Great additional information! Yes, the main constraint is the amount of focus throw available. The 45-175mm lens is particularly good for that, relative to other lenses I've tested. I have not tested most of the other zooms mentioned. And yes, this method does produce incredibly fast stacks, and is ...

Looks expensive and interesting.

I have noticed a recent change in behavior of notifications from the forum. Nowadays I do not get a notification of new replies to a post I have responded to. Maybe some flag got cleared by me accidentally?? It's also possible that some conflict has developed between the email servers used by you a...

Björn, Regarding your PM, see FAQ: There's a PM stuck in my Outbox. What's wrong? Most likely Lou is just away from his computer for a while and will see your message when he gets back. As for focus bracketing, I have no experience with that exact lens but perhaps some general info will help. A goo...

Hi Bjorn, I use flat adapters, not conical ones, which are prone to flare. A 46-52mm step-up ring plus 52-26mm step down ring should provide enough clearance between the objective and front element. Only the longer portion of the focal length range can be used without vignetting. The exact lower lim...

Only you would have thought of doing that! Brilliant.

Very nicely lit shots, hard to achieve in the field. That's a surprisingly colorful flower!

Those are good points about the stereo or 3-D imaging. For just plain 2D imaging, I don't think it matters too much. There is even one situation where flat-field objectives are actually a drawback. That is in multi-spectral and especially UV imaging. It takes extra elements to correct for field flat...

Yes, it was an S1R full frame Panasonic. The objectives were low-mag Mitutoyo objectives. I did check it with reversed lenses but I do not remember the results....

Excellent datum, thanks for checking.

Some very good lenses for stacking have significant curvature of field. A well-known example is the Lomo 3.7x objective. Stacks from this objective are excellent. Single images from this objective on a full frame sensor would not be so impressive.

I just checked and the lens can be pushed down to roughly 1.5x (holding the lens in my hand against my S1R) but the rear baffle cuts off the margins. The usable FOV is 20mm (1.8x). Judging from this, it seems that 2x is indeed possible without baffle interference. So it can match the AstrHori's spec...

I look forward to your results! Most modern macro and wide angle lenses have floating elements. My tests don't prove that there are no floating elements. As I mentioned, field flatness is one of the main reasons for making floating elements, and I have not looked at that, because it is irrelevant to...

There has been a lot of recent discussion on the forum about the Laowa 2.5x-5x lens. Some posters saw internal movements when changing magnification, indicating the presence of floating elements. Others thought there were no floating elements. There can be optical illusions when watching internal el...

Yes, I've posted about it on this forum some years ago. Excellent tube lens, sharpest center of all the 135mm tube lenses I have tested. Mine was in a Nikon mount and I used a Nikon-to-L mount adapter on my Panasonic camera. There was a tiny bit of hard corner vignetting probably caused by the adapt...