a magnification of about 2 to 2.6X.

No microscope objective I am aware of is going to be "better" than what you are currently using. A reverse mounted 50mm Componon-S or El Nikkor used at between f4 and f5.6 should be excellent. You might find a few lenses that do somewhat better, but not by all that much (if at all).

As Rik suggested, under time constraints, I think concentrating on technique would be more worthwhile.

One thing that presented a slight caution flag was the "studio strobes". Some of these have surprisingly long effective flash durations, even when powered down. Although I doubt it (can't see any signs of it in your 100% crop), it's not inconceivable that you could still be getting a little vibration coming through... worth checking out. Try a shot or two at rear curtain sync at the end of a 1 or 2 second exposure (subdued room light) and compare. Also pay attention to any possible heat "pulse" coming from a studio flash head. This can actually "jiggle" a subject. I've experienced this with a 400WS Lumidyne used directly too close to the subject. These two thoughts are a bit of a "reach", but you never know until you check.
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peterf



Joined: 12 Aug 2010
Posts: 18

PostPosted: Tue Aug 17, 2010 1:56 pm    Post subject: Reply with quote

"Heat Pulse" huh, okay, I'll mount the Nikkor again and back the light off. The rear curtain sync is a great idea too but I'll have to wait for evening to get the room dark enough. Thanks for all the help, I LOVE this forum! One more quick question: I've been looking at this objective on ebay:

NIKON 10X/0.30 WD 6.5 CF PLAN INFIN/0 BD OBJECTIVE

Do I understand correctly that I may use this directly in front of the sensor with no intermediate lens if I wish to explore a higher magnification? I'm really starting to get into this after having lurked around here for a while. What kind of working distances does this objective allow?

Thanks again Mr. Krebs.

Peter


Charles Krebs wrote:
Peter,

OK... if its 2mm wide, and you want "about 3 or 4 of them" across (vertical as pictured) then you are looking at a magnification of about 2 to 2.6X.

No microscope objective I am aware of is going to be "better" than what you are currently using. A reverse mounted 50mm Componon-S or El Nikkor used at between f4 and f5.6 should be excellent. You might find a few lenses that do somewhat better, but not by all that much (if at all).

As Rik suggested, under time constraints, I think concentrating on technique would be more worthwhile.

One thing that presented a slight caution flag was the "studio strobes". Some of these have surprisingly long effective flash durations, even when powered down. Although I doubt it (can't see any signs of it in your 100% crop), it's not inconceivable that you could still be getting a little vibration coming through... worth checking out. Try a shot or two at rear curtain sync at the end of a 1 or 2 second exposure (subdued room light) and compare. Also pay attention to any possible heat "pulse" coming from a studio flash head. This can actually "jiggle" a subject. I've experienced this with a 400WS Lumidyne used directly too close to the subject. These two thoughts are a bit of a "reach", but you never know until you check.
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AndrewC



Joined: 14 Feb 2008
Posts: 1436
Location: Belgium

PostPosted: Tue Aug 17, 2010 3:00 pm    Post subject: Reply with quote

If it's an infinity objective you'll need a relay lens. You need to look out for 160 or 210mm tube length objectives.
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rjlittlefield
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Joined: 01 Aug 2006
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PostPosted: Tue Aug 17, 2010 3:01 pm    Post subject: Reply with quote

peterf wrote:
NIKON 10X/0.30 WD 6.5 CF PLAN INFIN/0 BD OBJECTIVE

Do I understand correctly that I may use this directly in front of the sensor with no intermediate lens if I wish to explore a higher magnification? I'm really starting to get into this after having lurked around here for a while. What kind of working distances does this objective allow?

No, the "infinity" means that this objective is corrected for use with a tube lens that finishes the image formation. If you use it without the tube lens, directly in front of the sensor, the image will degrade quite a lot due to spherical aberration. However, it works well to use an ordinary telephoto lens as a tube lens, by using an adapter that fits the objective on the front of the telephoto. This approach is described HERE for a slightly different objective. Be aware that the thread on BD objectives is larger than the RMS standard used on most objectives, so you need a different adapter.

This objective is probably designed to give 10X when used with a 200 mm tube lens. The delivered magnification depends directly on the focal length of the tube lens, so to get 15X (and a 50% larger image circle), you would use it with a 300 mm telephoto.

Working distance of this objective is 6.5 mm, measured from the frontmost part of the objective.

--Rik

Edit: I see that Andrew posted just before me. The "160 or 210mm tube length objectives" that he speaks about are finite objectives, designed to be used without a tube lens.
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Charles Krebs



Joined: 01 Aug 2006
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Location: Issaquah, WA USA

PostPosted: Tue Aug 17, 2010 3:05 pm    Post subject: Reply with quote

Quote:
NIKON 10X/0.30 WD 6.5 CF PLAN INFIN/0 BD OBJECTIVE

Do I understand correctly that I may use this directly in front of the sensor with no intermediate lens if I wish to explore a higher magnification?


