Low Cost 200mm APO?

[scopejunkie]

Hi Ales,

I have designed what I call a super achromatic doublet lens. It's not totally color free but is pretty close at F/9. The residual secondary spectrum is a little less than twice the diameter of the airy disk. Better than a standard 200mm doublet at F/25 in performance. If producible, I believe this would be an excellent visual lens. I truly hate the fact that Meade Instruments stopped producing their ED APO's. My design is along the same lines but uses a different formula from Meade's design since the original glasses are no longer available (FK01 & KF3). As a visual observer I'm not interested in a "color free" astrograph. They are too expensive even if I wanted one but a 200mm true simi-APO would be just my cup of tea

Performance on and off axis (1/2 degree) is pretty good. The reason for this thread is that, with the glasses I have chosen for the design, I don't know it it feasible to try to have it produced. The glasses are LZOS BF1 & Schott PSK-52A.

Since you have access to the industry, I would like to know if these glasses are, purchasable (LZOS BF1), and usable as a lens. Sometimes some glasses are hard to work. Other times they are too unstable, soft or too expensive to be worth the effort.

I'm willing to share the design but first I would like to know if I'm living in the "twilight zone" trying to get produced such a large APO with the glasses I have chosen.

The JPG shows the basic overall performance of the lens. I will post the ATMOS results shortly.

BTW, I have a design using the same glasses that is good at F/7.5

Thanks for your time.

Keith

Attachments:

[scopejunkie]

Here are my results from ATMOS Optical Design Software.

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[Ales - iStar Optical]

Hello dear Keith,
I will reply about this via email. We are able to get most Schott, most Ohara and most CDGM glass types. I had a huge problem getting glass from Russians since I dont buy in huge quantity. If you find equivalents of these glass types in CDGM and Ohara catalog, please let me know. We will than re-crunch your design in our systems. I assume you did not optimize this design for production, right? This is something which MUST be done with each new design. As you konw nobody in this world can produce a lens which will perform AS DESIGNED. There are slight differences in radii, surface quality, glass specs etc.. all this combined can result in a really bad lens even though the design itself looks great. So get back with me on this. I must leave Europe next week, flying to USA for entire month of February, due back on 27th of Feb. 2012. I will have a very limited access to my emails during this time, bare with me guys. But Mike in Florida will help out Im sure, so will Gay Ann in Arizona or Petr in Europe. Cheers,
Ales

[josef]

Hello!

That's exactly what I would need!

A cheaper 200f9 Apochromat!

Lg!

Josef

[Ales - iStar Optical]

Josef, the above mentioned design uses a huge FPL51 element. This fact alone puts this lens in the highest price bracket and there wont be much difference in price between 200mm doublet and triplet. So I can say right away that people are not going to save much on any design using the most expensive fluorite glass. I wish we could be of more service on this one.. but our upcoming 200mm triplet in F9,8 should cost substantially less compared to any competitor. Also, if you can handle a little CA than our R30 Anastigmatic doulbets are way to go,
cheers,
Ales

[Ales - iStar Optical]

Keith,
I have a huge problem sending email replies to any of your email addresses. All are coming back to me as undelivered. So I asked Mike Harden to send my replies from his system in USA.. .same situation. All came back as undeliverable. Please help.. thank you.
cheers,
Ales

[josef]

Hi Ales!

"lso, if you can handle a little CA than our R30 Anastigmatic doulbets are way to go"

Yes I can, but you already have a 204mm f8, 8 Anastigmatic in production?

What price he would have and where I could order the lens?

Regards!

Josef

[Ales - iStar Optical]

Hello Josef,

no, we dont have 204 F9 R30 in production but once we get first order for this lens we will design and produce it. I dont have the price yet but I will run the calculations for you. The problem is that Im leaving my EU office tomorrow, due back by February 27th. I wont be able to reply to my emails on regular basis (if at all) so please expect my reply by end of February, the latest. We do have design for 180 F8 though, this one will be produced in about two month time. If you want this one, the price will be 1289 dollars. My very rough estimate for 204 would be around 1950 dollar price but again, this is my rough estimate. The 204 would be F8.8 similar to our Classic Achromatic doublet 204 F8,8. If you are interested in 180mm clear aperture (185mm lens diameter) you would be able to receive the lens about 6-10 weeks earlier as the 204mm one since we need time for designing this new lens and optimizing it for production, that takes time. Im looking forward to your reply,
best regards,
Ales
ISTAR Optical

[Ales - iStar Optical]

More info about the large R30.. what we can design for you in 204 would be more like R35 similar to the one designed and shipped to Mike Carman (250mm clear aperture F11), see comments from Mike on our web site or CN or even here on ISC. We use another type of short (heavy) flint in this R35 which performs better in large diameters compared to the Flint glass used in R30. His lens was a custom deal designed and produced from scratch and so far he is the only person owning one of these 10" Anastigmatic doublets. For any custom or non-stock lens we require a payment in advance. Contact [e-mail] for details, thank you.
cheers,
Ales