Who uses their refractor without a diagonal?

[Stu]

 

[Peter Drew]

We were discussing this very issue recently. It seems people are prepared to spend a small fortune on high end diagonals to improve over the performance of lesser ones yet relative perfection is available free by not using one! This means that you are just paying for comfort rather than increased performance, an unusual twist. 

[Timebandit]

23 minutes ago, Stu said:

I think @Timebandit does this with his 120ED

 

Yes your right I do at times Stu. In both Cyclops and binoviewers I go without extra interference in the optical path at times, a diagonal. On planetary mainly in mid and lower level sky positions. To my eyes on occasions when I have experimented with/without the diagonal . To my eyes I think you get a marginally better view of a target without the diagonal, we are talking very small differences. But as we know especially on planetary and lunar that those small details can make all the difference. Not always good for the neck I must admit, and sometimes i am on my knees. What we do for our hobby and getting that possible bit extra?. Then again if the Japanese do it this way ,maybe it's not so crazy after all☺ 

[iPeace]

I often find myself with the tripod at a given height where my highest observing stool setting is still too low for me to peer over into the eyepiece as it extends upwards out of the diagonal. I could lower the tripod, and continue adjusting the tripod height all night, but maybe this approach will help with a bit less faff.

[Paz]

I tried an eyepiece straight through  pirate-style in my st80 once out of curiosity. If I recall correctly I couldn't rack the focuser back far enough to get a focus.

I think without a set up that allows you to recline a straight through  set up will become uncomfortable on the neck and back quite quickly.

[DRT]

I used to do this with my Tele Vue Pronto and Panoptic 41mm as the ultimate wide-field finder on the top shoe of my SkyTee II

 

[John]

Some of the short tube refractors (eg: ST80, 102 etc) are designed to be used with a diagonal in place. You can use them straight through but you need an extension tube to get eyepieces to focus.

 

[DRT]

 

24 minutes ago, John said:

Some of the short tube refractors (eg: ST80, 102 etc) are designed to be used with a diagonal in place. You can use them straight through but you need an extension tube to get eyepieces to focus.

 

I can't remember whether or not I had to use an extension tube with the Pronto so must try it again and report back. 

 

[Piero]

I sometimes observe the planets in straight through mode with light eyepieces. Compared to the TV Everbrite, a straight through view shows less light scattering. 

Below I made an extension tube from the Baader VIP but the nosepiece containing the lens element was replaced with one without (which I use with my zoom).

[iPeace]

2 minutes ago, Piero said:

I sometimes observe the planets in straight through mode with light eyepieces. Compared to the TV Everbrite, a straight through view shows less light scattering. 

Below I made an extension tube from the Baader VIP but the nosepiece containing the lens element was replaced with one without (which I use with my zoom).

Really very, very nice.

[Piero]

Just now, iPeace said:

Really very, very nice.

Thank you!

I will likely make a "permanent extension tube" in June. I have a spare 2"-to-1.25" Baader adapter (like the one in the photo), a 40mm spacer which is not used, and the 1.25" Baader nosepiece screwed at the bottom. This will require the coarse focuser to be moved inward of 1cm which is good. 

[DRT]

13 minutes ago, Piero said:

Thank you!

I will likely make a "permanent extension tube" in June. I have a spare 2"-to-1.25" Baader adapter (like the one in the photo), a 40mm spacer which is not used, and the 1.25" Baader nosepiece screwed at the bottom. This will require the coarse focuser to be moved inward of 1cm which is good. 

Piero, what is the overall length of the extension?

[Piero]

38 minutes ago, DRT said:

Piero, what is the overall length of the extension?

Hi Derek, 

In the photo, the extension is as long as a Baader VIP. 

According to this: http://www.baader-planetarium.com/en/downloads/dl/file/id/240/product/1062/calculating_different_magnifications_with_the_vip_barlow.pdf

69mm (2"-to-1.25" adapter + 2 x 15mm spacers). This is what you see in the photo (between the eyepiece and the TV60 focuser).

Then you have there is the Baader T2 1.25" nosepiece (~30mm) which connects one 15mm spacer and is inserted into the focuser.

So the overall length of the extension is 69mm + 30mm = 99mm

 

Off topic comment for Derek:

The Baader VIP is a great tool and works wonderfully with zooms like your Leica ASPH. On my TV60 I generally use the VIP in 1.5x mode (basically without the 2x15mm spacers) after or before the diagonal. The latter configuration transforms the VIP 1.5x into 2.16x (=1+(64-30+40)/64), assuming the TV Everbrite 1.25" works as a 40mm spacer. 

[Timebandit]

 

I suppose that really speaking a purist refractor set up should not have a diagonal. As to look at the target directly then you should only have the lens of the refractor and the lens in the eyepiece. This way you are actually looking at the target. 

When you introduce a diagonal into the optical set up then you are introducing a reflector into the optical chain. Therefore instead of looking at the target ,with a diagonal in the optical set up you are looking at a reflection of the target?

I hope the Dob Mob are not reading this threat otherwise they will go on about us refractor folk really using reflectors to gain our views , and in that case may as well get a reflector newt?.  

[John]

Clouds prevented me from testing the stright through setup tonight. I'll try again on anohter occasion. Initial thoughts are that any objects above around 45 degrees in altitude are going to cause neck ache even with the tall tripod !