Nope, not this one. "INFIN" stands for "infinity" and designates an objective designed to be used with an additional "tube" lens after the objective. People have been successful using telephoto lenses of about 200mm as the "tube" lenses (instead of the "official" Nikon microscope lens), but if you want to keep things simpler and use an objective alone on a bellows you want what is known as a "finite" type objective. (A Nikon CF M Plan 210/0 or possibly certain 160mm tube length objectives like a Nikon 10/0.30 CFN Plan Achromat)

edit:
wow... a triple response overlap! Wink
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Bob S



Joined: 07 Aug 2010
Posts: 16

PostPosted: Tue Aug 17, 2010 5:24 pm    Post subject: Reply with quote

I would try cutting the step size in half.

Post another example and specify everything about it; aperture, lens, magnification, step size, flash type and settings, and everything you can think of. It might let someone see something obvious that is being overlooked.
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peterf



Joined: 12 Aug 2010
Posts: 18

PostPosted: Wed Aug 18, 2010 12:47 am    Post subject: Reply with quote

Thanks everyone, I had them backwards. So if I use an infinity lens with a long relay lens, I assume I can vary the magnification factor a bit by the focal length of the relay lens and that there is most likely a sweet spot? I think I will start out with a finite objective for now and see how I do with it. They seem to be a little lower priced from what I can see online.

I had a moment to try the reversed Nikkor again tonight with a little better success. I previously believed that I had a rigid setup but can see now that it was inconsistently rigid. I have learned from experience to change only one thing at a time and then evaluate the results so the problem is discovered. I tend to want to not do this but try to discipline myself into it. First I made another capture with everything as is was with similar results. Then I started checking piece by piece for anything that might wobble. There were several things including the T-mount adapter flange that I hadn't noticed before. I then moved the strobe as far overhead as possible and weighted down the camera assembly and "bedded" down the flower holder in lead shot bags. I took extra time to tighten the cross slide ways between captures and turned a rudimentary lens shade for the Nikkor and used the rear curtain sync with a 2 second exposure in a darkened room. This reminded me of when I used to do a similar thing with sheet film and multiple strobe pops years ago, it was one of my favorite techniques back then. This group definitely shows that one or two of the frames either had camera shake or the object moved a bit. I couldn't see it before because all the captures were similarly blurred so this has turned out to be very helpful indeed.

I did only tests tonight and as I said, two of the frames were blurred so the stack was marginal but will try again tomorrow hopefully and post an image or two. Maybe then you can evaluate it and tell me if the results are as they should be or can be improved upon.

Thanks again, this is really getting me juiced!


Charles Krebs wrote:
Quote:
NIKON 10X/0.30 WD 6.5 CF PLAN INFIN/0 BD OBJECTIVE

Do I understand correctly that I may use this directly in front of the sensor with no intermediate lens if I wish to explore a higher magnification?


Nope, not this one. "INFIN" stands for "infinity" and designates an objective designed to be used with an additional "tube" lens after the objective. People have been successful using telephoto lenses of about 200mm as the "tube" lenses (instead of the "official" Nikon microscope lens), but if you want to keep things simpler and use an objective alone on a bellows you want what is known as a "finite" type objective. (A Nikon CF M Plan 210/0 or possibly certain 160mm tube length objectives like a Nikon 10/0.30 CFN Plan Achromat)

edit:
wow... a triple response overlap! Wink
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elf



Joined: 18 Nov 2007
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PostPosted: Wed Aug 18, 2010 1:15 am    Post subject: Reply with quote

I don't think you need to worry as much about movement between images as you do about movement while the shutter is open. Watch the movie in this thread for an example of extreme movement that still stacked.

How light sensitive are these flowers? I've had several that moved through 90 degrees in less than half an hour. I usually wait a while to let the flower adjust to the light before starting a large stack.
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Chris S.
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PostPosted: Wed Aug 18, 2010 12:58 pm    Post subject: Reply with quote

peterf wrote:
The noise is a little high I agree, it was shot at ISO 160 but the room is quite hot. If I use live view to focus it heats up the cmos and increases noise.


Peter, you might find (as I do) that tethering works better than live view--it certainly helps avoid heating the senser up and increasing noise. If you haven't tried it, there is a free 30-day trial for the Nikon Camera Control Pro 2 software at this link:

http://support.nikonusa.com/app/answers/detail/a_id/61/~/current-versions-of-nikon-software#Anchor-3

There are of course other tethering programs, but I'm not familiar enough with current versions to comment on them. The Nikon software, though overpriced, does work pretty well.

I use a right angle adapter on my camera's viewfinder, partly because it has a 2X magnification setting that helps in focusing. Then I can take a quick throw-away photo, and within about a second it appears on the computer screen, so I get a nice, big image to check. Was using my laptop for this, but recently dedicated an old-cast off computer to my rig--image capture doesn't require much horsepower. I do, of course, send the images to a more powerful computer for stacking.

Cheers,

--Chris
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peterf



Joined: 12 Aug 2010
Posts: 18

PostPosted: Wed Aug 18, 2010 9:37 pm    Post subject: Reply with quote

I know what you mean, these can move a lot too. The other interesting thing is all the life that's crawling around inside. One sequence captured around a dozen little occupants and those are just the ones that made it through the stack :-)

elf wrote:
I don't think you need to worry as much about movement between images as you do about movement while the shutter is open. Watch the movie in this thread for an example of extreme movement that still stacked.

How light sensitive are these flowers? I've had several that moved through 90 degrees in less than half an hour. I usually wait a while to let the flower adjust to the light before starting a large stack.
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