Is this the best from my x10 objective?

[hellmill]

Hi Guys -

I haven't posted for a while but have been busy carrying out lots of stacks. It does seem to be one step forwards and sometimes two back! You solve one problem, only to find another!

Having realised that my set up had too much vibration, and finding a safer way to support my camera, I have been trying to take more images at x10. To date, I have been reasonably pleased with my main macro lens (Nikon 60mm micro) and my BE plan 4X/0.10 Nikon microscope objective on a 200mm tube lens. In this case a 100-200mm Nikon kit zoom lens.

I have several questions about this set up, now that I have been using it for a while -

1. does the quality of the lens make any difference to image quality?
2. does the quality of the objective make any difference to image quality?

In particular, the X10 lens has never seemed really sharp to me. Images seem 'soft', a bit lacking in contrast and slightly out of focus. Perhaps this is the nature of the beast, so I would appreciate any comments. I may be expecting too much - I don't know.

Here are the crops from two x10 images, differing only in exposure. I specialise in tiny orchid flowers, this is the anther cap from a Pleurothallid, any structural differences you may notice are due to the subject drying on my mount as I took the stacks (approx 140 images in each stack, using PMax only to stack them).
Image one, with and without sharpening






Image two, with and without sharpening





I would be glad of any comments that will help me to obtain better images -

Helen

[ChrisR]

Hi Helen
Well the answers 1 & 2 would be maybe and maybe, - all other things being equal!
This is the Nikon BE 10x, yes?
Which camera?
Is anything not "flocked" - which reduces contrast. I tried one "tube" lens which reflected badly from the front element, increasing the distance to the objective a little helped. Can't remeber which it was, but you might be "unlucky" in your combination. You're not using a filter in there are you?
Is the adapter flat or conical?

How are you lighting the subject - continuous or flash?
Could you try a "sharp" subject - a piece of laser printed text should work.
Then show us a crop of "actual pixels".

[EDIT]
You did already!! here

Well that looked OK - anyting changed?

The lighting can degrade things if it's too flat. Can't think of anything else at the moment!

[rjlittlefield]

Helen,

Assuming that the crops you're showing are actual pixels (camera resolution), and assuming that these are from a typical APS-C sensor, then what you're getting looks pretty good to me.

A key thing to realize is that any NA 0.25 objective, used at 10X, will be running at effective f/20 from the camera's standpoint. On any current APS-C sensor, that will be significantly into diffraction territory. Unprocessed images will not look sharp when viewed at actual pixels. Aggressive sharpening can and should be applied to push back up the contrast of fine detail that has been pushed down by diffraction. The best sharpening depends on your sensor and lenses, but as a rough guideline, something like Photoshop's USM at 100% or even 150% with 1 pixel width would not be unusual. See HERE for an example with a conventional lens at f/22.

That said, exactly the same thing is true for an NA 0.10 objective used at 4X. So, if your 10X objective is giving images that are significantly softer than your 4X objective, then probably something is going wrong with the 10X. The first suspect is always vibration. If you're not already shooting with flash, then you should definitely run a test using consumer flash at low power so that you get nice short pulses of light.

--Rik

[hellmill]

Thank you both for the speedy replies -

sorry I forgot some basic info - I was trying not to be too wordy!
I use a Nikon d7100, continuous lighting and exposure times >1sec, ususally at least 2 seconds.

The following is another anther cap and stigmatic surface X10 This one is much better (imho) but this may be due to the extra contrast in the subject. This has been sharpened etc to death, I couldn't find the original - sorry.
This is probably one of the better results I have obtained with the X10 lens
Lepanthopsis astrophora 'Stalky', actual size 1.5mm approx.



In contrast here are some pictures with firstly, my macro lens -
The stainode and stigmatic surface of a Paphiopedilum



A closer view with the X4 objective -



While not the best images in the world, both of these seem to have a 'crispness' about them, they have both been sharpened aggressively. At leas I am now happy that it is not somehow 'wrong' to do this, and this type of sharpening is actually needed.
In comparison, this is another Pleurothallid anther cap and stigmatic surface - the details are there, but even with sharpening, there is not that 'crispness' in the image.



I am trying to eliminate vibration, and now have the stackshot and camera fastened much more firmly and following your advice will try and run some tests with flash - not quite sure how to go about it, but I do have a very basic ring flash, so will try with that initially. I had not realised that diffraction could be a problem, although I know it could be with extension tubes. I had already ruined some shots because of it.

Anyway, thank you both for your replies. I will think carefully about what you have suggested, any advice in the past has always been very helpful and useful -

Helen