15 replies to this topic

[JonMain]

Interested in a few recommendations for a DSO astrograph. OTA shouldn't weigh much more than 20lbs but lighter is fine. Should have full-frame coverage. Will not be in an observatory. Will be driven/flown to various dark sky locations. Entry level recommendations not needed: looking for more of a 'forever' scope. For example, the Sky-Watcher Esprit 100ED seems like a decent choice. There are so many options these days, though, that I figured I'd see what those with more knowledge on this topic would recommend.

Edited by JonMain, 28 May 2023 - 03:31 PM.

[hyiger]

A lot of it depends on your budget and your mount. The mount is by far the most important element with the camera next and the scope last. I would put all your research into a mount first then consider which scopes to go with it. 

[idclimber]

There is only one 4" refractor that I would consider full frame and that is the FSQ106. I do not consider the Esprit 100 or my SVX102 to be full frame. At least not with reducers shooting near f/5. They may be fine with a large pixel full frame DSLR, but lack in image quality with something like a ASI6200mc. 

 

But are you fully committed to full frame? That pushes the budget and scope size up a lot. 

 

Otherwise I think the smallest refractors that I would be doing full frame with are the 5" like the SVX130 or the equivalent Tac. 

[JonMain]

There is only one 4" refractor that I would consider full frame and that is the FSQ106. I do not consider the Esprit 100 or my SVX102 to be full frame. At least not with reducers shooting near f/5. They may be fine with a large pixel full frame DSLR, but lack in image quality with something like a ASI6200mc. 

 

But are you fully committed to full frame? That pushes the budget and scope size up a lot. 

 

Otherwise I think the smallest refractors that I would be doing full frame with are the 5" like the SVX130 or the equivalent Tac. 

I have a Canon EOS R5 so full frame coverage would be nice. I'm not opposed to cropping a bit tho. My camera's pixels are only about 17% larger than those on the ASI6200mc. Of course, if the price of a scope that will perform well with an R5 exceeds the cost of a more reasonable astrograph plus a dedicated astro camera then that's an option.

[rgsalinger]

If you don't want to break the bank you can do what I did. I use an ASKAR 107PHQ and an ASI2400MC. The compromise I made is that I don't get the wide field of the Takahashi but the scope has enough focal length to work well on smaller objects. The use of the 2400MC is easier on the optics and so the scope produces nice stars when using it.  I get a picture every night when I use it. 

 

 

 

 

This is using a QHY600 but the results are better with the 2400 and I love just shooting OSC when I'm portable with my system. Unlike a Takahashi, you could get a bad ASKAR scope. So, if you want to save thousands of dollars, be prepared to test the one you get quickly and send it back if it's not to your liking. 

 

Rgrds-Ross

[JonMain]

A lot of it depends on your budget and your mount. The mount is by far the most important element with the camera next and the scope last. I would put all your research into a mount first then consider which scopes to go with it. 

I'm leaning towards the HAE29EC mount.

 https://www.ioptron....ct-p/he294a.htm

Edited by JonMain, 28 May 2023 - 04:11 PM.

[rgsalinger]

I think at this point if you are not planning to go very big/long scopewise, teh the strain wave mounts are definitely the way to go. I like the idea of the bigger ones as it's nice to be able to carry 40 pounds of imaging system. That's about the maximum that most portable imagers will every use. I've only used the AM5 so I can't comment based on usage. The Pegasus NYX and the iOptron HEM44 would be my choices if I decided to replace my trusty Paramount MYT.

 

I don't really get why the HAE's are popular but if you really think that you'll want an alt/az mount for visual, then they make sense. When I did star parties (been a while not) once I got the MYT star aligned, it worked as well for visual as any alt/az mount in general. 

 

Rgrds-Ross

[DeepSky Di]

HEM27 is one of the lightest and the payload is 29lb. It can go to 44lb with a counterweight. 

[bobzeq25]

Of course, if the price of a scope that will perform well with an R5 exceeds the cost of a more reasonable astrograph plus a dedicated astro camera then that's an option.

Will you be modding the R5, or do you want to avoid that to more easily use the camera for other purpose?

 

If not modding, a dedicated astro camera has 2 major advantages. 

 

Better imaging of emission nebulae.  The stock R5 will block some (could be a lot) of the signal from those, and poor signal to noise ratio is a fact of life in DSO astronomy, that is a constant struggle.

 

Lower thermal noise, and a better ability to correct for it, because of thermostatically controlled chip temperature.  Again, better signal to noise ratio, and it's a big deal.

