smr

1 hour ago, vlaiv said:

It is exactly like in terrestrial photography - in this case, F/4.8 will be faster than F/5.9

This is because pixel size remains the same.

There seems to be so much confusion on this topic. Don't know why is that.

When camera remains the same and pixel size remains the same - daytime photography rule applies - faster F/ratio is indeed faster - but only when paired with that particular camera.

In light dominated regime - rule from daytime photography also applies here - rule of F/stops and how much faster system will be.

What we can't extrapolate from above are following:

- F/4.8 scope is faster than F/5.9 scope. That does not hold in general - it does hold for same camera and if we keep pixel size the same, but if we start binning or using different pixel size or whatever - it is no longer true.

- F/stop rule can always be used to calculate how faster system is. Again - this only works in above case where we have the same camera and same pixel size and we operate in light dominated regime. Once we start imaging very faint targets - other noise sources start to dominate single exposure and that math no longer holds

Back to original question. Benefits of using reducer while keeping the same camera and same pixel size:

1. larger FOV

2. faster imaging (where speed of imaging is defined as time needed to reach target SNR)

 

The pixel size would be the same, 3.76 pixel size of the 2600MC-Pro. It would just be that I would add the 0.8 reducer.

So in essence the total integration time can be shorter, less time to gather more photons/higher snr for a set amount of imaging time, from what you are saying, which is what I am after.

Ie. If I were to image a Nebula on one night without the reducer and I spent 10 hours on it.

I then image it with the reducer the next night for 6 hours, the image would have the same snr as 5.9 to 4.7 is 2/3  stop.

On 12/02/2021 at 21:46, alacant said:

Hi

If you arrive at f4.8 by increasing the aperture, then yes. All you have done is reduce the focal length, so the amount of light collected is the same. The only benefit will be as outlined by @geordie85.

If you don't need the reducer to also flatten the field, I'd stay as you are.

Cheers

I don't quite understand it, I come from several years of terrestrial photography so I'm so used to diaphragm controlling light passage and apertures, so a wider aperture letting more light in, what is the point in defining an f stop with a focal reducer in astrophotography, if the aperture remains the same. 

If your focal length is reduced but the light transmittance to the sensor is unaltered it's f/5.9 430mm without the reducer, and f/5.9 344mm with the reducer. 

2 hours ago, Hallingskies said:

Laptops are real power eaters and you would need a biggish battery to run that plus your astro gear for more than three or four hours.  As an example, my Lenovo requires 65W: if you assume a 12v supply, that’s about 5A straight off.  If your astro equipment chews another (let’s conservatively say) 3A, that’s 8A total for every hour.  You’d need a 100A/h battery to get you through a full night’s session by my reckoning.  I think lithium’s at that capacity are coming in at around £600, lead/acids are a lot cheaper but you can’t run them below 50% too often without wrecking them.

Be interesting to see what others say.  One answer might be to get a mini-computer for mobile use, they pull a lot less power so I gather but other than that, I kno knothing...

Thanks for the reply...

I guess the work around would be to buy a laptop with an extraordinarily long battery life able to withstand cold temperatures as well.

A mini computer? How would that work? I'd need a screen for APT and PHD2 etc.

Hi,

I have always imaged with my astro gear from home and with mains power and rcd. 

I'd like to be able to travel with my mount to image and require a battery. 

The battery would need to power my heq5 pro, 2600mc pro, guidescope and laptop.

I dont really have any idea what battery would be suitable so I'm looking for advice and recommendations.

Thanks.

Joel

Thanks for the replies guys, I'll stay with my guidescope. 

5 hours ago, geordie85 said:

Since your aperture isn't changing size, the light grasp remains the same. You will have a slightly larger fov though.

So that is the only benefit ? A slightly larger FOV ? For some reason I was under the impression that more light would be gathered and I could shorten total integration time. 

Hi,

Just wondering what the difference is for deep sky imaging between the two focal ratios ? Is there a big difference in terms of light gathering ? 

I haven't bought a focal reducer before and it would change my scope from 430mm to 344mm and 4.8 instead of 5.9.

In Stellarium when viewing between the two focal lengths there doesn't seem to be too much difference between the focal lengths, so is it a no brainer to buy a focal reducer and improve light gathering or should I save my money?

Thanks for any advice,

Joel

Are you guys using eqmod or the native zwo driver with your imaging software?

2 minutes ago, tooth_dr said:

That looks really good, so smooth

That's what I thought when I saw the images appear on my laptop last night, I was stunned how smooth the subs looked. The details looks fantastic considering this is just 120 seconds, with probably less than optimal guiding and that it wasn't focused. 

I figured out how to focus by binning 4x4 and stretching the live view in APT, then using my bahitnov mask and the bahnitov aid in APT. Not sure if there's a better way to focus but I'll buy an autofocuser when they're in stock.

A single 120 sub from last night, this was taken before I managed to figure out how to focus properly. Even though it's not in focus, the stars seem a lot smaller than I ever managed with my DSLR. 

