Quote:

---

Hi David

Perhaps a Televue 40mm 1.25" Plossl and a 2" Televue 55" Plossl?

Or even a Meade 4000 Series 56mm Super Plossl Eyepiece 2"

A lot cheaper

---

Post Extras:

Quote:

---

Quote:

---

Hi David

Perhaps a Televue 40mm 1.25" Plossl and a 2" Televue 55" Plossl?

Or even a Meade 4000 Series 56mm Super Plossl Eyepiece 2"

A lot cheaper

---

An easy way to figure out what you need would be to plug your scope/eyepiece stats into an Eyepiece Calculator that computes exit pupils (among other things). Useful to have!

---

It would seam to me that it would be best to learn the formula. Then you could figure it in your head when you did not have access to a Eyepiece Calculator. It is really simple to calculate the exit pupil for any eyepiece.

Exit Pupil= eyepiece focal length/telescope focal ratio

Example: a 40mm eyepiece with a f/10 SCT = 4mm exit pupil



Edited by Erix (12/03/12 11:24 PM)

Post Extras:

Quote:

---

Quote:

---

Quote:

---

The brightness of IC434 is similar to that of the Veil.

---

I beg to differ. It must be considerably fainter. The Veil (eastern half) is easy as pie in any of my telescopes, even unfiltered, but I've never seen a hint of IC 434, despite looking for it on some very good nights in the past.


Clear skies!
Thomas, Denmark

---

Hmmm. I meant the unfiltered view. Then again, I don't usually check both on the same night.

---

Hmmm... Finally last night I had a chancve to test my above statement. Under SQM 21.04 (steady!) skies I had The Veil and IC 434 at approximately similar altitude - neither very high. Case is settled: Under similar conditions, in my 18", the Veil (all main segments) were considerably brighter than IC434. My previous statement was gloriously toppled! I guess the fact that by late October I rarely check the Veil and I don't normally bother for the HH until mid December created somehow in my mind the illusion that the unfiltered view of the Veil was similar to that of IC434. No chance. Without filter the Veil was readily visible with direct vision and with structure visible, and in the 31mm Nagler with UHC it became a superbly detailed object. On the other hand, IC 434 was barely visible with averted vision in unfiltered views (provided Zeta Orionis was not in the filed). With the 31mm Nagler and UHC, IC434 was visible with direct vision (including an ill-defined horsehead!) provided Zeta Orionis was kept out of the field. The UHC-filtered view of IC434 was considerably fainter than the unfiltered view of either Veil segment. Adding a H-Beta filter made IC434 more obvious, but still not as bright as unfiltered Veil views.

In another important aspect, I did check the HH visibility with two different eyepieces that gave me a similar true field of view: The TV Ethos 13mm (158x) and the TV Panoptic 19mm (108x), both providing a 0.63-degree TFOV. Using the H-Beta filter, the Horsehead was clearly visible in both eyepieces, but the Panoptic gave a much better, more 3-D view and dare I say, it provided a more detailed image of the HH (the "snout" was more pointy and overall more visible). The Ethos 13 is giving me a 2.9mm exit pupil, while the Panoptic 19 is giving me a 4.2mm exit pupil. The image difference was confirmed by the two astrobuddies who were there with me. So, at least under the good conditions we have had last night, the eyepiece that gave the greatyer exit pupil gave the best image!

Post Extras:

Quote:

---

Although I've never seen the actual horsehead form, I have been able to make out some structure in the surrounding nebulosity with a 4" refractor from my rural community (yellow zone) by slowly moving the scope back and forth with the manual declination control. I read somewhere that it's easier to see faint details in nebulous objects if the field is in motion and found that it actually does work - Bill.

---

Post Extras:

Quote:

---

I have been after the Horsehead for a few years now. No luck thus far.

I don't like to say I almost saw it....but that was the situation last week. Following all the advice that I have recieved on here over the years, I first found the Flame Nebula. Faint but definitely visible. I then went to Alnitak, and started to follow the faint nebula down to HP 26756, and that's where I loose it. I switched between my Oiii and omega NPB and even tried the light pollution filter, but to no avail. No matter. There are some very pretty clusters and stars in that area.

jake

---

Post Extras:

Quote:

---

A true OIII filter renders IC 434 invisible in any aperture. I'm not familiar with the passband characteristics of the Omega NPB. An H-beta is your best filter option to enhance IC 434 and, by extension, make B33 (the Horsehead nebula) more obvious to the eye. A UHC offers modest enhancement. An OIII will make it virtually impossible to observe this object.

Good luck with your pursuit of the Horsehead.

Bill in Flag

Quote:

---

I have been after the Horsehead for a few years now. No luck thus far.

I don't like to say I almost saw it....but that was the situation last week. Following all the advice that I have recieved on here over the years, I first found the Flame Nebula. Faint but definitely visible. I then went to Alnitak, and started to follow the faint nebula down to HP 26756, and that's where I loose it. I switched between my Oiii and omega NPB and even tried the light pollution filter, but to no avail. No matter. There are some very pretty clusters and stars in that area.

jake

---

---

The DGM Optics NPB filter is a narrow-band nebula filter with characteristics similar to the Lumicon UHC. The NPB has a very slightly narrower primary passband than the UHC, passing both the H-Beta and OIII lines at high transmission, along with a deep-red secondary passband. I have seen the Horsehead numerous times with the NPB filter, although it remains quite faint and somewhat marginal. The view in the H-Beta filter is quite a bit better in terms of contrast however. Clear skies to you.

Post Extras:

Quote:

---

The OIII filter will NOT work at all, a UHC filter will help some, I will leave the NPB filter to David, He knows and I have never used one. But let's get real here. NO ONE sees B33, it is dust and/or gas between us and IC434 that blocks our seeing IC434. So what you see is the absence of the nebula IC434 that is shaped like a horse head seen in silhouette. What you are trying to do is see the very faint nebula around the absence of the nebula because you can't see B33. If you are having trouble seeing IC434 you will never see the silhouette.

---

Post Extras: