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Eyepiece recommendation for HD C8,Baader Maxbright

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#1 pjensen

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Posted 17 June 2013 - 01:58 PM

Finally got the Maxbright binoviwers last week and now need to buy eyepieces. The scope is an HD C8 with a Televue short visual adapter and Maxbright T2 diagonal.

What eyepieces should I consider?

Thanks,
PAul

#2 Eddgie

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Posted 17 June 2013 - 02:47 PM

Any reasonably good eyepieces will work well, so much depends on what your own preferences toward AFOV would be.

I have to mention that narrower apparent fields don't seem to be as objectionable when using Binoviewers. 50 degree AFOV eyepeices just seem better when binoviewing than when Monoviewing.

The reason I mention this is because you may find that objects look a bit dimmer in binoviewers, and simply going to a lower power will help brighten things up quite a bit.

Remember, the focal length of your system with Binoviewers is going to be between 2300mm and 2350mm.

For example, 19mm Pans work wonderfully in the Maxbrights, but in your scope will give you about 121x with a .53 degree field (at 2300mm, so maybe you will have a bit more than this based on the actual focal length).

The exit pupil will be 1.7mm. This is OK for stellar targets, but a bit small for nebula and galaxies.

Now, compare that to a 25mm Plossl (both have the same field stop size, which is 21.3mm. The 25mm Plossl will give you 92x, and the same size true field (.53 degrees), but will give you a much brighter view because the exit pupil is 2.2mm. This does not sound like a lot, but it does indeed make a difference.

And if you don't mind seeing a slightly smaller apparent field, you can even go to something like 32mm Plossls, but they will vignette a bit.

I think the largest field stop you can use is about 23mm.

I tried an ES 20mm 68 degree apparent field eyepiece it and liked it a lot, but in one side of the Maxrbights, there was a tiny bit of cutoff at 5 O'clock in the field.

Another pair of eyepieces that I tried and liked (and often go on sale for deep discounts) was the Orion 19mm Flat Field eyepieces. I sold my pair and regret it.

My basic advice would be to start with a pair of decent 25mm or 26mm Plossls just to get you going.

Compliment those with a pair of 13mm Plossls, which will give you great planetary results.

You can do a lot of observing with just these two pairs, and once you get some experience, then perhaps decide if you find the AFOV to limiting.

I am using more 50 degree eyepeices in the Binoviewers now because for a given field size, the just make the view a little brighter than they would be in the widefields.

Also, even with 68 degree eyepieces, it is not as easy to take in the entire field because you really can't tilt your head to one side or the other when using binoviewers. The more I use 50 degree eyepieces in the binoviewers, the more I like them. They are also light and inexpensive.

Good luck, and looking forward to your first report.

#3 Wmacky

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Posted 17 June 2013 - 04:22 PM

How about the 40mm E-lux Plossls that come with alot of celestron SCT's? A lot of us have one thrown in a drawer, and I bet a second one could be scooped up on the cheap? Would that be to muh of a quality hit? Is a 40mm Plossls to much for binos? I was looking at 2 ES 26mm 68's, but after reading you comments perhaps thats not the best plan?

#4 denis0007dl

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Posted 17 June 2013 - 05:03 PM

For using Plossls 40, you misg consider for Mark V bino or Sieberts 2" binos, and this combo will work great for sure!

#5 Mark9473

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Posted 17 June 2013 - 05:08 PM

The 40 mm Plossl will have a very narrow AFOV (same TFOV as a 32mm Plossl) and will vignette. I tried my Meade 32mm Super-Plossl and didn't like what I saw. The 26mm ES68 will vignette because the field stop size exceeds the MaxBrights' aperture. Eddgie has given you a very good recommendation to go for a 25-26 mm Plossl as a low-power pair. Personally I use 25mm Circle-T Erfles and my next-up pair are 18mm orthos.

#6 orion61

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Posted 17 June 2013 - 06:10 PM

I use Edmund RKE (Rank Kellner Eyepiece) They have a surprisingly sharp and bright view on Axis.
if you are viewing the Moon a set of wide fields are outstanding. I go one step further and use 2 different color eyepieces, it really gives a breathtaking 3D effect.
It is even better if you turn off thr clock drive, It is like a Moon Orbit!
Good luck with your Toy!!!

#7 Wmacky

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Posted 17 June 2013 - 06:53 PM

The 40 mm Plossl will have a very narrow AFOV (same TFOV as a 32mm Plossl) and will vignette. I tried my Meade 32mm Super-Plossl and didn't like what I saw. The 26mm ES68 will vignette because the field stop size exceeds the MaxBrights' aperture. Eddgie has given you a very good recommendation to go for a 25-26 mm Plossl as a low-power pair. Personally I use 25mm Circle-T Erfles and my next-up pair are 18mm orthos.


Actually Edggie was addressing the thread originator. I just barged in. :)






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