Best Tracker For Night Sky Photography Using Medium Format Equipment

[JoeKitchen]

Hello,

First, thank you in advance for your advice.

I am a commercial photographer that partly works in the film and TV industry producing printed backdrops and translights.  As such, and for any night scenes, I need night sky photographs in my library.  Currently I have a few night skies that would make sense for a city night (these were captured at a high ISO for about 8 seconds), albeit only the brightest stars are really visible in these options.  They would not work well for any suburban and, especially, landscapes.  Also, none of our competitors have any great night skies either, so adding stellar skies into our catalog would set us apart for that genre.

So I am looking to get a tracker to allow me to capture longer exposures of the night sky to take full advantage of my camera’s base ISO (65).  Also, I do fly a lot for this work, and although I would not take this on every work trip, for the ones where I will be in a more rural state or country, it would be nice to be able to fly with it as well.  Of course, it would be checked. 

I was considering the Sky Watcher HEQ5 Pro, although I am concerned about it being a bit too large to be practical for flying.  I do like the fact that it uses ball bearings instead of bushings though.  

I also was looking at the EQM-3 and the Celestron Advanced VX, just from a portability stand point.  Although from what I read they do not work well out of the box and require tinkering with better bearings to get it up to the same level of quality.  So if the portability gain is minimum at a much greater sacrifice in usage, I would not consider these to be great options. 

Any thoughts?  Any other trackers I should be looking at?  

For reference, I work with a Phase One IQ260 medium format digital back (60 MP) with a sensor size of 40x54mm and a pixel pitch of 6 microns.  I may upgrade to an IQ4150 in the near future, which has an 150 MP sensor of same dimensions but with a pixel pitch of 3.76 microns.  I mainly use this on an Arca Swiss RM3Di technical camera with 28mm f/5.6, 35mm f/5.6, 55mm f/4.5 and 90mm f/5.6 lenses.  The latter two can be used wide open.  The former two really benefit from being closed down one stop and the 28mm is best used with a center filter, adding 2 stops to the exposure.  This setup, combined with a Arca Swiss Cube tripod head, will weigh about 3.5 kg to 4 kg, depending on the lens.  

I also would like use my back on a Phase One XF camera with a 240mm f/4.5 lens and a 2x convertor, which would weigh about 5.5 kg, on the same tracker if possible for deeper sky photography.  

Conversions for 28mm, 35mm, 55mm, 90mm, and 240mm focal lengths to full frame 35mm would approximately be 18mm, 23mm, 30mm, 45mm, and 150mm, respectively.  

I almost always shoot tethered to a lap top, so adding a guide would not be an issue if it helps dramatically with the much longer focal lengths.  

Insofar as tripods, I use a Gitzo Series 5 Carbon Fiber Giant, which has a 80+ lb pay load.  Outside of dedicated cine tripods, it is the most stable tripod I have ever used, and I’ve used many.  

Joe

[AstroMuni]

8 minutes ago, JoeKitchen said:

Any thoughts?  Any other trackers I should be looking at?  

Is there a budget that you have in mind? For travel, you need a light weight one so I would have said something like the ZWO AM5 would be best (compared to the HEQ5). But for simple star tracking these may suffice https://www.firstlightoptics.com/star-tracker-astronomy-mounts.html. Some of them may even be able to sit on top of your existing tripod.

 

Edited December 12, 2023 by AstroMuni

[JoeKitchen]

14 minutes ago, AstroMuni said:

Is there a budget that you have in mind? For travel, you need a light weight one so I would have said something like the ZWO AM5 would be best (compared to the HEQ5). But for simple star tracking these may suffice https://www.firstlightoptics.com/star-tracker-astronomy-mounts.html. Some of them may even be able to sit on top of your existing tripod.

 

Overall budget would be in the $1500 range, give or take. I am more concerned about usability and portability right now.

For $2K, if the ZWO AM5 gets me both of those, then I would consider it a good price. 

Edit

Also, from what I have read, the other mounts I first listed all appear to require some tinkering and replacements of better bearings and grease to get the best results.  Not that I would be skittish to do this myself, but I would rather save the extra expense and time by just getting a better made product. 

