My Christmas/Birthday Present

It came from Ed Richards in Melbourne. He built it for me.

The one I use now is a commercial product and folds up neatly into a unit a bit bigger than a briefcase (see photo). It also sits on our dining room table nicely, much to the annoyance of the boss!

You only need the big one if you collect Andrew-sized rocks!

Bob - 1 question - why sharpen 20%? That seems a bit extreme.



Regards
Steve

To be honest Steve, my answer would hve to be lack of knowledge

I was going into proper photoshopping after I got the basics down. Right now I am battling with what appears to be very small bits of dirt somewhere. They only show up under 4:1 and 5:1 but they do show up as black dots. Now to find and eliminate them so I can try other ideas I have.

Steve what do you do for sharpening? I see there I not just a percentage but radius as well.

Bob

Bob

those small bits of dirt are probably dust on the sensor - I found that a good quality sensor cleaner, and inspection of the sensor to verify cleanliness, with a microscope, is needed to get rid of them. They are mostly a problem at highest magnifications

If your camera saves as JPEG files. Never, ever ever sharpen. Ever. Please. Never. and I mean that. Never.

Just to be clear. That's NEVER.

Why? Because it just makes a nightmare mess with the compression artefacts. It looks horrid.

Your camera will automatically run a sharpening filter (to compensate for the filters in the camera and the way the pixels are built from separate R, G and B elements) if you are saving as JPEG, critically this is done before the image is compressed as JPEG.

Be happy with the end results and never mess around with sharpening. Never.

Thank you :)


If your camera saves as RAW files, then you may be able to use sharpening, but ONLY if you turn off the automatic sharpening option when you import it into Adobe Raw - You can then do sharpening on the image when it's converted to RGB inside Photoshop, Unsharp Mask is often used for this.

However.... in my experience converting to RGB and then doing Unsharp Mask doesn't usually work as well as letting Photoshop do the sharpening in the Adobe Raw loader - which is done before it is converted to RGB.

So. Unless you're an advanced Photoshop and Digital Image wizard who knows what they're doing with raw images, please avoid using sharpening functions at all!


Many people think a sharpened image looks "nicer". In fact, it just looks artificial. Because it is.

Jolyon

Ok, if I understand correctly, we should only sharpen JPEGs on Tuesdays

Here is a new shot with a FOV of about 3mm of a Red Cloud Wulfenite. No sharpening was done!



I think I should work on the micromount a bit. Some of the matrix is obscuring my ability to get a full shot. But I would be interested in peoples comments - how do I improve?

Thanks
Bob



Edited 1 time(s). Last edit at 12/31/2011 02:41AM by Jessica and Robert Simonoff.

Nice shot Bob. I personally like the view when a crystal is not fully exposed.

Also, take a copy of this shot and sharpen, then look at the two images side by side. You should be able to see what Jolyon wrote about.

I don't fully agree that you should never do anything, but look at the results before you decide what to keep. A little unsharpening can be beneficial and still look natural. But try it on a copy, always keep the original. Here's a quick shot taken this morning of an Elmwood fluorite with sphalerite. The first as is, the second with a slight unsharpening. I use Sagelight for most photo editing. There is a free version (Lightbox) with very basic capability. Sagelight is only in the $50-60 range though and gives me all the capabilities I want.





Regards
Steve

Bob,

That's a nice image! Am I correct in assuming that it is a 3/5 crop of the original? The only improvement that I can suggest is to either shoot at a different angle or get rid of some of the obscuring matrix. The latter may end up being a disaster, so I only mentioned it and did not recommend it.

Steve,

Why would you want to unsharpen you image?

Cheers,
Gene

Steve

Your second image shows horrible JPEG artifact sharpening. I much prefer the first! The background quartz is unnatural on the second.

Correct yet again Gene! Do you know this from knowing the camera, number of pixels in the image, then a little math I assume?

As fa as the angle, I played for awhile and the above is an improvement The crystal is in a slight indentation in the matrix. If I angle upward enough, I lose depth of field. The loss will cause me to play with the f stop or iso, which I think will degrade the image in a different way. I think one of my first lessons has to do with each improvement also costing something. Choose which evil you want.

Thanks Steve and Gene!

Bob

I don't disagree Jolyon. The point is you wouldn't necessarily see that unless you have both images to compare. I very rarely do this btw.

Gene - I read somewhere a while back that unsharpening is preferable to sharpening. Not that I had a choice. The menu option is listed as Sharpen (Unsharp Mask), and when you undo, shows as Undo Blur Image.

