Search found 1311 matches

by enricosavazzi
Sun Feb 28, 2010 7:47 am
Forum: Equipment Discussions
Topic: Different versions of EL-Nikkors
Replies: 19
Views: 22386

I have some information and tests of EL-Nikkors on my web site: http://goto.glocalnet.net/savazzi.net/photography/enlargerlensespm.htm and more on EL-Nikkors in history/collecting and for other applications: http://goto.glocalnet.net/savazzi.net/photography/enlarger_lenses.htm http://goto.glocalnet....
by enricosavazzi
Tue Feb 23, 2010 6:35 am
Forum: Equipment Discussions
Topic: Snowflake Rig
Replies: 25
Views: 5359

The Oly 20/2 is better than the leica 25/2 - at least as far as the ones I own are. The Oly is a very good lens. 8x and above a good 10x objective is the way to go. I'm surprised the Leica falls behind the OM considering the price and that it is a Leica after all. Dan I don't have the Olympus 20 mm...
by enricosavazzi
Mon Feb 08, 2010 7:46 am
Forum: Equipment Discussions
Topic: Metamaterials Will Make You GRIN
Replies: 1
Views: 1190

I don't think we are going to see applications of metamaterials to photomacrography any time soon. These materials and their properties are very real, but there are a couple of main concerns with their applications to photomacrography or general-purpose photography (besides enormous difficulty in ma...
by enricosavazzi
Mon Feb 08, 2010 6:50 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Nikon CF N 10/0.30 Plan Achromat. Phase vs BF version
Replies: 15
Views: 13170

It would seem that the bokeh of a phase objective is partly comparable with the "nisen bokeh" produced by catadioptric telephoto lenses, in which the secondary mirror is equivalent to a centre stop (the phase ring is clearly visible in the bokeh of OOF highlights). I should expect that diffraction i...
by enricosavazzi
Mon Feb 08, 2010 6:20 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Methods/equipment for precision focusing
Replies: 3
Views: 1568

Methods/equipment for precision focusing

In this post I try to summarise the methods/equipment that can be used for precision focusing in photomacrography with a current DSLR, from the obvious to the far-fetched, and their principal pluses and minuses. I am mainly covering the studio/laboratory techniques. Many of these techniques can be c...
by enricosavazzi
Mon Jan 18, 2010 2:02 pm
Forum: Equipment Discussions
Topic: Zeiss focus blocks
Replies: 5
Views: 2512

Actually, the best use is something like this, with camera/bellows vertical. I assumed from the earlier posts that this is the way you intend to use it. The scale of your montage should be approximately right. This is another Leica model I often use at present. The granite slab is a cheap patio/gard...
by enricosavazzi
Mon Jan 18, 2010 5:09 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: Left or right lighting?
Replies: 10
Views: 2307

It would not surprise me if editors would flip images (various categories of subjects, not just plants or animals) to get the required orientation (e.g. left view changed to right). I have seen it done for articles for general readership and have had my transparencies flipped. (The change which use...
by enricosavazzi
Sun Jan 17, 2010 1:05 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Left or right lighting?
Replies: 10
Views: 2307

... So are lateral views of insects meant to be looking left or right ? Andrew I am not an entomologist, so I don't know for sure if there are special conventions. For arthropods in general, when you have only dorsal and/or ventral views, they are most often vertical with the head uppermost. Latera...
by enricosavazzi
Sun Jan 17, 2010 12:25 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: Left or right lighting?
Replies: 10
Views: 2307

For illustrations of scientific literature, it is generally stated that the main illumination should come from a top-left direction. This is often specified as a requirement in the "instructions for authors" of scientific journals. It may be necessary to make exceptions, but in this case the directi...
by enricosavazzi
Sun Jan 17, 2010 4:09 am
Forum: Equipment Discussions
Topic: Zeiss focus blocks
Replies: 5
Views: 2512

This might also be something to consider: eBay item 270515876203. These are parts of Leica racks for stereomicroscopes. This particular one has only coarse focusing, but sometimes one finds models with both coarse and fine focus. The gear is steel/brass but the rack is plastic, which makes it potent...
by enricosavazzi
Thu Jan 14, 2010 7:18 am
Forum: Equipment Discussions
Topic: Zeiss Ikon Bellows
Replies: 4
Views: 1606

This type of bellows with fixed rear standard has a problem: when the bellows are closed at or near minimum extension, the front rails stick out and may be in the way of the subject, especially with a lens of short focal length. You might wish to check whether it is possible to mount the 4/3 camera ...
by enricosavazzi
Wed Jan 13, 2010 11:34 am
Forum: Equipment Discussions
Topic: Zeiss focus blocks
Replies: 5
Views: 2512

Well, the one at http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260535369591 seems to be the usual coarse/fine rack for the Universal and Photomicroscope models (from a U./P. II or III to be specific, but the rack from a P. I differs only for the paint colour). This rack has a coarse range of ap...
by enricosavazzi
Wed Jan 06, 2010 11:58 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: DOF and pupil ratio
Replies: 15
Views: 4289

... By the way, I measure my Luminar 16 mm f/2.5 as P=0.87 (exit pupil smaller). I wonder if the 25 mm is a different design, or is 1.1 using the other definition? ... --Rik They are somewhat different designs. The exit pupil of the 25 mm is visibly larger than the entry pupil. I believe the 16 mm ...
by enricosavazzi
Wed Jan 06, 2010 10:55 am
Forum: Macro and Micro Technique and Technical Discussions
Topic: DOF and pupil ratio
Replies: 15
Views: 4289

At this point, I believe I can re-state one of the examples I mentioned in my original post. I now use the equations D = 2CE / (M^2/P^2), which I derived in one of the posts above, and E = N(M/P +1), which can be found in Lefkowitz or also easily derived. I define P = P_x/P_n, which seems to be more...
by enricosavazzi
Tue Jan 05, 2010 1:49 pm
Forum: Macro and Micro Technique and Technical Discussions
Topic: DOF and pupil ratio
Replies: 15
Views: 4289

rjlittlefield wrote: ...
Lefkowitz pg.258, effective aperture f_e versus marked f-number f_r: f_e = f_r*((m/P)+1)
...
Thanks, it figures out. Changing m to m/P wherever m occurs should in fact be enough to take P into account, but initially I got stumped over the unusual (1/P)+(1/m) part.