Edited December 12, 2023 by JoeKitchen

[Bivanus]

For a photo application I can think at no other better source than a... professional photographer. Who also just happens to be dabbling into astrophotography and other ...ahem...dark arts 😄

So here it is by Nico Carver aka NebulaPhotos :

 

[vlaiv]

Fact that you work as photographer works against you in this case.

Many of day time photography concepts are useless and even misleading in astrophotography.

Given that you work with 6um pixel size and use short focal length lenses - most star trackers will do good a good job, but you really need to think in terms of:

1. pixel scale - or how many arc seconds per pixel you want to have in your final shot

2. what sort of sharpness lens provide. Camera lenses are optimized for close focus or rather range of foci, while astronomical telescopes are always optimized for infinity focus. They give much sharper image that is only limited by physics of light rather than design of the lens itself.

Do look up above concepts and learn a few things about wide field astrophotography as it will benefit you, but in order to get started quickly - I agree, look into small portable mounts that utilize strain wave drives. These will suit you the best.

https://www.firstlightoptics.com/harmonic-drive-mounts.html

Small enough for good portability

Able to carry enough weight and

Precise enough for what you need.

I'm afraid that I can't recommend any specific model as I have not worked with any of them nor taken keen interest in their performance.

[Elp]

Depends how you want to use it. People get great results with the Skywatcher Star Adventurer or Ioptron equivalent, there's also the Fornax Lighttrack and the more expensive Astrotrac. You now have the Skywatcher Star Adventurer GTI which is the developed all in one version over the Skywatcher AZGTI which many people me included use in fully autoguided EQ mode. Counterweights however are a pain to transport, even if you're only using 2Kg counterweights, it adds up in bag carriage. So my in between mount is an ioptron hem15, compared to the three mounts in Nico Carvers video above, it's much smaller, likely doesn't perform the same but I bought it for its size, carrying capacity and power usage. It works well whether I'm using my cameras lenses or telescopes, the 3/8 female centre hole fitting (as many HD mounts have, not all of them do) is a boon for choice of using light and sturdy CF photographic tripods.

[Icesheet]

As Vlaiv stated, astrophotography bears little resemblance to day photography. For example you mention conversions of focal length to full frame equivalent. The focal length is the focal length and that’s what will test the precision and accuracy of the mount you choose not the size of the sensor. Of course you should consider sensor size, FOV and pixel scale when considering the framing of your object but there is no crop factor as you commonly hear in landscape type photography. Also, it’s unlikely you will be shooting anywhere near ISO65. I’m not familiar with the PhaseOne’s but it’s unlikely to be under ISO800. 
 

It’s not clear to me exactly what you would plan to shoot. Is it landscape milkyway type photography or, do you plan to do deep sky astrophotography? You mentioned a 240mm lens with 2x tele-convertor. If you really plan to shoot at 480mm then one of the strainwave mounts mentioned would probably be your best bet as you would have to guide anyway. As an aside I wouldn’t use that lens with the tele-convertor as f9 would be slower than you want for night sky photography.
 

If it’s more widefield work then there are a plethora of sky trackers that would work for you. The Fornax Lighttrak ii is probably the most accurate on the market and will handle the 240mm lens without guiding. It lacks GoTo though. The Star Adventurer GTi has Go To and seems to be popular. Or you could consider the Benro Polaris if you will only shoot at shorter focal lengths as it negates the need for polar alignment and you can shoot fully automated panoramas which may be of interest to you.

There’s likely to be some great advice on this thread but also use YouTube as a resource as there are plenty of content creators doing a wide range of astro work. 
 

Edit: Apologies, re-reading, I see you mention deep sky. Then, I would not recommend the Benro Polaris for that. Probably a strainwave mount would be best but factor in what else you need for guiding and polar alignment. I would also look for another option other than using the 2x convertor with the 240mm lens. 

Edited December 12, 2023 by Icesheet

[Elp]

I suspect the OP is just looking for night skies, to composite into other images, for them to confirm. Only a basic star tracker is needed for this rather than a full on mount, if you're imaging wide and fast enough (less than 14mm) you don't even need one really, depends on how many stars they want to appear in the image.

Edited December 12, 2023 by Elp

[vlaiv]

1 minute ago, Elp said:

I suspect the OP is just looking for night skies, to composite into other images, for them to confirm. Only a basic star tracker is needed for this rather than a full on mount, if you're imaging wide and fast enough (less than 14mm) you don't even need one really, depends on how many stars they want to appear in the image.

