Couple of Barlow queries

[gdj1976]

Hello all

Newbie here to the world of astronomy. have had a Skywatcher 150p since Christmas and only now am I getting the skies to really spend some quality time with it. Have had a great day today viewing the Moon in detail, a nice sharp viewing of Jupiter and starting to explore the sights around Orion.

The main problem I've encountered to date is with my Barlow lens. using it with my 25mm and 10mm EP and it seems to make everything worse, blurry at best but generally just an EP full of white. I have spotted a few other threads touching on this subject so I will try out a few more things. My Barlow 2x is this one

http://www.cameracentreuk.com/skywatcher/skywatcher-125-deluxe-2x-barlow-lens-t-adapter-double-lens-1453-261-1485.php

I assume this is a pretty good one?

Some of the threads have referred to the poor quality of the factory EPs and this might contribute to the inability to use the Barlow. Out of interest what kind of money would be spent on a high quality EP?

My final question is about using an SLR. I know that astrophotography is a tough game but I'd like to have a go at some basic shots of the moon and planets. I am a little confused, however. The Barlow I linked to above has the T adapter and I have the correct attachment for my Sony SLR. However since the T adapter is on the Barlow does this mean I can only take photos using the Barlow, and not with the EPs also attached? Not only does this limit my photographic range it also means that I can't attach a moon filter and take a photo.

Sorry, a few scatter gun thoughts/questions there. I apologise if much of this has been covered before. This is an excellent forum and I have found the introductory guides extremely useful.

Glyn

[Scooot]

You should be getting just as good view using the Barlow with your 25mm as you do using the 10mm without it. If you don't there's a problem. Is it focusing?

[Pig]

Forgive the pun but the sky is the limit for eyepiece prices and quality.

The best way is to find an astronomy group located near you and ask if you can try theirs out (most people do not mind helping)

The speed of your scope will help determine the most suitable eyepieces. The faster the scope the better quality eyepiece you will need especially at higher magnifications.

My scope is F/10 (focal length/aperture) in my case 1500mm / 152mm = F/9.84. so I do not need very expensive eyepieces.

F/7 and lower is fast.

Having said that my eyepieces are not cheap nor expensive but most importantly they fit my eyes .

[gdj1976]

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You should be getting just as good view using the Barlow with your 25mm as you do using the 10mm without it. If you don't there's a problem. Is it focusing?

No, not focusing at all for either eyepiece.

All in all it was very strange. for Jupiter whilst we had a quite nice viewing with our 25mm and 10mm imtroducing the Barlow seemed to make the planet seem smaller.

Viewing the moon with the Barlow just filled the eyepiece with focussed light, despite the moon filter being on the eyepiece.

[Scooot]

No, not focusing at all for either eyepiece.

All in all it was very strange. for Jupiter whilst we had a quite nice viewing with our 25mm and 10mm imtroducing the Barlow seemed to make the planet seem smaller.

Viewing the moon with the Barlow just filled the eyepiece with focussed light, despite the moon filter being on the eyepiece.

Is the draw tube all the way out or in when trying to focuss

[gdj1976]

Have had it all the way in.

[Scooot]

Have had it all the way in.

So if you could go further in you might focus?. Not sure what scope you have but it sounds to me that its not compatible which seems a bit odd, or its faulty. I'm not trying to be funny but there isn't anything obscuring the Barlow, maybe a translucent cap or something. Otherwise I'd contact the supplier and discuss it with them, it's not right anyway.

[gdj1976]

So if you could go further in you might focus?. Not sure what scope you have but it sounds to me that its not compatible which seems a bit odd, or its faulty. I'm not trying to be funny but there isn't anything obscuring the Barlow, maybe a translucent cap or something. Otherwise I'd contact the supplier and discuss it with them, it's not right anyway.

No, nothing obscuring the Barlow whatsoever.

It's a Skywatcher 150p and this is a Skywatcher Barlow.

[Lenny147]

The EPs that they give with the scope really are not up to scratch, the 25mm is not too bad but the barlow and 10mm are well known for not being great. I would suggest sometime in the future upgrading the EPs as it will make a huge difference in what you are seeing. I think others will tell you the same on here to be honest

[gdj1976]

I've had another go tonight and the Barlow worked fine. Not sure what I was doing differently last night. Used a daylight viewing of the moon to have another test run with both the 25mm and 10mm with the Barlow and saw some stunning detail. Then, in an early evening suburban night, managed to view Jupiter and moons with the Barlow and same eyepieces.

I'm still confused about my final question in the original post. I can attach my SLR to both the Barlow and the eyepiece holder, but not with an eyepiece too. But using both of those without an eyepiece I can't focus nor use a moon filter, therefore any photos will be useless.

Should I be able to focus without an EP? Is this a stupid question?!

[E621Keith]

Have had it all the way in.

This sounds like a case of insufficient focuser travel, although it sounds a bit odd your focuser was all the way in, because a barlow usually move the focus further out.

Forgive the pun but the sky is the limit for eyepiece prices and quality.

...

BST Explorers they sell have a reputation for good quality on a budget

http://www.skystheli... eyepieces.html

[MrPadz]

I had a similar problem tonight with the Meade 2x Barlow I'd picked up. Had the focuser all the way in to the tube and was still very slightly out of focus. After a little bit of examination I discovered that the lens element of the Barlow could be unscrewed from the rest of the assembly, which had the effect of dropping the Barlow lens element further into the focuser barrel, after which I was able to get a clean focus (well relatively clean, given the seeing tonight!). Has anybody else tried this?

[MrPadz]

I had a similar problem tonight with the Meade 2x Barlow I'd picked up. Had the focuser all the way in to the tube and was still very slightly out of focus. After a little bit of examination I discovered that the lens element of the Barlow could be unscrewed from the rest of the assembly, which had the effect of dropping the Barlow lens element further into the focuser barrel, after which I was able to get a clean focus (well relatively clean, given the seeing tonight!). Has anybody else tried this?

Obviously I didn't unscrew the Barlow lens assembly from the rest of it completely, only by a few turns

[NGC 1502]

Hi there in Dublin, welcome to SGL. You were up late (or early)

If unscrewing the lens assembly slightly from the barlow sorted the problem, then the focuser doesn't have enough inward travel.

It may be possible to modify the focuser to give more inward travel, I've done that by filing an extra notch in the rack part of the focuser, at the outer end of the teeth. Another dodge, if it's a Newtonian scope is to tweak all of the collimation screws to bring the primary mirror a bit further up the tube. Or you could (perhaps) remove a bit from the end of the focuser, so the barlow sits further in. I'm sure that there are other tweaks that would work as well.

Please only try these modifications if you are confident of your DIY skills, I'd hate to think you messed up a working telescope, and if it's a new telescope, you will have voided the warranty.

Also, please be careful of partially unscrewing the lens section of the barlow. If that part should become detached, it will fall into the telescope and bounce off the optical parts.

Regards, Ed.

[P_Monty]

I'm still confused about my final question in the original post. I can attach my SLR to both the Barlow and the eyepiece holder, but not with an eyepiece too. But using both of those without an eyepiece I can't focus nor use a moon filter, therefore any photos will be useless.

Should I be able to focus without an EP? Is this a stupid question?!

So far I've only tried photography with the EP in. Most people appear to prefer it with the EP out, so I think you ought to be able to focus...