Hi,

I'm looking to add an electronic focuser to my imaging gear. I'm looking at both the Pegasus FocusCube v2, ZWO EAF and the PrimaLuce Lab Sesto Senso V2. I'll be pairing with my William Optics Z73 Refractor.

Just wondering if anyone has either of these and what are your thoughts/recommendations. 

Thanks.

Tonight was one of those technical nights. I thought things (naively) might go smoothly and I'd get a few hours of first light ! Nope!

First of all I was totally lost with how to focus... I slewed over to a bright star after PA, could just see one star, so I wasn't sure whether that was the star I had slewed to. I'd got so used to DSLR imaging and being able to use live view to magnify, take a few second exposure with my bahitnov mask and adjust focus.

Wasn't until about two hours later after fumbling about in the freezing cold that I came across a youtube video where someone else explained about having the same problem and using the stretch function, and binning 4x4.

Used the mask and the bahitnov mask and got focus just about on. 

It appears to be (now I've finally figured out how to) a lot easier to focus as with a DSLR the star would bounce around in live view mode when using the Bahitnov aid in APT.

I had a problem with PHD2 as well, because I'm now using two ZWO Cameras, when I went to auto connect it said the dark library wouldn't match my Camera, so I was like eh, it's always worked. Then I realised it must be because I have the new Camera and it's thinking that is the new guidecam, easy enough to set it back to the 120MM though.

By that time Orion had gone out of view, and once I realised how to focus and get PHD2 working I got a couple of subs of the Elephant's Trunk in, quite low in the sky at this time of the year but I was tired by this point. 

Decided to pack up and just as well as a few snow flakes had started to fall. 

So at least for the next night I know how to get imaging!

The settings I'm using in CCD Flats Aid:

So as above I'm testing taking flats, using APT's Flats wizard. It says an exposure length of 0.14531 seconds is required. Does this look right ? I'm totally new to taking flats with a dedicated astronomy camera. 

I'd read that I should be aiming for a minimum exposure setting of 3 seconds but if I try anything above 1 second it says the target ADU cannot be met.

Hi

Probably a simple question but I'm new to dedicated astronomy cameras. With my DSLR I would just set to AV mode and use an LED panel to take flats at the end of the imaging session. How do you do this in APT? By default, when selecting the Flat plan in APT the exposure length is 0.01, bin 1x1, gain is blank. Just wondering what settings I should set?

Also should I take Bias or Flat Darks with an OSC, along with Flats and Darks ?

Thanks for any help!

Thanks for that ^ Much appreciated. 

Do you know how to take flats and dark flats in APT? 

With my DSLR I'd simply set it to AV mode, and then run the Flats profile in APT with an LED panel over the scope. I'm not sure what the process is with an OSC though.

25 minutes ago, mackiedlm said:

I'm in much the same boat as you having recieved my 2600mc on Monday and been working on setting it up to build a dark frame library. From reading and checking various sites I'm going with offset 50, usb 40 and the dew heater on (the last only because I expect to use it most of the time so might as well do darks that way too). Im doing 2 sets 1 at gain 100 and one at gain 0 because there seems to be much discussion on which is best. If you are going to do gain 0 then make sure you have gain 0 set in field at bottom right. If you enter it as 0 in your dark plan it comes up as " and will then use the setting entered in bottom right. I only found this out after running a full dark plan that was supposed to be 0 gain but ended up 100.

HTH

Thanks, just setting things up myself. When building a dark library what should the procedure be ? 

Set the temperature of the Camera (say -10, and the gain and offset) and then shoot dark frames? Is there anything else to it, and how many dark frames are you doing ?

Also regarding the warming up feature in APT to avoid thermal shock, what would set the target temperature to be ? Presumably if imaging with the Camera at -10 you set the warming up whilst outside? 

Hi,

My ZWO ASI 2600MC Pro arrived today, my first dedicated Astronomy Camera, as such I'm totally new to all of the settings presented and am looking for some advice, specifically setting the Camera up with APT. I've installed ASCOM and the native driver etc. as per the manual. 

I'm not sure what settings I should set within APT.

Here's a screenshot of what I have at the moment:

What should I set for Offset, USB Speed and should enable dew heater be checked. Presumably I leave bin1x1? 

Thanks for any help!

My first dedicated Astronomy Camera arrived today

😂 ok thanks guys. Will stick with APT.

Hi guys, I've just bought my 2600MC Pro. At the moment I've only ever had a DSLR for Astrophotography and simply use Sharpcap for PA, then APT with PHD2.

Would you recommend I opt for different software with the 2600? What would the advantage of SGPro be and what does it do? 
 

7 hours ago, tooth_dr said:

Excellent! All the best with it.

Thanks. And to you with yours

https://www.youtube.com/watch?v=dZGH0HmhKBI

All images here were taken with my Z73. Some of which were taken with my stock 80D, some with my modded Canon 600D. 

I've just bought my first dedicated Astronomy Camera. I decided (after much thought!) to go with the ZWO 2600MC Pro, ordered from FLO because I'm  impressed with the customer service. Very excited!