Problem is that we don't really understand what is requirement for images.

I can imagine taking a very large format image and using it as drop in background for panning shot for example. In that case - image needs to quite a bit larger than the actual size of the shot (think scrolling background).

On the other hand - how big stars need to be in that shot? Tiny - barely visible or larger?

How much of distortion per star is acceptable? Is pixel level precision required or maybe it does not matter because image will be resampled for use and stars will end up tiny?

[Elp]

The OP needs to elaborate, they've mentioned a medium format camera so they'll have a large fov depending on the lens used which may or may not sample stars correctly (also any NR algorithm which could be operating in camera).

But it is as you say, how large or small will the stars need to be.

Might be easier to link or upload an image to show what you're looking to do OP.

[900SL]

Medium format and 240mm focal length with 2 x convertor requires a decent tracking mount, and likely guiding

 

I've shot full frame wide angle up to a 250mm redcat from a fornax LT 2 mount, doesn't need guiding

 

Examples

 

Edited December 12, 2023 by 900SL

[JoeKitchen]

Good afternoon and thank you for the responses so far, and apologies for the length here. 

Insofar as the lenses and 35mm conversions, I was just supplying that out of rote habit.  However it makes total sense that does not really matter; the focal length is the focal length.  I provided the pixel pitches because in my research I read this makes a huge difference in how many arc seconds of play you can handle before image quality is hit.  Correct me if I am wrong.  The stars can not be visibly oval is shape. 

Also, for noise reduction from heat on a long exposure, my camera will automatically take a second exposure of equal length as the sensor is cooling down to map out the heat distribution and use that mapping to reduce noise from heat for that specific capture.  I can not turn this function off.  So effectively if an exposure is 5 minutes, it will take 10 minutes to actually process.  (I am an extremely patient man by the way.)

Now in terms of my usage. 

Backdrops are, on average, printed roughly 24x70 feet in size, but we have gone as big as 28x186 feet for a near full wrap around the set.  In order to achieve this, I am creating panoramas from utilizing both panning and/or in camera shift to produce (for an average drop) ~280 MP file.  Depending on the specific view I need to produce, it could be a stitch of anywhere from 6 to 14 individual images.  The amount of images is dependent on both the size the directions of view in the set design.  So I would want to create a library of night sky images in a similar fashion producing equally as large files in order to keep the scale accurate when using them. 

When producing a translight, for a variety of reasons, the night version is usually a blend of the true night image with a "night-from-day" conversion of the day image.  As more and more plants become a part of the view, the amount of the true night image used goes to zero.  Regardless though, I always need an applicable sky to drop in order to make it work.  So this is the main reason I am looking into this, to create night sky images to drop in. 

With this being said, on the rare occasions where all the many conditions needed for a true Day|Night translight are met, I would prefer to actually capture the true night scene and use that since it will be more natural.  (I realize the landscape and sky would be two different images in this case.)

Likewise, if I were to get really nice stuff, it would not be out of the realm of possibility that a production may request a custom tighter drop of some portion of the night sky, say for a Sci Fi production.  Although you may think it would better to use one of the newer LED Volumes, like used in filming The Mandalorian, or just green scene it, the fact is those Volumes are extremely expensive to use and green scenes require so much editing in post, drops are significantly more cost effective for recurring sets. 

So whatever mount I were to get, I would want to make sure it is suitable for tighter shots with heavier pay loads as well just in case.  But, it needs to be portable. 

Not to mention, I am a photographer, and this is what I do in my free time as well. 

Last, and I can not stress this enough, as a professional I can not afford to deal with equipment that needs consistent tinkering and maintenance on my part.  I mean no offense to the non-professionals here, it is just that I make my living from my equipment and I can not afford to deal with buggy stuff that is down for weeks on end.  I do realize that periodic maintenance is required for all pieces of equipment, however a constant need to fix issues or worrying about a piece of equipment not working as it should is not practical.  And the equipment I do use, I tend to put a lot of demands on.  So a brand that is known for good service would be a plus too. 

Edited December 12, 2023 by JoeKitchen

[JoeKitchen]

41 minutes ago, 900SL said:

Medium format and 240mm focal length with 2 x convertor requires a decent tracking mount, and likely guiding

 

I've shot full frame wide angle up to a 250mm redcat from a fornax LT 2 mount, doesn't need guiding

 

Examples

 

Nice images! 

