jetstream

I really don't know much about these scopes. I like known things.....like when it says LZOS on the cell or that Canon makes Tak lenses (common consensus anyway). Do you know this for a certainty?

I'm almost positive now that I've been targeting the wrong spot. I go by Bartles sketches but his orientation confuses me. If you do process M31 with IFN it would be great to confirm if the extremely faint shade edge off the end of it I saw was real lol! Super super imaging!

Is this an offer to sell John? 😀 Maybe take my SW120ED as part trade?!

A complete tragedy for the optics and astro community. He was well liked and respected by many.

👍 There are reasons... I've found that early success with observing these faint objects and with maximum contrast develops and enhances ones "object recognition ability". I use the technique of repeated viewing of the same object, over and over really does develop ability. I've done it for years and still do it now. They make UHC's every day...no rush IMHO.

The reason I mention this is two fold- obviously the current/historical connection between Ludes and LZOS but also that Markus Ludes most likely knows the source of the TMB SS lenses. Maybe someone interested could contact him and ask? I'm not a gambler but I'd put a lot of money on that he knows...

Excellent image. This will help me with my slow, ongoing visual detection of IFN in this area. Having seen a bit of IFN in other areas Im always on the look out and have been doing the "Marty Feldman" near M81/M82 for years. @peter shah have you imaged IFN near M31? Superb work Peter.

What did you read? Theres a lot of " UHC is better than an OIII on this object" or the "emission lines primarily dictate the use of the OIII" etc etc. Both are nice to have for sure but to start with I think maximum contrast is the way to go. A widefield eyepiece is an excellent addition and would make sure I got one before 2 filters. Just my 2 cents.

There is a strong connection between TMB and Markus Ludes https://astromart.com/forums/astronomy-equipment/equipment-talk/tmbs-designs "Hi many of the APM-LZOS Apo's are TMB designed and in production. But the TMB Business does not exist anymore , a reason why the product was renamed into APM-LZOS. Apm has anyway the owner ship on those TMB designs, since we paid TMB the design fees cheers Markus Ludes"

If you buy the right stuff you can always sell it and get at least 2/3 of your money back. Did you email Astronomik for band pass?

The TMB is a vg scope and that fella has vg optics...

Heres the difference-I used a 25mm TV fs dia for calc and APM UFF 25mm-21.2/1200x57.3= 1 deg 30mm 38/1200x57.3= 1.8 deg TFOV This is a big difference IMHO.

You can buy the 1.25" filter and use your 25mm Super plossl more cost effectively. If you are really interested in viewing nebula, have access to dark skies and can afford it a 2" set up is the way to go. The 2" set up has a much wider TFOV.

I was off a bit-from a fellow that figured this stuff out https://www.cloudynights.com/topic/61467-binocular-vision-summation/ "Exit Pupil A telescope with binoviewer produces what I would call a false exit pupil. The exit pupil is always larger than the amount of light that it delivers (as compared to exit pupil from scope without binoviewer). That is due to the fact the beam splitter delivers half the light to each exit pupil. This mathematics is all discussed above. Think about it. A 6" scope with binoviewer at 30x has a 5mm exit pupil. But the light delivered to that exit pupil in each side of the binoviewer is (150x150)/2 = 11250, then sqrt11250 = 106mm. The true exit pupil would be 106/30 = 3.5mm, or an exit pupil with one half the area of the false exit pupil. The light delivered to the exit pupil in a binoviewer is not as bright as the light in an equal sized exit pupil from either a scope or binocular. Hence, it can be described as a false exit pupil."

Great report! The very best view of the Needle galaxy was with my binoviewers. Those Baaders look excellent and won't be behind any other bino IMHO- they will be on par with the best. So... have you explored the "false exit pupil" idea? Many thoughts, ideas and calculations... long story short is that the beam splitter halves the light to each eye making things dimmer and such that binocular summation does not recover it. With respect to your Delos 17.3 at 1.25x GPC =13.8mm fl. If we can believe the false exit pupil idea then the effective fl could be 6.9mm fl (whatever it really is its dimmer view). Not sure of your scopes fl. IMHO if you want to view galaxies lower the mag quite a bit, if your scope is f7 then the 17.3 might really be giving you a 1mm (false) exit pupil. I use 32mm TV plossls in my 15" dob with the powerswitch at 1.3x for a false exit pupil of about 2.56mm. I have had staggering views of the bright galaxies and also M42, but also had very limited success on the dimmer nebula that need filters. The Leo triplet is another favourite with this combo, any of the bigger and brighter ones can work well. Nothing beats clusters with binos... Another thought- my 15" dob/Moonlight will de collimate a bit with very heavy eyepieces/bino past half travel... are lighter eyepieces better for a dob? Excellent report and observing, Gerry Edit: The 15" would give 3.6mm false exit pupil not 2.56. 1828/24.6=74 . 269/74=3.6mm false exit pupil. Sorry for the mistake its been years since I thought about this. I just know what to do now.

Give us a while Heather, we'll work on you as well to get one Seriously though, if someone is interested in seeing nebula one of the mentioned filters is a must IMHO. AND 😀 seeing as you stopped by in this thread you must be interested.

Thing is he needs them to see what he wants to see. A 1.25" OIII will work with the 25mm but with a small TFOV. Not sure what to say!

My 2 truss dobs came with filter slides, that also function as focuser baffles. I leave them in the scopes, 2 each. The fracs have them screwed into the 42mm LVW when needed.Sure be nice to have a wheel system for the fracs. Filter slides/wheels are almost a must IMHO.

Because the new TV OIII squeaks by a really good old Lumicon OIII I'm biased towards it. Pensack has contributed in threads about filters (he's a vendor and avid astronomer) and might know Astronomiks bandwidth currently. If you email Astronomik Im sure they will tell you the bandwidth. These filters are expensive so knowing the specs will help you out. If possible get a 2" filter so that when the 2" low power widefields arrive the filter will fit! BTW- the 25mm Super Plossl isnt that bad as you say but your f6 scope might like a little lower power-28mm-30mm fl? a 30mm UFF APM?

are you really really good at amorphous shapes barely visible as shade edges?😀 Try the reflection nebula M78 in Orion, the Christmas Tree cluster in Monoceros and the Rosette nebula. You should be able to get something in the Rosette. Also try the reflection nebula in the Pleiades- the Merope. Use a low scatter eyepiece with low mag, 25mm-30mm in your scope. What eyepieces do you have?

Not sure... Astronomik tightened up their bandpass a few years ago which was good. Televue takes them and then tests them again.Gerd at Astronomik is vg IMHO.

If you want to add the Flaming Star in Auriga to the list then UHC, while under truly dark transparent skies the UHC can show more extensive nebulosity, the OIII provides more contrast- to my eyes, IMHO. OIII first IMHO.

Yes, I love this filter.

I really want to see how all these refractors compare. and the diagonals 😀

Once @vlaiv has the optics test program built maybe we'll run some test to see whats what.