FWIW, surplusshed.com has a Jaegers 41mm diam., 35 mm FL for 4.50 US, a Pyrex 44mm diam., 30mm FL for 6.00 US, and a double convex aspheric 44mm diam. 30mm FL for 5.00 US. Shipping is a flat 5.00 for an entire order. More expensive than some, cheaper than others, somewhere in between. Probably good quality; I don't have any of the three myself.
I'm only getting ready for my first aspheric mod, but I think the flange makes the job much easier. I also doubt if a double-convex lens would be suitable for this task.
Yes, they do have a flange, which should make grinding to size somewhat easier. I agree about the DCX, although someone in another thread (I haven't searched for it) did use a DCX successfully.
"For shipments going to Hawaii, Alaska or countries outside the U.S., we will e-mail shipping option prices for your approval prior to processing your order " This what they say about shipping outside the US.
The best way that I have found is to use a conventional bench-top grinder, resting the lens flat side down on the provided support in front of the wheel,with a piece of thin cardboard under the lens to prevent scratching. I bring the lens against the wheel and rotate it horizontally as methodically as I can to try to maintain a circular shape. A fairly slow process but not too bad; nonetheless,I hope someone has a better way.
ChicagoX, thefirst one (Jaegers 41diam./35FL) has a back FL of 30mm, 15mm center thickness,3mm edge thickness. For the second (Pyrex 44diam.,30 FL ) no back FL given,14 mm center thickness, 2.5 mm edge thickness. The last one, the DCX, again no back FL given, 17 mm center thickness, 3 mm edge thickness. All this from their website, again, I don't yet have any of them. Given the $5.00 flat rate shipping I may order all three for 20.50 rather than one for about 10.00. Spend money to save money.
I found dremelling to be very very slow, but I think it would have worked if I was more patient. The grinding wheel does create excessive heat if the lens isn't kept moving or "backed off" periodically.
I had no previous experience either. It turns out that glass is fairly soft so no issues with cracking or chipping.
My main concern was (as is) to wear a mask and to use the grinder where you can clean up the area easily. Keep the area around it clear so that powered glass dust don’t get on things.
I had no previous experience either. It turns out that glass is fairly soft so no issues with cracking or chipping.
My main concern was (as is) to wear a mask and to use the grinder where you can clean up the area easily. Keep the area around it clear so that powered glass dust doesn’t get all over everything. I wouldn’t want this dust in my lungs either!