I realizing guiding would be a part of these. 

[JoeKitchen]

From what I am reading so far, forget the Skywatchers.  The ZWO AM3 and AM5 appear to better fit my needs. 

Portable and good quality?

[Elp]

If you're looking to supply to VFX, photos don't necessarily work as they'll look different from the generated assets even with post work and you'd have to be 100pc sure there are no lens defects within the star field to create a clean panorama. Photos especially long exposure widefield capture thousands upon thousands of stars and don't have that typical "starfield" film look. It's far better to artificially generate the star field for this purpose.

Edited December 12, 2023 by Elp

[vlaiv]

@JoeKitchen

I think I understand your requirements a bit better now. I'm afraid that I will need to "swamp" you with a bit of technical stuff here, but as far as I can tell - you'll be able to follow it.

First thing to get a grip on is pixel scale and there is simple formula to do that:

pixel_scale = pixel_pitch * 206.3 / focal_length

Where pixel_pitch is in micrometers and focal_length is in millimeters. Above will give you pixel scale expressed in arc seconds per pixel.

In astrophotography, given the state of sky, you can expect stars to be between 2" and say 5" (that is arc seconds) FWHM. FWHM is Full width at half maximum and is measure related to roughly Gaussian shape of star image. You don't need to go over FWHM/1.6 in sampling rate as that leads to over sampling.

To put this into context - let's take your current 6um pixel camera and say 250mm lens.

Let's also say that you hit 4" FWHM stars in your image (actual star size will depend on several factors - sky conditions / how still or turbulent atmosphere is, then how good is your tracking and how sharp is your optics). Ideal sampling rate for such stars is 4 / 1.6 = 2.5"/px

With 250mm and 6um pixel size you'll be at 6 * 206.3 / 250 = ~4.95"/px - so you won't be over sampled, you will be under sampled - but this is not a bad thing. In fact this is very good sampling rate for wide field.

This is also number that is important for some other considerations - namely mount that you are using.

Every mount, if not guided will suffer two main types of tracking error. DEC drift due to error in polar alignment and RA drift due to periodic error of drive.

DEC drift can be calculated by using following calculator:

http://celestialwonders.com/tools/driftRateCalc.html

Say that you are off by 10 arc minutes from the NCP in your polar alignment and you are shooting target that is at 30 degree DEC.

Your total drift during exposure will be 11.34 arc seconds - which is about two pixels if you shoot at 4.95"/px. This might be acceptable as it won't create star streaking - just a bit oval shape and it depends if that will be noticeable in your backdrop for set or not (it depends on how well resolved background will be).

In any case - above will give you idea if you can shoot unguided for 5 minutes.

Second thing that happens to mounts is periodic error. It is there because imperfection of gears in mount drive train. They are not perfect circles and as such (think a bit egg shaped) and they rotate at different speeds - or rather they have constant angular velocity but have different radii at places so transfer rotation motion at different rates at times.

In any case - this periodic error is expressed as peak to peak periodic error and something called worm period. For example HEQ5 class mount out of the box has about 30 arc seconds p2p periodic error and its period is 638s (if I recall correctly).

This means that mount will be on spot then lead a bit then return to correct then trail a bit then return to correct position in period of about 10 minutes and total deviation will be 30 arc seconds. Another way to look at it - it will "travel" in error for 60 arc seconds in 10 minutes so average RA drift will be about 6 arc seconds per minute or 1 arc second every 10 seconds.

Mounts never have such smooth periodic error and sometimes their drift is less and sometimes it is more than average. This leads to people being able to take longer exposures than average drift rate suggests - but also that they need to discard some subs as well (depending on where on the worm cycle image was taken).

Here is graph of such cycle for EQ6 mount:

Above graph is used to create general correction - or what is called PEC - periodic error correction (average of several cycles of such leading / trailing - btw, if you read the numbers above mount has about 26" p2p).

Now, you can compare periodic error and p2p with your working resolution.

If you for example use 28mm lens with 6um then you'll be working at 6 * 206.3 / 28 = ~44.2"/px

Above p2p error is simply insignificant in this case - as it all falls on single pixel - you won't see any elongation, however - for first case and 5"/px - you will see elongation in some exposures.