 

DSLRs used to be very popular.  Now that economical CMOS cameras offer both increased hydrogen alpha sensitivity and cooling, DSLRs and mirrorless have lost popularity, for good technical reasons.  People aren't buying astro specific cameras for prestige.  They're not Rolexes.  <smile>

 

The iOptron strainwave mounts have limited cable management.  After having experienced the virtues of good mount cable management on my CEM60, I'm never going to give that feature up.    One lightweight mount with excellent cable management is the CEM40 NUC.  3 12VDC outlets on the mount.  4 USB inputs (maybe more) for main camera, guide camera, filterwheel, focuser, on a carefully chosen NUC.  18 pound mount, 40 pound capacity.

Edited by bobzeq25, 28 May 2023 - 05:18 PM.

[Spaceman 56]

Interested in a few recommendations for a DSO astrograph. OTA shouldn't weigh much more than 20lbs but lighter is fine. Should have full-frame coverage. Will not be in an observatory. Will be driven/flown to various dark sky locations.

 

Entry level recommendations not needed: looking for more of a 'forever' scope. 

I was also interested in a very high quality Astrograph.

 

I have been imaging with a Doublet, (successfully) and therefore immediately considered a Triplet, but then wondered about the potential advantages for imaging of a Quadruplet. 

 

Mr Kennedy iDClimber brought the FSQ-106 to my attention, and Bob25Eq also recommended it. thanks Dave  & Bob   

 

I read a few months in the Refractors forum, and discovered a bit of a consensus as to the Quality of Takahashi and AstroPhysics

scopes, which are generally regarded as being number 1 and number 2, but in no specific order. they are viewed as being equal.

 

Astrophysics are just about impossible to obtain, and you can go in a lottery, and perhaps get one if you are lucky. 

Takahashi are incredibly expensive , but can be obtained. 

 

for imaging and full frame the Takahashi FSQ106 Quadruplet is often regarded as the premier scope, and has the advantages of being

able to be used at multiple Focal lengths, and F Ratios.

 

for example it is native at 530mm (good for many targets) at F5, and using a 1.6x extender it can be 848mm focal at F/8.

this makes it potentially a very useful choice, and opens up more target availability.

 

there are also 0.73x and 0.60x Focal reducers available, that bring the focal length down as low as 386mm or 320mm respectively

and F Ratios as low as F/3.

 

based on all this excellent information I decided to purchase an FSQ 106. 

 

the question then became, if I should buy a new one with Non Fluorite Lenses, or if I should try an obtain the original Fluorite version. as I am a bit of a collector of OLD things (audio equipment) I decided a Fluorite original would be my choice.

 

I was fortunate to find a Fluorite FSQ106 in Japan and despite the obvious challenges purchased the Takahashi. 

 

 

Fluorite is written on the front objective, so no confusion exists there.

 

 

the original Fluorites also have a non retracting lens hood. there was a later version the FSQ106N that has a sliding lens hood.

 

I will update everyone with some actual imaging results, once I dial the scope in, and possibly buy a bigger and higher quality mount. 

 

sorry for the long post, but I hope this information is helpful.  

 

Spaceman

Edited by Spaceman 56, 28 May 2023 - 05:10 PM.

[JonMain]

I think at this point if you are not planning to go very big/long scopewise, teh the strain wave mounts are definitely the way to go. I like the idea of the bigger ones as it's nice to be able to carry 40 pounds of imaging system. That's about the maximum that most portable imagers will every use. I've only used the AM5 so I can't comment based on usage. The Pegasus NYX and the iOptron HEM44 would be my choices if I decided to replace my trusty Paramount MYT.

 

I don't really get why the HAE's are popular but if you really think that you'll want an alt/az mount for visual, then they make sense. When I did star parties (been a while not) once I got the MYT star aligned, it worked as well for visual as any alt/az mount in general. 

 

Rgrds-Ross

I don't have any particular attachment to the HAE29EC. I just chose it because it has 0.5" RMs and 2" P2P tracking unguided, has a 30lb capacity, and only weighs 8lbs. It's about $1000 cheaper than the HEM44 and about 5lbs lighter. Of course, the 44 has 10 more lbs of payload. Any particular reason you prefer the HEM line over the HAE? Thanks!

[JonMain]

HEM27 is one of the lightest and the payload is 29lb. It can go to 44lb with a counterweight. 

Looks like the HAE29 is basically the same as the HEM27 except the alt/az bit.

[JonMain]

Will you be modding the R5, or do you want to avoid that to more easily use the camera for other purpose?

 

If not modding, a dedicated astro camera has 2 major advantages. 

 

Better imaging of emission nebulae.  The stock R5 will block some (could be a lot) of the signal from those, and poor signal to noise ratio is a fact of life in DSO astronomy, that is a constant struggle.

 

Lower thermal noise, and a better ability to correct for it, because of thermostatically controlled chip temperature.  Again, better signal to noise ratio, and it's a big deal.