Regards
Steve

Bob

Unless you don't have Tuesdays on your calendar then as J said - Never on Tuesdays either!!.
Better to do it if you only sharpen on the third full moon in the month (i.e the one that occurs after the Blue Moon) !!!

Cheers and Happy New Year - think I'll start early !!

Cheers



Edited 1 time(s). Last edit at 01/02/2012 10:54PM by Keith Compton.

Bob,

You may be able to go up an f-stop or so without any/much degradation of the image. Some degradation may be apparent at the pixel level but may not be bad at all in reduced images that are suitable for the internet. Still, that will only give an incremental increase in DOF. You may want to consider the multi-focus technique, which can synthesize any amount of DOF required. You are correct that every improvement incurs a cost, or tradeoff. Multi-focus comes at the expense of technical complexity and time invested to make a better image. So far, I still haven't had a free lunch...have you?

Gene

No, no free lunch, but I am still waiting. I have done some stacking and it has worked well, but not with this lens. The black spots mentioned earlier are apparently on the lens not the sensor. I determine this by taking pictures of white paper with this lens and a different lens. The black spots were in 2 entirely different places,

When I stack with this lens, the black dots become long black lines. These are much harder for me to edit out than the few black dots which I currently am editing out when I take pics. So, I need to wait to hear back from Canon to see what the accepted method is of lens cleaning. Since it is brand new, I don't want to do anything that will void my ability to return the lens if there is a problem.

Thanks
Bob

Bob,

I can't explain why your black spots move with the different lenses. More thought required on this one. However, I find it hard to believe that the spots are caused by anything on the lens. Nothing that is on the lens should be in focus at the focal plane. In fact, if you put an obstruction in front of the lens, the result should be a little less light and resolution. But, you will not see an image of the obstruction. For example, consider a catadioptric lens, with a large central obstruction.

Gene

I'm a newbie here so I should I really ought to restrain myself from diving in with opinions. But I can't resist, sorry.

If you can tell an image is “sharpened”, then it's been done wrong.
There's a good argument for something around 80% at 0.8 pixel radius unsharp mask, to put back some of what the low-pass filter in the camera, and the MTF curve of the lens, took out. You really do get to see more detail – if the lens is up to it.
Also, if you use a large radius, say 30 pixels, and a much lower degree of sharpening, perhaps 15%, it can do a lot to clear down the "haze" you often get in the shadows, from stacking.
Use Smart Sharpen for "Lens" blur not "Gaussian" blur and "Less precise" to help avoid any fringeing from sharpening - something I hate to see.
Best quality Jpegs don't have any artefacts to get worse in sharpening. Canon's Jpegs (best on eg Rebels) aren't all quite that good, but you have to look really hard to see it. (100% on screen at least). Nikon's algorithm is a bit better - no sign of anything. (I use both and am not religious about them. They each have "best" points.)

Having said all that you need a top lens to get anywhere near sharpness at a few pixels level, at high magnification. If you're only looking at ( or showing, as here) the image 1000 or 2000 pixels wide then you're using what, about 2 megapixels worth! At that size, most that sharpening is really doing on a typical image is altering contrast. Anything from jpeg compression of the original size will be long gone if the image has been shrunk by 4-5 times.

The "Spots" across your stacked image are from dust on the sensor. They do move around! (Spots on the lens lose you contrast, is all, usually.) "Dust bunnies" are a major problem with stacking (I have a 650 image stack running at the moment, and I forgot to check the sensor first... ) If you look close you'll possibly see one spot per exposure, per trail, and probably in a curve as the stacking aligner shifted the image about.
Some stacking algorithms (including the most useful) are worse than others for dust trails.
At 5x magnification your lens, if used at a marked f/4, is effectively f/24. Any smaller and you'll just get blur from diffraction, on anything like an APS 15MP sensor. You see dust spots at small effective apertures - or very small effective apertures. Take a low iso photo of a neutral blank thing (out of focus is good) at your smallest aperture, shutter timed as long as it takes to get a light/mid grey overall. You can move the camera about to make the exposure even across the frame. A marked f/32, say. (If you want to be nasty to yourself, a marked f/32 on a long bellows!!). Then look at the image at pixels level, and you'll probably be horrified. I was. (If the camera's newish, and the dust doesn't blow off, it's likely to be oil spots - I would (now) send it back for cleaning if it happened again to me.)
They only show at tiny apertures because you need a sharp "shadow" of the dust ( which is on the sensor's filter) on the sensor itself, behind it.