Bottom line - compare your working resolution with what mount can deliver - in some cases you'll need to use PEC, but you can always guide, and even simplest guide setup (which consists out of guide scope, guide camera, usb cable and software running on your laptop that is connected to mount - about $300-$400 additional expense) will give you performance that will be more than sufficient for your working resolutions.

I haven't even touched on the fact that sharpness of the lens will contribute to how big FWHM of stars in your image will be - but just to say that it lowers sharpness of the image and increases FWHM so it decreases need for high precision in mount and guiding.

Hope above gives you some idea of what you should be considering and sorry for the long post.

 

[JoeKitchen]

54 minutes ago, vlaiv said:

@JoeKitchen

I think I understand your requirements a bit better now. I'm afraid that I will need to "swamp" you with a bit of technical stuff here, but as far as I can tell - you'll be able to follow it.

First thing to get a grip on is pixel scale and there is simple formula to do that:

pixel_scale = pixel_pitch * 206.3 / focal_length

Where pixel_pitch is in micrometers and focal_length is in millimeters. Above will give you pixel scale expressed in arc seconds per pixel.

In astrophotography, given the state of sky, you can expect stars to be between 2" and say 5" (that is arc seconds) FWHM. FWHM is Full width at half maximum and is measure related to roughly Gaussian shape of star image. You don't need to go over FWHM/1.6 in sampling rate as that leads to over sampling.

To put this into context - let's take your current 6um pixel camera and say 250mm lens.

Let's also say that you hit 4" FWHM stars in your image (actual star size will depend on several factors - sky conditions / how still or turbulent atmosphere is, then how good is your tracking and how sharp is your optics). Ideal sampling rate for such stars is 4 / 1.6 = 2.5"/px

With 250mm and 6um pixel size you'll be at 6 * 206.3 / 250 = ~4.95"/px - so you won't be over sampled, you will be under sampled - but this is not a bad thing. In fact this is very good sampling rate for wide field.

This is also number that is important for some other considerations - namely mount that you are using.

Every mount, if not guided will suffer two main types of tracking error. DEC drift due to error in polar alignment and RA drift due to periodic error of drive.

DEC drift can be calculated by using following calculator:

http://celestialwonders.com/tools/driftRateCalc.html

Say that you are off by 10 arc minutes from the NCP in your polar alignment and you are shooting target that is at 30 degree DEC.

Your total drift during exposure will be 11.34 arc seconds - which is about two pixels if you shoot at 4.95"/px. This might be acceptable as it won't create star streaking - just a bit oval shape and it depends if that will be noticeable in your backdrop for set or not (it depends on how well resolved background will be).

In any case - above will give you idea if you can shoot unguided for 5 minutes.

Second thing that happens to mounts is periodic error. It is there because imperfection of gears in mount drive train. They are not perfect circles and as such (think a bit egg shaped) and they rotate at different speeds - or rather they have constant angular velocity but have different radii at places so transfer rotation motion at different rates at times.

In any case - this periodic error is expressed as peak to peak periodic error and something called worm period. For example HEQ5 class mount out of the box has about 30 arc seconds p2p periodic error and its period is 638s (if I recall correctly).

This means that mount will be on spot then lead a bit then return to correct then trail a bit then return to correct position in period of about 10 minutes and total deviation will be 30 arc seconds. Another way to look at it - it will "travel" in error for 60 arc seconds in 10 minutes so average RA drift will be about 6 arc seconds per minute or 1 arc second every 10 seconds.

Mounts never have such smooth periodic error and sometimes their drift is less and sometimes it is more than average. This leads to people being able to take longer exposures than average drift rate suggests - but also that they need to discard some subs as well (depending on where on the worm cycle image was taken).

Here is graph of such cycle for EQ6 mount:

Above graph is used to create general correction - or what is called PEC - periodic error correction (average of several cycles of such leading / trailing - btw, if you read the numbers above mount has about 26" p2p).

Now, you can compare periodic error and p2p with your working resolution.

If you for example use 28mm lens with 6um then you'll be working at 6 * 206.3 / 28 = ~44.2"/px

Above p2p error is simply insignificant in this case - as it all falls on single pixel - you won't see any elongation, however - for first case and 5"/px - you will see elongation in some exposures.