 

DSLRs used to be very popular.  Now that economical CMOS cameras offer both increased hydrogen alpha sensitivity and cooling, DSLRs and mirrorless have lost popularity, for good technical reasons.  People aren't buying astro specific cameras for prestige.  They're not Rolexes.  <smile>

 

The iOptron strainwave mounts have limited cable management.  After having experienced the virtues of good mount cable management on my CEM60, I'm never going to give that feature up.    One lightweight mount with excellent cable management is the CEM40 NUC.  3 12VDC outlets on the mount.  4 USB inputs (maybe more) for main camera, guide camera, filterwheel, focuser, on a carefully chosen NUC.  18 pound mount, 40 pound capacity.

Thanks! My reason for using an unmodded R5 is personal preference. I want images that are as close to what the human eye WOULD see if able to collect enough light. Limitations acknowledged I've still been able to get some decent results with it. https://www.astrobin.../users/JonMain/

[JonMain]

I was also interested in a very high quality Astrograph.

 

I have been imaging with a Doublet, (successfully) and therefore immediately considered a Triplet, but then wondered about the potential advantages for imaging of a Quadruplet. 

 

Mr Kennedy iDClimber brought the FSQ-106 to my attention, and Bob25Eq also recommended it. thanks Dave  & Bob   

 

I read a few months in the Refractors forum, and discovered a bit of a consensus as to the Quality of Takahashi and AstroPhysics

scopes, which are generally regarded as being number 1 and number 2, but in no specific order. they are viewed as being equal.

 

Astrophysics are just about impossible to obtain, and you can go in a lottery, and perhaps get one if you are lucky. 

Takahashi are incredibly expensive , but can be obtained. 

 

for imaging and full frame the Takahashi FSQ106 Quadruplet is often regarded as the premier scope, and has the advantages of being

able to be used at multiple Focal lengths, and F Ratios.

 

for example it is native at 530mm (good for many targets) at F5, and using a 1.6x extender it can be 848mm focal at F/8.

this makes it potentially a very useful choice, and opens up more target availability.

 

there are also 0.73x and 0.60x Focal reducers available, that bring the focal length down as low as 386mm or 320mm respectively

and F Ratios as low as F/3.

 

based on all this excellent information I decided to purchase an FSQ 106. 

 

the question then became, if I should buy a new one with Non Fluorite Lenses, or if I should try an obtain the original Fluorite version. as I am a bit of a collector of OLD things (audio equipment) I decided a Fluorite original would be my choice.

 

I was fortunate to find a Fluorite FSQ106 in Japan and despite the obvious challenges purchased the Takahashi. 

 

Takahasi Objective.jpg

 

Fluorite is written on the front objective, so no confusion exists there.

 

Takahashi OTA LQ.jpg

 

the original Fluorites also have a non retracting lens hood. there was a later version the FSQ106N that has a sliding lens hood.

 

I will update everyone with some actual imaging results, once I dial the scope in, and possibly buy a bigger and higher quality mount. 

 

sorry for the long post, but I hope this information is helpful.  

 

Spaceman

Thanks for the info! I like long posts! That OG fluorite has got some definite cool factor

[bobzeq25]

Thanks! My reason for using an unmodded R5 is personal preference. I want images that are as close to what the human eye WOULD see if able to collect enough light. Limitations acknowledged I've still been able to get some decent results with it. https://www.astrobin.../users/JonMain/

Color in astrophotography is a very slippery concept.  Things are so dim the only realistic color would be none.  You'd see the object with your eye's rods, but not its cones, which is where color is perceived.  So, the light has to be brightened.  As the person behind the counter in the Sherwin Williams store can tell you, RGB = 24, 12, 18 is a different color than 96, 48, 72.    Data from a camera has to be "stretched" to deal with the dynamic range of your eyes, linear data from the camera is just about invisible to your eyes.  Example of a linear sub of M67 below, click on it to enlarge. 

 

That inevitably reduces color intensity.  Standard practice is to increase saturation to compensate.

 

Bottom line is that this is nothing at all like terrestrial photography, and color is different.  Astronomers generally don't use visual images, because the human eye does not work well at these levels, and is inappropriate for scientific work, instead they analyze numeric data.

 

Good books about this.  The first is pretty important stuff for anyone interested in the topic.  "Coloring the Universe".  Get the hardcover, it has beautiful images.  The second has some good information, but it's pretty scattered.  "Lessons from the Masters : Current concepts in astrophotography images"

 

Some people think low color saturation makes images more "realistic".  But the degree of saturation is really just an arbitrary thing, as pointed out in Lessons.

 

Edited by bobzeq25, 28 May 2023 - 08:51 PM.

[mayhem13]

The Esprit 100ed is a solid, affordable choice that’s both light and compact enough for air travel. The relatively fast optics at f5.5 are capable of producing a flat and well lit field of a full frame sensor with minor vignette that’s manageable in post processing. I have been traveling with mine for almost a year now and appreciate its reliability and build quality.