Oh – you don’t need to use a Canon "tethered" to get the Electronic Front Shutter Curtain. It's easiest really to just go from Live View. (It doesn’t work either way on a 60D, by the way, they still shake!!)
I've reverted to flash though, with wooden floors I get sharper pictures that way, when using high magnifications. On my Nikons with jack-hammer full frame mirror, that needs Mirror Lockup as well :).

Oh - a SPLENDID Christmas present, by the way, one reason for going "Canon"! Beatable, but not by much, and only with a lot of money and more than one lens.



Edited 2 time(s). Last edit at 12/31/2011 11:10PM by Justin Case (2).

I used a Nikon D300 prior to getting a Canon T2i. Using mirror lockup on the D300 is not an advantage as the mirror drops, raises, and shutter fires when the shutter is triggered. I believe this is true with most of the Nikon line. We had a discussion about this over on photomacrography.net sometime in the past year or so.

Doug

You're absolutely right, using Live View on a Nikon has no advantage at all - in fact on most models it cycles the mirror to make things worse. The D7000 is improved, I believe, but of course there's still no Canon-equivalent Electronic First Shutter Curtain. This is a big benefit for high magnification photography. It's a pity that it doesn't appear to be something Canon value very highly. I say that because of the shift in operation of the recent 60D, which appears to be "the same" but in fact the little noise you get (present wih all models), DOES vibrate the camera as well.
I'd be interested to see how the new 1DX(?) does it.

If you Aren't using Live View then in both (Canon Nikon) cases it's worth using mirror lockup of course.
There's no "silent mode" equivalent on any Nikon, On the Canons, you have different methods on different models, to invoke it. Going from Live View is easier than digging into the Custom Settings - depending on the camera somewhat. LV locks the mirror AS WELL in effect.

Perhaps surprisingly, if you're using flash at high magnification, then it is also worth using mirror lockup - depends on the camera and the flash duration. With a Full Frame (Canon or Nikon) and a full flash at around 1000th, it's easy to show a difference. Smaller format and flash operating at 1/32nd power, (1/32,000th of a second) then I would very much doubt it would be possible to see anything much!
You can avoid the shutter first curtain vibration when using flash, (C or N) by using Rear Curtain Sync for the flash, in a darkened room, with say a 1 second exposure doing nothing, then the flash at the end. This is the only way on a Canon too - you can't use Flash at all with any Electronic First Shutter Curtain mode, on any Canon.

Simply using Live View on a Canon then, means using long exposures. If you take the image out to a larger screen (tethered, or a separate HDMI monitor), expand the view, and can't see ANY vibration, all is well, But that depends on the building you're in and the floor you're on and how rigid your "rig" is. Nothing is ever 100% still!

Canon makes things slightly more un-straightforward in other ways too:- you can't use rear-curtain sync with a non Canon dedicated flash, and if you use the Infra Red Remote, Canon won't let you have Mirror Lockup!
Nikon don't have those (particular) interactions so life is simpler - though some models may differ from mine.

Quote
Justin
You can avoid the shutter first curtain vibration when using flash, (C or N) by using Rear Curtain Sync for the flash, in a darkened room, with say a 1 second exposure doing nothing, then the flash at the end. This is the only way on a Canon too - you can't use Flash at all with any Electronic First Shutter Curtain mode, on any Canon.

I noticed a notable improvement in sharpness after switching to this method, but I am using 2 second exposure just to allow all vibrations to dampen out. The key is a camera and flash unit that allows for manual mode and second curtain sync on the flash.

That's on a D300 Jeff?
Is this going from Live view (Car Crash) mode with front curtain sync, or
from normal view, front surtain sync?
What about the flash exposure (percentage)?

Interesting, I thought it might only be on the ones with the barn doors for mirrors.

Most vibrations, as seen in a few tests published, die away in the first tenth second or so. One second seems to be OK, I haven't done careful tests. Maybe you're right, 2 seconds would be better.
I do worry about this sort of thing ... Are we being paranoid enough??


I think apologies are due to Steve Sorell - this topic had been thoroughly hijacked!
Ok, Steve did you know that if you can find a few adapters to put a teleconverter ( which is of course a negative lens) on the front of your MPE-65, you can get it to focus at much lower magnification than 1:1. Google for "Lord V" and his observations on that.

Hi Justin - Bob's thread, not mine

Regards
Steve