Bottom line - compare your working resolution with what mount can deliver - in some cases you'll need to use PEC, but you can always guide, and even simplest guide setup (which consists out of guide scope, guide camera, usb cable and software running on your laptop that is connected to mount - about $300-$400 additional expense) will give you performance that will be more than sufficient for your working resolutions.

I haven't even touched on the fact that sharpness of the lens will contribute to how big FWHM of stars in your image will be - but just to say that it lowers sharpness of the image and increases FWHM so it decreases need for high precision in mount and guiding.

Hope above gives you some idea of what you should be considering and sorry for the long post.

 

Thanks.  This all makes sense and not too hard to follow.  Kind of makes me think about circles of confusion and DoF calculations in photography.  All good stuff to know. 

[Icesheet]

Vlaiv nails the technical stuff, but to answer your question the ZWO mounts or other harmonic mounts in that price range, e.g iOptron, will do the job you want. Rainbow Astro is a consideration at a price notch above. There are several with encoders that are worth a look too. However, I would caution you that these are not professional grade premium mounts either. In fact the strain wave mounts have a higher (albeit smoother) native periodic error than the HEQ5. It can be easily guided out (as it can with an HEQ5). What you’re really paying for here is the weight to payload ratio which has really revolutionised the beginner/ intermediate mount category recently. It’s still fairly new technology in this arena though so there are also quirks and bugs that need ironed out. Take a look through the forums and you’ll find numerous examples. That being said for your use case at the moment I think they are the best bet, although I would still consider the Fornax LT2 as well. 
 

Just a note on the camera. Is it a must to use it? The fact you can’t turn off the in house noise reduction is a real time killer and it may lack support for astrophotography software you would likely use. Believe me there’s many an astrophotographer that’s thrown in the towel from frustration when one piece of hardware does not communicate with another. I suppose as long as you can program multiple long exposures in some way it shouldn’t be too much of an issue. 

Edited December 12, 2023 by Icesheet

[JoeKitchen]

2 hours ago, Icesheet said:

Vlaiv nails the technical stuff, but to answer your question the ZWO mounts or other harmonic mounts in that price range, e.g iOptron, will do the job you want. Rainbow Astro is a consideration at a price notch above. There are several with encoders that are worth a look too. However, I would caution you that these are not professional grade premium mounts either. In fact the strain wave mounts have a higher (albeit smoother) native periodic error than the HEQ5. It can be easily guided out (as it can with an HEQ5). What you’re really paying for here is the weight to payload ratio which has really revolutionised the beginner/ intermediate mount category recently. It’s still fairly new technology in this arena though so there are also quirks and bugs that need ironed out. Take a look through the forums and you’ll find numerous examples. That being said for your use case at the moment I think they are the best bet, although I would still consider the Fornax LT2 as well. 
 

Just a note on the camera. Is it a must to use it? The fact you can’t turn off the in house noise reduction is a real time killer and it may lack support for astrophotography software you would likely use. Believe me there’s many an astrophotographer that’s thrown in the towel from frustration when one piece of hardware does not communicate with another. I suppose as long as you can program multiple long exposures in some way it shouldn’t be too much of an issue. 

There would be no way to communicate between my camera and any astro software or hardware. 

The tracker and guide would need to be able to act independent of the camera, and just start tracking.  I assume this is possible? 

FYI, my camera, although digital, is still completely manual with Copal 0 shutters and a analog shutter release.  In the future, if I upgrade my digital back, I would be able to control a digital shutter via the computer.  However, that is an expensive upgrade, and given we are just now coming off of the strikes in Hollywood, not something I am looking to do any time in the next 6 months. 

Edited December 13, 2023 by JoeKitchen

[Icesheet]

5 hours ago, JoeKitchen said:

There would be no way to communicate between my camera and any astro software or hardware. 

The tracker and guide would need to be able to act independent of the camera, and just start tracking.  I assume this is possible? 

Yes, the tracker and guide set up can act independently but then you lose a lot of the benefits of an integrated system. 
 

5 hours ago, JoeKitchen said:

FYI, my camera, although digital, is still completely manual with Copal 0 shutters and an analog shutter release.  In the future, if I upgrade my digital back, I would be able to control a digital shutter via the computer.  However, that is an expensive upgrade, and given we are just now coming off of the strikes in Hollywood, not something I am looking to do any time in the next 6 months. 

