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500mm Triplet
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PostPosted: Thu Jun 23, 2011 12:59 pm    Post subject: 500mm Triplet Reply with quote

Well, just to prove what everyone has been saying recently, I had to get myself a bazooka.

This one branded D & N. Somone has been inside to clean it.......

Seems to perform OK stopped down to f22. No mountains to shoot I'm afraid. Sorry!

Even with a Tamron SP F-System 2x tele-converter attached.....


although a little vignetting Smile


PostPosted: Thu Jun 23, 2011 2:13 pm    Post subject: Reply with quote

Oh yes, the famous D&N. f/22? Good grief. Although this looks a lot better than my Komura 500mm.


PostPosted: Thu Jun 23, 2011 3:21 pm    Post subject: Reply with quote

woodrim wrote:
Oh yes, the famous D&N. f/22? Good grief. Although this looks a lot better than my Komura 500mm.

And that's not the limit. It has a click stop at f32 and goes further than that (f64?) but it's unmarked. With the 2x tele what does that make? f256? Better make sure it's a bright day Smile.

Of course, the major problem is camera shake at 1000mm and f256 !!!!


PostPosted: Thu Jun 23, 2011 4:50 pm    Post subject: Reply with quote

martyn_bannister wrote:
woodrim wrote:
Oh yes, the famous D&N. f/22? Good grief. Although this looks a lot better than my Komura 500mm.

And that's not the limit. It has a click stop at f32 and goes further than that (f64?) but it's unmarked. With the 2x tele what does that make? f256? Better make sure it's a bright day Smile.

Of course, the major problem is camera shake at 1000mm and f256 !!!!


f/45 is next after f/22...

Most of these 500/8 triplet bazookas seem to perform pretty well, including the modern versions. I have a Quantaray (Laughing) that performs surprising well. A better faster lens will have better corners sharpness and less light falloff, but not much more resolution, if any. Nice examples!


PostPosted: Thu Jun 23, 2011 5:12 pm    Post subject: Reply with quote

visualopsins wrote:
martyn_bannister wrote:
woodrim wrote:
Oh yes, the famous D&N. f/22? Good grief. Although this looks a lot better than my Komura 500mm.

And that's not the limit. It has a click stop at f32 and goes further than that (f64?) but it's unmarked. With the 2x tele what does that make? f256? Better make sure it's a bright day Smile.

Of course, the major problem is camera shake at 1000mm and f256 !!!!


f/45 is next after f/22...



No, honestly, it is marked as f32 at the next click stop Smile


PostPosted: Thu Jun 23, 2011 8:29 pm    Post subject: Reply with quote

martyn_bannister wrote:
visualopsins wrote:
martyn_bannister wrote:
woodrim wrote:
Oh yes, the famous D&N. f/22? Good grief. Although this looks a lot better than my Komura 500mm.

And that's not the limit. It has a click stop at f32 and goes further than that (f64?) but it's unmarked. With the 2x tele what does that make? f256? Better make sure it's a bright day Smile.

Of course, the major problem is camera shake at 1000mm and f256 !!!!


f/45 is next after f/22...



No, honestly, it is marked as f32 at the next click stop Smile


Embarassed Typo. I meant f/45 is next after f/32...


PostPosted: Fri Jun 24, 2011 7:30 am    Post subject: Reply with quote

Sorry, yes, I was utilising my tongue before engaging my brain.......

Should go 22/32/45/64/96/128 ???

In which case the tele would add two stops to f45, making it f96 ???


PostPosted: Fri Jun 24, 2011 11:38 am    Post subject: Reply with quote

martyn_bannister wrote:
Sorry, yes, I was utilising my tongue before engaging my brain.......

Should go 22/32/45/64/96/128 ???

In which case the tele would add two stops to f45, making it f96 ???


and my typing fingers have a mind of their own sometimes! Laughing (thought f/32, typed f/22...)

f/90 is after f/64:

Wikipedia -- F-number has "f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45, f/64, f/90, f/128"


PostPosted: Fri Jun 24, 2011 3:26 pm    Post subject: Reply with quote

martyn_bannister wrote:

In which case the tele would add two stops to f45, making it f96 ???


We are getting dangerously close to pinhole camera f numbers now... Very Happy


PostPosted: Fri Jun 24, 2011 3:40 pm    Post subject: Reply with quote

eggboy wrote:
martyn_bannister wrote:

In which case the tele would add two stops to f45, making it f96 ???


We are getting dangerously close to pinhole camera f numbers now... Very Happy


All the more amazing that it gives a half way sharp image I think!


PostPosted: Fri Jun 24, 2011 3:47 pm    Post subject: Reply with quote

Is this really a triplet?

I'm not saying it is or isn't, but all the preset lenses of this type that I have had (two 400mm and two 500mm) have had 4 elements in 3 groups. The front group being a cemented doublet and two singlets after the aperture.

A triplet is either three air-spaced elements or three elements cemented together, depending on context. Any lens with a cemented doublet can't really be a triplet whatever the overall configuration.

Mark


PostPosted: Fri Jun 24, 2011 3:53 pm    Post subject: Reply with quote

SXR_Mark wrote:
Is this really a triplet?

I'm not saying it is or isn't, but all the preset lenses of this type that I have had (two 400mm and two 500mm) have had 4 elements in 3 groups. The front group being a cemented doublet and two singlets after the aperture.

A triplet is either three air-spaced elements or three elements cemented together, depending on context. Any lens with a cemented doublet can't really be a triplet whatever the overall configuration.

Mark


I might be wrong. It certainly has two single elements with an aliminium spacer behind the aperture because I took those out to clean them. I couldn't get the front element out, so it may well be a cemented doublet, rather than a single element.


PostPosted: Fri Jun 24, 2011 5:57 pm    Post subject: Reply with quote

I suspect it is a doublet. A single lens of that size would have pretty bad chromatic aberration.

I found the coatings on these lenses to be very delicate. The front element was very easy to scratch whilst cleaning and one of the rear elements goes hazy. Very hard to find one in really good condition.

Mark


PostPosted: Fri Jun 24, 2011 7:41 pm    Post subject: Reply with quote

The rear elements cleaned up very well. Although the rear-most had lost most of the black paint on it's rim. A permanent marker cured that.

The front group seemed to be held in by the main ring, but there were two side screws, one of which might have locked the group, but the second locked onto nothing. Is suspect that someone had it apart in the past and it might not be assembled correctly.

I bottled out and cleaned this group in place Smile