 

[Piero]

4 minutes ago, John said:

Clouds prevented me from testing the stright through setup tonight. I'll try again on anohter occasion. Initial thoughts are that any objects above around 45 degrees in altitude are going to cause neck ache even with the tall tripod !

 

I can confirm your thought!

 

I would also add that a very good clean diagonal mirror reduces the difference between diagonal and straight views. 

[iPeace]

Trying it out with the Mak on Jupiter

[Piero]

Just had a brief observation of Jupiter in straight through mode. There are high clouds right now so, this was not really the right moment for testing light scattering. 

Anyway, the view was a tad cleaner, but I could not spot details that I haven't already seen with the diagonal between the telescope and the eyepiece. The GRS was out and quite bright at 150x (..oh man, what a beauty that eyepiece..!) and a white non-uniform lane cut the middle of the remaining part of the SEB. I did my best to spot barges on the NEB, but I couldn't. I will certainly try again and again. Both the polar regions were well visible as well as the north temperate belt. Overall, a lovely picture.  

 

Important remark:

Make sure that the eyepiece is safely attached when observing in straight way. You certainly don't want to test with one of your nice eyepieces what Isaac Newton proved with his apple.

[chiltonstar]

I have used a Mak straight through once or twice but with a tripod I like to keep the legs in their minimum position for stability because of the weight of the 180 Mak, which means using a diagonal.

Chris

[Alien 13]

If you want a straight through view without the neck ache and the "shaving mirror effect" you can always use a prism diagonal.

Alan

[iPeace]

Found myself stranded at this location for the night, while Stanley and his diagonal reside at my dark site. So I have the Mak here, another Mark IV Zoom, Stu's old Induro tripod and a GSO slo-mo head. The ClickLock keeps the zoom nicely off the planet.

The tripod / head combo puts the Mak over six feet up at max extension, so plenty of height.

Enjoyed the details on Jupiter with a big juicy GRS. Moved over to split Castor, just because. Can't say it's a noticeable visual improvement over using a diagonal, but for once I'm not hunched over the eyepiece.

The experience is closer to using mounted binoculars. The newtonian orientation wasn't as confusing as I thought it might be. Had it sorted within minutes. I did enjoy it, nothing off-putting at all.

The shorter assembly length of the Mak undoubtedly helps. Will try with Stanley next chance I get.

[mikeDnight]

I used to view straight through nearly all the time for lunar and planetary, but it meant having my scope mounted high up. However, after a short time at the eyepiece, discomfort from being in an unnatural position detracted from the enjoyment of observing. Still I was a stubborn devil and persisted observing that way for years in the belief I was getting a better view. I was not, and now I've a bad back and a creaking neck, dry rott and wood worm, that I'm putting down to bad observing posture.

After spending quite some time observing straight through with my latest scope, and then comparing the diffraction pattern both inside and outside focus, as well as comparing planetary detail, I am totally convinced there is zero difference in image quality between the straight and diagonal view. I honestly believe that a modern, good quality diagonal, mirror or prism, will not degrade the image. Also, any perceived improvement in the diagonal free view is probably illusory. Discomfort will cause an observer to see less over time. Conversely, a comfortable observer is likely to see more.

Attached is my silly straight through set-up from ten years ago , and my more sensible and comfortable set-up that I use today. 

Mike

 

 

[iPeace]

3 minutes ago, mikeDnight said:

I used to view straight through nearly all the time for lunar and planetary, but it meant having my scope mounted high up. However, after a short time at the eyepiece, discomfort from being in an unnatural position detracted from the enjoyment of observing. Still I was a stubborn devil and persisted observing that way for years in the belief I was getting a better view. I was not, and now I've a bad back and a creaking neck, dry rott and wood worm, that I'm putting down to bad observing posture.

After spending quite some time observing straight through with my latest scope, and then comparing the diffraction pattern both inside and outside focus, as well as comparing planetary detail, I am totally convinced there is zero difference in image quality between the straight and diagonal view. I honestly believe that a modern, good quality diagonal, mirror or prism, will not degrade the image. Also, any perceived improvement in the diagonal free view is probably illusory. Discomfort will cause an observer to see less over time. Conversely, a comfortable observer is likely to see more.

Attached is my silly straight through set-up from ten years ago , and my more sensible and comfortable set-up that I use today. 

Mike

 

 

Makes perfect sense. What I am contemplating now is a mode in which I alternate the two, using a diagonal when observing closer to the zenith, and not using one when observing closer to the horizon, whichever is more comfortable for a given target. If it feels like a strain, it certainly can't be right.

[John]

My Vixen rig did feel like a strain when I used it albeit briefly the other night. Won't be bothering again as I like to enjoy my viewing

 

[Timebandit]

1 hour ago, John said:

My Vixen rig did feel like a strain when I used it albeit briefly the other night. Won't be bothering again as I like to enjoy my viewing

 

 

Owwww John , that's just being a lightweight?

But what after MikeDnight has said , maybe it's all in my head. Especially as Mike has tried this for so many years already? And the Japanese folk and myself are just giving ourselves a bad neck , back for no reason?

I will have to wait for another clean crisp night( these are rare in the UK unfortunately,) and try experimenting again with diagonal v no diagonal. But then again do I wish to see the target or a reflection of the target?