So, you will need to manually trigger each exposure? If so that is really going to test your patience and sanity, especially if it’s a cold night! How are the vibrations when releasing the shutter? It’s something you might want to consider, particularly at longer focal lengths. 
 

I’ll be honest, overall I feel your equipment might not be best suited to your intended goal and may be a source of frustration. For sure give it a go but if this is likely to be something you pursue further it would be wise to budget for a dedicated astro camera with lenses/ small telescopes. Good luck with it. Would be interested to see some shots if you are able to share them!

[900SL]

Look at the Vixen SXP2 with Starbook 10

This is a well made Japanese mount, belt drive with 16 kg capacity, doesn't need guiding at shorter focal lengths, has built in periodic error correction. 

Offset head design reduces size of counterweight, and does not require maintenance or tinkering. Way better QA QC than the Skywatcher mounts

Only drawback is it isn't lightweight. I've shipped my SXD2 by air but its not backpack portable 

[JoeKitchen]

4 hours ago, Icesheet said:

Yes, the tracker and guide set up can act independently but then you lose a lot of the benefits of an integrated system. 
 

So, you will need to manually trigger each exposure? If so that is really going to test your patience and sanity, especially if it’s a cold night! How are the vibrations when releasing the shutter? It’s something you might want to consider, particularly at longer focal lengths. 
 

I’ll be honest, overall I feel your equipment might not be best suited to your intended goal and may be a source of frustration. For sure give it a go but if this is likely to be something you pursue further it would be wise to budget for a dedicated astro camera with lenses/ small telescopes. Good luck with it. Would be interested to see some shots if you are able to share them!

As I said, I am a very patient man and use to being behind the camera hours on end.  In my other business I photograph architecture and have been outside on many a cold day and night. 

The shutter vibration is almost non-existent.  Leaf shutters have 6 or 8 leaves that rotate within the lens at the nodal point.  As such, they only need to open a little bit to clear the incoming light.  Also, each leaf as a leaf opposite it moving in the opposite direction, so movements cancel each other out.  I have never had shutter vibration in my images with leaf shutter like I have with focal plane shutters. 

I'll be sure to share some images when I get around to getting a system.  Right now things are just start to appear like they are coming back, so I am waiting for my cash flow to return. 

Speaking of nodal points, is it important to have the nodal point of the lens over the axis of rotation of the mount?  Or are the stars so far away it does not really matter?

Edited December 13, 2023 by JoeKitchen

[JoeKitchen]

5 hours ago, 900SL said:

Look at the Vixen SXP2 with Starbook 10

This is a well made Japanese mount, belt drive with 16 kg capacity, doesn't need guiding at shorter focal lengths, has built in periodic error correction. 

Offset head design reduces size of counterweight, and does not require maintenance or tinkering. Way better QA QC than the Skywatcher mounts

Only drawback is it isn't lightweight. I've shipped my SXD2 by air but its not backpack portable 

That is way too heavy for my needs. 

[900SL]

1 hour ago, JoeKitchen said:

That is way too heavy for my needs. 

Reading your earlier post, are you planning to shoot panoramas  (ie multi frame mosaics)?

If so, I'd look at piggybacking your camera and lens on a ASI Air controlled mount like the AM5. You can set a shooting plan for a mosaic in the ASI air and control the mount this way

 

You would need a scope and camera on the mount to match your medium format FOV, because ASI air needs to plate solve check images to work out where it is pointing. This could also be used for polar alignment

 

Edited December 13, 2023 by 900SL

[Elp]

The issues you'll have with your existing camera is whilst you're imaging even doing 30s or so exposures, if you're capturing multiple panels of the sky in order to stitch them together (you will need to do this if you want high resolution paired with a long focal length lens) plus taking multiple exposures per panel, you'll find framing the panoramic stitch will not be perfectly landscape, it'll be stepped in a zigzag arrangement and you'll have to crop. You'll be surprised how quickly the earth rotates.

Regarding manual function of the shutter, have you tested this on star fields? A lot of DSLRs have a shutter lock function to stop the mechanicals from moving, minute vibrations are disastrous for star imaging, even walking around your setup whilst imaging is enough to cause this.

 

Edited December 13, 2023 by Elp