CurtPalme.com Home Theater Forum

seamaide · Joined: 12 Jan 2011 Posts: 4 Location: Ireland

I tried the lens sticky but the relevant links were dead, so I thought I'd ask it here.

I'm a university student working on an astronomical optics project hoping to use a cannibalized Delta HD 8M lens. But first I have to characterize the lens and find it's optimum performance using ZEMAX to see if it is suitable for the project. I need to know it's technical specifications, things like radii of curvature, refractive index, spacing etc. for the lens elements.

I know that there is 2 patents related to the lens, reading through the convoluted legal-ese of them, it's hard to tell what exactly is in the lens, and I won't be able to take it apart for the moment to find out what is there.

Would anyone happen to have any of these specifications, or indeed know of any issues or aberrations with these lens?
Thanks!

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Hi Guys, I led this Person here in hopes some one might have an answer for them.
Anyone?

Athanasios

Tom.W · Joined: 09 Mar 2006 Posts: 6635

Never heard of an HD-8M lens. Is this the same as an HD-8 revision B ?

What are you planning on using if for....... Astronomical ?

kschmit2 · Posted: Thu Jan 13, 2011 10:40 am Post subject:

Let's see if any of this will help, but I fear there is not enough info in those documents for you

Kai

seamaide · Joined: 12 Jan 2011 Posts: 4 Location: Ireland

Thanks for the pdfs! From the little I've been able to find, I think the 'M' refers to a multi-layer coating, so the 8B may be similar lens with a different coating?

I don't have access to a camera at this moment, so here is the other details on the sticker.

Delta HD - 8M
Patent no:4300817/4776681
Part no.: 4-047-750-01

The AR gives the lens a purple and orange shade to the lens. It has a plastic housing, connected to an Al(?) base at the CRT end.

Got the ok from my supervisor to talk about the project. He is involved in neutron star research, and there are these theoretical flashes of light from a certain type. My project is to design a wide-field imaging system, that could look at a large section of sky and look for these flashes. The plan is to hope to use the lens in reverse, coupled with a high-spec cameras to image the sky. But to see if the lens is at all suitable, I need to know the specs in details. See what the aberrations are, and if they can be corrected by adding more elements.

kschmit2 · Posted: Thu Jan 13, 2011 2:51 pm Post subject:

probably an old version (series "A") with ML coating.

That would point to 3 types of HD-8 lenses:

HD-8 (possibly w/o coating, though that would be unlikely)
HD-8M (with multilayer coating)
HD-8 Rev. B (upgraded, and with multilayer coating)

similar to the HD-6 series, that was followed by a HD-6C ML, and then HD-C ML color-filtered lenses

kschmit2 · Posted: Thu Jan 13, 2011 2:53 pm Post subject:

HD-145 and HD-144 would be optically superior to any of the HD-8 series lenses btw, and have similar resolution to the better versions of HD-10 lenses.

Tom.W · Joined: 09 Mar 2006 Posts: 6635

You might also consider an Aero Ektar...

http://www.bnphoto.org/bnphoto/KodakAeroEktarGall.htm

http://www.johndesq.com/graflex/aeroektar.htm

ecrabb · Posted: Thu Jan 13, 2011 3:51 pm Post subject:

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

You should right Ecrabb, the velvia 50 color film (one of the best photo film ever made) has 160 line/mm resolution Wink

zGman · Joined: 22 May 2006 Posts: 599

The older HD8 lenses had pretty darn poor focus, and probably aren't worth the effort.
I have lots of of the later version here if you want to pay shipping for two or three.
You can then take one apart to access the components. However, as has been mentioned,
these are not likely to be to be as suitable as a camera lens for your purpose, either in
quality or design. Consider that the image in a projector is only a few millimeters from
the lens....
G

ecrabb · Posted: Thu Jan 13, 2011 4:39 pm Post subject:

ecrabb · Posted: Thu Jan 13, 2011 4:47 pm Post subject:

OK, I checked the sticky and it looks like HD-10's were rated about 10 line pairs/mm... HD-8's (any flavor) have to be much, much worse than that... So again, I would think a 4x5 view camera lens would be much better for this kind of research. But, then I guess it depends on the resolution and size of the imaging sensor.

SC

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

Yeah, the gloryous HD145 has 10 lp/mm Thumbs Up

Anyway who heard digital projector owners talking about lens resolution?
But these lenses have much better f numbers than most stock photographic lens which is a big advantage at night.

Tom.W · Joined: 09 Mar 2006 Posts: 6635

I made a wide field telescope out of one of these....

Quote : A 24-inch f /6 Aero Ektar reported to give 142 lines/mm at f /6 with excellent achromatic correction.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Get a Minolta DLP zoom lens, 1.5-3x. I made a small telescope out of one of those, with a custom machined adapter and a helical focuser,
and aside from a SLIGHT amount of chromatic aberration, it delivers outstanding results. I'd like to get the resulting telescope fully
characterized for competitive analysis. The images it delivers are bright and clear without visible coma or smearing at the edges of the visual field.

It qualifies as a very high performance short throw refractor, about f/4 with a 4" objective lens, and based on the cost of the Minolta lens
alone, it should be in the elite class for telescopes featuring similar basic parameters.

I need to make a new adapter assembly for it. The original one was just thrown together for basic testing. I need to spend a day or
two in my machine shop and do the job right.

CJ

Tom.W · Joined: 09 Mar 2006 Posts: 6635

If I understand the need correctly the lens needs to to have a very low F #. The 7 inch (177.8mm) Aero Ektar is F 2.5

ecrabb · Posted: Thu Jan 13, 2011 7:30 pm Post subject:

It's astro work, so I can the requirement for fast glass. The HD-144 is something like and f/1.1 or f/1.2 lens. But, what about the size requirement? Why does it need to be so big? What sort of imager will be used that requires a 5" image circle? If we're talking about the size of most types of imagers, then there would be a large pool of 35mm lenses from which to choose that would be nearly as fast and would be far superior to any CRT glass.

SC

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

hm not bad Smile

There is one up on ebay located in England!
http://cgi.ebay.com/KODAK-AERO-EKTAR-7-178mm-f-2-5-LENS-5X5-FORMAT-/120671152158?pt=UK_CamerasPhoto_CameraAccessories_CameraLensesFilters_JN&hash=item1c188fa81e
9days left... I think the prices would go up a bit :/

Tom.W · Joined: 09 Mar 2006 Posts: 6635