The problem with straight though binos is the mounting. You need to find way for your body to be physically under the tripod. Which is a problem because typically where you and your chin want to be is the center column, leading to contortions of the neck. (One trick is to be with the back to the tripod to look straight up. This creates space.)
I have the APM MS 20x100 ED and have spent considerable money and time trying to find the best way of using it (take a good look at here, here and here).
As you can see I found a solution that involves a little bit of cutting, grinding and epoxy and as a result of building this mini parallelogram mount my body has space under the binoculars in a camping chair with leaning backrest. I ended up with a compact, lightweight and easy to transport package for 100mm. I didn't save any money.
The APM 28x110 MS is cheaper and doesn't weight much more. (APM specs are difficult to trust though. Quite often pictures and specs don't match the product.) I was often tempted by the sale price, but why did I never get it?
I am sure the optics are fine for stars. 28x isn't much and the eyepieces look like they are of the flat field type.
There are 3 problems that I see:
1) Length: The APM MS 20/25x100 ED use super fast f/3.7 optics and are physically very short for their size. That is their "secret" killer feature. The FK-61 ED glass is used not to improve optics/magnification, but make the binos "small". Nearly all other big straight through binoculars on the market are f/5+-ish, which ensures that their optics are decent even if not using special glass. But they are looong. In the case of the APM 28x110 (according to specs so with some salt) we have a longer tube length of 530mm (so arund f/4.8...5) instead of 370mm for the 20x100, or physically nearly 50% longer. The problem with straight through binos is mounting in comfort. Which ever way one does that it involves finding a stable tripod column to raise them as the eyepieces swing down a lot as you point the binos up. (The center of gravity is near the lenses, so the swing is near full bino length.) So this 28x110 will probably need 14cm more column lift than the 20x100 or 25x100. Long and stable columns are difficult to find.
2) Eye relief: the 28x has decent eye relief of 16mm if one doesn't use glasses. If one does use glasses then it is not enough and 20mm like in the 20x would be better. One trick when pointing up is to not have the glasses at the perfect 90 degree angle to the binos. Having some play with the eye angle saves the neck but eats eye relief. More eye relief is better in this case.
3) The center rod of the 20x100 is a little thin and has a bit of play where it connects the bino halves, which in my copy adds to collimation issues. Not a deal breaker, but if the same happens with the 28x then the problems are 1.4 times bigger than at 20x. A lot of people don't seem to have play issues and many people find that tweaking alignment/collimation works for them.
I think if you don't wear glasses, are not afraid to work a little on the binos, and have some ideas on how to build a tripod/parallelogram then maybe the 28x110 are for you. Then againI am probably overly critical as lots of folks have bought large straight through binos and pointing them up must work for them? I am always interested to learn!
P.S. If you don't mind some assembly you could also look into the 3D printed AnalogSky Heart kit. It is an 80mm f/5 achromat with 90 degree viewing and 2 inch eyepieces.
Edited by ihf, 31 October 2024 - 10:32 AM.
